Tag: biology

Questions Related to biology

Plant ash indicates.

  1. Organic matter of plant

  2. Mineral salts absorbed by plants

  3. Both mineral salts and organic matter

  4. Silica absorbed by plants


Correct Option: B

Which of the following part of a plant absorbs water from the soil?

  1. Stem

  2. Root hairs

  3. Leaves

  4. All of the above


Correct Option: B
Explanation:

Stems and leaves are a part of the shoot which is present away from the soil .

Root hair are present on the surface of roots which are responsible for the absorption of water and minerals from the soil.
So the correct answer is ' Root hairs'.

When the temperature of soil is $0^o$C then.

  1. The absorption of water increases

  2. The absorption of water is not affected by temperature

  3. The absorption of water decreases

  4. The soil will lose capillary water


Correct Option: A

The movement of water from one cell of the cortex to the adjacent one in roots is due to _________________.

  1. Water potential gradient

  2. Accumulation of inorganic salts in the cells

  3. Accumulation of organic compounds in the cell

  4. Chemical gradient


Correct Option: A
Explanation:

Accumulation of solutes in the cells caused the cell to take up water from the surroundings. This is seen when the water is absorbed into the roots from the soil. This is due to the development of chemical gradient (both inorganic and organic solutes may develop a chemical gradient).

When we are considering the movement of water from one cell of the cortex to the adjacent one in the root, it is due to the development of water potential gradient which forces the water to move from one cell to the other.
So the correct answer is ' Water potential gradient'.

Water absorption through roots can be increased by keeping the plants

  1. In the shade

  2. In dim light

  3. Under the fan

  4. None of the above


Correct Option: C
Explanation:

Water absorption can be increased by increasing Transpiration which can be increased by

1. Increasing the intensity of light
2. Increasing the wind speed.
Hence if kept under the fan, the water absorption increases.
So the correct answer is 'Under the fan'.

The root-hairs are suited for absorbing water from the soil because

  1. Root-hairs have a large surface area

  2. Roots have a semi-permeable membrane

  3. Roots contain a solution of higher concentration than the surrounding water.

  4. All the three


Correct Option: D

Choose the correct answers from the alternatives given.
Field capacity is

  1. The same as permanent wilting point

  2. The amount of water in soil after drainage takes place

  3. Higher for sandy soils than clay soils

  4. The amount of water in soil available to plants


Correct Option: B
Explanation:

Field capacity is the amount of soil moisture or water content held in the soil after excess of water has been drained out. Wilting point or permanent wilting point is the minimal amount of soil moisture that is required by the plant not to wilt. This is not the same as field capacity because sometimes drainage of water occurs more than required that causes wilting and even death of the plant.

Hence, the correct answer is 'The amount of water in the soil after drainage takes place'.

State whether the following statements are true or false.
A membrane which allows certain substances to pass through it, but not others is called a selectively permeable membrane.

  1. True

  2. False


Correct Option: A
Explanation:

A membrane that allows certain substances to pass through it either by diffusion, passive transport or active transport, it is called selectively permeable membrane. For example, water moves passively through small pores of this membrane.

So, the correct option is 'True'.


The mineral ions absorbed by roots reach the leaves through sieve elements

  1. True

  2. False


Correct Option: B
Explanation:

Sieve elements are used to transport organic compounds made during photosynthesis in plants. Sieve elements are the major conducting cells in the phloem. But sieve elements don't transfer the mineral ions absorbed by roots to the leaves

So the given statement is false

What is an isotonic solution?

  1. A solution whose water concentration is lower than the internal concentration.

  2. A solution whose water concentration is same as compared to internal concentration.

  3. A solution whose water concentration is more than the internal concentration.

  4. None of the above.


Correct Option: B
Explanation:
  • If both the medium and cell has exactly the same water concentration and thus, there will be no net movement of water across the cell membrane is known as an isotonic solution. 
  • The cells remain of the same size.

    Hence, the correct option is B.