Nutrition — Practice

Question 1

Which of the following organisms are parasites? (i) Yeast (ii) Mushrooms (iii) Cuscuta (iv) Leeches

Accepted Answer

Both (iii) and (iv)

Question 2

The rate of photosynthesis is not affected by

Accepted Answer

Humidity

Question 3

A plant is kept in dark for about 48 hours before conducting any experiment on photosynthesis in order to

Accepted Answer

Ensure that leaves are free from the starch

Question 4

The digestive juice without enzyme is

Accepted Answer

Bile

Question 5

The finger-like projections which increase the surface area in the small intestine are called ______, and the vitamin synthesised by bacteria present in the intestine is ______.

Accepted Answer

Villi (the book also calls them microvilli); vitamin B12, cyanocobalamin

Question 6

Why is it right to call the dark phase of photosynthesis a light independent phase?

Accepted Answer

Because it does not require light, not because it happens in darkness.

Question 7

What is the role of acid in the stomach, and what happens to protein digestion as the medium of the intestine is gradually rendered alkaline?

Accepted Answer

HCl makes the stomach medium acidic so pepsin can break proteins into peptones; in the alkaline intestine, trypsin and then peptidases take over and carry protein digestion to amino acids.

Question 8

How would you demonstrate that a green plant releases oxygen when exposed to light?

Accepted Answer

Set up two identical Hydrilla-and-funnel assemblies under inverted water-filled test tubes; keep one in sunlight and one covered with black paper in shade, and test the collected gas with a glowing splint.

Question 9

What will happen to the rate of photosynthesis if we keep on increasing the CO2 concentration in air, and what happens if the rate of respiration in a plant exceeds the rate of photosynthesis?

Accepted Answer

Carbon dioxide is one of the essential materials, so raising it raises the rate — but only while the other factors, light, water and chlorophyll, are not themselves limiting; beyond that point more CO2 changes nothing. If respiration exceeds photosynthesis, the plant consumes more food than it makes and loses mass, and cannot sustain growth.

Question 10

In most leaves the upper surface is more green and shiny than the lower surface. Why? Relate your answer to the transverse section of a leaf.

Accepted Answer

Because the palisade parenchyma, packed with chloroplasts, lies just under the upper epidermis, while the lower side holds the loosely arranged spongy parenchyma with air spaces and the stomata.

Practice — Nutrition

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