7th Standard, Science, Chapter 1
Nutrition in Plants
Exercise
- Why do organisms take food?
Answer: Organisms take food to build their bodies, to grow, to repair damaged parts of their bodies and provide the energy to carry out life processes. - Distinguish between a parasite and a saprotroph.
Answer:
Parasite: The living organisms which take food from other living organisms. The plant on which it climbs is called the host. Since it deprives the host of valuable nutrients, Eg: Cuscuta Saprotrophs: Organisms are getting food from dead or decaying substances. Nutrition in which organisms take in nutrients from dead and decaying matter is called saprotrophic nutrition. Such organisms with saprotrophic mode of nutrition are called saprotrophs. Eg: Mushroom, Fungus - How would you test the presence of starch in leaves?
Answer: Take two potted plants of the same kind. Keep one in the dark (or in a black box) for 72 hours and the other in sunlight. Perform iodine test with the leaves of both the plants. Now leave the pot which was earlier kept in the dark, in the sunlight for 3 – 4 days and perform the iodine test again on its leaves. The leaf kept in the sunlight will turn blue-black due to the presence of starch. The leaf kept in the dark will not turn blue-black because of the absence of starch. - Give a brief description of the process of synthesis of food in green plants.
Answer: (i) Leaves are food factories of the plant.
(ii) Water and minerals present in the soil are absorbed by roots and transferred to other part.
(iii) Carbon dioxide present in the air is taken through tiny pores present on surface of leaves. It is called as Stomata.
(iv) Sunlight is absorbed by green pigment present in the leaf called as chlorophyll.
(v) Solar energy: it helps to prepare food from Co2 and water.
(vi) The process of synthesis of food in green plant is called photosynthesis. - Show with the help of a sketch that plants are the ultimate source of food.
Answer: (i) Grass — Grasshooper —- frog— snake—- eagle— decompose
( i) Plant—- deer— Tiger—- Decompose - 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 carbohydrate.
(c) In photosynthesis solar energy is absorbed by the pigment called
Chlorophyll.
(d) During photosynthesis plants take in carbondioxide and release oxygen gas. - Name the following:
(i) A parasitic plant with yellow, slender and branched stem.
Answer: Cuscuta
(ii) A plant that is partially autotrophic.
Answer: Pitcher plant
(iii) The pores through which leaves exchange gases.
Answer: Stomata - Tick the correct answer:
(a) Cuscuta is an example of:
(i) autotroph (ii) parasite (iii) saprotroph (iv) host
Answer: Parasite
(b) The plant which traps and feeds on insects is:
(i) Cuscuta (ii) china rose (iv) pitcher plant (iv) rose
Answer: pitcher plant - Match the items given in Column I with those in Column II:
Column I Column II
Chlorophyll Rhizobium
Nitrogen Heterotrophs
Cuscuta Pitcher plant
Animals Leaf
Insects Parasite
Answer:
Column I Column II
Chlorophyll Leaf
Nitrogen Rhizobium
Cuscuta Parasite
Animals Heterotrophs
Insects Pitcher plan
- Mark T if the statement is true and F if it is false:
(i) Carbon dioxide is released during photosynthesis. (T/F)
Answer: False
(ii) Plants which synthesise their food are called saprotrophs. (T/F)
Answer: False
(iii) The product of photosynthesis is not a protein. (T/F)
Answer: True
(iv) Solar energy is converted into chemical energy during photosynthesis. (T/F)
Answer: True - Choose the correct option from the following:
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: Stomata - 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: leaves - 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 vegetables inside large green house because to protect their crops from heavy rain, heavy wind, temperature, birds, insects and animals. The advantage for farmer that they get more yield.
