（a）A student investigated the effect of windspeed on the rate of transpiration． The student placed a fan at different distances from a plant shoot and measured the distance the air bubble moved in three minutes． The distance the air bubble moved can be used to calculate the rate of water uptake，which is equivalent to the rate of transpiration． Fig． 5.1 shows the apparatus the student used． Fig． 5.1 (i) Calculate the rate of water uptake when the fan is 0.6 m from the plant shoot. Give your answer to two decimal places. Space for working. ............................ mm per second (ii) Using the information in Fig. 5.1 and Table 5.1, complete the sentences by writing a word or phrase in the spaces to describe the results. As the fan is moved further away from the shoot, the windspeed ...................................... and the ...................................... moved by the air bubble decreased. During transpiration water evaporates from the surfaces of the ...................................... cells into the air spaces inside the leaf. The water vapour diffuses out of the leaf through the ...................................... This causes water to move through the capillary tube causing the air bubble to move towards ...................................... . . (iii) State one other factor that affects the rate of transpiration. .................................................................................................................................

Biology

IGCSE&ALevel

CAIE

Exam No：0610_w24_qp_32 Year：2024 Question No：5(a)

Answer:

Knowledge points:

8.3.1 State that water is transported from the roots to leaves through the xylem vessels

8.3.2 Define transpiration as loss of water vapour from plant leaves by evaporation of water at the surfaces of the mesophyll cells followed by diffusion of water vapour through the stomata

8.3.3 Investigate and describe the effects of variation of temperature and humidity on transpiration rate

8.3.4 Explain how water vapour loss is related to the large surface area of cell surfaces, interconnecting air spaces and stomata

8.3.5 Explain the mechanism by which water moves upwards in the xylem in terms of a transpiration pull that draws up a column of water molecules, held together by cohesion

8.3.6 Explain how and why wilting occurs

8.3.7 Explain the effects of variation of temperature and humidity on transpiration rate

Answer:

Knowledge points:

Solution:

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