1.Why do organisms need to take food?
Answer:- All organisms need to take food to get energy for the growth, development and maintenance of their bodies.
2.Distinguish between a parasite and a saprotroph.
Answer:- 1. Organisms derive nutrition from the body of other living organisms (host) are parasites. Plants which derive nutrition from dead and decaying organisms are called saprotrophs.
2. Parasite Example: Cuscata (Amar bel) Saprotroph Example: Mushrooms.
3.How would you test the presence of starch in leaves?
Answer : Take a potted plant with variegated leaves – for example, money plant or crotons. Keep the plant in a dark room for three days so that all the starch gets used up. Now select a leaf cover its portion with a black strip paper and keep the plant in sunlight for about six hours. Pluck the leaf from the plant. Mark the uncovered area in it and trace them on a sheet of paper. Dip the leaf in boiling water for a few minutes. After this, immerse it in a beaker containing alcohol. Carefully place the above beaker in a water-bath and heat till the alcohol begins to boil. Now dip the leaf in a dilute solution of iodine for a few minutes. Take out the leaf and rinse off the iodine solution. You observe that the presence of starch in various areas of the leaf which was uncovered.
4.Give a brief description of the process of synthesis of food in green plants.
Answer: 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 is 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.
5.Show with the help of a sketch that the plants are the ultimate source of food.
Answer:- All the living being depends on plants whether directly or indirectly. For example, the plant eater animals depends directly on plants but carnivore depends indirectly on plants. The following sketch shows some examples of plant dependency.
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 __________________.
Answer : (a) Green 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.
Answer :
(i) A parasitic plant with yellow, slender and tubular stem – Cuscuta
(ii) A plant that has both autotrophic and heterotrophic mode of nutrition – Pitcher plant, Venus flytrap.
(iii) The pores through which leaves exchange gases – Stomata.
8.Tick the correct answer:
(a) Amarbel is an example of: (i) autotroph (ii) parasite (iii) saprotroph (iv) host (b) The plant which traps and feeds on insects is: (i) Cuscuta (ii) china rose (iv) pitcher plant (iv) rose Answer 8: (a) Amarbel is an example of (ii) parasite. (b) The plant which traps and feeds on insects is (iv) pitcher plant.