NCERT Solutions for Class 7 Science

Students can find NCERT Solutions for Class 7 Science on the website or app of Extramarks. The solutions provided here are prepared by subject matter experts that give special attention to providing accurate and thorough solutions. Students can use these resources to prepare well for their examinations,  do last-minute revision, and  can also get help for their assignments. 

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

NCERT Solutions for Class 7 Science

In Class 7, students are introduced to a number of core concepts of Science which will be further studied in depth  in higher grades. This makes it very important for them to pay special attention to such important concepts . Since practising NCERT questions is a major part of the students’ preparation, Extramarks offers NCERT Solutions for all the chapters covered in the Class 7 Science NCERT textbook. Students can access them from the Extramarks website or the app.

Chapter 1 – Nutrition in Plants

Chapter 1 of Class 7 Science textbook explains the process by which plants get their nutrition. Plants are the only living organisms that have the ability to synthesise their own food using the process of photosynthesis. The chapter discusses the entire process of photosynthesis in detail while also providing a great deal of interesting information to students. 

NCERT Solutions for Class 7 Science Chapter 1

1.1 Mode of Nutrition in Plants

Plants synthesise food for themselves . They use  sunlight, water, CO2, and minerals to produce food. Nutrition is a term used for food taken and utilised by organisms which provides them energy. The nutrients aid in the building of plants bodies, their growth, and for healing of their injured body parts. Nutrients also offer the energy needed to carry out crucial biological functions.. Autotrophic nutrition and heterotrophic nutrition are the two types of nutrition. The mode of nutrition where organisms synthesise food for themselves using simple substances present in nature is called Autotrophic nutrition.. Therefore,  plants are called autotrophs.  In Heterotrophic nutrition,  the organisms are unable to make their own food and hence, are dependent on plants or other organisms to obtain nutrition. All animals, for example, are heterotrophs. 

1.2 Photosynthesis- Food Making Process in Plants

Leaves are called the food factories of a plant. The roots absorb both water and minerals from the soil which are then transported to the leaves by the numerous body parts of the plant. .  Carbon dioxide gets absorbed via tiny pores present on the leaves called stomata. Every leaf contains chlorophyll. The chlorophyll in the leaves is responsible for their green hue. Chlorophyll absorbs energy from the sunlight which helps in the preparation of food using carbon dioxide and water. This process is known as photosynthesis through which plants obtain their nutrition.. During photosynthesis, chlorophyll on the leaves uses sunlight, water, and carbon dioxide to produce carbohydrates. Carbohydrate, often known as starch, is the plant's primary source of nutrition. The following is the equation for photosynthesis  :

Carbon dioxide + water  (in the presence of sunlight & chlorophyll)−→ Carbohydrate + oxygen

Photosynthesis occurs in yellow, red, or multicoloured leaves. Algae are slimy, chlorophyll-rich patches which can also produce food through photosynthesis.

1.3 Other Modes of Nutrition in Plants

Chlorophyll isn’t found in all plants and hence, they cannot synthesise food. Cuscuta, for example, is frequently found twining around the stems or branches of trees since it lacks chlorophyll. Plants that lack chlorophyll rely on a heterotrophic mode of nutrition to survive. It climbs on other plants and trees to get ready-made food. The plants and trees it climbs upon are called hosts. We can consider such plants as parasites as they rob the host of vital nutrients. Plants can consume insects as well. A pitcher plant, for example, has a pitcher-shaped structure that is a modification of a leaf. The top part of the pitcher has a cover that closes when an insect (prey) falls into it. Inside the pitcher, there is hair pointing downwards which traps the insect. Such plants are known as insectivorous plants.

1.4 Saprotrophs

Mushrooms are a well-known example of Fungi. They are not plants, and they feed themselves by other means. They obtain nutrients from rotting or dead organic stuff by secreting digestive fluids and chemicals. The fungus is known as saprotrophs. Fungi may also develop on leather, pickles, bread, and other surfaces. You can find the majority of fungi during wet seasons. May food and clothing deteriorate during this season due to these saprotrophs. Fungi reproduce by dispersing spores that may move through the air. These spores can settle down, germinate, and develop once they come into touch with a damp surface. Other sorts of organism-to-organism connections exist. Two species stay together in a single relationship because they both benefit. Various fungi, for example, live close to the roots of some plants. They get their nutrients from plants and provide the plant's nitrogen in exchange. The term symbiotic connection refers to a partnership in which both organisms benefit. Fungi and algae live together in lichens. The algae distributes the food it produces through photosynthesis. Water, minerals, and shelter are all provided by the fungus.

1.5 How are nutrients replenished in the soil?

If plants use all of the minerals and nutrients in the soil, the amounts of these nutrients should decrease. Farmers frequently apply manures and fertilisers to the ground to replace the nutritional supply. The nutrients will allow plants to continue to develop in this soil. Soils, in general, require a lot of nitrogen to flourish. The clay becomes nitrogen-depleted after each harvest. Farmers frequently produce leguminous crops. It can boost the soil's nitrogen content to increase planting on these soils. Leguminous crops such as pulses, grams, dal, and others have a symbiotic connection with a bacteria called rhizobium, which fixes nitrogen from the atmosphere into the soil. In exchange, the plants supply food and habitat for the bacteria. When farmers cultivate leguminous crops in the field, the usage of nitrogen-containing artificial fertilisers in the soil gets minimised.

Facts that Matter

  • All creatures eat food and are used to get energy for growth, maintenance, and numerous living functions.
  • We can classify organisms into autotrophs or heterotrophs based on how they obtain nourishment.
  • Autotrophs use simple inorganic elements such as carbon dioxide and water to make their sustenance.
  • Chlorophyll and sunshine are two of the most crucial components of photosynthesis.
  • Heterotrophs are creatures that cannot produce food themselves and must rely on autotrophs for nourishment, either directly or indirectly.
  • The diverse types of heterotrophic nourishment in plants include parasitic, saprophytic, insectivorous, and symbiotic.
  • Cuscuta plants are parasites that feed on the host plant's nutrients.
  • Fungi are saprotrophs that feed on dead and decaying organic substances.
  • Rhizobium and legumes have a symbiotic connection that serves to replenish nitrogen in the soil.
  • Plant leaves are known as the plant's food factory because they prepare food.
  • Carbohydrates, lipids, proteins, vitamins, and minerals are all vital components of meals.
  • For all living things, the sun is the most significant energy source.

Key Features of NCERT Solutions for Class 7 Science Chapter 1

Every student wants to get excellent grades in their exams. To do so, they must have a thorough understanding of the subject and more importantly, they should practise as many questions as they can. This is where students will find NCERT Solutions for Class 7 Science Chapter 1 by Extramarks really helpful. Other features and advantages of these solutions are listed below;

  • Subject matter experts prepare these solutions by making sure that each answer is thoroughly explained in easy-to-understand language for a better understanding of the students
  • The NCERT Solutions for Class 7 Science Chapter 1 have  all the answers in a well-organised form, allowing students to save time while studying
  • Students will find these resources very helpful for their last-minute revisions and preparations.

Q.1 Why do organisms take food?

Ans-

Organisms take food to meet their requirements of nutrients and energy. Nutrients and energy enable the organisms to grow, reproduce and repair their damaged body parts.

Q.2 Distinguish between a parasite and a saprotroph.

Ans-

A parasite derives nutrition from the body of a living host by invading its tissues whereas, a saprotroph derives its nutrition from dead and decaying organic matter.
Examples of parasite: Cuscuta and leech
Examples of saprotrophs: Fungi and bacteria

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

Ans-

The presence of starch in the leaves can be tested with the help of iodine solution that gives blue-black colour with starch. Boil few green leaves in alcohol in a test tube, till they turn colourless or pale green. Then wash the leaves in tap water and transfer them into a petridish. Add some drops of iodine. A change in colour of leaves to blue-black indicates the presence of starch in them.

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

Ans-

The leaves of green plants contain chlorophyll pigment which traps solar energy. This energy is utilized by the leaves for the synthesis of organic food from water and carbon dioxide. Water is absorbed by the roots and carbon dioxide is taken up from the atmosphere through the tiny pores present on the leaf surface called stomata. Thus, sunlight, chlorophyll, water and carbon dioxide are the important raw materials required for photosynthesis.

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

Ans-

The following diagram depicts the synthesis of carbohydrates or glucose by the green plants in the presence of sunlight and the transfer of energy to herbivores and then, to carnivores on consumption:

Explanation: In this food chain, we observe that carnivores (like tigers, lions) depend on herbivores (like deer) for food and energy. A herbivore gets it food and energy by consuming plants. Plants manufacture their food with the help of sunlight. Thus, herbivores and carnivores are all directly or indirectly dependent on plants for food.

Q.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 __________________.

Ans-

(a) Autotrophs
(b) Starch
(c) Chlorophyll
(d) Carbon dioxide, Oxygen

Q.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.

Ans-

(i) Cuscuta
(ii) Pitcher plant
(iii) Stomata

Q.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

Ans-

(a) Cuscuta is an example of: (ii) parasite
(b) The plant which traps and feeds on insects is: (iii) pitcher plant

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

Column I Column II
Chlorophyll Rhizobium
Nitrogen Heterotrophs
Cuscuta Pitcher Plant
Animals Leaf
Insect Parasite

Ans-

The correctly matched contents of Column I and Column II are as follows:

Column I Column II
Chlorophyll Leaf
Nitrogen Rhizobium
Cuscuta Parasite
Animals Heterotrophs
Insect Pitcher Plant

Q.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 that 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)

Ans-

(i) False
(ii) False
(iii) True
(iv) True

Q.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

Ans-

(ii) Stomata

Q.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

Ans-

(iv) leaves

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

Ans-

Green house provides a suitable climatic condition for the plants’ growth by maintaining an average temperature.
This method protects the fruits and vegetables from winds, birds and insects.

For viewing question paper please click here

FAQs (Frequently Asked Questions)
1. How can I acquire good grades in my exams with study materials by Extramarks?

Extramarks has highly qualified and experienced teachers. They are familiar with each student’s academic demands. The resources they created are as per the CBSE’s updated guidelines. This would undoubtedly assist students in performing better in exams.

2. What is the fungus's source of nutrition?

Fungi are saprotrophic organisms. They consume organic things that have perished or are degrading. The digestive secretions of the fungus break down the dead materials into a soluble state that may get absorbed.