This page contains revision sheet for class 7 science chapter 1 Nutrition in Plants
Question 1: Why do organisms need to take food? Answer:
Food is essential for all living organisms to survive . It is necessary to perform life processes such as respiration, growth, repair and replacement of damaged body cells or tissues. All living organisms require a continuous supply of energy for various activities. The various components present in our food such as carbohydrates, proteins, fats, vitamins, and minerals provide energy to our body. Hence, all living organisms need to take food for their survival.
Question 2: Distinguish between a parasite and a saprotroph. Answer:
The organism that grows on the body of another organism and derives nutrients from it is known as a parasite.
The organism that obtains nutrients from the dead or decaying organic matter is called saprotroph.
Parasite develops special organs like suckers, hooks or haustoria to obtain nourishment from the host.
Saprotroph is capable of secreting some enzymes which can digest complex molecules of into simpler forms.
Examples of parasites are Cuscuta , orchids etc.
Examples of saprotrophs are fungi , bacteria etc.
Question 3: How would you test the presence of starch in leaves? Answer:
The presence of starch on leaves can be tested by Iodine Test. Iodine turns starch solution blue. Steps to do it
Pluck a healthy leaf from a plant
Boil the leaf in water for 10 minutes
Boil the leaf in alcohol over water bath to remove chlorophyll from it
Wash the decolourised leaf with water to remove any chlorophyll sticking to it
Pour a few drops of iodine on the leaf.
Appearance of blue colour in leaf shows the presence of starch in it.
Question 4: Give a brief description of the process of synthesis of food in green plants. Answer: Photosynthesis is food making process in plants from simple substances like carbon dioxide and water in the presence of sunlight.
The process of photosynthesis takes place in the green leaves of a plant.
The conditions necessary for photosynthesis to take place are:
c. Carbon dioxide
This process begin by absorption of sunlight energy by chlorophyll.
Light energy gets converted into chemical energy, and water is splitted into hydrogen and oxygen by light energy.
Finally there is reduction of carbon dioxide by hydrogen to form carbohydrate like glucose by utilizing the chemical energy.
Thus, photosynthesis can be represented by the following equation.
Question 5: Show with the help of a sketch that the plants are the ultimate source of food. Answer:
Plants are autotrophs since they make their own food. Animals including humans depends on them for all their nutrition needs. Figure below shows that how meet eating animals ultimately depends on plants for their nutrition.
Question 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.
Question 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) Cuscuta
(ii) Pitcher plant
(iii) Stomata Question 8: Tick the correct answer:
(a) Amarbel is an example of
(b)The plant which traps and feeds on insects is
(ii) china rose
(iii) pitcher plant
(iv) rose Answer: (a)Amarbel is an example of
(ii) parasite- correct
(b)The plant which traps and feeds on insects is
(ii) China rose
(iii) pitcher plant- correct
(iv) rose Question 9: Match the items given in Column I with those in Column II:
Question 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) Answer: (i) Carbon dioxide is released during photosynthesis. (F)
(ii) Plants which synthesise their food themselves are called saprotrophs. (F)
(iii) The product of photosynthesis is not a protein. (T)
(iv) Solar energy is converted into chemical energy during photosynthesis. (T) Question 11: Choose the correct option from the following:
Which part of the plant takes in carbon dioxide from the air for photosynthesis?
(i) Root hair
(iii) Leaf veins
(iv) Sepals Answer: (ii) Stomata Question 12: Choose the correct option from the following:
Plants take carbon dioxide from the atmosphere mainly through their:
(iv) leaves Answer: (iv) leaves
Resources for further reading
These are most of the resources we referred while preparing the notes for this chapter Nutretion in plants