Page 11 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

present on the surface of leaf of the plant. Stomata, on opening and closing, help

taking in carbon dioxide and giving out oxygen during photosynthesis.
2. How would you test the presence of starch in leaves?

Ans. To test the presence of starch in leaves, we use a chemical solution called iodine
solution.

First, decolourise the leaf (to be tested),by boiling it in alcohol (which removes the
chlorophyll). Second, put some drops of iodine solution on the leaf.

If the colour of the leaf changes to blue-black, it indicates that starch is present in the
leaf.

3. Explain the symbiotic relationship in organisms.
Ans. Symbiotic relationship is a relationship between organisms in which they share shelter

and nutrition. This relationship is mutual and is beneficial for both the organisms. For
example, fungi and algae live on lichens in symbiotic relationship. Algae provides

food to the fungus which in turn provides shelter to algae.
4. Distinguish between saprotrophic and parasitic modes of nutrition.

Ans. Saprotrophic Nutrition Parasitic Nutrition

1. It is a mode of nutrition in which It is a mode of nutrition in which an
organisms obtain nutrients by organism (the parasite) lives on or

decomposing dead and decaying inside another living organism (the
organic matter. host) and derives nutrients from it.
2. For example, fungi (mushrooms) and For example, mistletoe and cuscuta

certain bacteria. (Amarbel)

5. Why are green plants called autotrophs?
Ans. Green plants are called autotrophs because they can make their own food using

sunlight, water and carbon dioxide in the presence of a pigment named chlorophyll.

Chlorophyll helps capture sunlight, which is further used by the leaves of plants in a

process named photosynthesis.
6. What do you mean by transpiration?

Ans. Transpiration is a process of releasing excess water through stomata on the leaves

of the plant. It creates an upward pull that helps in the transportation of water and

minerals from the roots to the leaves of the plant.
7. Write a note on parasitic plant.

Ans. Parasitic plants are plants that rely on other living plants for their nutrients. Unlike

other plants, they attach themselves to a host plant and extract water and nutrients

11