Goa Board Class 7 Solutions for Science – Nutrition in Plants (English Medium)
Page No. 9:
Question 1:
Why do organisms need to take food?
Solution :
All living organisms require food to survive because of the following reasons:
i.It gives 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 and fats provide energy to our body.
ii.Some components like minerals and vitamins are important for growth and development of the body.
Concept insight: Organisms need food to produce energy for growth and development.
Question 2:
Distinguish between a parasite and a saprotroph.
Solution :
Parasite | Saprotroph |
i. The organism that grows on the body of another organism and derives nutrients from it is known as a parasite. ii. Parasites absorb prepared food from the host.
Example of parasites are cuscuta and orchids. |
i. The organism that obtains nutrients from the dead or decaying organic matter is called saprotroph. ii. Saprotrophs digest food outside the body and absorbs digested food. Example of saprotrophs are fungi and some bacteria. |
Concept insight: Parasites absorb prepared food the host. Saprotrophs digest food outside the body and absorbs digested food.
Question 3:
How would you test the presence of starch in leaves?
Solution :
Experiment to test the presence of starch in leaves:
i. Take two healthy green potted plants of the same type.
ii. Keep one potted plants in a dark room for one or two days in order to remove all the starch from the leaves.
iii. Keep the other plant in sunlight.
iv. Now, take one leaf from each potted plant and put a few drops of iodine solution on them.
v. Note down the change in the colour of both the leaves.
Observation: No blue-black colour will be observed on the leaves of plant kept in the dark room. This indicates the absence of starch. Blue-black colour will be observed on the leaves of the plant kept in sunlight. This indicates the presence of starch.
Concept insight: Plants prepare glucose during photosynthesis which gets stored in plants in the form of starch. Iodine turns blue-black when reacted with starch.
Question 4:
Give a brief description of the process of synthesis of food in green plants.
Solution :
Photosynthesis is defined as the process in which the chlorophyll- containing plant cells synthesize food in the form of carbohydrates, using carbon dioxide and water in the presence of solar energy.
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 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.
Concept insight: Photosynthesis is the process through which plants prepare their food.
Question 5:
Show with the help of a sketch that plants are the ultimate source of food.
Solution :
Concept insight: Recall the process of photosynthesis.
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___________________.
Solution :
Green plants are called __autotrophs__ since they synthesize their own food.
(b) The food synthesized 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.
Concept insight: Recall the process of photosynthesis
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.
Solution :
i) Cuscuta
(ii) Pitcher plant
(iii) Stomata
Concept insight: Nutrition in plants
Question 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
(iii) pitcher plant
(iv) rose
Solution :
(a)Amarbel is an example of
(ii) parasite
(b)The plant which traps and feeds on insects is
(iii) pitcher plant
Concept insight: Recall the modes of nutrition in plants
Question 9:
Solution :
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)
Solution :
(i) Carbon dioxide is released during photosynthesis. (F)
Concept insight: Oxygen is released during photosynthesis.
(ii) Plants which synthesize their food themselves are called saprotrophs. (F)
Concept insight: Saprotrophs are organisms which feed on dead and decaying matter.
(iii) The product of photosynthesis is not a protein. (T)
Concept insight: The product of photosynthesis is a carbohydrate.
(iv) Solar energy is converted into chemical energy during photosynthesis. (T)
Concept insight: As solar energy is used to prepare starch from carbon dioxide and water so solar energy is converted into chemical energy.
Page No. 10:
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
(ii) Stomata
(iii) Leaf veins
(iv) Sepals
Solution :
(ii) Stomata
Concept insight: Recall the process of photosynthesis.
Question 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) leave
Solution :
(iv) leaves
Concept insight: Recall the process of photosynthesis.