CHAPTER 1 Nutrition in Plants

1. Why do organisms take food?

Answer:  

Organisms take food to obtain the necessary nutrients that are required for their growth, development, and maintenance of their bodies. Nutrients such as carbohydrates, proteins, fats, vitamins, and minerals are essential for various metabolic processes that occur in the body. These processes include providing energy for cellular activities, repairing and maintaining tissues, and synthesizing new molecules required for the body's functioning. Ultimately, the nutrients obtained from food enable organisms to carry out the life processes necessary for their survival.  

2. Distinguish between a parasite and a saprotroph.

Answer:

A parasite is an organism that lives in or on another organism (the host) and obtains nutrients and shelter from the host, often causing harm to the host in the process. Parasites can be harmful to the host and may cause diseases.

A saprotroph, on the other hand, is an organism that obtains its nutrients by feeding on dead and decaying organic matter. Unlike parasites, saprotrophs do not depend on a living host for their nutrition and do not cause harm to the host. Examples of saprotrophs include fungi and bacteria.

3. How would you test the presence of starch in leaves? 

Answer:

To test the presence of starch in leaves, we can perform the following steps:

• Take a leaf and dip it in boiling water to soften it.
• Then, place the leaf in a test tube containing alcohol and heat the test tube gently in a water bath. This will remove the green pigment chlorophyll from the leaf.
• Remove the leaf and dip it in hot water to soften it again.
• Place a few drops of iodine solution on the leaf.
• If the leaf turns blue-black, it indicates the presence of starch. If the leaf remains brown, it indicates the absence of starch.

4. Give a brief description of the process of synthesis of food in green plants

Answer:

Plants use chlorophyll to capture sunlight and turn carbon dioxide and water into food through photosynthesis. Oxygen is also produced during this process. Without photosynthesis, there would be no food or oxygen for life on Earth. Photosynthesis can occur in leaves, green stems, and branches. Different colored leaves may or may not carry out photosynthesis. The process is essential for the survival of all living organisms.  

5. Show with the help of a sketch that plants are the ultimate source of food.

Answer:

*Sketch*

6. Fill in the blanks:

(a) Green plants are called __autotrophs__ since they synthesise their own food.  

(b) The food synthesised by plants is stored as __starch__. 

(c) In photosynthesis solar energy is absorbed by the pigment called __chlorophyll__.

(d) During photosynthesis plants take in __carbon dioxide__ and release __oxygen gas__. 

7. Name the following:  

(i) A parasitic plant with yellow, slender and branched stem.  

Answer: Cuscuta or dodder.  

(ii) A plant that is partially autotrophic.  

Answer: Epiphytes.

(iii) The pores through which leaves exchange gases  

Answer: Stomata.  

8. Tick the correct answer:

(a) Cuscuta is an example of:  

(i) autotroph

(ii) parasite

(iii) saprotroph

(iv) host

Answer: (ii) parasite

(b) The plant which traps and feeds on insects is:  

(i) Cuscuta

(ii) china rose

(iv) pitcher plant

(iv) rose  

Answer: (iv) pitcher plant  

9. Match the items given in Column I with those in Column II

Column I………. Column II  

(i) Chlorophyll      (4) Leaf  

(ii) Nitrogen      (1) Rhizobium  

(iii) Cuscuta     (5) Parasite  

(iv) Animals     (2) Heterotrophs  

(v) Insects      (3) Pitcher plant  

(i) Carbon dioxide is released during photosynthesis.  

(i) False (carbon dioxide is taken in during photosynthesis)  

(ii) Plants which synthesise their food are called saprotrophs.

(ii) False (plants which synthesise their own food are called autotrophs, not saprotrophs which obtain nutrients from dead organic matter)  

(iii) The product of photosynthesis is not a protein. 

(iii)True. (The product of photosynthesis is glucose, which is a type of carbohydrate, not a protein.)  

(iv) Solar energy is converted into chemical energy during photosynthesis.  

True.  

Choose the correct option from the following:  

11. Which part of the plant takes in carbon dioxide from the air for photosynthesis?  

(i) Root hair

(ii) Stomata

(iii) Leaf veins

(iv) Petals

Answer: (ii) Stomata 

12. Choose the correct option from the following: Plants take carbon dioxide from the atmosphere mainly through their: (i) roots (ii) stem (iii) flowers (iv)

leaves  

Answer: (iv) leaves  

13. Why do farmers grow many fruits and vegetable crops inside large green houses? What are the advantages to the farmers?

Answer:  

Farmers grow many fruits and vegetable crops inside large greenhouses to protect them from adverse weather conditions such as extreme temperatures, wind, and rain. Greenhouses provide a controlled environment for the crops where temperature, humidity, and light can be regulated to ensure optimal growth and yield. The advantages to the farmers include a longer growing season, higher yields, better quality crops, and protection from pests and diseases. Additionally, greenhouses allow farmers to grow crops in areas where the climate is not suitable for their growth.  

 A. How do plants prepare their own food? Explain the process.  

Schoolvally answer:  

This is an important question if asked in exam and carries 5 makes make diagram along with answer as below:  

Water and minerals absorbed by roots reach the leaves through a network of specialized tissues called xylem and phloem. The xylem tissue is responsible for the transport of water and minerals from the roots to the leaves, while the phloem tissue transports food materials such as glucose from the leaves to other parts of the plant.  

Water and minerals are absorbed by the roots from the soil through the root hairs, which increase the surface area of the roots for better absorption. The absorbed water and minerals then enter the root cells and move into the xylem vessels. These vessels extend from the roots all the way to the leaves, and they are interconnected to form a continuous pathway for water and mineral transport. The movement of water and minerals in the xylem tissue is driven by a process called transpiration.

Transpiration is the loss of water from the leaves through small pores called stomata. As water evaporates from the leaves, it creates a negative pressure, or suction, that pulls water up from the roots to the leaves. In summary, water and minerals are absorbed by the roots and transported to the leaves through xylem tissue. The movement of water and minerals is driven by transpiration, which is the loss of water from the leaves.  

*Sketch*

1. Fill in the blanks:  

(a) The main steps of nutrition in humans are _ingestion_, _digestion_, _absorption_, _assimilation_, and _egestion_. 

(b) The largest gland in the human body is the _liver_.

(Schoolvally Tips: Liver is an organ which can regenerate itself)  

(c) The stomach releases hydrochloric acid and _digestive juices_which act on food.  

(d) The inner wall of the small intestine has many finger-like outgrowths called _villi_. 

(e) Amoeba digests its food in the food _vacuole_.

2. Mark ‘T’ if the statement is true and ‘F’ if it is false:

Answer:

(a) Digestion of starch starts in the stomach. (False) 

(b) The tongue helps in mixing food with saliva. (True) 

(c) The gall bladder temporarily stores bile. (True) 

(d) The ruminants bring back swallowed grass into their mouth and chew it for some time. (True) 

3. Tick (V) mark the correct answer in each of the following: 

(a) Fat is completely digested in the (i) stomach (ii) mouth (iii) small intestine (iv) large intestine

Answer:

(iv) Small intestine

(b) Water from the undigested food is absorbed mainly in the 

(i) stomach (ii) foodpipe (iii) small intestine (iv) large intestine  

Answer:

(iii) Large intestine

4. Match the items of Column I with those given in Column II

(Food components) (Product(s) of digestion)

Column I……. Column II  

(i) Carbohydrates - Sugar  

(ii) Proteins - Amino acids  

(iii) Fats - Fatty acids and glycerol

5. What are villi? What is their location and function

Answer:

Villi are finger-like outgrowths present in the inner walls of the small intestine. Their function is to increase the surface area for absorption of the digested food. Each villus has a network of thin and small blood vessels close to its surface, which absorb the digested food materials and transport them via the blood vessels to different organs of the body where they are used to build complex substances such as proteins required by the body.

6. Where is the bile produced? Which component of the food does it help to digest?

Answer:

Bile is produced in the liver and it helps to digest fats in the food.

Bile is produced in the liver and stored in the gallbladder until it is needed for digestion. Bile plays an important role in the digestion and absorption of fats. Specifically, it helps to emulsify or break down fats into smaller droplets, which increases their surface area and makes them more accessible to enzymes that can break them down further. Additionally, bile helps to absorb fat-soluble vitamins such as vitamins A, D, E, and K.  

7. Name the type of carbohydrate that can be digested by ruminants but not by humans. Give the reason also.  

Answer:

The type of carbohydrate that can be digested by ruminants but not by humans is cellulose. Ruminants, such as cows and deer, have a specialized stomach compartment called the rumen, which contains microorganisms that can break down cellulose. The microorganisms produce enzymes that can hydrolyze cellulose into simpler compounds that can be absorbed by the animal. Humans lack the necessary enzymes to break down cellulose, and thus cannot digest it.  

8. Why do we get instant energy from glucose?

Answer:

Glucose is broken down into simpler molecules such as carbon dioxide and water, and energy is released in the cells. This means that glucose can be easily and quickly metabolized by cells to produce energy, making it a quick source of energy. Therefore, we get instant energy from glucose.

9. Which part of the digestive canal is involved in:

Answer:

(i) absorption of food - small intestine  

(ii) chewing of food - mouth  

(iii) killing of bacteria - stomach  

(iv) complete digestion of food - small intestine  

(v) formation of faeces - large intestine  

10. Write one similarity and one difference between the nutrition in amoeba and human beings.  

Answer:

Similarity: Both amoeba and human beings obtain nutrients from their food to support their growth, maintenance, and survival.

Difference: Amoeba is a unicellular organism that directly engulfs its food using pseudopodia and digests it within its food vacuoles. On the other hand, human beings are multicellular organisms with a complex digestive system that breaks down food into simpler substances in specialized organs such as the mouth, stomach, and small intestine before absorption and utilization by cells.

11. Match the items of Column I with suitable items in Column

Answer:

Column I…… Column II

(a) Salivary gland     (iii) Saliva secretion

(b) Stomach      (iv) Acid release

(c) Liver      (i) Bile juice secretion

(d) Rectum     (vii) Release of faeces

(e) Small intestine     (v) Digestion is completed

(f) Large intestine     (vi) Absorption of water  

12. Label Fig. 2.11 of the digestive system.  

Answer:

*Sketch*

The parts that need to be labeled are:

• Mouth
• Salivary glands
• Oesophagus
• Liver
• Stomach
• Pancreas
• Small intestine
• Large intestine
• Rectum
• Anus

13. Can we survive only on raw, leafy vegetables/grass? Discuss.

Answer:

• No, we cannot survive only on raw, leafy vegetables/grass. Raw, leafy vegetables and grass are a good source of vitamins and minerals, but they lack certain essential nutrients that our body needs to survive.  
• Raw, leafy vegetables and grass only provide us vitamins and minerals, but they lack certain essential nutrients that our body needs to survive. For example, they do not contain all the essential amino acids required to make proteins. 
• "some proteins are called essential amino acids because they cannot be synthesized by our body and must be supplied through food."  
  Animal products like meat, fish, eggs, and dairy are a good source of all essential amino acids. Therefore, we need to consume these compounds from the food we eat.
• Additionally, raw, leafy vegetables and grass do not provide enough energy for our daily activities. "carbohydrates and fats are the main sources of energy." While these foods do contain carbohydrates, they do not contain enough to meet our energy needs. Therefore, we need to consume these compounds from the food we eat.
  For proper growth and functioning of the body we need balanced diet that includes a variety of nutrients from all food groups. It is necessary for our health and well-being, and we cannot survive only on raw, leafy  vegetables/grass. 

Visit a doctor and find out:  

(i) Under what conditions does a patient need to be on a drip of glucose?

Answer:

(i) A patient may need to be on a drip of glucose when they are unable to eat or drink normally due to illness, injury or surgery. Glucose provides energy to the body, and a drip is a way to deliver it directly into the bloodstream.

(ii) Till when does a patient need to be given glucose?

Answer:

(ii) The duration for which a patient may need to be given glucose can vary depending on the severity of the illness, the patient's age and overall health, and other factors. The doctor will determine the length of treatment based on the patient's individual needs.

(iii) How does glucose help the patient recover? Write the answers in your notebook

Answer:

(iii) Glucose helps the patient recover by providing energy to the body's cells, which are necessary for the body to function properly. When the patient is unable to eat or drink normally, glucose delivered through a drip can help maintain the body's energy levels and support the healing process.

2. Find out what vitamins are and get the following information.  

(i) Why are vitamins necessary in the diet?

Answer:

Vitamins are essential nutrients required by the body in small quantities for various functions such as growth, development, and maintenance of the body. They play a vital role in maintaining the immune system, healthy skin, hair, and eyesight. Different vitamins have different functions, and their deficiency can lead to various diseases. For example, the deficiency of vitamin A can cause night blindness, vitamin C deficiency can cause scurvy, and vitamin D deficiency can lead to rickets. Therefore, it is essential to include a balanced diet containing all the required vitamins to maintain a healthy body. 

(ii) Which fruits or vegetables should be eaten regularly to get vitamins?

Answer:

Different vitamins are found in different fruits and vegetables. Here are some examples:

• Vitamin A: found in carrots, sweet potatoes, spinach, kale, mangoes, and papayas.
• Vitamin C: found in citrus fruits (like oranges and lemons), strawberries, bell peppers, broccoli, and tomatoes.
• Vitamin D: found in fatty fish (like salmon and tuna) and in fortified dairy products (like milk and yogurt).
• Vitamin E: found in nuts and seeds (like almonds and sunflower seeds) and in leafy greens (like spinach).
• Vitamin K: found in leafy greens (like spinach and kale), broccoli, and Brussels sprouts.

It is important to eat a variety of fruits and vegetables to ensure that you are getting all the necessary vitamins and minerals for your body.

3. Collect data from your friends, neighbours and classmates to know more about “milk teeth”. Tabulate your data. One way of doing it is given below:

Best answer:

1. Age at which first tooth fell  

Sohan: 6 Years

Rohit: 6 Years

Noorima: 6 Years

Hdiaka: 6 Years

Evanka: 6 Years

2.  Age at which last tooth fell  

Sohan: 11 Years

Rohit: 12 Years

Noorima: 11 Years

Hdiaka: 11 Years

Evanka: 11 Years

3. No. of teeth lost

Sohan: 20 Years

Rohit: 20 Years

Noorima: 20 Years

Hdiaka: 20 Years

Evanka: 20 Years

4. No. of teeth replaced  

Sohan: 27 Years

Rohit: 25 Years

Noorima: 28 Years

Hdiaka: 28 Years

Evanka: 26 Years

Important Questions

1. You must be familiar with the following nursery rhymes:

(i) ‘Baa baa black sheep, have you any wool.’

(ii) ‘Mary had a little lamb, whose fleece was white as snow.’

Answer the following:  

(a) Which parts of the black sheep have wool?  

Answer:

The wool of the black sheep is obtained from its body and not any specific part.

(b) What is meant by the white fleece of the lamb?  

Answer: 

The term 'white fleece' refers to the white wool of the lamb that covers its body.

2. The silkworm is 

(a) a caterpillar. 

(b) a larva.  

Choose the correct option. 

(i) a (ii) b (iii) both a and b (iv) neither a nor b.  

Answer:  

(a)The silkworm is a caterpillar.

3. Which of the following does not yield wool?

(i) Yak (ii) Camel (iii) Goat (iv) Woolly dog

Answer:  

(iv) Woolly dog does not yield wool.

4. What is meant by the following terms?

(i) Rearing (ii) Shearing (iii) Sericulture

Answer:  

(i) Rearing refers to the process of keeping and taking care of animals.

(ii) Shearing refers to the process of removing the fleece or hair of an animal.

(iii) Sericulture refers to the process of rearing silkworms to obtain silk.

5. Given below is a sequence of steps in the processing of wool. Which are the missing steps? Add them. Shearing, __________, sorting, __________, __________, _________.  

Answer:  

The sequence is as under  

Shearing, __scouring_, sorting, ___Cleaning of burrs __, __Dyeing __, __Rolling __.

6. Make sketches of the two stages in the life history of the silk moth which are directly related to the production of silk.

Answer:  

Stage 1: Larva or caterpillar stage of the silk moth which spins a cocoon around itself.

Stage 2: Pupa stage of the silk moth which develops into an adult moth and breaks out of the cocoon.

*Sketch*

7. Out of the following, which are the two terms related to silk production? Sericulture, floriculture, moriculture, apiculture and silviculture.

Hints:  

(i) Silk production involves cultivation of mulberry leaves and rearing silkworms.

(ii) Scientific name of mulberry is Morus alba.  

Answer:  

Sericulture and Moriculture are the two terms related to silk production.

Explanation: Floriculture is cutivation on flowers.

Apiculture is culturing of Honeybee.

Silviculture is culturing of forest crops.

8. Match the words of Column I with those given in Column II: 

Column I..... Column II

1. Scouring (a) Yields silk fibres

2. Mulberry leaves (b) Wool yielding animal

3. Yak (c) Food of silk worm

4. Cocoon (d) Reeling (e) Cleaning sheared skin  

Answer:   

1. Scouring …..(d) Reeling

2. Mulberry leaves …..(c) Food of silk worm

3. Yak …..(b) Wool yielding animal

4. Cocoon  …..(a) Yields silk fibres

9. Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.  

Answer:  

Here's the completed crossword puzzle:

D O W N 1 : S C O U R I N G 2 : W O O L 3 : F I B R E

A C R O S S 1 : I N S U L A T E S 2 : M U L B E R R Y 3 : L A R V A B R E A K

Explanation:

   • Down:

   1. Scouring is the process of thorough washing to remove impurities from wool or other fibers.

   2. Wool is an animal fiber obtained from the fleece of sheep or goats.

   3. Fibre is a long thread-like structure that is used to make textiles.

   • Across:

   1. Insulates refers to the property of wool to trap air and keep us warm.

   2. Mulberry is the plant whose leaves are eaten by silkworms in the process of silk production.

   3. Larva is the developmental stage of a silk moth after it hatches from an egg. Break refers to the process of breaking the silk thread to obtain shorter strands from the cocoon.

Important Questions

1. State similarities and differences between the laboratory thermometer and the clinical  

thermometer.

Answer:  

Similarities and differences between the laboratory thermometer and the clinical  

thermometer are as under:  

Similarities include:

1. Similarities between the laboratory thermometer and the clinical thermometer are that both measure temperature and contain mercury as the measuring element.

Differences include:

   • The range of the laboratory thermometer is -10 to 110°C and the clinical thermometer is 35 to 42°C.

   • The laboratory thermometer has a narrower tube, while the clinical thermometer has a wider tube.

   • The laboratory thermometer has markings for every degree, while the clinical thermometer has markings for every 0.1 degree.

   • The laboratory thermometer is used to measure the temperature of objects and substances in a laboratory setting, while the clinical thermometer is used to measure the temperature of the human body.

2. Give two examples each of conductors and insulators of heat

Answer:  

Examples of conductors of heat: metals (such as copper, aluminum, iron etc.), water.  

Examples of insulators of heat: wood, rubber, air, plastic (bakelite).

3. Fill in the blanks :

Answer:  

(a) The hotness of an object is determined by its __temperature__.  

(b) Temperature of boiling water cannot be measured by a __clinical__ thermometer.  

(c) Temperature is measured in degree __Celsius__.

(d) No medium is required for transfer of heat by the process of __radiation__.

(e) A cold steel spoon is dipped in a cup of hot milk. Heat is transferred to its other end by the process of ___conduction__.  

(f ) Clothes of __dark  _ colours absorb more heat better than clothes of light colours.  

4. Match the following:

(i) Land breeze blows during (a) summer

(ii) Sea breeze blows during (b) winter

(iii) Dark coloured clothes are preferred during (c) day

(iv) Light coloured clothes are preferred during (d) night  

Answer:  

(i) Land breeze blows during      (d) night 

(ii) Sea breeze blows during      (c) day 

(iii) Dark coloured clothes are preferred during      (b) winter

(iv) Light coloured clothes are preferred during      (a) summer

5. Discuss why wearing more layers of clothing during winter keeps us warmer than wearing just one thick piece of clothing.

Answer:  

Wearing more layers of clothing during winter keeps us warmer than wearing just one thick piece of clothing because the layers trap air between them, which serves as an insulating layer. The trapped air gets heated by the body, thus keeping the body warm. Additionally, wearing multiple layers allows for better regulation of body temperature as we can remove or add layers depending on the temperature changes. In contrast, a single thick piece of clothing may not trap enough air to insulate the body, and may also cause overheating if the temperature rises.  

6. Look at Fig. 4.13. Mark where the heat is being transferred by conduction, by convection and by radiation.

Answer:  

   Mark 1. on the tip of the burner here the heat is transferred by the process of radiation.

Radiation: The process of heat transfer by radiation is shown by the emission of heat from the flame to the metal rod and from the metal rod to the beaker. The heat energy is transferred from one object to another in the form of electromagnetic waves, which is called radiation.

   Mark 2. on the inner layer of the container here the heat is transferred by the process of conduction.

Conduction: The process of heat transfer by conduction is shown by the movement of heat from the warmer end of the metal rod to the cooler end when one end is heated. This process is happening through the process of conduction.

   Mark 3. on the bottom layer of the water in the container here the heat is transferred by the process of Convection to the upper layer.

The process of heat transfer by convection is shown by the movement of heat from the hotter end to the cooler end of the liquid in the beaker. This is because the hotter liquid near the flame expands and becomes less dense, so it rises up, while the cooler liquid near the top sinks down. This creates a circular motion of the liquid, which transfers the heat energy from the hotter end to the cooler end.

7. In places of hot climate it is advised that the outer walls of houses be painted white. Explain.

Answer:  

In places of hot climate, it is advised that the outer walls of houses be painted white because white surfaces reflect most of the sunlight falling on them. As a result, less heat is absorbed by the walls, and the interiors of the house remain cooler.

8. One litre of water at 30°C is mixed with one litre of water at 50°C. The temperature of the mixture will be (a) 80°C (b) more than 50°C but less than 80°C (c) 20°C (d) between 30°C and

50°C

Answer:  

Option (d) is correct: between 30°C but less than 50°C.

Explanation: When water at different temperatures is mixed, the temperature of the mixture will always lie between the temperatures of the two liquids. In this case, the water at 50°C will lose some heat to the water at 30°C, and the final temperature of the mixture will be between 30°C and 50°C.

9. An iron ball at 40°C is dropped in a mug containing water at 40°C. The heat will

(a) flow from iron ball to water.  

(b) not flow from iron ball to water or from water to iron ball.  

(c) flow from water to iron ball.

(d) increase the temperature of both.

Answer:  

The correct option is (b) not flow from iron ball to water or from water to iron ball.

Explanation: Heat flows from a body at a higher temperature to a body at a lower temperature. Since the iron ball and the water are at the same temperature, there will be no heat flow between them.

10. A wooden spoon is dipped in a cup of ice cream. Its other end

(a) becomes cold by the process of conduction.  

(b) becomes cold by the process of convection.  

(c) becomes cold by the process of radiation.

(d) does not become cold.

Answer:  

The correct option is (d) does not become cold.

Explanation: Wood is a bad conductor or insulator of heat. In this case, the wooden spoon is in contact with the cold ice cream, in general heat is transferred from the spoon to the ice cream through conduction. But here the spoon is made of wood and wood is insulator.

11. Stainless steel pans are usually provided with copper bottoms. The reason for this could be that

(a) copper bottom makes the pan more durable.  

(b) such pans appear colourful.  

(c) copper is a better conductor of heat than the stainless steel.

(d) copper is easier to clean than the stainless steel

Answer:  

The correct option is (c) copper is a better conductor of heat than the stainless steel. Stainless steel is a poor conductor of heat compared to copper. Therefore, stainless steel pans are usually provided with copper bottoms, which are better at conducting heat. The copper bottom ensures even heating of the pan and prevents hot spots.

Important Questions

1. State differences between acids and bases.

Answer:  

The differences between acids and bases are as under:     

   • Acids have a sour taste, while bases have a bitter taste.

   • Acids turn blue litmus paper red, while bases turn red litmus paper blue.

   • Acids release hydrogen ions (H+) in aqueous solution, while bases release hydroxide ions (OH-) in aqueous solution.

   • Acids have a pH value less than 7, while bases have a pH value greater than 7.

2. Ammonia is found in many household products, such as window cleaners. It turns red litmus blue. What is its nature?

Answer:  

Ammonia turns red litmus paper blue, which indicates that it is a base in nature.

3. Name the source from which litmus solution is obtained. What is the use of this solution? 

Answer:  

Litmus solution is obtained from lichens. It is used as an indicator to distinguish between acidic and basic solutions.

4. Is the distilled water acidic/basic/neutral? How would you verify it?      

Answer:  

Distilled water is neutral as it has a pH value of 7. This can be verified by testing its pH with a pH paper or a pH meter.

5. Describe the process of neutralisation with the help of an example.

Answer:  

Neutralization is a chemical reaction between an acid and a base that results in the formation of salt and water. For example, when hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH), sodium chloride (NaCl) and water (H2O) are formed: HCl + NaOH → NaCl + H2O

6. Mark ‘T’ if the statement is true and ‘F’ if it is false:

(i) Nitric acid turn red litmus blue. (T/F)

(ii) Sodium hydroxide turns blue litmus red. (T/F)

(iii) Sodium hydroxide and hydrochloric acid neutralise each other and form salt and water. (T/F)

(iv) Indicator is a substance which shows different colours in acidic and basic solutions. (T/F) (v) Tooth decay is caused by the presence of a base. (T/F)

Answer:  

(i) False, Nitric acid turns blue litmus paper red.

(ii) True, Sodium hydroxide turns red litmus paper blue.

(iii) True, Sodium hydroxide (a base) and hydrochloric acid (an acid) neutralize each other to form salt (sodium chloride) and water.

(iv) True, Indicators are substances that change color depending on whether they are in acidic or basic solutions.

(v) False, Tooth decay is caused by the presence of acids produced by bacteria.

7. Dorji has a few bottles of soft drink in his restaurant. But, unfortunately, these are not labelled. He has to serve the drinks on the demand of customers. One customer wants acidic drink, another wants basic and third one wants neutral drink. How will Dorji decide which drink is to be served to whom?

Answer:  

Dorji can use litmus paper or an indicator to identify the nature of the drinks. If the litmus paper turns red, the drink is acidic. If it turns blue, the drink is basic. If it doesn't change color, the drink is neutral.

8. Explain why:

(a) An antacid tablet is taken when you suffer from acidity. Keywords Acid Acidic Base Basic Indicator Neutral Neutralisation Salt  

Answer:  

(a) Antacid tablets contain bases such as magnesium hydroxide or aluminum hydroxide, which neutralize the excess acid in the stomach and provide relief from acidity.  

(b) Calamine solution is applied on the skin when an ant bites.  

Answer:  

(b) Calamine solution contains zinc oxide, which has antiseptic and astringent properties. It helps to reduce the swelling and itching caused by the ant bite.  

(c) Factory waste is neutralised before disposing it into the water bodies.

Answer:  

(c) Factory waste contains acidic or basic chemicals that can harm aquatic life. Neutralization is the process of adding a base to an acidic waste or an acid to a basic waste to bring its pH value closer to 7, making it less harmful to the environment.

9. Three liquids are given to you. One is hydrochloric acid, another is sodium hydroxide and third is a sugar solution. How will you identify them? You have only turmeric indicator.

Answer:  

To identify the given liquids, turmeric indicator can be used. Hydrochloric acid and sodium hydroxide are acidic and basic in nature, respectively. Turmeric indicator gives a reddish-brown color with bases and remains yellow with acids. So, the liquid that turns reddish-brown with turmeric indicator is sodium hydroxide, the one that remains yellow is the sugar solution, and the liquid that turns reddish-brown and gives off a pungent smell is hydrochloric acid.

10. Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.

Answer:  

If blue litmus paper is dipped in a solution and it remains blue, then the solution is either neutral or basic in nature. Blue litmus paper turns red in acidic solutions and remains blue in neutral or basic solutions.

11. Consider the following statements: (a) Both acids and bases change colour of all indicators. 

(b) If an indicator gives a colour change with an acid, it does not give a change with a base. 

(c) If an indicator changes colour with a base, it does not change colour with an acid. 

(d) Change of colour in an acid and a base depends on the type of the indicator. Which of these statements are correct?

(i) All four (ii) a and d (iii) b, c and d (iv) only d  

Answer:  

The correct statement is (iv) only d.  

Change of color in an acid and a base depends on the type of the indicator. Different indicators show different color changes with acids and bases. For example, litmus paper turns red in acidic solutions and blue in basic solutions, while phenolphthalein turns colorless in acidic solutions and pink in basic solutions  

Important Questions

1. Classify the changes involved in the following processes as physical or chemical changes:

Answer:  

(a) Photosynthesis - Chemical change  

(b) Dissolving sugar in water - Physical change  

(c) Burning of coal - Chemical change

(d) Melting of wax - Physical change

(e) Beating aluminium to make aluminium foil - Physical change  

(f) Digestion of food - Chemical change

2. State whether the following statements are true or false. In case a statement is false, write the corrected statement in your notebook.

(a) Cutting a log of wood into pieces is a chemical change. (True/False)

(b) Formation of manure from leaves is a physical change. (True/False)  

(c) Iron pipes coated with zinc do not get rusted easily. (True/False)

(d) Iron and rust are the same substances. (True/False)

(e) Condensation of steam is not a chemical change. (True/False

Answer:  

(a) Cutting a log of wood into pieces is a chemical change. - False.  

Cutting a log of wood into pieces is a physical change.  

(b) Formation of manure from leaves is a physical change. - False.  

Formation of manure from leaves is a chemical change.

3. Fill in the blanks in the following statements:

Answer:  

(a) When carbon dioxide is passed through lime water, it turns milky due to the formation of ___calcium carbonate___.  

(b) The chemical name of baking soda is ___sodium hydrogen carbonate___.  

(c) Two methods by which rusting of iron can be prevented are __painting__ and __galvanisation__.

(d) Changes in which only __physical__ properties of a substance change are called physical changes.

(e) Changes in which new substances are formed are called __chemical__ changes.

4. When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain

Answer:  

When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. This is a chemical change because a new substance (carbon dioxide) is formed.

5. When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.

Answer:  

When a candle burns, both physical and chemical changes take place. The melting of the wax is a physical change, while the burning of the wax is a chemical change. Another example of a familiar process in which both physical and chemical changes take place is cooking food.

6. How would you show that setting of curd is a chemical change?

Answer:  

To show that setting of curd is a chemical change, we can observe that milk, which is a liquid, transforms into curd, which is a solid with a different taste and texture. This change is irreversible and involves the formation of new substances.

7. Explain why burning of wood and cutting it into small pieces are considered as two different types of changes.

Answer:  

Burning of wood and cutting it into small pieces are considered as two different types of changes because burning of wood is a chemical change, while cutting it into small pieces is a physical change.

8. Describe how crystals of copper sulphate are prepared.

Answer:  

Crystals of copper sulphate can be prepared by dissolving copper sulphate in hot water and leaving the solution to cool slowly. As the solution cools, the solubility of copper sulphate decreases, causing it to crystallize out of the solution.

9. Explain how painting of an iron gate prevents it from rusting.

Answer:  

Painting of an iron gate prevents it from rusting by creating a barrier between the iron and the oxygen and moisture in the air. This prevents the iron from coming into contact with these substances, which are required for rusting to occur.

10. Explain why rusting of iron objects is faster in coastal areas than in deserts.

Answer:  

Rusting of iron objects is faster in coastal areas than in deserts because the air in coastal areas is more humid, which provides more moisture for rusting to occur. In deserts, the air is drier, so rusting occurs more slowly.

11. The gas we use in the kitchen is called liquified petroleum gas (LPG). In the cylinder it exist as a liquid. When it comes out from the cylinder it becomes a gas (Change – A) then it burns (Change – B).

The following statements pertain to these changes. Choose the correct one.  

(i) Process – A is a chemical change.

(ii) Process – B is a chemical change.

(iii) Both processes A and B are chemical changes.

(iv) None of these processes is a chemical change.

The gas we use in the kitchen is called liquified petroleum gas (LPG). In the cylinder, it exists as a liquid. When it comes out from the cylinder, it becomes a gas (Change – A) then it burns (Change – B). The following statements pertain to these changes. Choose the correct one. (ii) Process – B is a chemical change.

12. Anaerobic bacteria digest animal waste and produce biogas (Change – A). The biogas is then burnt as fuel (Change – B). The following statements pertain to these changes. Choose the correct one.

(i) Process – A is a chemical change.

(ii) Process – B is a chemical change.

(iii) Both processes A and B are chemical changes.

(iv) None of these processes is a chemical change

Answer:  

The correct option is:

(iii) Both processes A and B are chemical changes.

Important Questions

1. Name the elements that determine the weather of a place.

Answer:  

The elements that determine the weather of a place are temperature, humidity, rainfall, wind speed, and direction.

2. When are the maximum and minimum temperatures likely to occur during the day?

Answer:  

The maximum temperature is likely to occur during the day, usually in the afternoon, while the minimum temperature is likely to occur during the night, usually just before sunrise.

3. Fill in the blanks:

Answer:  

(i) The average weather taken over a long time is called ___climate___.

(ii) A place receives very little rainfall and the temperature is high throughout the year, the climate of that place will be __hot_ and __dry_ .

(iii) The two regions of the earth with extreme climatic conditions are ___tropical__ and __polar regions___.

4. Indicate the type of climate of the following areas:

(a) Jammu and Kashmir: ___________  

Answer: The type of climate in Jammu and Kashmir is subtropical.  

(b) Kerala: ___________  

Answer: The type of climate in Kerala is tropical monsoon.  

(c) Rajasthan: ___________

Answer: The type of climate in Rajasthan is arid.  

(d) North-east India: ___________

Answer: The type of climate in North-east India is tropical rainforest.

5. Which of the two changes frequently, weather or climate?

Answer:  

Weather changes frequently, while climate changes slowly over a long period of time.

6. Following are some of the characteristics of animals:

(i) Diets heavy on fruits

(ii) White fur

(iii) Need to migrate

(iv) Loud voice

(v) Sticky pads on feet

(vi) Layer of fat under skin

(vii) Wide and large paws

(viii) Bright colours

(ix) Strong tails

(x) Long and large beak

For each characteristic indicate whether it is an adaptation for tropical rainforests or polar regions. Do you think that some of these characteristics can be adapted for both regions? 

Answer:  

(i) Diets heavy on fruits - Adaptation for tropical rainforests  

(ii) White fur - Adaptation for polar regions

(iii) Need to migrate - Adaptation for both regions

(iv) Loud voice - Adaptation for tropical rainforests

(v) Sticky pads on feet - Adaptation for tropical rainforests

(vi) Layer of fat under skin - Adaptation for polar regions

(vii) Wide and large paws - Adaptation for both regions

(viii) Bright colours - Adaptation for tropical rainforests

(ix) Strong tails - Adaptation for both regions

(x) Long and large beak - Adaptation for tropical rainforests and some polar regions.

7. The tropical rainforest has a large population of animals. Explain why it is so.

Answer:  

The tropical rainforest has a large population of animals because of the abundant rainfall and sunlight, which leads to the growth of a large variety of plants and trees that provide food and shelter to a diverse range of animals.

8. Explain, with examples, why we find animals of certain kind living in particular climatic conditions.  

Answer:  

Animals are adapted to live in particular climatic conditions due to the specific physical and behavioral adaptations they possess. For example, polar bears have white fur and a layer of fat under their skin to survive in extremely cold temperatures. Similarly, camels

9. How do elephants living in the tropical rainforest adapt themselves?

9. How do elephants living in the tropical rainforest adapt themselves?

Answer:  

Elephants living in the tropical rainforest adapt themselves in the following ways:

• They use their long trunks to get food from trees and plants.
• They have strong and sharp tusks which help them to clear their path in the dense forest.
• They have big ears which help them to hear the sounds of other animals in the forest.
• They have thick skin which protects them from insect bites and other injuries.

Choose the correct option which answers the following question:  

10. A carnivore with stripes on its body moves very fast while catching its prey. It is likely to be found in 

(i) polar regions 

(ii) deserts 

(iii) oceans 

(iv) tropical rainforests  

Answer:  

(iv) tropical rainforests

11. Which features adapt polar bears to live in extremely cold climate?

(i) A white fur, fat below skin, keen sense of smell.

(ii) Thin skin, large eyes, a white fur.

(iii) A long tail, strong claws, white large paws.

(iv) White body, paws for swimming, gills for respiration.

Answer:  

The correct option is

(i) White fur, fat below skin, keen sense of smell.

12. Which option best describes a tropical region?

(i) hot and humid

(ii) moderate temperature, heavy rainfall

(iii) cold and humid

(iv) hot and dry

Answer:  

The correct option is

(ii) moderate temperature, heavy rainfall

Important Questions

1. Why does an athlete breathe faster and deeper than usual after finishing the race?

Answer:  

An athlete breathes faster and deeper than usual after finishing the race to take in more oxygen to meet the increased demand of the body cells during the strenuous physical activity.

2. List the similarities and differences between aerobic and anaerobic respiration.

Answer:  

Similarities:  

Both aerobic and anaerobic respiration involve the breakdown of glucose to release energy.

Differences:

Aerobic respiration occurs in the presence of oxygen, releases a large amount of energy, and produces carbon dioxide and water as end products.

Anaerobic respiration occurs in the absence of oxygen, releases a small amount of energy, and produces lactic acid or alcohol as end products.

3. Why do we often sneeze when we inhale a lot of dust-laden air?

Answer:  

We often sneeze when we inhale a lot of dust-laden air because the dust particles irritate the lining of the nasal passage, and sneezing helps to remove these particles by expelling them out of the body.

4. Take three test-tubes. Fill ¾th of each with water. Label them A, B and C. Keep a snail in test-tube A, a water plant in test-tube B and in C, keep snail and plant both. Which test-tube would have the highest concentration of CO2?

Answer:  

The test-tube containing both the snail and the plant (C) would have the highest concentration of CO2. The snail would release CO2 during respiration, and the plant would also release CO2 during the night due to respiration.

5. Tick the correct answer:

Answer:  

(a) In cockroaches, air enters the body through (iii) spiracles  

(b) During heavy exercise, we get cramps in the legs due to the accumulation of (ii) lactic acid  

(c) Normal range of breathing rate per minute in an average adult person at rest is: (ii) 15–18

(d) During exhalation, the ribs (i) move outwards

6. Match the items in Column I with those in Column II:

Answer:  

Column I……. Column II

(a) Yeast                   (iii) Alcohol  

(b) Diaphragm          (iv) Chest cavity  

(c) Skin(vii) Tracheae(i)Earthworm  

(d) Leaves                  (v) Stomata

(e) Fish                       (ii) Gills  

(f) Frog                       (vi) Lungs and skin  

7. Mark ‘T’ if the statement is true and ‘F’ if it is false:

Answer:  

(i) During heavy exercise the breathing rate of a person slows down. (F)

(ii) Plants carry out photosynthesis only during the day and respiration only at night. (F)

(iii) Frogs breathe through their skins as well as their lungs.

(T) (iv) The fishes have lungs for respiration. (F)  

(v) The size of the chest cavity increases during inhalation. (T)

8. Words related to respiration in organisms hidden in the given square:

Answer:  

LUNG

TRACHEA

DIAPHRAGM

STOMATA

SPIRACLES

ALVEOLI

NOSTRILS

ANAEROBE

INSECT

Explanation:

LUNG: can be found horizontally in the first row.

TRACHEA: can be found diagonally from top left to bottom right in the first column.

DIAPHRAGM: can be found vertically in the last column.

STOMATA: can be found diagonally from top right to bottom left in the third row.

SPIRACLES: can be found horizontally in the eighth row.

ALVEOLI: can be found vertically in the second column.

NOSTRILS: can be found horizontally in the seventh row.

ANAEROBE: can be found diagonally from top left to bottom right in the fifth row.

INSECT: can be found vertically in the first column.

9. The mountaineers carry oxygen with them because:

(a) At an altitude of more than 5 km there is no air.  

(b) The amount of air available to a person is less than that available on the ground.  

(c) The temperature of air is higher than that on the ground.

(d) The pressure of air is higher than that on the ground.

Answer:  

(b) The amount of air available to a person is less than that available on the ground.

Explanation: At higher altitudes, the air becomes less dense, which means that there is less oxygen available per unit volume of air. This can lead to altitude sickness and other health problems. To avoid this, mountaineers carry oxygen with them to supplement the amount of oxygen available in the air.  

The other options listed are not correct:  

There is still air at high altitudes (option a),  

The temperature of air generally decreases with altitude (option c),  

The pressure of air decreases with altitude (option d).

Important Questions

1. Match structures given in Column I with functions given in Column II.

Answer:  

Column I……….Column II  

(i) Stomata       (b) Transpiration

(ii) Xylem        (d) Transport of water

(iii) Root hairs (a) Absorption of water

(iv) Phloem      (c) Transport of food

                        (e) Synthesis of carbohydrates

2. Fill in the blanks.

(i) The blood from the heart is transported to all parts of the body by the_ arteries_.

(ii) Haemoglobin is present in _red blood_ cells.

(iii) Arteries and veins are joined by a network of _capillaries_.

(iv) The rhythmic expansion and contraction of the heart is called _heartbeat_.

(v) The main excretory product in human beings is _urea_.

(vi) Sweat contains water and _salts_.

(vii) Kidneys eliminate the waste materials in the liquid form called _urine_.

(viii) Water reaches great heights in the trees because of suction pull caused by _transpiration_.

3. Choose the correct option:

(a) In plants, water is transported through  

Answer:  

(i) xylem.  

(b) Water absorption through roots can be increased by keeping the plants  

Answer:  

(iii) under the fan.

4. Why is transport of materials necessary in a plant or in an animal? Explain

Answer:  

Transport of materials is necessary in a plant or in an animal to ensure that all the cells in the organism get the required nutrients and oxygen for their survival and to remove waste products. The transport of materials is essential for maintaining the proper functioning of different organs and tissues.

5. What will happen if there are no platelets in the blood?

Answer:  

Platelets help in the clotting of blood. If there are no platelets in the blood, then the person may suffer from excessive bleeding even from a minor injury.

6. What are stomata? Give two functions of stomata.

Answer:  

Stomata are tiny openings present on the surface of leaves and stems of plants. Two functions of stomata are:  

(i) They allow the exchange of gases (carbon dioxide and oxygen) between the plant and the atmosphere.

(ii) They help in the loss of excess water through transpiration.

7. Does transpiration serve any useful function in the plants? Explain. 

Answer:  

Yes, transpiration serves a useful function in plants. Transpiration helps in the absorption of water and minerals from the soil by creating a suction force that pulls the water up the plant through the roots. Transpiration also helps in the cooling of the plant by releasing excess water vapor into the atmosphere.

8. What are the components of blood? 

Answer:  

The components of blood are red blood cells, white blood cells, platelets, and plasma.

9. Why is blood needed by all the parts of a body?  

Answer:  

Blood is needed by all the parts of a body for the supply of oxygen and nutrients required for their proper functioning. Blood also carries waste products away from the cells and helps in maintaining the pH and temperature of the body.

10. What makes the blood look red?  

Answer:  

Hemoglobin, a protein present in red blood cells, makes the blood look red.

11. Describe the function of the heart.  

Answer:  

The heart is a muscular organ that pumps blood throughout the body. It receives deoxygenated blood from the body and pumps it to the lungs for oxygenation. The heart also receives oxygenated blood from the lungs and pumps it to the body.

12. Why is it necessary to excrete waste products?  

Answer:  

It is necessary to excrete waste products to remove harmful substances from the body. Accumulation of waste products in the body can lead to various health problems.

13. Draw a diagram of the human excretory system and label the various parts.  

Answer:  

*Sketch*

Important Questions

1. Fill in the blanks:

(i) Production of new individuals from the vegetative part of parent is called ___vegetative propagation___.

(ii) A flower may have either male or female reproductive parts. Such flowers are called __unisexual__.

(iii) The transfer of pollen grains from the anther to the stigma of the same or of another flower of the same kind is known as __pollination__.

(iv) The fusion of male and female gametes is termed as __fertilization__.

(v) Seed dispersal takes place by means of __wind__, __water__ and __animals__.

2. Describe the different methods of asexual reproduction. Give examples.

Answer:  

Asexual reproduction is the production of new individuals from a single parent without the involvement of sex cells. Some common methods of asexual reproduction are:  

(i) Budding - Yeast and Hydra

(ii) Fragmentation - Spirogyra and flatworm

(iii) Spore formation - Rhizopus and Penicillium

(iv) Vegetative propagation - Potato and Banana

3. Explain what you understand by sexual reproduction.

Answer:  

Sexual reproduction is the process of producing new individuals from the fusion of male and female gametes. In plants, sexual reproduction occurs through the production of flowers, where the male and female reproductive organs are located.

4. State the various ways by which seeds are dispersed.

Answer:  

Seeds are dispersed by various ways such as wind, water, and animals. Wind-dispersed seeds have wings or hair-like structures that help them to fly away.  

Water-dispersed seeds have a waterproof coat and are light-weighted to float on the water surface. Animal-dispersed seeds have hooks, spines, or fleshy fruits that help them to stick to the fur of animals and birds.

5. Sketch the reproductive parts of a flower.

Answer:

*Sketch*

6. Explain the difference between self-pollination and cross-pollination. 

Answer:  

Pollination is the process of transfer of pollen grains from the anther to the stigma of a flower. It can be of two types:  

(i) Self-pollination - transfer of pollen grains from the anther to the stigma of the same flower or another flower of the same plant.

(ii) Cross-pollination - transfer of pollen grains from the anther to the stigma of a different flower on another plant of the same kind.

7. How does the process of fertilisation take place in flowers?

Answer:  

Fertilization takes place when the male gamete present in the pollen grain fuses with the female gamete present in the ovule inside the ovary of a flower. This results in the formation of a zygote which develops into an embryo and a seed.

8. Describe the various ways by which seeds are dispersed. 

Answer:  

Seeds can be dispersed in various ways such as wind, water, animals, and explosion. Wind dispersal is observed in light and small seeds, water dispersal is observed in aquatic plants, animal dispersal takes place when seeds get stuck on the fur of animals or when animals eat fruits and excrete the seeds, explosion dispersal is observed in plants like peas and beans which eject their seeds with force.

9. Match items in Column I with those in Column II:

Column I…… Column II  

(a) Bud                (vi) Rose  

(b) Eyes               (v) Potato  

(c) Fragmentation (ii) Spirogyra

(d) Wings             (i) Maple

(e) Spores            (iv) Bread mould

10. Tick (V) the correct answer:

(a) The reproductive part of a plant is the  

(i) leaf

(ii) stem

(iii) root

(iv) flower

Answer:  

(iv) flower

(b) The process of fusion of the male and the female gametes is called  

(i) fertilisation (ii) pollination (iii) reproduction (iv) seed formation

Answer:  

(i) fertilisation

(c) Mature ovary forms the

(i) seed (ii) stamen (iii) pistil (iv) fruit

Answer: (iv) fruit

(d) A spore producing organism is

(i) rose

(ii) bread mould

(iii) potato

(iv) ginger

Answer:  

(ii) bread mould

(e) Bryophyllum can reproduce by its  

(i) stem

(ii) leaves

(iii) roots

(iv) flower

Answer:  

(ii) leaves

11. Explain the role of the following in the process of reproduction in plants:  

(i) Flower (ii) Pollen grains (iii) Embryo (iv) Seed

Answer:  

(i) Flower - The flower is the reproductive part of a plant. It contains both male and female reproductive organs and is responsible for sexual reproduction in plants.  

(ii) Pollen grains - Pollen grains contain male reproductive cells that fertilize the female reproductive cells of the flower during pollination, resulting in the formation of seeds.

(iii) Embryo - The embryo is a small, undeveloped plant that develops from the fertilized egg cell. It is the starting point of a new plant.

(iv) Seed - A seed is a matured ovule containing a plant embryo, stored food material, and a protective seed coat. It is the result of the fertilization of the ovules by the pollen grains during sexual reproduction.

12. For the following: Give name of agent of dispersal and part of plant involved.

Name of fruit- Agent- through which Part of or seed which bearing plant seeds are dispersed helps in dispersal

Answer:

(i) Coconut - Water - Endosperm

(ii) Maple - Wind - Wing

(iii) Barberry - Animals - Seed coat

Important Questions

1. Classify the following as motion along a straight line, circular or oscillatory motion:

Schoolvally answer:

(i) Motion of your hands while running. - Oscillatory motion

(ii) Motion of a horse pulling a cart on a straight road. - Motion along a straight line

(iii) Motion of a child in a merry-go-round. - Circular motion

(iv) Motion of a child on a see-saw. - Oscillatory motion

(v) Motion of the hammer of an electric bell. - Oscillatory motion

(vi) Motion of a train on a straight bridge. - Motion along a straight line

2. Which of the following are not correct?

Schoolvally answer:

(i) The basic unit of time is second. - Correct

(ii) Every object moves with a constant speed. - Not correct

(iii) Distances between two cities are measured in kilometres. - Correct

(iv) The time period of a given pendulum is constant. - Correct

(v) The speed of a train is expressed in m/h. - Not correct

3. A simple pendulum takes 32 s to complete 20 oscillations. What is the time period of the pendulum?

Schoolvally answer:

Time period of a simple pendulum = Total time taken for given number of oscillations ÷ Number of oscillations

= 32 s ÷ 20 = 1.6 s

4. The distance between two stations is 240 km. A train takes 4 hours to cover this distance. Calculate the speed of the train.

Schoolvally answer:

Speed of the train = Distance ÷ Time taken = 240 km ÷ 4 h = 60 km/h

5. The odometer of a car reads 57321.0 km when the clock shows the time 08:30 AM.

What is the distance moved by the car, if at 08:50 AM, the odometer reading has changed to 57336.0 km? Calculate the speed of the car in km/min during this time. Express the speed in Km/h also.  

Schoolvally answer:

Distance moved by the car = Final reading of the odometer - Initial reading of the odometer

= 57336.0 km - 57321.0 km  

= 15 km  

Time taken by the car = 20 minutes  

= 20/60  

= 1/3 hour  

Speed of the car = Distance ÷ Time taken  

= 15 km ÷ (1/3) hour  

= 45 km/h  

Speed of the car in km/min  

= 45 km/h ÷ 60  

= 0.75 km/min

6. Salma takes 15 minutes from her house to reach her school on a bicycle. If the bicycle has a speed of 2 m/s, calculate the distance between her house and the school.

Schoolvally answer:

Distance = Speed × Time taken  

= 2 m/s × (15 × 60) s  

= 1800 m = 1.8 km

7. Show the shape of the distance-time graph for the motion in the following cases:

(i) A car moving with a constant speed.

Schoolvally answer:

(i) Straight line

(ii) A car parked on a side road.

Schoolvally answer:   

(ii) Horizontal line

8. Which of the following relations is correct?

(i) Speed = Distance × Time

(ii) Speed = Distance Time

(iii) Speed = Time Distance

(iv) Speed = 1 Distance Time   

Schoolvally answer:

(ii) Speed = Distance/Time

9. The basic unit of speed is:

(i) km/min (ii) m/min (iii) km/h (iv) m/s  

Schoolvally answer:

(iv) m/s

10. A car moves with a speed of 40 km/h for 15 minutes and then with a speed of 60 km/h for the next 15 minutes. The total distance covered by the car is:

(i) 100 km (ii) 25 km (iii) 15 km (iv) 10 km  

Total time taken by the car =  

15 minutes + 15 minutes = 30 minutes  

= 1/2 hour  

Total distance covered by the car = Distance covered in the first 15 minutes + Distance covered in the next 15 minutes  

= 40 km/h × (15/60) hour + 60 km/h × (15/60) hour  

= 10 km + 15 km = 25 km  

Therefore, the total distance covered by the car is 25 km.

11. Suppose the two photographs, shown in Fig. 13.1 and Fig. 13.2, had been taken at an interval of 10 seconds. If a distance of 100 metres is shown by 1 cm in these photographs, calculate the speed of the fastest car  

Distance shown by 1 cm = 100 m  

Distance covered by the car in 10 seconds = Distance shown in the photograph  

= 2.5 cm  

Speed of the car = Distance covered ÷ Time taken  

= 1000 m ÷ 10 s = 100 m/s

12. Fig. 13.15, shows the distance-time graph for the motion of two vehicles A and B. Which one of them is moving faster?

Schoolvally answer:

Vehicle A is moving faster because it covers a greater distance in the same time as compared to vehicle B.

13. Which of the following distance-time graphs shows a truck moving with speed which is not constant?

Schoolvally answer:

Option (iii)

Explanation: 

Option (i) The distance-time graphs shows that the vehicle is moving in non constant speed, as the distance covered by the object is changing unevenly over time.  

Option (ii) shows the vehicle is parked as there is no change in the distance.

Option (iii) shows the vehicle moving in non constant speed or non uniform as the graph forms the curved line.

Option (iv) shows the vehicle is moving in constant speed or is seen in uniform motion as the graph forms the straight line and all the reference points are equidistant. 

Important Questions

1. Draw in your notebook the symbols to represent the following components of electrical circuits: connecting wires, switch in the ‘OFF’ position, bulb, cell, switch in the ‘ON’ position, and battery.

Answer:

Connecting wires: A straight line.

Switch in the ‘OFF’ position: An open switch symbol (a break in the line).

Bulb: A circle with a cross inside.

Cell: A circle with a short and a long line on opposite sides.

Switch in the ‘ON’ position: A closed switch symbol (a line connecting the two ends).

Battery: A combination of cells placed in a line.

2. Draw the circuit diagram to represent the circuit shown in Fig.14.21.

Answer:

*Sketch*

3. Fig.14.22 shows four cells fixed on a board. Draw lines to indicate how you will connect their terminals with wires to make a battery of four cells.

Answer:

To make a battery of four cells, we can connect the positive terminal of the first cell to the negative terminal of the second cell, and so on, using connecting wires.  

Finally, we will have a free positive terminal of the first cell and a free negative terminal of the fourth cell, which can be used to connect to the circuit.

4. The bulb in the circuit shown in Fig.14.23 does not glow. Can you identify the problem? Make necessary changes in the circuit to make the bulb glow.

*Sketch*

Answer:

In Fig. 14.23, the bulb does not glow because the positive and negative terminals of the cell are connected to the same side of the bulb.  

We need to break the circuit and connect the positive and negative terminals of the cell to the opposite sides of the bulb.  

The circuit should look like this: cell - switch - bulb - switch - cell.

5. Name any two effects of electric current.

Answer:

Two effects of electric current are:

Heating effect: When an electric current flows through a conductor, the conductor heats up. This effect is used in electric heaters, electric irons, etc.

Magnetic effect: When an electric current flows through a conductor, it creates a magnetic field around the conductor. This effect is used in electromagnets, electric motors, etc.

6. When the current is switched on through a wire, a compass needle kept nearby gets deflected from its north-south position. Explain.

Answer:

When the current flows through a wire, it creates a magnetic field around the wire. This magnetic field interacts with the Earth's magnetic field, which causes the compass needle to get deflected from its north-south position.

7. Will the compass needle show deflection when the switch in the circuit shown by Fig.14.24 is closed?

Answer:

Yes, the compass needle will show deflection when the switch in the circuit shown in Fig.14.24 is closed. This is because current flows through the wire when the switch is closed, which creates a magnetic field around the wire that interacts with the Earth's magnetic field and causes the compass needle to get deflected.

8. Fill in the blanks:  

(a) Longer line in the symbol for a cell represents its _+ve_ terminal. 

(b) The combination of two or more cells is called a _battery_.  

(c) When current is switched ‘on’ in a room heater, it produces _heat_.

(d) The safety device based on the heating effect of electric current is called a _fuse_.

9. Mark ‘T’ if the statement is true and ‘F’ if it is false:

(a) To make a battery of two cells, the negative terminal of one cell is connected to the negative terminal of the other cell. (False )  

(b) When the electric current through the fuse exceeds a certain limit, the fuse wire melts and breaks. (True)  

(c) An electromagnet does not attract a piece of iron. (False )

(d) An electric bell has an electromagnet. (True)

10. Do you think an electromagnet can be used for separating plastic bags from a garbage heap? Explain. 

Answer:

Yes, an electromagnet can be used for separating plastic bags from a garbage heap. The electromagnet can be turned on and off to attract and release magnetic materials. As plastic bags are not magnetic, they will not be attracted to the electromagnet, and therefore can be separated from other magnetic materials in the garbage heap.

11. An electrician is carrying out some repairs in your house. He wants to replace a fuse by a piece of wire. Would you agree? Give reasons for your response.

Answer:

No, we should not agree with the electrician to replace a fuse with a piece of wire. This is because a fuse is a safety device that is designed to protect the circuit and the devices connected to it from damage due to excessive current. When the current exceeds a certain limit, the fuse wire melts and breaks the circuit, thus preventing any further damage. On the other hand, replacing a fuse with a wire can lead to overheating, which can result in a fire or damage to the devices connected to the circuit.

12. Zubeda made an electric circuit using a cell holder shown in Fig. 14.4, a switch and a bulb. When she put the switch in the ‘ON’ position, the bulb did not glow. Help Zubeda in identifying the possible defects in the circuit.

Answer:

Zubeda could check for the following possible defects in her circuit:

Make sure that the bulb is not fused, and the filament inside the bulb is intact.

Check if the wires are connected correctly and not loose.

Check if the switch is working properly.

Check if the cell is not exhausted and is connected in the correct polarity.

13. In the circuit shown in Fig. 14.25 Fig. 14.25

*Sketch*

(i) Would any of the bulb glow when the switch is in the ‘OFF’ position?

Answer:

No, none of the bulbs A, B and C will glow when the switch is in the ‘OFF’ position because the circuit will be incomplete.  

(ii) What will be the order in which the bulbs A, B and C will glow when the switch is moved to the ‘ON’ position?

Answer:

When the switch is moved to the ‘ON’ position, bulb A will glow first, followed by bulb B and then bulb C. This is because bulb A is connected in parallel to the switch, so it will receive full voltage as soon as the switch is turned on. Bulbs B and C are connected in series, so they will glow in sequence, starting from the one closest to the switch. 

Important Questions

1. Fill in the blanks:

(a) An image that cannot be obtained on a screen is called _virtual image_. 

(b) Image formed by a convex _lens_ is always virtual and smaller in size.  

(c) An image formed by a _plane_ mirror is always of the same size as that of the object.

(d) An image which can be obtained on a screen is called a _real_ image.

(e) An image formed by a concave _lens_ cannot be obtained on a screen.

2. Mark ‘T’ if the statement is true and ‘F’ if it is false:

Answer:

(a) We can obtain an enlarged and erect image by a convex mirror...... (False)  

(b) A concave lens always forms a virtual image...... (True)  

(c) We can obtain a real, enlarged, and inverted image by a concave mirror...... (True)

(d) A real image cannot be obtained on a screen...... (False)

(e) A concave mirror always forms a real image...... (False)

3. Match the items given in Column I with one or more items of Column II.

Column I .....   Column II 

(a) A plane mirror      (i) Used as a magnifying glass.  

(b) A convex mirror   (ii) Can form an image of objects spread over a large area.  

(c) A convex lens       (iii) Used by dentists to see an enlarged image of teeth.

(d) A concave mirror  (iv) The image is always inverted and magnified.

(e) A concave lens      (v) The image is erect and of the same size as the object.  

                                  (vi) The image is erect and smaller in size than the object.

4. State the characteristics of the image formed by a plane mirror.

Answer:

The image formed by a plane mirror is virtual, erect, and of the same size as the object.

5. Find out the letters of the English alphabet or any other language known to you in which the image formed in a plane mirror appears exactly like the letter itself. Discuss your findings. Answer:

Letters such as A, H, I, M, O, T, U, V, W, X, and Y appear the same in the image as they do in real life.

However, letters such as B, C, D, E, K, P, and S are different in the image.

6. What is a virtual image? Give one situation where a virtual image is formed.

Answer:

A virtual image is an image that cannot be obtained on a screen, and it is always erect. A virtual image is formed when light appears to be coming from a point behind the mirror or lens. A situation where a virtual image is formed is when we look into a plane mirror.

7. State two differences between a convex and a concave lens.

Answer:

Two differences between a convex and a concave lens are:

A convex lens converges light rays, while a concave lens diverges light rays.

A convex lens always forms a real or virtual image, while a concave lens forms a virtual image only.

8. Give one use each of a concave and a convex mirror.

Answer:

A convex mirror is used as a rear view mirror in vehicles as it provides a wider field of view.  

A concave mirror is used in torches and headlights of vehicles to focus light into a parallel beam.

9. Which type of mirror can form a real image?

Answer:

A concave mirror can form a real image.

10. Which type of lens forms always a virtual image?

Answer:

A concave lens always forms a virtual image.

Choose the correct option in questions 11–13  

11. A virtual image larger than the object can be produced by a

(i) concave lens

(ii) concave mirror

(iii) convex mirror

(iv) plane mirror

Answer:

(iii) convex mirror A virtual image larger than the object can be produced by a convex mirror. When an object is placed in front of a convex mirror, the image formed is always virtual, erect, and smaller than the object. However, as the object moves closer to the mirror, the size of the virtual image increases.

12. David is observing his image in a plane mirror. The distance between the mirror and his image is 4 m. If he moves 1 m towards the mirror, then the distance between David and his image will be

(i) 3 m

(ii) 5 m

(iii) 6 m

(iv) 8 m

Answer:

(ii) 5 m When David moves 1 m towards the plane mirror, the distance between him and the mirror reduces by 1 m, so it becomes 3 m. Since the distance between the mirror and his image is always twice the distance between David and the mirror, the distance between David and his image will also reduce by 1 m, becoming 1 m + 3 m = 4 m. So, the new distance between David and his image will be 5 m.

13. The rear view mirror of a car is a plane mirror. A driver is reversing his car at a speed of 2 m/s. The driver sees in his rear view mirror the image of a truck parked behind his car. The speed at which the image of the truck appears to approach the driver will be

(i) 1 m/s

(ii) 2 m/s

(iii) 4 m/s

(iv) 8 m/s  

Answer:

(ii) 2 m/s The image of the truck in the rear-view mirror appears to be at the same distance behind the mirror as the actual truck is in front of it. So, when the driver is moving backward at a speed of 2 m/s, the image of the truck appears to be moving towards the driver at the same speed, which is 2 m/s.

Important Questions

1. Mark ‘T’ if the statement is true and ‘F’ if it is false:

Answer:

(a) The freshwater stored in the ground is much more than that present in the rivers and lakes of the world..... (True)  

(b) Water shortage is a problem faced only by people living in rural areas..... (False)  

(c) Water from rivers is the only source for irrigation in the fields...... (False)

(d) Rain is the ultimate source of water. ..... (True)

2. Explain how groundwater is recharged?

Answer:

Groundwater is recharged through the seepage of rainwater or surface water into the ground. The water percolates through the soil and fills the spaces and cracks in the rock formations underground, thereby replenishing the groundwater.

3. There are ten tube-wells in a lane of fifty houses. What could be the long term impact on the water table?

Answer:

If there are ten tubewells in a lane of fifty houses, the long term impact on the water table could be that the water table may get depleted as excessive pumping of groundwater may reduce the recharge of groundwater.

4. You have been asked to maintain a garden. How will you minimise the use of water?

Answer:

To minimize the use of water in a garden, one can:

Choose plants that require less water and are well adapted to local climate and soil conditions

Water the plants in the early morning or late evening when there is less evaporation

Use mulch around the plants to retain moisture in the soil

Use a drip irrigation system that delivers water directly to the plant roots, reducing wastage.

5. Explain the factors responsible for the depletion of water table.  

Answer:

The factors responsible for the depletion of the water table are:

Overuse of groundwater for domestic, agricultural and industrial purposes

Lack of recharge of groundwater due to deforestation, urbanization, and construction of concrete structures

Climate change and variability leading to erratic rainfall patterns and prolonged droughts.

6. Fill in the blanks with the appropriate answers:

(a) People obtain groundwater through _wells_ and _tube-wells_. 

(b) Three forms of water are _solid_, _liquid_ and _gas_. 

(c) The water bearing layer of the earth is _aquifer_.

(d) The process of water seepage into the ground is called _infiltration_.

7. Which one of the following is not responsible for water shortage?

(i) Rapid growth of industries

(ii) Increasing population

(iii) Heavy rainfall

(iv) Mismanagement of water resource

Answer:

(iii) Heavy rainfall is not responsible for water shortage as it is a natural source of water and can replenish water bodies and groundwater reserves.

8. Choose the correct option. The total water

(i) in the lakes and rivers of the world remains constant.

(ii) under the ground remains constant.

(iii) in the seas and oceans of the world remains constant.

(iv) of the world remains constant.

Answer:  

The correct option is (iv) of the world remains constant. While the distribution and availability of water in different forms can vary, the total amount of water on Earth remains constant as water is continuously recycled through the water cycle.

9. Make a sketch showing groundwater and water table. Label it  

Answer:

*Sketch*

Here's a simple sketch showing groundwater and water table:

Zone of Aeration

        \/

Water Table

        \/

Zone of saturation

The zone of aeration is the area above the water table where the spaces between the soil and rock particles are filled with both air and water. The water table is the upper surface of the zone of saturation, where the soil and rock are saturated with water. The zone of saturation is the area below the water table where all the spaces between the soil and rock particles are filled with water.

Important Questions

1. Explain how animals dwelling in the forest help it grow and regenerate.

Answer:  

Animals dwelling in the forest help in the growth and regeneration of the forest in various ways. They help in seed dispersal, pollination, and nutrient recycling. They also help in controlling the population of other animals and maintaining the balance of the ecosystem.

2. Explain how forests prevent floods.

Answer:  

Forests prevent floods by absorbing and retaining rainwater. The trees and plants in the forest act as a natural sponge, which absorbs water and holds it in the soil. This reduces the amount of surface water, which could otherwise cause floods. Forests also slow down the flow of water, which reduces the speed and force of floods.

3. What are decomposers? Name any two of them. What do they do in the forest?

Answer:  

Decomposers are organisms that break down dead and decaying organic matter into simpler substances. They play an essential role in the ecosystem by recycling nutrients and making them available to plants. Two examples of decomposers are bacteria and fungi. In the forest, decomposers help in the breakdown of dead plant and animal matter, which helps in the growth of new plants.

4. Explain the role of forest in maintaining the balance between oxygen and carbon dioxide in the atmosphere.

Answer:  

Forests play a crucial role in maintaining the balance between oxygen and carbon dioxide in the atmosphere. During photosynthesis, trees absorb carbon dioxide from the atmosphere and release oxygen. This helps in reducing the concentration of carbon dioxide in the atmosphere and increasing the concentration of oxygen.

5. Explain why there is no waste in a forest.

Answer:  

There is no waste in a forest because the ecosystem of the forest is a closed loop. The dead and decaying organic matter is recycled by decomposers and converted into nutrients, which are then used by the plants. The waste produced by one organism becomes food for another, and nothing goes to waste.

6. List five products we get from forests?

Answer:  

Five products we get from forests are wood, paper, medicines, fruits, and rubber.

7. Fill in the blanks:

(a) The insects, butterflies, honeybees and birds help flowering plants in _pollination_.  

(b) A forest is a purifier of _air_ and _water_.  

(c) Herbs form the _ground_ layer in the forest.

(d) The decaying leaves and animal droppings in a forest enrich the _soil_.

8. Why should we worry about the conditions and issues related to forests far from us?

Answer:

We should worry about the conditions and issues related to forests far from us because forests provide numerous ecological services that are vital for life on earth, such as regulating the climate, maintaining the water cycle, and conserving biodiversity. The degradation or loss of forests in one region can have severe impacts on other regions as well.

9. Explain why there is a need for a variety of animals and plants in a forest.

Answer:

There is a need for a variety of animals and plants in a forest because they depend on each other for their survival. Different animals and plants have adapted to different roles and niches within the forest ecosystem, and each plays a unique role in maintaining the balance and health of the forest. The loss of one species can have a cascading effect on the entire ecosystem, leading to the decline of other species and the degradation of the forest. A diverse forest ecosystem is more resilient to disturbances and is better able to adapt to changing environmental conditions.

10. In Fig. 17.15, the artist has forgotten to put the labels and directions on the arrows. Mark the directions on the arrows and label the diagram using the following labels: clouds, rain, atmosphere, carbon dioxide, oxygen, plants, animals, soil, roots, water table.

Answer:

The labels and directions on the arrows are:

Clouds (arrow pointing upwards towards the Earth)

Rain (arrow pointing downwards towards the Earth)

Atmosphere (arrow pointing upwards)

Carbon dioxide (arrow pointing towards the plants)

Oxygen (arrow pointing away from the plants)

Plants (arrow pointing towards them)

Animals (arrow pointing towards them)

Soil (arrow pointing downwards)

Roots (arrow pointing inwards the soil)

Water table (arrow pointing downwards and inward towards the Earth)

11. Which of the following is not a forest product?

(i) Gum (ii) Plywood (iii) Sealing wax (iv) Kerosene

Answer:

(iv) Kerosene is not a forest product. It is a fossil fuel derived from crude oil.

12. Which of the following statements is not correct?

(i) Forests protect the soil from erosion.

(ii) Plants and animals in a forest are not dependent on one another.

(iii) Forests influence the climate and water cycle.

(iv) Soil helps forests to grow and regenerate

Answer: 

Option (ii) Plants and animals in a forest are not dependent on one another is not correct.

Explanation: Plants and animals in a forest are interdependent on each other for their survival. Plants provide food and shelter to animals, while animals help in pollination and seed dispersal. This interdependence ensures a balance in the forest ecosystem.

13. Micro-organisms act upon the dead plants to produce

(i) sand (ii) mushrooms (iii) humus (iv) wood

Answer:

(iii) humus

Explanation: The micro-organisms which convert the dead plants and animals to humus are known as decomposers. These micro-organisms feed upon the dead plant and animal tissues and convert them into a dark coloured substance called humus.

Important Questions

1. Fill in the blanks:

(a) Cleaning of water is a process of removing _impurities_.  

(b) Wastewater released by houses is called _sewage_.  

(c) Dried _sludge_ is used as manure.

(d) Drains get blocked by _garbage_ and _oil_.

2. What is sewage? Explain why it is harmful to discharge untreated sewage into rivers or seas.  

Answer:

Sewage is the wastewater that is generated by human activities such as washing, bathing, flushing toilets, and industrial processes. It contains harmful pollutants such as disease-causing organisms, chemicals, and organic matter. Discharging untreated sewage into rivers or seas can pollute the water and harm aquatic life, and can also cause the spread of waterborne diseases.

3. Why should oils and fats be not released in the drain? Explain.

Answer:

Oils and fats should not be released in the drain because they can clog pipes and cause blockages in sewage systems. This can lead to backups and overflows, which can cause damage to homes and the environment. Moreover, oils and fats can accumulate in wastewater treatment plants, reducing their efficiency and increasing the cost of treatment.

4. Describe the steps involved in getting clarified water from wastewater.

Answer:

The steps involved in getting clarified water from wastewater are: (i) Screening: Large objects such as sticks, stones, and rags are removed using screens. (ii) Grit and sand removal: Small particles such as sand and grit are removed by settling. (iii) Sedimentation: Heavy particles such as sludge settle at the bottom of the tank. (iv) Filtration: The remaining water is passed through filters made of sand and gravel. (v) Disinfection: The water is disinfected using chlorine or ultraviolet light.

5. What is sludge? Explain how it is treated.  

Answer:

Sludge is the semi-solid material that is left over after wastewater treatment. It contains organic matter, nutrients, and disease-causing organisms. Sludge is treated by anaerobic digestion, which breaks down the organic matter into biogas and a solid residue. The solid residue is then further treated to remove pathogens and can be used as fertilizer.

6. Untreated human excreta is a health hazard. Explain.  

Answer:

Untreated human excreta contains harmful pathogens such as bacteria, viruses, and parasites that can cause waterborne diseases such as cholera, typhoid, and diarrhea. If it is not properly disposed of, it can contaminate water sources and cause outbreaks of disease.

7. Name two chemicals used to disinfect water.  

Answer:

Two chemicals used to disinfect water are chlorine and ozone.

8. Explain the function of bar screens in a wastewater treatment plant.  

Answer:

Bar screens are used in wastewater treatment plants to remove large objects such as sticks, stones, and rags that could damage or clog pumps and other equipment.

9. Explain the relationship between sanitation and disease.  

Answer:

Sanitation refers to the provision of facilities and services for the safe disposal of human waste and wastewater. Poor sanitation can lead to the spread of waterborne diseases such as cholera, typhoid, and diarrhea. Improving sanitation can help prevent the spread of these diseases and improve public health.

10. Outline your role as an active citizen in relation to sanitation.  

Answer:

As an active citizen, one can play a role in promoting sanitation by: 

(i) Properly disposing of household waste and sewage. 

(ii) Encouraging others to do the same. (iii) Supporting the construction and maintenance of sanitation facilities. 

(iv) Advocating for policies and programs that promote sanitation and public health.

11. Here is a crossword puzzle: Good luck!  

Across 3. Sewage

Sludge

Sanitation

Feces

Down

Wastewater

Sewer

Vibrio

Chlorine

12. Study the following statements about ozone:

(a) It is essential for breathing of living organisms.  

(b) It is used to disinfect water.  

(c) It absorbs ultraviolet rays.

(d) Its proportion in air is about 3%.

Which of these statements are correct?

(i) (a),

(ii) (b) and (c)

(iii) (a) and (d)

(iv) All four  

Answer:

The correct statement is-(ii) (b) and (c)  

Explanation: Statement (ii) (b) and (c)-Ozone is used to disinfect water and it absorbs ultraviolet rays.  

Statement (a) is incorrect because ozone is harmful to living organisms when inhaled in large quantities.  

Statement (d) is incorrect because ozone is present in very small amounts in the atmosphere.

Important Questions