Nutrition in Plants Complete Question Answers | SCIENCE CLASS 7 , CHAPTER 1 SOLUTIONS

III. Q. What is nutrition?

Ans 1. The process of taking in food and using it for growth , repair and other processes to maintain life is called nutrition.

Q. Are birds autotrophs ?

Ans 2. No, birds are not autotrophs.

Q.What is a heterotroph?

Ans 3. Organisms which cannot produce their own food and depend on other sources are called heterotrophs.

Q. Give an example of saprophyte.

Ans 4. Fungi is an example of saprophyte.

Q. What do chloroplast contain?

Ans 5. Chloroplast contain green pigments called chlorophyll.

Q. Do coloured leaves have chlorophyll?

Ans 6. Yes , coloured leaves have chlorophyll.

Q. Name the gas that is produced during photosynthesis.

Ans 7. Oxygen is produced during photosynthesis.

Q. Where do rhizobium bacteria live?

Ans 8. Rhizobium bacteria live in the roots of plants like gram ,pea , beans etc.

Q. Give an example of partial parasitic plant.

Ans 9. Mistletoe is an example of partial parasitic plant.

Q. What do phloem tubes transport in the plant?

Ans 10. Phloem tubes transport food that is prepared in the leaves of plants in the form of sugar.

IV. Q. Distinguish between autotrophs and heterotrophs.

Ans 1. Autotrophs are organisms that can prepare their own food from simple substances from their surroundings. Eg: Plants .

Heterotrophs are organisms that cannot prepare their own food and depends on other sources for food . Eg : Animals , Human beings etc

Q. Write the chemical formula for photosynthesis.

Ans 2. The chemical equation for photosynthesis is : 6 CO2 + 6 H2O ———-> C6H12O6 + 6O2.

Q. List the function of xylem and phloem.

Ans 3. Function of xylem is to transport water and dissolved ions from roots throughout the plant body.

Function of phloem is to transport food particles in form of sugar to plant body.

Q. Define rotation of crops.

Ans 4. Crop rotation is the process of planting different crops alternatively in same plot of land to improve soil health , optimize nutrients in the soil , control weed , pests and diseases .

Q. What are parasitic plants? Explain with an example.

Ans 5. Plants which obtain all or a part of its nutrition from another plant (host) without contributing the benifit of host are called parasitic plants.

Eg: Cuscata and Mistletoe are such parasitic plants which obtain nutrition from host plant body.

Q. What is a lichen?

Ans 6. Lichens are symbiotic association between algae and fungi .The algae contains chlorophyll and makes it own food and shares it with the fungi which in return provides water and minerals to algae .

V. Q. How to leaves help a plant make its food?

Ans 1. Photosynthesis which absorbs sunlight are present on the leaves of plants and with help of this plants are able to make their own food in the form of glucose and starch .

Q. How does a saprophyte obtain nutrition?

Ans 2. Saprophytes grows on dead organic matter and then starts secreting digestive juices .These digestive juices then break the organic matter into simple substances and converts it into a solution . After completion of this ,they start absorbing the solution and obtains nutrition.

Q. How do bean plants enrich the soil?

Ans 3. The roots of bean plants contain , bacteria such as rhizobium , and this bacteria forms nodules which helps in nitrogen fixation and serves as a major fertilizer required by major plants .In this way ,the bean plant as well as the soil are benifited.

Q. Differentiate between total and partial parasitic plants.

Ans 4. Total parasitic plants are those which depend completely on their host for growth and survival ,as they lack chlorophyll. Eg; Cuscata.

On the other hand, partial parasitic plants are those which contain chlorophyll and can prepare their own food but are dependent on the host only for water and certain nutrients . Eg: Mistletoe.

Q. How are parasitic plants different from saprophytes?

Ans 5. The main difference between parasitic plants and saprophytes is that parasitic plants obtain their requirements from other living organisms whereas saprophytes obtain nutrients from dead and decaying organic matter.

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

Ans 6. To test the presence of starch in leaves iodine solution is used.

First we need to boil the leaves in alcoholic water in order to remove its chlorophyll, and then add a few drops of iodine solution to it , its colour changes to blue thus indicating the presence of starch in it.

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