NCTB Class 8 science Chapter 3“Diffusion, Osmosis and Transpiration” Solution

Bangladesh Board Class 8 science Solution Chapter 3“Diffusion, Osmosis and Transpiration” Exercises Question and Answer by Experienced Teacher.

NCTB Solution Class 8 Chapter 3 “Diffusion, Osmosis and Transpiration”

Board	NCTB Bangladesh Board
Class	8
Subject	science
Chapter	Three
Chapter Name	“Diffusion, Osmosis and Transpiration”

Fill in the blanks:

(1) In terrestrial plants transpiration occurs through ———.

Answer:- Leaves.

(2) Cell membrane is a ——- membrane.

Answer:- Semi-permeable.

Multiple choice questions:

(1) What do you mean by the process of release of body water of plants through leaves?

Answer:- Transpiration.

(2) During osmosis-

Answer:- (i) (iii).

(3) What is the special process cited in the stem?

Answer:- Diffusion.

(4) In the cited process-

Answer:- (i) & (iii).

Creative questions:

(1) (a) What is permeable membrane?

 Answer:- Permeable membrane is the membrane through which molecule of both solute and solvent can pass easily.

 Example: Cell wall.

(1) (b) What do you understand by imbibitions?

Answer:- The process by which colloidal substances absorb different liquid is called imbibitions.

(1) (c) By which process does the dye from the bruse of Zarif’s sister spread out in the water? Explain.

Answer:- The dye from the brush of Zarif’s sister spreads out in the water by diffusion. In case, the motion of the molecules of dye are very fast and show tendency to diffuse towards the water with lower concentration from higher ones. This movement of molecules as long as the concentration of the two regions becomes equal.

(1) (d) Why is the swollen up process of dried grapes (kismis) that Zarif observed important for plants? Explain.

Answer:- The swollen up process of dried grapes (Kismis) that Zarif observed is important for plants. This process play a very important role in maintaining different physic-chemical process of the cell. By this process, plants absorb water and minerals dissolved in water from soil, through unicellular root hair.

(2) (a) What is diffusion?

Answer:-  The process in which the movement of molecules with lower concentration from higher ones continues as long as the concentration of the two regions becomes equal, is called diffusion.

(2) (b) Why is transpiration called the’ necessary evil’?

Answer:- Transpiration is a very essential and inevitable process for plants and the high rate of transpiration is harmful for the plants. This is why apparently transpiration is known as the ‘Necessary evil.’

(2) (c) Why did the plants of the tub wither away? Explain.

 Answer:- The plants of the tub were wither away due to high rate of transpiration. For this a huge amount of water is released in the atmosphere and there is no water available in plant’s body and soil of tub.

(2) (d) How did the plants become alive? Explain.

 Answer:- The plants became alive due to the absorption of water that Adiba gave in the tub. The plants absorb water and minerals dissolved in the water form soil and for this process turgidity of the cell of the plants is increased that keeps stem and leaf fresh and straight.