NCERT Solutions for CBSE Class 7 Science Chapter 1 - Nutrition in Plants

Q1. Why do organisms need to take food?

Ans: 

Organism needs food to:-

1. Survive

2. Grow

3. Gain energy

4. Damage repair

5. Maintain bodily functions

6. Other activities

Q2. Distinguish between a parasite and saprophyte.

Ans: Differences between parasites and saprophytes are as follows:

Q3. How would you test the presence of starch in leaves?

Ans: When starch reacts with an iodine solution, it takes on a characteristic dark blue colour. If a few drops of iodine solution are applied to a leaf and a dark blue colour develops, the existence of starch in the leaf is confirmed.

Q4. Give a brief description of the process of synthesis of food in green plants.

Ans: In green plants, the synthesis of food occurs by a process called photosynthesis. During this process, chlorophyll in the cells of the leaves uses carbon dioxide and water to synthesize carbohydrates in the presence of sunlight. The process can be represented by an equation:

• \[Carbon\:dioxide\:+\:\:Water\:\xrightarrow[Chlorophyll]{Sunlight}\:Carbohydrates\:+Oxygen\]

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During this process, oxygen is released, and the carbohydrates generated are stored as starch.

Q5. Show with the help of a sketch that the plants are the ultimate source of food. 

Ans:

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6. Fill in the blanks:

1. Green plants are called ----------- since they synthesize their own food.b. The food synthesized by the plants is stored as ---------------. 

Ans: Green plants are called autotrophs since they synthesize their own food.

2. The food synthesized by the plants is stored as ---------------. 

Ans: The food synthesized by the plants is stored as starch.

3. In photosynthesis, solar energy is captured by the pigment called------------.

Ans: In photosynthesis, solar energy is captured by the pigment called chlorophyll.

4. During photosynthesis plants take in ------------- and release -------------. 

Ans: During photosynthesis, plants take in carbon dioxide and release oxygen.

Q7. Name the following: 

1. A Parasitic plant with a yellow, slender, and tubular stem.

Ans: Cuscuta- The Cuscuta plant is classified as a parasite since it lacks chlorophyll and feeds on the host. The host loses vital nutrients as a result of this process.

2. A plant that has both autotrophic and heterotrophic modes of nutrition.

Ans: Pitcher plant - The pitcher plant is an autotrophic plant that performs photosynthesis, but it also has a partly heterotrophic method of nutrition because it grows in nitrogen-deficient soil.

3. The pores through which leaves exchange gases.

Ans: Stomata- Gases such as carbon dioxide, water vapour, and oxygen can diffuse into and out of the plant's interior tissues through stomata.

Q8. Tick the Correct Answer: 

a. Amarbel is an example of:

1. Autotroph

2. Parasite

3. Saprophyte

4. Host 

Ans: (ii) Parasite- 

Cuscuta or Dodder are other names for Amarbel. A parasite is an organism that grows on the body of another organism and feeds on its nutrition.

b. The plant which traps and feeds on insects is:

1. Cuscuta

2. China rose

3. Pitcher plant 

4. Rose 

Ans: (iii) Pitcher plant

The pitcher plant is a type of plant with trapping and digesting leaves. Medicine is made from the leaf and roots.

Q9. Match the item in given column I with those in column II.

Ans: 

Q10. Mark “T” if the statement is true and “F” if it is false:

1. Carbon dioxide is released during photosynthesis. (T/F) 

Ans: False- Oxygen is released during photosynthesis.

2. Plants that synthesize their food themselves are called saprotrophs. (T/F) 

Ans: False- Plants which synthesize their food themselves are called autotrophs. 

3. The product of photosynthesis is not a protein. (T/F)

Ans: True- The product of photosynthesis is not a protein.  

4. Solar energy is converted into chemical energy during photosynthesis. (T/F)

Ans: True- Solar energy is converted into chemical energy during photosynthesis.

Q11. Choose the Correct Option From the Following:

Which part of the plant gets carbon dioxide from the air for photosynthesis?

1. Root hair

2. Stomata 

3. Leaf veins

4. Sepals 

Ans: (b) Stomata get carbon dioxide from the air for photosynthesis.

Q12. Choose the correct option from the following:

Plants take carbon dioxide from the atmosphere mainly through their:

1. Roots 

2. Stem

3. Flowers

4. Leaves

Ans: (d) Plants take carbon dioxide from the atmosphere mainly through their leaves.

NCERT Solutions for Class 7 Science- Free PDF Download

Nutrition in plants Class 7 NCERT is a conceptual chapter for the students of Class 7. Vedantu provides all Class 7 Science Chapter 1 Solutions in PDF format for students to get easy access. These solutions have the entire Ch 1 Science for Class 7 covered and will help students to score better marks in Science exams.

Important Topics Covered in NCERT Solutions for Chapter 1 of Class 7 Science- Nutrition in Plants 

In Class 7 Chapter 1 Nutrition in Plants, students will learn many concepts related to plants and how they get nutrition for themselves. Other important topics that students will learn about are as follows:

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

NCERT Solutions for CBSE Class 7 Science Chapter 1 Nutrition in Plants will help the students to answer the NCERT questions in a more appropriate way  so as to score better marks in the examination. The free PDF will also allow them to access this important study resource from anywhere and anytime, which will help them build a strong foundation on the above-mentioned concepts at their convenient time. 

Therefore, students are advised to thoroughly study NCERT Solutions for CBSE Class 7 Science Chapter 1 Nutrition in Plants to aid their preparation for the exams. 

1.1 Mode of Nutrition in Plants

Among all living beings, plants are the only ones who can make their own food. They prepare their food from sunlight, minerals, water, and carbon dioxide that exist in the surrounding. The nutrients help the plant to grow, build itself, and repair damaged body parts. The nutrients also provide the required energy to perform vital life processes. The mode is nutrition by which an organism takes nutrients from its surroundings and utilizes them in its body.

There are two modes of nutrition- autotrophic and heterotrophic nutrition mode. The autotrophic nutrition mode enables the organisms to make their food from simpler substances from the surrounding. For example, plants are autotrophs. The heterotrophic nutrition mode allows the organisms to derive their nutrients from other animals. For example, all animals are heterotrophs.

Since plants are autotrophs, the next questions that will come to you are how do plants make their food.

1.2 Photosynthesis- Food Making Process in Plants

You must have learned that leaves are considered food factories in plants. They synthesize the food for all parts of the plant. The different body parts transport different raw materials to the parts of the leaves. The roots absorb water and minerals from the soil and send them to leaves through vessels that run all over the root, stem, and leaves. Tiny pores on the leaves, called stomata, absorb carbon dioxide. The guard cells control the opening and closing of stomata on the leaves.

All leaves contain chlorophyll. The chlorophyll is responsible for the green colour of the leaves. The chlorophyll traps sunlight and uses solar energy to produce food from carbon dioxide and water. Therefore, to produce food, plants require sunlight, water, and carbon dioxide. The process by which plants produce their own food from sunlight, carbon dioxide, and water is called photosynthesis. Photosynthesis is an exclusive process that takes place in plants and some algae. It uses solar energy.

Therefore, you can imagine the importance of photosynthesis for maintaining life on earth. Without photosynthesis, there will be no food, since all animals depend indirectly or directly on the plants for food. Without food for plants, life is impossible on earth.

At the time of photosynthesis, the chlorophyll present on the leaves uses sunlight, water and carbon dioxide to produce carbohydrates. Carbohydrate or starch is the food for the plant. The equation for photosynthesis is:

\[\text{Carbon dioxide + water} \xrightarrow[Chlorophyll]{Sunlight} \text{Carbohydrate + oxygen}\]

As you can see in the equation, oxygen is known to release during photosynthesis. The carbohydrate thus formed is converted to starch, which is another carbohydrate. Photosynthesis is indicated by the presence of starch in the leaves. 

Green plants do not only conduct photosynthesis. Yellow, red or multicolored leaves also perform photosynthesis. Chlorophyll is also present in the leaves that are of other colors.

If you look at the pond or any other stagnant water bodies, you will observe green slimy patches on the water surface. These slimy patches are algae and contain chlorophyll, which makes them green coloured. With the help of these chlorophylls, algae, too, can make their food by the process of photosynthesis.

Every living body is made up of numerous tiny building blocks called cells. Cells play numerous functions in the body. During photosynthesis, the stomata are responsible for gaseous exchange. The opening and closing of stomata are controlled by the guide cells.

1.3 Other Modes of Nutrition in Plants

Not all plants contain chlorophyll. For example, you will often find yellow tubular plants twining around the stem of other plants. It is called Cuscuta and they do not contain chlorophyll. Then how exactly do they get their food? Such plants that lack chlorophyll obtain food by heterotrophic nutrition mode. That means that the plants obtain food from other living organisms. The other living organism is called the host. If the plants deprive the valuable nutrients of the host, they are called parasites. You have often come across the word parasite in terms of insects and other animals. But can plants also be a parasite? Well, yes!

Do you know that plants can also eat animals? Yes, they do so. For example, a pitcher plant has a pitcher-shaped structure which is a modification of a leaf. It has a lid at the top which closes when any insect (prey) falls into the pitcher. Some hairs are directed downwards on the inside of the pitcher. These plants are insect-eating and known as insectivorous plants.

1.4 Saprotrophs

You must have seen mushrooms selling in the market. They are club-shaped structures mostly white or cream in colour. If they do not contain chlorophyll, then how do they prepare their food?

Mushrooms are fungi. They are not plants and they obtain food from other nutrition modes. They secrete digestive juices and chemicals on decaying or dead organic matters and extract nutrients from them. Such a nutrition mode is called the saprophytic nutrition mode and the fungi are known as saprotrophs.

You will also find fungi growing on leather, pickle, bread, and other surfaces, which are kept in hot and humid weather for a long time.

You will find most fungi in rainy seasons. These saprotrophs are the reasons why most food and clothes get spoiled in this season. The fungi propagate with the help of spores that can travel through the air. Once these spores come in contact with a wet surface, they can settle down, germinate and grow. So now you can understand why your food or wet clothes get spoiled in the rainy season.

There are other types of relationships between organisms. In one relationship, two organisms stay together since both of them are benefiting. For example, some fungi live in close association with the roots of some plants. They derive their nutrients from plants while providing nitrogen to the plants in return. Such a type of relationship where both the organisms are benefitted is called a symbiotic relationship.

In lichens, fungi and algae stay together. The alga delivers food it makes by photosynthesis. The fungus provides water, minerals, and shelter.

1.5 How Nutrients are Replenished in the Soil

If plants use all the minerals and nutrients from the soil, the levels of these nutrients in the soil are supposed to go down. To replenish the nutrient content of the soil, farmers often add manures and fertilizers to the soil. In this way, the nutrients are replenished, and it will support the continued growth of plants on this soil.

In general, soils require plenty of nitrogen for their growth. After each harvest, the soil gets devoid of nitrogen. To have further plantation on these soils, farmers often grow leguminous crops that can increase the nitrogen content of the soil. These leguminous crops like pulses, grams, dal, etc. are in a symbiotic relationship with a bacteria called rhizobium, which fixes atmospheric nitrogen into the soil. The bacteria obtain food and shelter in return from the plants. Growing leguminous crops in the field reduces the need to add nitrogen-containing artificial fertilizers to the soil.

In this CBSE Class 7 Science Chapter 1 nutrition in plants, you learned about plants that are autotrophs. You also learned about different nutrition modes amongst plants like heterotrophic, saprophytic, parasitic, insectivorous and symbiotic.

Facts that Matter

• All organisms take food and utilize it to get energy for growth, maintenance and various life processes.

• Based on the mode of getting food, organisms are classified as autotrophs and heterotrophs.  

• Autotrophs prepare their own food using simple inorganic materials like carbon dioxide and water. 

• The essential requirements for photosynthesis are chlorophyll and sunlight.

• Heterotrophs are organisms that cannot make food on their own and so they depend on autotrophs directly or indirectly for food.

• Parasitic, saprophytic, insectivorous and symbiotic are the different modes of heterotrophic nutrition in plants.

• Plants like Cuscuta are parasites as they take nutrition from the host plant.

• Saprotrophs like Fungi obtain nutrition from dead and decaying organic matter. 

• Symbiotic relationship between Rhizobium and legumes helps in enriching the soil of the nitrogen that was lost.

• Leaves of the plants prepare the food so they are called the food factory of the plant.

• The important components of food are carbohydrates, fats, proteins, vitamins and minerals. 

• The Sun is the fundamental source of energy for all living organisms.

NCERT Solutions Class 7 Science Other Chapters

• Chapter 2 - Nutrition in Animals

• Chapter 3 - Fibre to Fabric

• Chapter 4 - Heat

• Chapter 5 - Acids

• Chapter 6 - Physical and Chemical Changes

• Chapter 7 - Weather

• Chapter 8 - Winds

• Chapter 9 - Soil

• Chapter 10 - Respiration in Organisms

• Chapter 11 - Transportation in Animals and Plants

• Chapter 12 - Reproduction in Plants

• Chapter 13 - Motion and Time

• Chapter 14 - Electric Current and Its Effects

• Chapter 15 - Light

• Chapter 16 - Water: A Precious Resource

• Chapter 17 - Forests: Our Lifeline

• Chapter 18 - Wastewater Story

Additional Materials for CBSE Class 7 Science 

• CBSE Class 7 Important Questions

• CBSE Class 7 Revision Notes

• CBSE Class 7 Exemplar Solutions

Key Features of NCERT Solutions for Class 7 Science Chapter 1

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