1. Why do organisms need to take food?  

Ans: All living organisms require food to survive. It gives them energy to perform various  activities. All activities such as playing, running, walking, studying, etc. require energy. The  various components present in our food such as carbohydrates, proteins,fats, vitamins, and  minerals provide energy to our body. These are also important for growth and development  of the body. 

2. Distinguish between a parasite and a saprotroph.  

Ans: Parasite (Parasitic Plant): Plants that get their food from other plants by living on them are  called parasite. Example; Cuscuta, mistletoe. Cuscuta is a vine-like plant with yellowish  stem. It twines around big trees, like banyan tree. Cuscuta gets nutrition from the tree on  which it lives. 

Saprotrophs: Saprotrophs are non-green plants e.g. Agaricus (Mushroom) fungi, yeasts  and bacteria. Saprotrophs get their food from dead or decaying organic matters. They grow  on decaying organic matters such as cow-dung, wood, bread, etc. 

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

Ans: Aim: To test for the presence of starch in leaf.  

Materials Required: 

Green leaf, beaker, tripod stand, burner, test tube, alcohol, iodine  solution, tap water and petri dish.  Procedure:  

Pluck a healthy green leaf of a plant which was kept in sunlight.   

Boil it in water contained in a beaker for about two minutes. This will make the leaf soft  and stop any further chemical changes in it.  

Put the leaf in a test tube containing .  

The alcohol will bleach the leaf and make it free from chlorophyll.  

Wash the leaf in water. Place it in a petri dish and add a few drops of iodine solution.   

 Observation : The leaf turns blue-black.  

Conclusion : The leaf changes into blue-black colour due to presence of starch in it.  

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


Photosynthesis is defined as the process in which the chlorophyll-containing plant  cells synthesise food in the form of carbohydrates, using carbon dioxide and water in the  presence of solar energy.  

Photosynthesis:Sources of raw materials required for photosynthesis: 

(a) Water is taken in from the roots of the plant and is transported to the leaves.

(b) Carbon dioxide from the air enters the leaves through the tiny pores called stomata and  diffuses to the cells containing chlorophyll.  

(c) Solar energy is used to break water into hydrogen and oxygen. This hydrogen is  combined with carbon dioxide to form food for the plants, which is ultimately used by the  animals as well. 


Thus, photosynthesis can be represented by the following equation

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

Ans: The mode of nutrition shows that the plant is the ultimate pro Only plant can  produce food and rest of other organisms are directly or indirectly dependent on it.


6. Fill in the blanks: 

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

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

(c) In photosynthesis solar energy is captured by the pigment called ___________

(d) During photosynthesis plants take in ______________________ and release  __________________. 

Ans: (a) Gren plants are called autotrophs since they synthesise their own food.

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

(c) In photosynthesis solar energy is captured by the pigment called chlorophyll.

(d) During photosynthesis plants take in carbon dioxide and release oxygen. 

7. Name the following: 

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

(ii) A plant that has both autotrophic and heterotrophic mode of nutrition.

(iii) The pores through which leaves exchange gases. 

Ans: (i) Cuscuta

(ii) Pitcher plant

 8. Tick the correct answer: (a) Amarbel is an example of: (i) autotroph (ii) parasite (iii) saprotroph (iv) host

Ans: (ii) parasite 

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

(i) cuscuta (ii) china rose (iv) pitcher plant (iv) rose 

Ans: (iii) pitcher plant 

10. Mark ‘T’ if the statement is true and ‘F’ if it is false: (i) Carbon dioxide is released during photosynthesis. (T/F) (ii) Plants which synthesise their food themselves are called saprotrophs. (T/F) .(iii) The product of photosynthesis is not a protein. (T/F) (iv) Solar energy is converted into chemical energy during photosynthesis. (T/F) .

Ans: (i) False (ii) False (iii) True (iv) True 

11. Choose the correct option from the following: Which part of the plant gets carbon dioxide from the air for photosynthesis.

(i) root hair

(ii) stomata

(iii) leaf veins

(iv) sepals

 Ans: (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 

Ans: (iv) leaves

13. What are the components of food? 

Answer: Carbohydrates, proteins, fats, vitamins and minerals are the components of food.

14. What is nutrition? 

Answer: The process of utilization of food by a living organism to obtain energy is called  nutrition. 

15. Why is need of nutrition? 

Answer: Animals do not make their food themselves which plants do. Animals eat plants or  plant eating animals. Hence, animals are directly or indirectly depend on plants. 

16. What is autotroph? 

Answer: Organisms that make their food themselves are called autotrophs. 

17. What is autotrophic mode of nutrition? 

Answer: The mode of nutrition in which the organism makes its own food is called  autotrophic mode of nutrition. 

18. Give some example of autotrophs. 

Answer: All green plants, such as grass, mango, bougainvillea, etc. are the examples of  autotrophs. Some bacteria also show autotrophic nutrition. 

19. What is photosynthesis? 

Answer: The process of making food in green plants in the presence of sunlight is known as  photosynthesis. 

20. What are the essentials factors for the photosynthesis? 

Answer: Carbon dioxide, water, chlorophyll and sunlight are essentials factors for  photosynthesis to take place. 

21. What is chlorophyll? 

Answer: Chlorophyll is the green pigment present in green leaves. 

22. Why do leaves look green? 

Answer: Leaves look green because of the presence of chlorophyll, which is a green  pigment. 

23. What is the function of chlorophyll? 

Answer: Chlorophyll absorbs the sunlight for photosynthesis. 

24. What are the final products made after photosynthesis? 

Answer: Glucose and oxygen are the final products after photosynthesis. 

25. What are stomata? 

Answer: The small pores present on the lower surface of leaf, are called stomata. 

26. What is function of stomata? 

Answer: Stomata absorb carbon dioxide from air for photosynthesis. Stomata facilitates  exchange of gases and transpiration.

27. What is the ultimate source of energy? 

Answer: Sun is the ultimate source of energy.

28. How water is transported to the leaves? 

Answer: Water is transported to the leaves through pipe like structures from the roots of  plant. These pipe-like structures are present from root to leaves through branches  throughout. 

29. What is heterotrophic mode of nutrition? 

Answer: The mode of nutrition in which an organism takes food from another organism is  called heterotrophic mode of nutrition. The nutrition in animals and non-green plants is the  example of heterotrophic mode of nutrition. 

30. Give examples of Heterotrophs. 

Answer: Animals and non green plants are the examples of heterotrophs. 

31. What are saprotrophs? 

Answer: Organisms which get their nutrition from dead or decaying plants in liquid form are  called saprotrophs. 

32. What are the nutrients other than carbohydrates which are required by plants?

Answer: Proteins and fats are the nutrients; other than carbohydrates; which are required by  plants. 

33. In which form do plants absorb nitrogen? 

Answer: Plants absorb soluble form of nitrogen. 

34. Why do farmers add nitrogenous fertilizers to the soil? 

Answer: Farmers add nitrogenous fertilizers to the soil to fulfill the requirement of nitrogen  of the plants. Nitrogen is necessary to synthesize proteins. 

35. Which microorganism help to provide nitrogen to the plants? 

Answer: A certain type of bacteria called rhizobium helps to provide nitrogen to the plants. 

36. How do plants absorb nutrients other than carbohydrates from the soil?

Answer: Other nutrients are available in the soil in the form of minerals. Plants absorb these  minerals from the soil; along with water. 

37. What do you understand by parasitic plants? 

Answer: A plant which lives on another plant and takes nutrients is called a parasitic plant. 

38. Give some examples of parasitic plants. 

Answer: Cuscuta and mistletoe 

39. Why some plants are called parasites? 

Answer: Some plants are unable to prepare their own food and need to take food from  another plant. Hence, they are called parasites. 

40. What is the mode of nutrition in non-green plants? 

Answer: Non-green plants show heterotrophic mode of nutrition. 

41. What do you understand by non-green plants? 

Answer: A plant which lacks chlorophyll is called non-green plant.

42. What do you understand by host?

Answer: An organism which provides shelter and nutrition to another organism is called a  host.

43. What is partial parasite? 

Answer: A parasite which depends for some of the nutrients; on another organism; is called  a partial parasite. 

44. Give example of partial parasitic plants? 

Answer: Mistletoe

45. What is an insectivorous plant? 

Answer: A plant which fulfills its nitrogenous needs by eating insects is called an  insectivorous plant. 

46. Give an example of insectivores plant? 

Answer: Pitcher plant, Venus Fly trap, Bladderwort, Drosera, Rafflesia 

47. Why does a plant eat insects? 

Answer: Plants living in marshy areas do not get nitrogen from the soil. To fulfill their  nitrogenous need, they need to eat insects. 

48. Write a brief note on pitcher plants? 

Answer: In a pitcher plant, the leaf is modified into a pitcher like structure. The pitcher is  complete with a lid. The inside of pitcher is full of hair-like structures. The pitcher is used to  trap insects which may fall in it. 

49. What do you understand by saprotrophs? 

Answer: An organism which feed on dead and decaying material is called a saprotroph. In  this mode of nutrition, digestive enzymes are secreted on the food. The digested food is then  absorbed by the organism. In saprotrophs digestion takes place outside the body of the  organism. 

50. Saprophytes grow in which type of places? 

Answer: Saprophytes grow in humid and hot conditions. 

51. Give some example of saptrotrophs. 

Answer: Mushroom, yeast, toadstool, etc. 

52. What is the meaning of word ‘Symbiosis’? 

Answer: It is a relationship between two organisms in which both the organisms benefit  each other. 

53. What is Lichen? 

Answer: The lichen is a composite organism formed because of symbiosis of algae and  fungi. 

54. Give an example of symbiotic relationship. 

Answer: A small bird; called plover; cleans the crocodile’s teeth. The crocodile keeps its  mouth open and the bird takes out meat fibres stuck between the teeth. The bird gets food in  lieu of providing dentist’s services to the crocodile.