Transpiration

Question 1

define transpiration

Answer 1

process of loss of water in the form of water vapour from leaves or other aerial parts of the plant

Question 2

how to measure transpiration?

Answer 2

1. weighing
2. potometer

Question 3

define potometer

Answer 3

a device that measures the rate of water intake by a plant, which is equal to the water lost by transpiration

Question 4

types of potometers

Answer 4

Farmer’s
Ganong’s
Darwin’s
Garreau’s

Question 5

precautions in potometer

Answer 5

1. potometer should be airtights
2. twig should be cut obliquely and underwater

Question 6

limitations of potometer

Answer 6

1. introducing air bubble is not easy
2. any change in outside temp affects position of water bubble
3. twig may not be alive for a long time

Question 7

kinds of transpiration

Answer 7

1. stomatal
2. cuticular
3. lenticelular (openings on surface of old woody stems)

Question 8

number of stomata

Answer 8

1000-10000 per square cm

Question 9

role of turgor pressure in stomatal transpiration

Answer 9

cell sap exerts turgor pressure on cell wall, and forces out some water into the intercellular space of a stomata cell

Question 10

where does more transpiration occur?

Answer 10

under surface of a dicot leaf, because of more stomatal opening under

Question 11

what are lenticels?

Answer 11

special openings that develop on the barks of older stems. they never close

Question 12

external factors affecting transpiration

Answer 12

1. sunlight
2. temperature
3. humidity
4. atmospheric pressure
5. velocity of wind
6. CO2 in air

Question 13

what happens to transpiration when CO2 increases?

Answer 13

stomata closes and transpiration decreases

Question 14

internal factors affecting transpiration

Answer 14

1. water content in leaves

Question 15

adaptations in plants to reduce excessive transpiration

Answer 15

1. sunken stomata
2. fewer stomata
3. thick cuticle
4. narrow leaves
5. loss of leaves
6. reduced exposed surfaces

Question 16

significance of transpiration

Answer 16

1. cooling
2. creating suction force
3. distributing water

Question 17

define exudation

Answer 17

when plants lose water or other fluids with dissolved substance directly as liquid and not in vapour form.

Question 18

two ways in which exudation occurs

Answer 18

1. guttation
2. bleeding

Question 19

what are hydathodes?

Answer 19

special pore-bearing structures on leaves to allow exudation

Question 20

define bleeding

Answer 20

during injury, plant sap excapes from ruptured cuts