Biology Form 5

Topics: Water, Evaporation, Chart Pages: 4 (747 words) Published: March 17, 2013
PAPER 3
Answer all question. Question 1 Transpiration is the evaporation of water vapour from the leaves surface. Air movement is one of the factor that affects the evaporation of water vapour. A group of student carried out an experiment to study the effect of air movement on rate of transpiration of plants. Diagram 1 shows the apparatus used by the students. The experiment was conducted under still air and strong fan speed.

Diagram 1 The time taken for the air bubble in the capillary tube to move 10 cm is shown in Table 1 Condition Time taken for the air bubble to move 10 cm (mins) 1 2 Average reading

Still air

20.5

1

21.0

20.0

6.0 Strong fan speed

6.0

6.0

Table 1 (a) Record the time taken for air bubble to move 10cm distance and find average reading in Table 1 [ 3 marks] (b) Classify all the apparatus and material used in this experiment as shown in Diagram 1. Apparatus Retord stand Capillary tube Water Beaker Air bubble Fan [ 3 marks] (c)(i) Record two different observations made from Table 1. Observation 1: At still air, the average time taken for air bubble to moves 10 cm distance is 20.5 minutes Observation 2: At strong fan speed, the average time taken for air bubble to moves 10 cm distance is 6.0 minutes. [ 3 marks] 2

Materials Plant

(ii) State two inferences from the observation in 1(c)(i). Inference from observation 1: At still air, there is no air movement so the evaporation of water vapour is low/ rate of transpiration is low/ slow/ less causing less water being absorbs by roots Inference from observation 2: At strong fan speed, air movement is highest / high / rate of transpiration is high causing more water loss/ evaporates from the leaves/ more water being absorbs by the roots [ 3 marks] (d) Complete Table 2 based on this experiment. Variabe Method to handle the variable Manipulated variable: Used still air or strong fan speed in this experiment // used different speed of fan Condition of experiment / still...
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