Transpiration

Through which process does a leaf lose water?

Feb/March 2016

Through which process is water lost from a leaf?

Feb/March 2016

Four leafy plant stems were each put into measuring cylinders containing $100\, \text{cm}^3$ of water. An oil layer stopped the water in the measuring cylinder from evaporating. The stems were then kept in air with different humidities and temperatures for $48$ hours, as listed in the table. The final volume of water left in the measuring cylinders is given for plant stems 1, 3 and 4. What is a likely final volume for plant stem 2?

Feb/March 2017

Water is one requirement for photosynthesis. Table 4.1 gives the number of hectares of forested land in several African countries for 1990, 2000 and 2005.

Feb/March 2017

The diagrams illustrate the stages in water transport through a plant. Which arrow indicates water moving as water vapour?

Feb/March 2019

Scientists examined how cuticle thickness affected water loss from the leaves of balsam fir, Abies balsamea. The leaves were sorted into three sets: A - thick cuticle, B - medium cuticle, C - thin cuticle. Samples from each set were weighed. The leaves were then left on a tray in dry air at 20 ^{\circ}C. At intervals over 15 hours, the samples were weighed again. The scientists worked out the mass of each sample as a percentage of its initial mass. Fig. 5.1 presents the findings.

Feb/March 2019

Which process causes water vapour to be released into the atmosphere from the leaves of trees?

Feb/March 2020

What process causes water vapour to be released into the atmosphere from tree leaves?

Feb/March 2020

Complete the definition of the term transpiration. Transpiration is the loss of water vapour from plant leaves through [BLANK] of water at the surfaces of the [BLANK] cells, then diffusion of water vapour through the [BLANK].

Feb/March 2020

What forms part of the definition of transpiration?

Feb/March 2021

What forms part of the definition of transpiration?

Feb/March 2021

Through which process does water vapour pass out from the stomata in leaves?

Feb/March 2023

Through which process does water leave the stomata in leaves?

Feb/March 2023

A student compared how fast water is lost from leaves at two different temperatures. Every day for seven days, the student recorded the mass of one leaf at the same time. The leaf was kept at 15 ^{\circ}C. The student then repeated this using a similar-sized leaf kept at 25 ^{\circ}C. Fig. 2.1 shows some of the apparatus that was used. The results are displayed in Fig. 2.2.

Feb/March 2023

Which graph best represents how transpiration rate changes when wind speed increases?

Feb/March 2024

Under which conditions does transpiration happen at the greatest rate?

Feb/March 2025

The diagram illustrates four mesophyll cells, W, X, Y and Z. Water passes through these cells. Which arrow indicates the direction in which water moves through these cells?

Feb/March 2025

Which graph makes it clearest what happens to the rate of transpiration as humidity increases?

May/June 2016

The diagram shows a potted plant and that same plant after 24 hours. What is responsible for the change in the plant’s appearance?

May/June 2016

The diagram illustrates a potted plant and the same plant 24 hours later. What causes the change in the plant’s appearance?

May/June 2016

Which graph most clearly shows how the rate of transpiration will change as humidity increases?

May/June 2016

Which graph best shows how the rate of transpiration changes as humidity rises?

May/June 2016

The diagram compares a potted plant with the same plant after 24 hours. What is responsible for the change in the plant’s appearance?

May/June 2016

Which graph most clearly indicates what will happen to the rate of transpiration as humidity increases?

May/June 2016

The diagram shows a potted plant at first and then the same plant 24 hours later. What causes the change in the plant’s appearance?

May/June 2016

The diagram shows a potted plant and then that same plant 24 hours later. What is the reason for the change in the plant’s appearance?

May/June 2016

Which graph indicates most clearly how the rate of transpiration will change as humidity rises?

May/June 2016

For stomata in a leaf to open, the guard cells must contain a greater amount of potassium ions than the cells around them. Which row shows this process?

May/June 2016

Which graph shows most clearly how the rate of transpiration will change as humidity increases?

May/June 2016

The diagram presents a potted plant and that same plant $24$ hours later. What is the reason for the change in the plant’s appearance?

May/June 2016

Fig. 5.1 illustrates some apparatus used to investigate transpiration. The transpiration rate can be worked out by measuring the distance travelled by the meniscus in five minutes.

May/June 2016

Water is taken up by plant root hairs and then released into the air from the leaves.

May/June 2016

A strip of blue cobalt(II) chloride paper is attached to the underside of a fresh leaf and then covered with plastic, as shown. After a few minutes, part of the paper becomes pink, which shows that water is present. Which process in leaves makes the paper turn pink?

May/June 2017

Through which process does water leave the leaves via the stomata?

May/June 2017

A strip of blue cobalt(II) chloride paper is attached to the underside of a fresh leaf and then enclosed with plastic, as illustrated. A few minutes later, part of the paper changes to pink, indicating that water is present. Which process in leaves causes the paper to become pink?

May/June 2017

A strip of blue cobalt(II) chloride paper is fastened to the underside of a fresh leaf and then enclosed with plastic. After a few minutes, part of the paper becomes pink, which shows that water is present. Which process carried out by leaves makes the paper turn pink?

May/June 2017

Which of the following causes transpiration to increase?

May/June 2017

During transpiration, which process takes place?

May/June 2017

The diagrams illustrate an experiment about transpiration. Four leaves from the same species are balanced on two drinking straws. Grease is applied to one side of each leaf, or to both sides. If their masses are not equal, the heavier end moves down. Initially, the straws were arranged so that the leaves were level. Which leaves will be lower after an hour?

May/June 2017

Petroleum jelly does not let water through and is see-through. If a plant’s leaf undersides are coated with a thin film of petroleum jelly, the rate at which water is lost from the plant will decrease. Which statement gives the explanation?

May/June 2018

A student is investigating how temperature affects the rate of transpiration. Which environmental conditions should be kept unchanged during this investigation?

May/June 2018

What factor will not influence the rate of transpiration?

May/June 2018

Petroleum jelly does not allow water to pass through it and is transparent. If the lower surface of a plant’s leaves is coated with a thin layer of petroleum jelly, the rate at which water is lost from the plant will decrease. Which statement explains this?

May/June 2018

A student is carrying out an investigation into how temperature affects the rate of transpiration. Which environmental conditions must remain constant in this investigation?

May/June 2018

Which factor will not change the rate of transpiration?

May/June 2018

Identify the position of the xylem tissue by adding a label line and the letter X to Fig. 3.1.

May/June 2018

The table gives the rate at which water flows through a tree during a 12 hour period. What conclusion can be drawn from the table?

May/June 2019

The table gives the rate at which water moves through a tree during a $12$ hour period. What conclusion can be drawn from the table?

May/June 2019

The table gives the rate at which water moves through a tree during a 12 hour period. What conclusion can be drawn from the table?

May/June 2019

The diagram illustrates part of the water cycle. Which process in living plants is responsible for releasing water vapour into the air at P?

May/June 2019

The table presents the water flow rate through a tree during a 12 hour period. What conclusion can be drawn from the table?

May/June 2019

The apparatus shown was assembled. After some hours, the water in the beaker had become blue, and the liquid in the glass tube had risen. Which processes produced these changes?

May/June 2019

The table shows the rate at which water flows through a tree during a $12$ hour period. What conclusion may be drawn from the table?

May/June 2019

The table records the rate at which water flows through a tree during a 12-hour period. What conclusion can be made from the table?

May/June 2019

Transpiration means the loss of water from plant leaves.

May/June 2019

A plant shoot is put into a dye solution. The dye travels upward through the stem. In which conditions will the dye travel the slowest?

May/June 2021

Which sequence describes the route water follows as it passes through a plant?

May/June 2021

A plant shoot is put into a solution of dye. The dye then rises up the stem. In which conditions would the dye move most slowly?

May/June 2021

Which stage of the water cycle involves only living organisms?

May/June 2021

The diagram shows one stomata in a leaf, together with some cells close to it. During transpiration, which statement describes the movement of water at X and at Y?

May/June 2021

A plant shoot is put into a dye solution. The dye travels upwards through the stem. In which conditions will the dye travel most slowly?

May/June 2021

The graph illustrates the plant Agave americana’s daily carbon dioxide uptake and transpiration. This plant is adapted for survival in very dry conditions. What can be concluded from this graph?

May/June 2021

The graph illustrates the plant Agave americana's daily carbon dioxide uptake and transpiration. This plant is adapted to survive in very dry conditions. What conclusion can be drawn from this graph?

May/June 2021

Which sequence shows the route water follows as it moves through a plant?

May/June 2021

The graph presents the daily carbon dioxide uptake and transpiration of the plant Agave americana. This plant is adapted to survive in very dry conditions. What conclusion can be drawn from this graph?

May/June 2021

The diagram illustrates one stomate of a leaf, together with some of the nearby cells. During transpiration, what describes the movement of water at X and at Y?

May/June 2021

All living organisms require water, and most plants take it up from the soil.

May/June 2021

Predict the results of this investigation. Explain why you made that prediction.

May/June 2021

The diagram illustrates a cross-section of a leaf. From which cell does most water evaporate during transpiration?

May/June 2022

In a leaf, water travels from the surface of a mesophyll cell and then leaves the leaf into the atmosphere. What is the correct sequence of the processes involved?

May/June 2022

The apparatus illustrated can be used to study how temperature and humidity affect the rate of transpiration. Which combination of conditions would produce the highest rate of transpiration and the largest fall in mass?

May/June 2022

The diagram shows a cross-section of a leaf. From which cell does most water evaporate during transpiration?

May/June 2022

The apparatus illustrated can be used to study how temperature and humidity affect the rate of transpiration. Which combination of conditions would produce the highest rate of transpiration and the largest fall in mass?

May/June 2022

Fig. 1.1 shows a photograph of a plant. Fig. 1.2 shows a graph illustrating how temperature affects the rate of transpiration from the upper and lower leaf surfaces. Key: solid line - lower surface dashed line - upper surface Fig. 1.3 shows a diagram of the water cycle.

May/June 2022

Which row gives the transpiration rate under the conditions described?

May/June 2023

Which two processes lead to transpiration in plant leaves?

May/June 2023

Which statement explains the effect that atmospheric humidity has on the rate of transpiration?

May/June 2023

Humidity and wind speed are two variables that influence the rate of transpiration. In what way do these two factors change the concentration gradient of water molecules between the leaf interior and the surrounding atmosphere?

May/June 2023

Which combination of environmental factors would lead to the greatest rise in a plant’s transpiration rate?

May/June 2023

Transpiration is the process by which water vapour is lost from a plant’s leaves.

May/June 2023

Which option most accurately defines transpiration?

May/June 2024

At what time is the transpiration rate of a well-watered plant greatest?

May/June 2024

Which alteration in an environmental factor will raise the rate of transpiration?

May/June 2024

Desert plants have adapted to live in environments where water is extremely scarce. Which process is reduced so that they can keep as much water as possible?

May/June 2024

Fig. 3.1 shows a photomicrograph of a plant stem section.

May/June 2024

Fig. 5.1 shows how temperature affects the transpiration rate from the upper and lower leaf surfaces when the leaf is supplied with water at a constant rate.

May/June 2024

The diagram illustrates water molecules moving from a plant leaf into the surrounding environment. Two processes have been labelled with numbers. Which row correctly names the numbered processes?

May/June 2025

What route does water follow through a plant?

May/June 2025

Which graph illustrates how humidity in the air influences the rate of transpiration in a plant?

May/June 2025

A student aimed to find out how humidity affects transpiration. She arranged two sets of apparatus using plants of the same species and identical size. The masses of the water in both tubes were recorded at the beginning of the investigation and then again after five days. Which statement describes and explains these results?

May/June 2025

The diagrams illustrate stages in the movement of water through a plant. Which arrow indicates water moving as water vapour?

Oct/Nov 2016

Which graph illustrates how increasing humidity affects the rate of transpiration?

Oct/Nov 2016

A plant shoot is put into a dye solution. The dye then travels up the stem. In which conditions will the dye travel most slowly?

Oct/Nov 2016

Which process sends water vapour from tree leaves into the atmosphere?

Oct/Nov 2016

The diagrams illustrate stages in the movement of water through a plant. Which arrow indicates water moving in the form of water vapour?

Oct/Nov 2016

A plant shoot is placed in a dye solution. The dye travels upwards through the stem. In which conditions will the dye travel most slowly?

Oct/Nov 2016

What alterations in atmospheric conditions may cause a plant to wilt?

Oct/Nov 2016

A student carried out an investigation into transpiration from leaves. She selected leaves from the same plant that were similar in size. She measured their mass and then put them under different conditions. While the leaves transpired, their mass decreased.

Oct/Nov 2016

Name the plant cell specialised for absorbing water from the soil.

Oct/Nov 2016

What does transpiration mean?

Oct/Nov 2017