1.1. Extended Only

Fig.1 is a photomicrograph of some xylem vessels.

Fig. 1

(i)

State one structural feature of xylem vessels and explain how this is related to the function of water transport.

[2]

(ii)

Explain the mechanism that is responsible for the movement of water in xylem vessels.

[4]

(iii)

State one role of xylem vessels other than transport.

[1]

1.2. Extended Only

The rate of transpiration is affected by several factors including the temperature and the humidity of the air.

State and explain the effect of an increase in temperature on the rate of transpiration.