Transport in Plants (Edexcel GCSE Biology)

The graph shows the changes in stomatal size over a 12 hour period throughout the day.

Describe the changes in stomatal size over the 12 hour period.

The temperature increased from 8 am to 1 pm. 

Explain why this affected the size of the stomata.

Figure 1 shows a stoma before and after opening. 

Figure 1

Name the cells shown in this image and describe the changes that occur in these cells that cause the stoma to open.

A pair of students wanted to investigate how water moves through a plant.

They placed a plant with exposed roots into a conical flask containing water. They then placed a mass balance below to measure how the mass of water changed during the experiment.

They set up their equipment as shown in Figure 1. 

Figure 1

(i) Explain how water moves into the roots of plants. 

(3)

(ii) Salt was added to the water in the conical flask to form a salt solution.
Explain how the salt solution would affect the movement of water into or out of the plant.

(2)

Explain how water is moved through a plant from the roots to the surrounding air.

(i) The students repeated their experiment with a new plant and fresh water.  Suggest how they could change their experiment to measure the effect of light intensity on the rate of transpiration. 

(3)

(ii) Explain how varying light intensity affects the rate of transpiration in plants.

(2)

Glucose is produced in the leaves of a plant through the process of photosynthesis. 

It can then be transported to other areas around the plant in order to be used. 

Explain how glucose is transported through a plant.

When the sugars travel through the plant they are transported to the place where they are required, known as a sink. 

(i) In a photosynthesising plant, which part of the plant acts as a sink?

(1)

(ii) When the sugars arrive at the sink, what can they be used for? 

(2)

The process of transporting sugars through the plant is aided by active transport.

Describe how active transport can be used to transport sugars in a plant. 

A student set up a potometer to investigate the effect of temperature on the rate of transpiration. 

Figure 1 shows the equipment they used. 

Figure 1

Explain the function of the reservoir in this equipment. 

The student placed the equipment in areas with different air temperatures. They left the equipment for 45 minutes and recorded the rate of transpiration during that time. 

Their results are shown in Figure 2. 

Figure 2

(i) When the air temperature was 10°C, the air bubble in the potometer moved 36 mm.

Calculate the rate of transpiration at 10°C. 

(1)

(ii) Explain why the rate of transpiration decreases between 25°C and 30°C.

(2)

Explain how glucose production could be affected if this plant lost a lot of water. 

An investigation was carried out over a 12-hour period to compare transpiration in two species of plant, Coleus and Begonia. 

The mass of each plant was recorded before and after the 12-hour period to find out the effect of transpiration.

The investigation was repeated five times with the same plants.

Figure 1 shows the change in mass of each plant over each 12-hour period.

Figure 1

(i) Calculate the mean change in mass of the Begonia plant for the five 12-hour periods.

(2)

(ii) Using Figure 1, compare the water loss in the Coleus plant with the water loss in the Begonia plant. 

(2)

The wilted Coleus plant was observed to recover more quickly than the wilted Begonia plant after they were both watered.

Explain this observation.

A student compared the number of stomata on the upper and lower surfaces of a leaf.

She completed a leaf peel as shown in Figure 1.

Figure 1

The layer of nail varnish shows an impression of the cells on the surface of the leaf.

(i) State why a coverslip is placed on top of the leaf peel.

(1)

(ii) Explain why the leaf peel rather than the whole leaf was viewed with a microscope.

(2)

The student drew a biological diagram of the leaf peel taken from the underside of the leaf. Figure 2 shows this diagram.

Figure 2

(i) State the number of stomata visible in Figure 2.

(1)

(ii) The student observed that the stomata were open. Describe how stomata open.

(3)

Figure 3 shows xylem and phloem.

Xylem and phloem are involved in the transport of substances through a plant.

Figure 3

Use Figure 3 to help you describe how water and sucrose move through a plant.

Fig. 1 shows a potometer set up to measure the rate of transpiration in a piece of cut plant. 

Fig. 1

Identify labels W, X, Y and Z.

In the experiment shown in Fig. 1, the bubble moved a distance of 23 mm in 47 minutes of experiment time. 

The bore (internal diameter) of the capillary tube that the bubble is in is 1 mm.

(i) Calculate the volume of water taken up by the plant in the time of the experiment.

[2]

(ii) Calculate the rate of transpiration of the piece of plant.

State your answer in mm³hr^-1.

[2]

For the experiment described in part (b), a subsequent experiment used an electric fan to blow air across the leaves of the plant throughout the experiment. 

Predict the rate of transpiration that would be measured. State your answer as a number with units. 

Explain your reasoning. 

A different piece of the plant (from a species of tree) was measured and its transpiration rate was found to be 350 mm³hr^-1.

The piece of the tree being studied contained 8 leaves whereas a mature tree of the same species would consist of an average of 65 000 leaves.

(i) Estimate the rate of transpiration of a mature tree of this species.

Express your answer in litres per day (dm³day^-1)

1dm³ = 1 000 000 mm³

[3]

(ii) Give three reasons to suggest why the estimate in part (d) (i) is likely to be inaccurate.

[3]

Compare the structures of the phloem and the xylem vessels.

Explain how translocation aids the process of transpiration in plants.

Figure 1 shows an aphid feeding on a plant stem.

Figure 1

Explain why they target structure X.

Which statement from A to D would indicate that transport of materials in the phloem involves metabolic processes rather than just a physical process?

Describe how the xylem is adapted for the transport of water.

Compare the transport systems in plants and animals.