Exercise Questions

1. Why do organisms take food?

Solution:

All organisms require energy for their life processes. Plants prepare their food and acquire nutrients from abiotic components like soil, air, water and sunlight. On the other hand, animals need to get food from either plants or other animals to obtain nutrients; hence animals need to take food to acquire nutrients and energy.

2. Distinguish between a parasite and a saprophyte.

Solution:

3. How would you test the presence of starch in leaves?

Solution:

Take two potted plants of the same kind. Keep one in the dark for 72 hours and the other in sunlight. Perform the iodine test with the leaves of both the plants as given below. Now leave the pot which was earlier kept in the dark, undisturbed for 3 – 4 days and perform the iodine test again on its leaves.

Iodine test:

Put iodine solution on the leaf

Observation:

Blue-black colour will be observed on the leaves of the plant kept in sunlight, which indicates the presence of starch.

Blue-black colour will not be observed on the leaves of plant kept in the darkroom. This indicates the absence of starch.

4. Give a brief description of the process of synthesis of food in green plants

Solution:

Green plants use a process called as photosynthesis to prepare their food. The process is as follows

• Water is taken from the roots of the plant, and it is transported to leaves of the plant.
• Carbon dioxide from air enter the leaves through pores called stomata. This diffuses the cell containing chlorophyll.
• Water molecule is broken down into Hydrogen and Oxygen with the help of sunlight.
• Hydrogen combines with Oxygen and Hydrogen to form carbohydrates.
• Photosynthesis is represented by the following equation.

5. Show with the help of a sketch that plants are the ultimate source of food.

Solution:

6. Fill in the blanks:

(a) Green plants are called _________________ since they synthesise their own food.

(b) The food synthesised by plants is stored as _________________.

(c) In photosynthesis solar energy is absorbed by the pigment called ___________.

(d) During photosynthesis plants take in ______________________ and release __________________ gas.

Solution:

(a) Green plants are called autotrophs since they synthesise their food.

(b) The food synthesised by plants is stored as starch.

(c) In photosynthesis, solar energy is absorbed by the pigment called chlorophyll.

(d) During photosynthesis, plants take in carbon dioxide and release oxygen gas.

7. Name the following:

i) A parasitic plant with yellow, slender and branched stem.

ii) A plant that is partially autotrophic.

iii) The pores through which leaves exchange gases.

Solution:

i) Cuscuta

ii) Pitcher plant

iii) Stomata

8. Tick the correct answer:

(a) Cuscuta 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) (ii) Parasite

(b) (iii) pitcher plant

9. Match the items given in Column I with those in Column II:

Solution:

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 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:

1. False
2. False
3. True
4. True

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) Petals

Solution:

The answer is (ii) Stomata

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) leaves

Solution:

Answer is(iv) leaves

13. Why do farmers grow many fruits and vegetable crops inside large greenhouses? What are the advantages to the farmers?

Solution:

Fruits and vegetable crops are grown in large greenhouses because it protects crops from external climatic condition and to provide suitable temperature for the growth of crops.

Advantages to farmers while growing fruits and vegetable crops inside greenhouses are

• It protects crops from diseases and adverse climatic conditions.
• It protects crops from wind and rodents

Important topics covered in NCERT Solutions for Class 7 Science Chapter 1– Nutrition in Plants

1. Mode of Nutrition in Plants
2. Photosynthesis – food making process in Plants
3. The alternative mode of nutrition in Plants
4. Saprophytes
5. Nutrient replenishment in the soil

6. Fill in the blanks:

(a) Green plants are called _________________ since they synthesise their own food.

(b) The food synthesised by plants is stored as _________________.

(c) In photosynthesis solar energy is absorbed by the pigment called ___________.

(d) During photosynthesis plants take in ______________________ and release __________________ gas.

Solution:

(a) Green plants are called autotrophs since they synthesise their food.

(b) The food synthesised by plants is stored as starch.

(c) In photosynthesis, solar energy is absorbed by the pigment called chlorophyll.

(d) During photosynthesis, plants take in carbon dioxide and release oxygen gas.

7. Name the following:

i) A parasitic plant with yellow, slender and branched stem.

ii) A plant that is partially autotrophic.

iii) The pores through which leaves exchange gases.

Solution:

i) Cuscuta

ii) Pitcher plant

iii) Stomata

8. Tick the correct answer:

(a) Cuscuta 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) (ii) Parasite

(b) (iii) pitcher plant

9. Match the items given in Column I with those in Column II:

Solution:

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 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:

1. False
2. False
3. True
4. True

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) Petals

Solution:

The answer is (ii) Stomata

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) leaves

Solution:

Answer is(iv) leaves

13. Why do farmers grow many fruits and vegetable crops inside large greenhouses? What are the advantages to the farmers?

Solution:

Fruits and vegetable crops are grown in large greenhouses because it protects crops from external climatic condition and to provide suitable temperature for the growth of crops.

Advantages to farmers while growing fruits and vegetable crops inside greenhouses are

• It protects crops from diseases and adverse climatic conditions.
• It protects crops from wind and rodents

Important topics covered in NCERT Solutions for Class 7 Science Chapter 1– Nutrition in Plants

1. Mode of Nutrition in Plants
2. Photosynthesis – food making process in Plants
3. The alternative mode of nutrition in Plants
4. Saprophytes
5. Nutrient replenishment in the soil

Question 3.
Name the pigment which makes leaves green.
Answer:
Chlorophyll

Question 4.
State the function of chlorophyll.
Answer:
It captures energy of sunlight.

Question 5.
Name the unit which makes the bodies of living organisms.
Answer:
Cell

Question 6.
Give an example of an insectivorous plant.
Answer:
Sundew plant

Question 7.
What is the mode of nutrition of Cuscuta?
Answer:
Parasitic

Question 8.
What are the main parts of a cell?
Answer:

• Cell membrane
• Nucleus
• Cytoplasm

Question 9.
Which mode of nutrition is used by green plants?
Answer:
Autotrophic mode

Question 10.
Why insectivorous plants feed on insects?
Answer:
Insectivorous plants feed on insects to fulfill their nitrogen needs.

Question 11.
What are the raw materials for photosynthesis?
Answer:

• Water
• CO₂
• Sunlight
• Chlorophyll

Question 12.
What is autotrophic nutrition?
Answer:
The type of nutrition in which organism prepare their own food is known as autotrophic nutrition.

Question 13.
What is photos3mthesis?
Answer:
The process by which green plants prepare their own food using CO₂ and water in the presence of sunlight and chlorophyll is called photosynthesis.

Question 14.
What are heterotrophs?
Answer:
The type of organisms which depend on other organisms for their food are known as heterotrophs.

Question 15.
What do you mean by saprophytic nutrition?
Answer:
The type of nutrition in which organisms depend upon dead and decaying matter for their food is known as saprophytic nutrition.

Question 16.
Name two plants that have a symbiotic relationship with Rhizobium bacteria.
Answer:
Peas and moong

Question 17.
What are insectivorous plants? Give an example.
Answer:
The plants which trap insects for feeding are called insectivorous plants. For example, pitcher plant.

Question 18.
What are parasites?
Answer:
The organisms which obtain nutrients from other organisms are called parasites.

Question 19.
What is host?
Answer:
The organisms which provide nutrients to another organism, known as parasites, is called host.

Extra Questions for Class 7 Science Chapter 1 Short Answer Type

Question 1.
What is haustoria?
Answer:
Haustoria is the root of a parasitic plant that penetrates the host’s tissue and draws nutrients from it.

Question 2.
Differentiate between parasitism and symbiosis.
Answer:
Parasitism

• It is a relationship between two organisms which is beneficial to one and harmful to the other.
• One of the partner which draws food is called parasite and the other which provide nutrients is called host.
• Example: Cuscuta

Symbiosis:

• It is a relationship in which two organisms live together in a manner benefited.
• Each partner of the relationship is called a symbiont.
• Example: Lichen

Question 3.
List some harmful effect of fungi.
Answer:

• They cause diseases in crops, animals and humans.
• They spoil fruits, vegetables and all kinds of foodstuff.
• They spoil leather items and clothes.

Question 4.
How does a pitcher plant trap insects?
Answer:
The leaf of pitcher plant is modified into a pitcher-like structure. The apex of the leaf forms a lid over it which can open and close. Inside the pitcher, there are hair which are directed downwards. When an insect lands in the pitcher, the lid closes and the insect get trapped into the hair and then insect is digested by the digestive juice secreted by the pitcher.

Question 5.
From where do the plants obtain nitrogen?
Answer:
Soil has certain bacteria that convert gaseous nitrogen into a usable form and release it into the soil. These soluble forms are absorbed by the plants along with water. Plants also obtain nitrogen from the fertilizers added by the farmers.

Question 6.
Explain the symbiotic relationship in lichens.
Answer:
In lichens, a chlorophyll-containing partner, an alga, live together with a fungus. The fungus provides shelter, water, and minerals to the alga and in return, the alga provides food which it prepares by photosynthesis.

Question 7.
Explain the symbiotic relationship between Rhizobium bacteria and leguminous plants.
Answer:
Nitrogen gas is available in plenty in the air but plants cannot use it in manner they can use carbon dioxide. They need nitrogen in soluble form. The bacterium called Rhizobium can take atmospheric nitrogen and convert it into soluble form. But Rhizobium cannot make its own food. So it lives in the roots of leguminous plants and provide them with nitrogen and in turn gets food and shelter from the plant.

Extra Questions for Class 7 Science Chapter 1 Long Answer Type

Question 1.
Differentiate between autotrophic and heterotrophic modes of nutrition.
Answer:
Autotrophic:

• This type of nutrition is found in green plants.
• Autotrophic organism can prepare their own food.
• In this mode of nutrition, carbon dioxide is utilized to prepare food in presence of sunlight.

Heterotrophic:

• This type of nutrition is found in some plants and all animals.
• Heterotrophic organisms cannot prepare their own food.
• They cannot use carbon dioxide to prepare food in presence of sunlight.

Nutrition in Plants HOTS Questions With Answers

Question 1.
Why most of the things are spoiled by fungi during rainy season only?
Answer:
Spores of fungi germinate and grow when they get wet and warm conditions. Rainy season provides them the hostile condition, so they grow and spoil most of the things in rainy season only.

Question 2.
Do leaves other than green color also have chlorophyll?
Answer:
Yes, leaves other than green color also have chlorophyll. A large amount of red, brown and other pigments mask the green color. Photosynthesis takes place in these leaves also.

Question 3.
If pitcher plant is green and carries out photosynthesis, then why does it feed on insects?
Answer:
Generally, pitcher plants grow in locations where the soil is too poor in minerals, particularly in nitrogen and phosphorous. So to fulfill its mineral requirements it feed on insects.

Question 4.
Potato and ginger are both underground parts that store food. Where is the food prepared in these plants?
Answer:
Food is prepared in the leaves of these plants and then it is transported to underground parts for storage.

Question 5.
Why farmers do not add fertilizers during cultivation of leguminous crop?
Answer:
Farmers do not add fertilisers during cultivation of leguminous crop because roots of leguminous plants have symbiotic association with a bacterium called Rhizobium which fixes atmospheric nitrogen into the soil.

Question 6.
Why Cuscuta have parasitic mode of nutrition?
Answer:
Cuscuta does not have chlorophyll, so it cannot synthesize its own food. Thus it obtains nutrition from its host through modified roots called haustoria. Haustoria penetrate into the host cell and derive their nutrition from there.

Extra Questions for Class 7 Science Chapter 1 Value Based Questions

Question 1.
During a rainy season Radhika’s, mother seems to be very busy in cleaning and keeping things in proper places. Radhika being feeling bored went to her mother and asked her what she is up to. Her mother affectionately explained her that this is the time when fungus grow very much. So she is keeping all things safe from their attack. Radhika on understanding this started helping her mother.
(a) What is fungi?
(b) What is the mode of nutrition in fungi?
(c) Why fungi appear suddenly during rainy season?
(d) How can you keep your things safe from fungi?
(e) What value of Radhika is shown here?
Answer:
(a) Fungi is single-celled or multicelled, spore-producing organisms which feed on organic matter.
(b) Fungi feed on dead and decaying matter so their mode of nutrition is saprotrophic.
(c) Spores of fungi germinate and grow when they get hot and wet condition. This condition is met during rainy season.
(d) We can keep our things safe from fungi by

• Keeping them in dry and clean places.
• Putting or wrapping them with suitable materials.
• Keeping food items in refrigerator and closing them with proper lids.

(e) Radhika is inquisitive, enthusiastic, and helpful.

Question 2.
Raman once saw Raghav planning of cutting all the trees around his house. Raman asked Raghav the reason for this step. Raghav replied that these trees do not provide him anything like fruits, timber, etc., so he is cutting them. Raman explained him though they are not providing him fruits, timber, flower, etc., but still they are very useful to all.
(a) How plants are still useful to all?
(b) List some items we get from plants.
(c) A cow ate all the leaves of a small plant but then also new leaves seen sprouting after a few days. How did the plant survived without leaves?
(d) What values of Raman and Raghav is shown here?
(e) What will you do if you also have a tree near your house which is of no use to you?
Answer:
(a) Plants give out oxygen and takes in carbon dioxide during the process of photosynthesis. Thus helps to keep the atmosphere clean.
(b) We get food, clothes, timber, fuel, medicines, fruit, flower, etc., from plants.
(c) Plant survived on the food stored in plant stem and roots for that time being still the leaves started sprouting.
(d) Raman is a good thinker, intelligent, eco-friendly with future vision. Whereas Raghav is self-oriented and ignorant.
(e) If it is of no use then also I will try to guard it because at least it will provide us with fresh air and shade.