Transport in Plants Practice Questions

Question 1

4 marks

Figure 1 shows part of the lower epidermis of a leaf, seen through a microscope.

(a)

Name the cell labelled A.

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(b)

Name one substance that leaves the leaf through the opening labelled B on a warm, sunny day.

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(c)

Most plants close the opening labelled B at night.

Explain the advantage to the plant of closing these openings at night.

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Question 2

4 marks

A potato plant makes sucrose in its leaves. In late summer, much of this sucrose is moved to the potato tubers growing underground, where it is stored as starch.

(a)

Name the tissue that transports sucrose through the potato plant.

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(b)

Name the process by which sucrose is moved from the leaves to the tubers.

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(c)

Explain why the potato tubers are described as a sink.

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(d)

Give one difference between the substances moved by transpiration and the substances moved by translocation.

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Question 0

7 marks

A student used a potometer to measure the rate of water uptake by a leafy shoot. The potometer contained a capillary tube with a cross-sectional area of $2.0\ \text{mm}^2$ . The student measured the distance moved by an air bubble in the capillary tube in 5 minutes, and repeated the measurement three times.

Repeat	Distance moved by bubble in 5 minutes, in mm
1	60
2	75
3	66

(a)

Give two variables the student should keep the same for each repeat.

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(b)

Calculate the mean rate of water uptake, in mm per minute.

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(c)

Use your answer to part (b) to calculate the mean volume of water taken up by the shoot in one minute, in $\text{mm}^3$ per minute.

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Question 0

6 marks

A gardener investigated the rate of water uptake by four identical geranium plants. Each plant had its stem sealed into a measuring tube of water. The results are shown in the table.

Condition	Surroundings	Rate of water uptake in $\text{cm}^3$ per hour
A	still air, $20\ ^\circ\text{C}$ , in the light	1.2
B	moving air from a fan, $20\ ^\circ\text{C}$ , in the light	3.0
C	still air, $30\ ^\circ\text{C}$ , in the light	2.1
D	still air, $20\ ^\circ\text{C}$ , in the dark	0.4

(a)

Calculate the percentage increase in the rate of water uptake in condition B compared with condition A.

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(b)

Explain the difference between the rate of water uptake in condition A and in condition D.

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(c)

Explain why the rate of water uptake in condition C is higher than in condition A.

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Question 0

7 marks

A grower produces lettuce plants with their roots in a tank of dilute nutrient solution. The concentration of nitrate ions inside the root cells is higher than the concentration of nitrate ions in the solution.

Lettuces grown in a tank with no nitrate ions have small, pale, stunted leaves.

(a)

Explain how nitrate ions are taken into the root cells of the lettuce from the nutrient solution.

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(b)

Describe how nitrate ions are transported from the roots to the leaves of the lettuce.

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(c)

Explain why lettuces grown without nitrate ions are stunted.

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Question 0

6 marks

Substances are moved around a plant by transpiration and by translocation.

(a)

Complete the table to compare transpiration and translocation.

Feature	Transpiration	Translocation
Main substance transported	water	.....................
Tissue used	.....................	phloem
Direction of movement	roots to leaves only	.....................
Energy from respiration needed?	no	.....................

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(b)

A scientist treated the stem of a plant with a chemical that stops respiration. Translocation in the stem stopped, but water continued to move up the stem.

Explain these results.

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Question 0

6 marks

On a hot, windy day a gardener notices that a plant in an open field takes up much more water from the soil than an identical plant kept in a cool, sheltered greenhouse.

Explain how water moves from the soil, through the plant, and out of the leaves, and why the rate of this movement is increased by high temperature and by air movement.

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Question 0

6 marks

A student measured water loss from a small potted plant. The pot and soil were sealed inside a plastic bag, leaving the leaves and stem exposed. The whole apparatus was placed on a balance in a laboratory at $22\ ^\circ\text{C}$ and its mass recorded every two hours.

Time	Mass of apparatus in g
09:00	486.0
11:00	481.2
13:00	476.4
15:00	471.6

(a)

Calculate the mean rate of water loss from the plant between 09:00 and 15:00, in grams per hour.

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(b)

The total surface area of the leaves on the plant was $240\ \text{cm}^2$ .

Use your answer to part (a) to calculate the rate of water loss in milligrams per $\text{cm}^2$ per hour.

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(c)

The student repeated the investigation with an identical plant kept in a dark cupboard at $22\ ^\circ\text{C}$ .

Predict the effect on the rate of water loss and explain your prediction.

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Key Concepts in Biology

Cells & Control

Genetics

Natural Selection & Genetic Modification

Health, Disease & the Development of Medicines

Plant Structures & their Functions

Animal Coordination, Control & Homeostasis

Exchange & Transport in Animals

Ecosystems & Material Cycles

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Question 2

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