Transpiration and translocation

In which combination of conditions will a well-watered plant transpire most rapidly?

May/June 2015

In an experiment to investigate transpiration, the leaves of four identical shoots are treated in the following ways: 1 upper surfaces coated with waterproof jelly, 2 lower surfaces coated with waterproof jelly, 3 both upper and lower surfaces coated with waterproof jelly, 4 left untreated. The graph shows the amount of water lost by the four shoots. Which line represents the result for shoot 4?

May/June 2015

Describe and explain the effect on the rate of transpiration of an increase in each of the following factors around a plant: • temperature • light intensity • humidity.

May/June 2015

Which statement most accurately describes how water moves through a plant stem?

May/June 2016

What indicates how the rate of transpiration changes when atmospheric conditions change?

May/June 2016

What is the main factor causing water to move up to the leaves in xylem vessels?

May/June 2016

The diagrams illustrate a cylindrical net that is packed with rubber balloons containing air. A teacher uses this model to explain wilting. What does each part of the model stand for?

May/June 2016

A potometer is an instrument for measuring the uptake of water by a plant. Fig. 2.1 shows a plant stem and flower placed in a potometer. When water is taken in, the bubble travels in the direction shown.

May/June 2017

Table 4.1 compares the loss of water vapour from two similarly sized potted plants, F and G, which were grown in the same environment over 14 hours.

May/June 2017

The diagram shows a cross-section of part of a leaf viewed under a microscope. In which part does translocation (movement of sucrose and amino acids) take place?

May/June 2018

The diagram illustrates the route followed by water molecules through part of a leaf, as viewed in transverse section under a microscope. At what point does water evaporate?

May/June 2018

The diagram illustrates the outcome of an experiment. After three hours, the liquid in the glass tube had risen to point $X$. In a second experiment, what change could be made so that the liquid rises above $X$?

May/June 2018

The diagram shows a microscope view of a cross-section through part of a leaf. In which part does translocation (movement of sucrose and amino acids) take place?

May/June 2018

This diagram presents an enlarged transverse section of a leaf.

May/June 2018

Which statement most accurately describes how water moves through a plant stem?

May/June 2019

Which option gives the best description of how water moves through a plant stem?

May/June 2019

Describe the route taken by water molecules from the soil, through a plant and into the atmosphere.

May/June 2019

The diagram illustrates the route taken by water molecules through part of a leaf, viewed in transverse section with a microscope. At which point does water evaporate?

May/June 2021

The diagram illustrates the route taken by water molecules through a section of a leaf, viewed in transverse section under a microscope. At what point does the water evaporate?

May/June 2021

Four plant shoots were arranged as shown in the diagram, under identical environmental conditions. Waterproof petroleum jelly was placed on the plant leaf surfaces, as shown. Each beaker, together with its plant shoot and water, was weighed at the beginning of the experiment and again after $24$ hours. After $24$ hours, the percentage loss in mass was worked out for each plant shoot. Which row gives the results of this experiment?

May/June 2022

What is the principal reason that water moves upward to the leaves in xylem vessels?

May/June 2022

A student carried out an experiment to examine the rate of transpiration in a plant. The student prepared two identical apparatus setups. One was put in a room at $20^{\circ}\text{C}$ with bright light, and the other was put in a room at $20^{\circ}\text{C}$ in the dark. Which graph shows the student’s results?

May/June 2022

What is the principal cause of water moving up to the leaves in xylem vessels?

May/June 2022

Environmental conditions affect biological processes in plants.

May/June 2022

Under which conditions does a plant experience the greatest rate of transpiration?

May/June 2023

A herbaceous plant, growing in a nutrient solution, is placed inside a container with strong light. Humid air is blown through the container. The diagram shows a section through part of the plant. The rates of movement of the fluids in tissues R and S are measured. The humid air is then changed to dry air, and the rates of movement of the fluids are measured once more. Which effect does the switch to dry air have on the measurements?

May/June 2023

In a laboratory, a student used the apparatus in Fig. 1.1, a potometer, to study water uptake by a leafy plant stem. As transpiration causes water to leave the leaves, water is drawn into the cut end of the stem. The water meniscus in the capillary tube then shifts towards the cut end of the stem. At the start of the investigation, the student recorded where the meniscus was on the scale. This was the starting position. The apparatus was then left for 20 minutes, after which the meniscus position was read from the scale again. This was the ending position. Fig. 1.2 shows the starting and ending positions of the meniscus.

May/June 2023

A student carried out an investigation into the rate of transpiration in a green plant. The plant was growing in soil inside a pot. After watering the plant, the student placed a plastic bag around the pot while keeping the leaves outside the bag. She recorded the mass of the plant and pot at the beginning, then repeated the measurement every two hours for six hours. The findings from the investigation are shown. What is the mean rate of transpiration during the six-hour period?

May/June 2024

The graph illustrates the amount of water vapour lost by two different plants that are growing under identical conditions. What could explain the difference in the volume of water vapour lost from the two plants?

May/June 2024

Learners assembled the apparatus to determine how much water a leafy shoot takes up. At the beginning, they noted the position of the air bubble. They left the apparatus for $10$ minutes, recording the distance the air bubble moved at one-minute intervals. After that, they turned on a fan directed at the leafy shoot and, for a further $10$ minutes, recorded the distance the air bubble moved from the start at each minute. Which graph should they plot using their results?

May/June 2025

What direction do water molecules travel in the phloem and in the xylem of a plant stem?

Oct/Nov 2016

In what direction do water molecules travel in the phloem and in the xylem of a plant stem?

Oct/Nov 2016

Under which conditions does a plant transpire at the fastest rate?

Oct/Nov 2017

The diagram shows a cut plant shoot placed in a container of water. What will prevent water from moving up this stem?

Oct/Nov 2017

The diagram shows a cross-section of a plant stem. Which process causes substances to move through region Z?

Oct/Nov 2017

Through which process does water vapour leave a leaf?

Oct/Nov 2017

Which factor is least likely to increase the transpiration rate in a plant?

Oct/Nov 2018

The illustration depicts a section of a tree trunk. A strip of bark, with the phloem included, has been taken away. The tree will eventually die because taking off the bark prevents the movement of

Oct/Nov 2018

Which of the following is not a function of transpiration?

Oct/Nov 2018

The diagram depicts a section of a tree trunk. A strip of bark, together with the phloem, has been taken away. In time, the tree will die because removing the bark prevents the movement of

Oct/Nov 2018

What is the principal reason for water rising to the leaves in xylem vessels?

Oct/Nov 2019

What is the primary reason for water being transported up to the leaves in xylem vessels?

Oct/Nov 2019

The graph plots the water-loss rates of three plants, D, E and F, over the first 14 minutes of an experiment. These plants are from different species, but they are all grown under identical conditions.

Oct/Nov 2019

The diagram shows a section of a leaf. Which arrows indicate translocation and transpiration?

Oct/Nov 2020

The diagrams illustrate transverse sections of a dicotyledonous root and stem. Which tissues are involved in the movement of sugar?

Oct/Nov 2020

The diagram shows a cut plant shoot placed in a container of water. What will prevent water from moving up this stem?

Oct/Nov 2020

The diagram presents a transverse section of a plant stem. Which process causes substances to be transported in region Z?

Oct/Nov 2021

Which statement accounts for why a leaf wilts?

Oct/Nov 2021

The diagram presents a cross-section of a plant stem. Which process causes substances to move in region Z?

Oct/Nov 2021

What does transpiration mean?

Oct/Nov 2021

The graph presents the transpiration rates of two plants over the course of a single day. The two plants were grown in identical conditions. Which statement accounts for what the graph shows?

Oct/Nov 2022

The table presents weather conditions in a field. Which row indicates the conditions that would make a plant wilt most quickly?

Oct/Nov 2022

The diagram illustrates several cells from the lower region of a leaf that is transpiring.

Oct/Nov 2022

Describe and explain the gas exchange between a plant leaf and the surrounding atmosphere over a 24-hour cycle.

Oct/Nov 2022

The apparatus illustrated was used by a student to determine how the rate of water loss from the leafy stem changed as wind speed increased. Which graph could have been drawn from the results?

Oct/Nov 2023

Which alteration in conditions will lower the rate of transpiration?

Oct/Nov 2023

The diagram illustrates how water moves through part of a leaf. Which processes are involved in water movement at these stages?

Oct/Nov 2024

Four leafy shoots taken from the same plant were placed in beakers of coloured water and kept in rooms at different temperatures. In two of the rooms, electric fans were arranged to blow air over the stems. For each stem, the time for the coloured water to arrive at the leaves was recorded. In which stem will the coloured water reach the leaves the fastest?

Oct/Nov 2024

Fig. 1.1 presents an experiment designed to measure how much water a small plant loses over 24 hours.

Oct/Nov 2024

Which graph illustrates how light intensity affects the rate of transpiration?

Oct/Nov 2025