CLASS 8 ANSWERS LESSON 1

DEFINE :

1. Osmosis : Osmosis is the process in which molecules move from an area where they are more in number to an area where they are less in number through a semipermeable .

2. Ascent of sap : The upward movement of sap that contains watertand minerals from the roots towards the other parts of the plant is known as ascent of sap.

3. : It is the process by which molecules of minerals move from an area of low concentration to an area of high concentration by using energy.

4. Transportation : is a process of transporting water,minerals and food to all parts of the plant body.

5. Root : The pressure developed in the roots due to continuous inflow of water is called root pressure.This helps in pushing he plant sap upwards into the stem

6. Plant nutrients : Plants require certain elements for their growth and development which are known as plant nutrients.They obtain these materials from soil,air and water.

7. Translocation of food : The tranport of food from one part of the plant to another is called translocation of food. The food prepared in the leaves is translocated to diffrent part of the plant by phloem.

8. : The loss of water in the form of water vapour through the stomata of leaves and other aerial parts of a plant is called transpiration. It always takes place against the force of gravity.

FILL IN THE BLANKS:

1. Transpirational 2.

3. Vessels

4. Osmosis

5. Energy

6. Translocation

STATE WHETHER THE GIVEN STATEMENTS ARE TRUE OR FALSE:

1. true

2. false

3. true

4. false

5. false

6. true

C.1. error phloem answer xylem

2. error phloem answer xylem

3. error downwards answer upwards

4.error answer osmosis

5. error transporation answer transpiraion

6. error decrease answer increase

D.1. translocaion

2. leaves

3. minerals

4. xylem 5. all three

6. nitrogen

SHORT AND PRECISE

A. soil -----root hair-----corex-----xylem

B. xylem---xylem vessels---upward movement to all parts of plant

Give reasons for the following :

1. because in osmosis semi permeable membrane is needed but in diffusion their is no need of his membrane.

2. Because of active trasport where their is involvement of enegy which helps in absorption.

3. Because the air already contains a lot of moisture.

4. Because they are needed in small amount by plants.

ANSWER IN SHORT

1. The role of vascular tissue is to transport water and minerals and food to all the parts of the plants.

2. The two functions of roots are : a)Fix the plant to the soil.

b) Absorbs water and minerals from the soil.

3. The processes b which plants absorb water and minerals from the soil is osmosis.

4. Root hair are unicellular,delicate are easily damaged. They are replaced daily by new cells.They increase the surface area for absorption of water and nutrients from the soil. 5. Transpiration not only helps to cool the plants but also helps in maintaining the concentration of sap inside the plant body.

6. Macronutrients: nitrogen, phosphorus Micronutrients : Zinc , Iron

EXPLAIN THE FOLLOWING TERMS:

1.Vascular system : Plants do not have a circulatory system.Transportation is carried out in plants by a system called vascular system. It is composed of conducting tissues forming special tubes called xylem and phlome.Vascular tissues are the tissues that perform the function of transport of materials in plant.Vascular tissues are of two types : 1. Xylem(transports water and minerals) 2.Phloem(transports food)

2.Osmosis :Osmosis is the process in which water molecules move from an area where they are more in number to an area where they are less in number through a .Normally, the concentration of water moiecules is higher in soil than in the root hair. Hence ,there is a flow of water from the soil into the root hair through the membrane.

3.Ascent of sap : The water along with minerals move further upwards through the xylem of stem towards the leaves.This is due to transpiration which exerts a pull from above.The upward movement of sap that contains water and minerals from the roots towards the other parts of the plant is known as ascent of sap.

4.Transpirational pull : The greater the transpiration, the greater is the rate of absorption of water from the soil.When water is lost through leaves, a sucion force is created which pulls up water from the xylem of roots to the stem and then to the leaves.This is called transpirational pull.As a result,the amount of water in the roots gets reduced and water from the soil enters the root hair by the process of osmosis.This process continues and water moves up.

DIFFERENTIATE BETWEEN THE FOLLOWING :

XYLEM PHLOEM 1. Transports water and minerals Transports food prepared by leaves to all th

From soil to all the parts of the plant e parts of the plant.

2. Flow is unidirectional Flow is bidirectional.

3. Mainly composed of dead cells except Mainly composed of living cells.

Xylem parenchyma.

DIFFUSION OSMOSIS

1. Occurs in all mediums- Solid, Liquid and gas. It is limited only to the liquid medium.

2. Do not require a semipermeable membrane. Requires a semipermeable membrane.

3. Depends on the presence of other particles. Depends on the number of solute particles

dissolved in the .

TRANSPIRATION TRANSSLOCATION

1. Transpiration refers to the movement of Translocation refers to the movement of

water vapour through the stomata of plants. nutrients from leaves to the other tissues in the plant.

2. Water vapour is transported. Sucrose is transported.

3. Allows the inward movement of water in the Carried out by the phloem.

Xylem.

TRESCHEIDS SIEVE TUBES

1. Present in xylem. Present in phloem.

2. Help in transports of water and Help in transports of food prepared by

minerals. leaves.

3. Do not have end plates. Have perforated end plates.