transpiration - paper 2

Question 1

what is transpiration?

Answer 1

the loss of water from the plant
–> it diffuses onto the leaf and then evaporates

Question 2

what is the transpiration rate affected by?

Answer 2

• LIGHT INTENSITY
• TEMPERATURE
• WIND SPEED
• HUMIDITY

Question 3

what do you use to measure transpiration?

Answer 3

a potometer

Question 4

Light intensity affects transpiration through…

Answer 4

POSITIVE
the brighter the light, the greater the transpiration rate

–> the stomata closes in the dark so less water can escape

Question 5

Why does the stomata close in the dark?

Answer 5

Photosynthesis can’t happen in the dark so the stomata closes because it doesn’t need C02

Question 6

Temperature affects transpiration through…

Answer 6

POSITIVE
the warmer it is, the faster transpiration can occur

—> the water particles are hotter, so have more energy for diffusion and evaporation

Question 7

Wind speed affects transpiration through

Answer 7

POSITIVE
the more windy it is, the more transpiration occurs

–> the water vapour is swept away quickly, so the concentration gradient from the inside and outside of the leaf is greater and diffusion happens more quickly

Question 8

Humidity affects transpiration through…

Answer 8

NEGATIVE
the more humid it is, the less transpiration occurs

—> if there is more water existing in the air outside the leaf the concentration gradient is lower

Question 9

in practice:
it is a hot, sunny day. What factors will affect transpiration and how?

Answer 9

• light intensity
• temperature
  transpiration will increase

Question 10

in practice: it is very humid and is also warm. What factors will affect transpiration and how?

Answer 10

• humidity - decreases rate of transpiration
• temperature - increases rate of transpiration