09 Gep Plt Tpt

Maris Stella High School GCE O Level Science Biology GEP: Topic 13

Name: ___________________ Class (Index No.): _____ ( ) Date: ________________

Transport in plants 1.

The diagram below shows an apparatus set up to investigate the rate of water loss and the rate of water uptake by a green plant. The weight of the apparatus was recorded at the start of the investigation and again after 24 hours. The scale on the measuring cylinder was used to read the volume of the water before and after the 24 hour period.

The table below shows the results after the investigation.

(i)

Calculate the decrease in mass of the apparatus per hour, over the 24 hour period. Show your working. [2]

(ii)

Calculate the volume of water absorbed by the plant per hour, over the 24 hour period. Show your working. [2]

(iii) Given the density of water is 1g/cm3, calculate the mass of water absorbed by the plant per hour, over the 24 hour period. [1] (iv) Based on your knowledge of how water moves up a plant, explain why your answers to parts (i) and (iii) are quite similar. [3]

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(v)

Why is the amount of water absorbed by the roots not equal to the amount of water loss by the plant? [2] _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ [Total: 10 marks]

2. The graph below shows the rates of transpiration and absorption of water of the sunflower during a hot day. Water transpired/ absorbed (gram)

Absorption

Transpiration nn

Time (hour) a.

List two environmental factors responsible for the slight drop in the rate of transpiration between 1300 and 1430 hours. [2] _________________________________________________________________ _________________________________________________________________ _________________________________________________________________

b.

Between the period 0630 to 1730 hours, the rate of transpiration is higher than the rate of water absorption. i. Describe the texture of the leaves during this period? [1] _________________________________________________________________ _________________________________________________________________ 2

ii.

Provide one explanation for the texture of the leaves stated in b(i).

[1]

_________________________________________________________________ _________________________________________________________________ c.

The following photomicrographs show two different conditions of the stomata.

Photomicrograph A

Photomicrograph B

Using information from the graph, which photomicrograph represents stomata at 1200 hours? Explain your choice [3] _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ d.

Scientists in Britain have discovered that the leaves of certain plants can communicate changes in environmental conditions to emerging leaves to help them adapt. Sheffield University's research on Arabidopsis thaliana a small plant often studied in laboratories, says mature leaves detect and transmit information about the number of stomata on their surface to new leaves of the same plant. This information lets young leaves control the number of stomata they produce according to environmental conditions.' Adapted from Nature magazine (May 2005 edition) i.

What role do the stomata play in relation to environmental changes?

[1]

_________________________________________________________________ _________________________________________________________________ ii.

What change would you expect in the stomatal development if the daily humidity of the environment has become lower for the past two weeks? [1]

_________________________________________________________________ _________________________________________________________________ 3

Maris Stella High School GCE O Level Biology GEP: Topic 13 MS

Name: ___________________ Class (Index No.): _____ ( ) Date: ________________

Transport in plants 1.(i)

Rate of decrease = (185g – 171g)/ 24h = 0.58g/hr

(ii)

Rate of water absorbed= (80 – 64)cm3/24h = 0.67 cm3/hr

(iii)

Mass of water absorbed = 0.67g/hr

(iv)

Water vapour is lost through the stomata via transpiration. This create a suction force called transpiration pull which pulls water from the roots. Water that is lost will be replaced by transpiration.

(v)

Water absorbed is used for photosynthesis. Water is retained for turgidity.

2a.

2b. 2c. 2d

The surrounding became: (any two of the following) cloudy/ lower light intensity in environment [1]. less windy [1]. more humid [1]. cooler/ lower environmental temperature [1]. i. soft/ limp/ flaccid [1] ii. The cells of the leaves have lost their turgidity due to reduced amount of water in them [1]. Photomicrograph A [1]. It shows stomatal pores of bigger size/ stomata open [1] which aligns to the high transpiration [1] indicated in the graph. i. It controls the amount of water (vapour) loss by the plant OR transpiration rate [1] OR regulates the movement of gases in/out of the plant. ii. There will be fewer stomata formed [1] on the new leaves.

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