Active Science Solutions for Class 7 Science Chapter 1 Food For Plants are provided here with simple step-by-step explanations. These solutions for Food For Plants are extremely popular among Class 7 students for Science Food For Plants Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Active Science Book of Class 7 Science Chapter 1 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Active Science Solutions. All Active Science Solutions for class Class 7 Science are prepared by experts and are 100% accurate.

Page No 10:

Question 1:

Organisms having heterotrophic nutrition lack
(a) sugar.
(b) chlorophyll.
(c) carbon dioxide.
(d) oxygen.

Answer:

(b) chlorophyll
Organisms having heterotrophic nutrition lack chlorophyll.

Page No 10:

Question 2:

When two organisms together for mutual benefit; the relationship is known as
(a) autotrophic.
(b) heterotrophic.
(c) symbiosis.
(d) parasitism.

Answer:

(c) symbiosis
A mutual relationship between two organisms is termed as symbiosis.

Page No 10:

Question 3:

Which of the following is not an example of a macronutrient?
(a) calcium.
(b) magnesium.
(c) nitrogen.
(d) iron.
    

Answer:

(d) iron
Iron is a micronutrient.

Page No 10:

Question 4:

Stomata open when they
(a) do not have sufficient water.
(b) are full of water.
(c) do not have water at all.
(d) are thin walled.

Answer:

(b) are full of water
Stomata open when the guard cells around them are turgid and full of water.

Page No 10:

Question 5:

Parasites are organisms that
(a) live on other organisms.
(b) harm the organisms they live in.
(c) can not make their own food.
(d) all the above.
            

Answer:

(d) all the above
Parasites cannot make their own food. Therefore, they live on other organisms called host. They harm their hosts by obtaining nutrition from them.

Page No 10:

Question 6:

Saprophytes are organisms that
(A) live on other organisms.
(B) live on dead and decaying matter.
(C) are useful to us.
(D) are all harmful to us.

(a) Only A and D are correct.
(b) Only B and C are correct.
(c) Only A and C are correct.
(d) Only C and D are correct.
    

Answer:

(b) Only B and C are correct.
Saprophytes live on dead and decaying matter in order to obtain nutrition. They are useful to us as they help in keeping the environment clean by removing the dead matter. 

Page No 10:

Question 7:

The gas given out in photosynthesis is
(a) nitrogen.
(b) carbon dioxide.      
(c) oxygen.
(d) hydrogen.

Answer:

(c) oxygen
Oxygen is given out in photosynthesis. It is formed through the breakdown of water during photosynthesis.

Page No 10:

Question 8:

The pigment that absorbs sunlight is
(a) haemoglobin.
(b) chlorophyll.
(c) chloroplast.
(d) starch.

Answer:

(b) chlorophyll
Chlorophyll is the green pigment that absorbs sunlight.

Page No 10:

Question 9:

The stomata take in and give out
(A) hydrogen.
(B) oxygen carbon dioxide, water.
(C) water and oxygen only.
(D) carbon dioxide only.

(a) Only B is correct.
(b) Only A is correct.
(c) Both B and C are correct.
(d) Both B and D are correct.

Answer:

(a) Only B is correct.
The stomata aid in the gaseous exchange of oxygen and carbon dioxide. They also take part in the process of transpiration.

Page No 10:

Question 10:

Which of the following is not a saprophyte?
(a) mushroom
(b) bacteria
(c) mistletoe.
(d) mould.

Answer:

(c) mistletoe
Mistletoe is a parasitic plant.

Page No 10:

Question 11:

Which of the following represents photosynthesis?
(a) water + oxygen----> carbon dioxide + carbohydrate
(b) carbon dioxide + water---->oxygen + carbohydrate
(c) carbohydrate + oxygen---> water + oxygen
(d) carbon dioxide + oxygen---> water + carbohydrate

Answer:

(b) carbon dioxide + water oxygen + carbohydrate

In photosynthesis, carbon dioxide reacts with water to from oxygen and carbohydrate in the presence of sunlight.



Page No 11:

Question 12:

What is common to the following: mistletoe, dodder, tapeworm, roundworm?
(a) All of them have a symbiotic relationship with a plant.
(b) All of them are types of lichens.
(c) All of them are parasites.
(d) All of them can prepare their own food.

Answer:

(c) All of them are parasites.
Mistletoe, dodder, tapeworm and roundworm cannot make their own food and they live on hosts. Hence, they are parasites.

Page No 11:

Question 13:

Some water plants are placed in a jar of water. The jar is then left in a sunny place. Little bubbles can be seen coming out of the plant. These bubbles contain__________.
(a) oxygen
(b) water vapour
(c) carbon dioxide
(d) hydrogen

Answer:

(a) oxygen

In aquatic plants, photosynthesis takes place. Such plants release oxygen into the water, which can be seen in the form of bubbles.

Page No 11:

Question 14:

Which one of the following is a common product between photosynthesis and transpiration?
(a) carbon dioxide
(b) water
(c) oxygen
(d) There is nothing common between the two.

Answer:

(d) There is nothing common between the two.

During photosynthesis, oxygen is released, while during transpiration, water is released.

Page No 11:

Question 15:

(a) What chemical substances are needed for photosynthesis to take place?
(b) Define photosynthesis.
(c) How can the starch test show that food has been prepared in the leaf?

Answer:

(a) The chemical substances needed for photosynthesis to take place are water and carbon dioxide.

(b) Photosynthesis is the process of manufacturing food in plants by using water and carbon dioxide in the presence of sunlight.

(c) The food formed by plants is starch. The presence of starch in the leaf can be tested through the iodine test. The iodine turns blue-black on reaction with starch. In this way, the starch test can show that food has been prepared in the leaf.

Page No 11:

Question 16:

(a) why is the leaf boiled in alcohol for a short time?
(b) why do we dip the leaf in water before adding the iodine solution?

Answer:

(a) The leaf is boiled for a short time to remove the chlorophyll.

(b) The leaf is dipped in water before adding the iodine solution in order to soften it.

Page No 11:

Question 17:

Give one word for the following:
(a) an organism living on dead and decaying organic matter
(b) the pigment which gives the green colour to plants.
(c) one example of a total plant parasite.
(d) one example of a heterotrophic organism
(e) saprophytes lack this

Answer:

(a) Saprophyte is an organism living on dead and decaying organic matter.
(b) Chlorophyll is the pigment that gives the green colour to plants.
(c) Dodder is an example of a total plant parasite.
(d) Lion is an example of a heterotrophic organism.
(e) Saprophytes lack chlorophyll.

Page No 11:

Question 18:

Differentiate between the following pairs of words giving one example each.
(a) saprophytes and parasites.
(b) autotrophy and heterotrophy.

Answer:

(a)

Saprophytes Parasites
They live on dead and decaying matter. They live on host organisms and obtain nutrition from them.
Example: Mushroom Example: Dodder

(b)
Autotrophy Heterotrophy
It is the process of making one's own food. It is the process of obtaining food from other organisms.
For example, it is exhibited by green plants like neem. For example, it is exhibited by animals like lion.

Page No 11:

Question 19:

(a) Explain the following terms: tanspiration, turgid, flaccid, macronutrients, trace elements.
(b) State one function of xylem and phloem each.
(c) Which one of the following is responsible for transpiration?

i. xylem
ii. phloem
iii. stomata
iv. root

Answer:

(a) Transpiration is the loss of water from the surface of the leaf.
Turgid means swollen cells that are full of water.
Flaccid means cells that lack water.
Macronutrients are minerals that are required in large quantities by plants.
Trace elements are minerals that are required in small quantities by plants.

(b) Xylem helps in the transportation of water and minerals in a plant. Phloem helps in the translocation or transportation of food in a plant.

(c) (iii) stomata
Transpiration is the loss of water from the stomata of the leaves.

Page No 11:

Question 20:

Which one of these sets of apparatus can be used to test for the presence of starch in leaves?

Figure...

Answer:

(d) and (e) form the set of apparatus that can be used to test the presence of starch in leaves.
(d) shows the boiling of leaves in alcohol to remove chlorophyll, while in set up (e), iodine is added to the boiled leaf to test the presence of starch.



Page No 12:

Question 21:

(a) What does this diagram show? Where are these openings found?
(b) Label the different parts of the diagram that are marked by arrows.

Figure...

(c) Mention two ways in which these tiny openings are useful to plants.

Answer:

(a) This diagram shows stomata. Stomata are found on the surface of leaves.

(b)



(c) These tiny openings called stomata are useful to plants as they facilitate gaseous exchange. Transpiration also takes place through them.

Page No 12:

Question 22:

What do you think would happen if plants did not possess chlorophyll?

Answer:

If plants did not possess chlorophyll, then they would not have been able to make their own food using sunlight and other raw materials.

Page No 12:

Question 23:

Copy these sentences in your notebook and complete them.
Leaves carry out photosynthesis..
___________________ is one of the substances required  for photosynthesis. It is absorbed by roots and conducted to leaves through a tissue called ____________________. Leaves prepare food in the form of glucose which is stored as __________________. Prepared food is conducted to all parts of the plant body through a tissue known as __________________. Leaves also lose excess ________________ by the process called ________________. Leaves do this through the tiny pores on their surface called _____________________.

Answer:

Leaves carry out photosynthesis. Water is one of the substances required for photosynthesis. It is absorbed by roots and conducted to leaves through a tissue called xylem. Leaves prepare food in the form of glucose which is stored as starch. Prepared food is conducted to all parts of the plant body through a tissue known as phloem. Leaves also lose excess water by the process called transpiration. Leaves do this through the tiny pores on their surface called stomata.

Page No 12:

Question 24:

Arun carried out the following experiment with a croton (variegated) leaf. He drew the leaf in his notebook marking the green and the non-green area. He put the leaf in hot alcohol till all the green colour came out and the leaf turned white. He then washed the leaf in water and covered the leaf in iodine solution.
(a) Why did he draw the leaf and mark the green and non-green areas?
(b) What was the colour change in iodine solution?
(c) Which portions of the leaf show colour change?
(d) what can you conclude from this experiment?

Answer:

(a) Arun drew the leaf and marked the green and the non-green areas to identify the part of the leaf that can make food in the form of starch.
(b) The colour of the iodine solution turned blue-black from brown.
(c) The green portions of the leaf show the change in colour.
(d) We can conclude that the green portion of the leaf can make food, i.e. starch, in the presence of sunlight. This is because this portion has chlorophyll.

Page No 12:

Question 25:

Can you name the missing substance(s) from the following word equation representing photosynthesis?
carbon dioxide + water      sunlight     food (glucose) + oxygen

Answer:

Chlorophyll, the green pigment needed for fixing sunlight, is missing from the equation.
The correct equation is as follows:
carbon dioxide + water chlorophyllsunlight food (glucose) + oxygen



View NCERT Solutions for all chapters of Class 7