Limiting factors in photosynthesis

Plants produce glucose by photosynthesis.

Complete the word equation for photosynthesis shown in Figure 2.

Figure 2

State why photosynthesis does not occur in the roots of plants.

Which is transported in the phloem?

Chlorophyll is found in green leaf cells.

Describe the role of chlorophyll in leaf cells.

A greenhouse contained an oil burning heater.

State two ways this could increase the rate of photosynthesis in the greenhouse.

Plants need light for photosynthesis.

Part of the photosynthesis equation is shown below.

reactant A + water glucose + product B

Which row in the table shows reactant A and product B?

Name the green chemical in chloroplasts that absorbs light.

Plan an experiment to investigate if plants grow faster when they receive more light. Use the equipment shown in Figure 3.

State one factor that you would keep the same in this experiment.

A plant was kept at a very high temperature of 60C.

Explain the effect of this temperature on photosynthesis.

A student investigated the effect of light intensity on the photosynthesis of pondweed.

A light source was placed at different distances from the pondweed.

The bubbles produced were counted for 2 minutes.

Figure 5 shows the apparatus that was used.

State why the student included a water bath in the apparatus.

State two variables that should be controlled when completing this investigation.

Figure 6 shows the results of this investigation.

The light intensity was calculated using the inverse square law for photosynthesis.

Calculate the light intensity at a distance of 25 cm from the lamp.

Include the equation for the inverse square law in your answer.

_........ arbitrary units

Explain how the student could improve this investigation to get a more accurate measurement of the gas produced.

Devise a plan to show that temperature is a limiting factor in photosynthesis.

Use the apparatus shown in Figure 5.

Figure 6 shows a method of investigating the rate of photosynthesis in a water plant.

What are the products of photosynthesis?

The rate of photosynthesis can be measured by counting the number of bubbles of gas produced in one minute.

Figure 7 shows some results from this investigation in different light intensities.

Light intensity was changed by moving the lamp towards or away from the water plant.

Describe the effect of light intensity on the rate of photosynthesis. Use information from Figure 7 to help you.

The bubbles are different sizes and can be difficult to count.

Describe how the quality of the results from this investigation could be improved.

Describe how this investigation could be changed to find the effect of temperature on the rate of photosynthesis.

Increased nitrates can cause eutrophication in lakes.

Explain how eutrophication will affect the fish living in the lakes.

Figure 9 shows an area of woodland with some small plants growing in the ground between the trees.

(Source: © Maksym Holovinov/Shutterstock)

Figure 9

The leaves of the small plants are green.

Describe how these plants make glucose.

Name a group of organisms that break down the dead leaves and release mineral ions into the soil.

The mineral ions are absorbed from the soil into the roots of plants.

Describe how these mineral ions are transported from the roots to the leaves of the plants.

A scientist recorded the mean light intensity and the mean number of small plants per m² for six 25 m² areas of the woodland.

Figure 10 shows the results.

Explain the effect of light intensity on the number of small plants per m².

State one variable the scientist should have controlled to make sure the light intensity measurements could be compared.

The scientist selects an area near the edge of the woodland where many stinging nettles are growing.

This area is partly shaded by the trees.

Describe how the scientist should use a belt transect to investigate how light intensity affects the growth of stinging nettles.

A slide of potato cells was viewed using a light microscope.

Figure 12 is a drawing of the slide showing starch grains in the potato cells.

Calculate the mean number of starch grains in potato cells P, Q and R.

_........ starch grains

Which structures are found in plant cells but are not found in animal cells?

A scientist investigated how the length of starch grains in potatoes changed when the potatoes were stored in the dark.

Figure 13 shows a potato after being stored in the dark.

Three potatoes were used in the investigation.

The length of starch grains in potato 1 were measured at the start.

The length of starch grains were measured in potato 2 after 5 weeks in the dark.

The length of starch grains were measured in potato 3 after 10 weeks in the dark.

Figure 14 shows the results.

Calculate the percentage difference in the mean length of starch grains in potato 2 at 5 weeks and in potato 3 at 10 weeks.

_........ %

State two variables the scientist should have controlled to improve this investigation.

The starch grains in the potatoes became smaller as the starch was converted into glucose.

State why the potatoes need glucose.

*(c) Figure 15 shows a diagram of some equipment that can be used to investigate the rate of photosynthesis.

Devise a plan to investigate the effect of light intensity on the rate of photosynthesis.

Include variables you would need to control.

(a) Plants use nitrate ions to make proteins and chlorophyll.

What effects will a low nitrate ion concentration in soils have on plants?

Which organisms convert nitrogen to nitrate ions during the nitrogen cycle?

Figure 5 shows part of a root as seen using a light microscope.

Figure 6 shows information about the two types of cell labelled in Figure 5.

Calculate the surface area to volume ratio of the root hair cell.

Explain the benefit to the plant of having root hair cells.

Algae are green plants.

Figure 7 shows the number of algae in a lake in the United Kingdom during one year.

Explain the changes in the number of algae in the lake from February to June.

(a) Figure 9 shows the effect of light intensity and temperature on the rate of photosynthesis.

Describe the effect of light intensity on the rate of photosynthesis.

Explain the effect of temperature on the rate of photosynthesis.

A student measured the rate of photosynthesis using algal balls in a laboratory. The tube of algal balls was kept at a temperature of 25 °C and was moved to different distances from a light source.

The results of this investigation showed that the rate of photosynthesis is

*(c) Explain how substances are moved through a plant by transpiration and translocation.