NCERT Solutions Std 7 Science Nutrition in Plants

Nutrition in Plants

Exercise:

1). Why do organisms take food?

     Organisms need food for growth and development. Food also provides energy.

 

2). Distinguish between a parasite and a saprotroph.

Parasite Saprotroph
1. A parasite is an organism that takes the food from the living thing on which it survives. 1. An organism that takes in nutrients from dead and decaying matter is called saprotroph.
2. Example: Cuscuta 2. Example: Fungi
   

 

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

            The presence of starch in leaves can be tested by the Iodine test.

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

     During photosynthesis, chlorophyll-containing cells of leaves (Fig. 1.2), in the presence of sunlight, use carbon dioxide and water to synthesize carbohydrates. The process can be represented in an equation:

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

6). Fill in the blanks:

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

(b) The food synthesized 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.

     Cuscuta

(ii) A plant that is partially autotrophic.

     Insectivorous plant.

(iii) The pores through which leaves exchange gases.

     Stomata.

8). Tick the correct answer:

(a) Cuscuta is an example of:

(i) autotroph (ii) parasite (iii) saprotroph (iv) host

     Parasite.

(b) The plant which traps and feeds on insects is:

(i) Cuscuta (ii) china rose (iv) pitcher plant (iv) rose

     Pitcher plant.

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

Insects                                     Parasite

Answers:

Chlorophyll – Leaf                    

Nitrogen – Rhizobium                      

Cuscuta – Parasite                                       

Animals – Heterotrophs                                

Insects   – Pitcher plant                                 

10). Mark ‘T’ if the statement is true and ‘F’ if it is false:

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

     F

(ii) Plants which synthesize their food are called saprotrophs. (T/F)

     F

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

     T

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

     T

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

      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

      Leaves.

Additional Questions:

True or false

1). All living organisms require food.

     True.

2). Humans can synthesise food for themselves.

     False.

3). Sun is the ultimate source of energy for all living organisms.

     True.

4). During photosynthesis, carbon dioxide is released.

     False.

5). Starch is also a carbohydrate.

     True.

6). The leaves other than green also have chlorophyll

     True.

7). Algae can also prepare their own food by photosynthesis.

     True.

8). Proteins are nitrogenous substances.

     True.

9). There are few plants which can trap insects and digest them.

     True.

Fill in the blanks

1). All living organisms require food.

2). Leaves are the food factories of plants.

3). During photosynthesis, oxygen is released.

4). Carbohydrates are made up of carbon, hydrogen and oxygen.

Answer in short

1). What are nutrients?

     The components of food like carbohydrates, fats, proteins, vitamins and minerals are called as nutrients.

2). What things are necessary to carry out the process of photosynthesis?

     Chlorophyll, sunlight, carbon dioxide and water are necessary to carry out the process of photosynthesis.

Define the following.

1). Nutrition

     Nutrition is the mode of taking food by an organism and its utilization by the body.

2). Autotrophic nutrition

     The mode of nutrition in which organisms make food themselves from simple substances is called autotrophic nutrition.

3). Heterotrophic nutrition

     The mode of nutrition in which organisms depend upon other plants and animals for food is called heterotrophic nutrition.

4). Saprotropic nutrition

            The mode of nutrition in which organisms take in nutrients from dead and decaying matter is called saprotropic nutrition.

5). Symbiosis

            Some organisms live together and share both shelter and nutrients. This relationship is called symbiosis.

Give reason

1). Nutrients are very important to living things.

     The nutrients enable living things to build their bodies, to grow, to repair damaged parts of their bodies and provide the energy to carry out life processes. Therefore, nutrients are very important to living things.

2). In the absence of photosynthesis, life would be impossible on the earth.

     In the absence of photosynthesis there would not be any food. The survival of almost all living organisms directly or indirectly depends upon the food made by the plants. Besides, oxygen which is essential for the survival of all organisms is produced during photosynthesis. In the absence of photosynthesis, life would be impossible on the earth.

3). The sun is the ultimate source of energy for all living organisms.

              The solar energy is captured by the leaves and stored in the plant in the form of food. Thus, sun in the ultimate source of energy for all living organisms.

 

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