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.

Figure 12 shows the lower epidermis of a leaf, with a stoma labelled.

(Source: © Quagga Media/Alamy Stock Photo)

Figure 12

State the number of guard cells shown in Figure 12.

State one gas that leaves the stomata and one gas that enters the stomata during daylight.

gas leaving stomata

gas entering stomata

State why the stomata close.

A student wanted to view the cross-section of a leaf on a prepared slide.

Describe how a light microscope would be used to observe this slide.

Sugars are transported from the leaves to the rest of the plant.

Explain how sugars are moved through the plant.

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.

7 A farmer wants to make sunflower seeds germinate faster.

(a) Which is the best hormone for the farmer to use?

(b) The sunflower plants grew and flowered. The farmer noticed that the flowers faced a different direction at different times of the day. Figure 8 shows a sunflower at different times of the day. This movement is an example of phototropism.

(Source: © yevgeniy11/Shutterstock)

Figure 8

(i) This movement of the flower was in response to the light. Explain how the sunflower changed direction throughout the day.

(ii) Explain how water moves through the stem of the sunflower plant to the leaves.

(iii) Sunflower leaves are large. Explain why large leaves are an advantage to the plant.

7 (a) Figure 13 shows three organisms that live in pond water. Oxygen diffuses across the cell membranes of these organisms.

species A species B species C

Figure 13

(i) Which row of the table shows the conditions needed for oxygen to diffuse from species A into the pond water?

(ii) Species B has a surface area of 9 000μm² and a volume of 6 000μm³. Calculate surface area to volume ratio for species B.

(iii) The surface area to volume ratio for a cell of species A is 1: 1. The surface area to volume ratio for each cell in species C is 1: 4. Explain how the different surface areas will affect the diffusion of oxygen out of the cells of species A and species C.

(b) Some species of algae that photosynthesise have vacuoles that are filled with gas. These vacuoles help the algae to float in water. State how these vacuoles help the algae survive.

*(c) Figure 14 shows leaves on a branch of a tree.

(Source: © Butus/Shutterstock)

Figure 14

Explain how leaves are adapted for photosynthesis.

Respiration occurs in cells.

Why do cells respire?

An athlete runs every day as part of their training.

Explain why the breathing rate of the athlete increases when running.

When the athlete is running, their muscle cells use both aerobic respiration and anaerobic respiration.

State two differences between aerobic respiration and anaerobic respiration.

Bromothymol blue (BTB) solution is an indicator of pH.

Figure 5 shows the colour of BTB at different pH levels.

When air is passed through green BTB, for one minute, the solution stays green.

When a person breathes out through a straw into BTB for one minute the solution turns yellow.

Explain why the air breathed out turns the BTB solution yellow.

A scientist placed pondweed into two sealed test tubes containing green BTB solution.

Test tube A was kept in the dark. Test tube B was kept in the light. All other conditions were kept the same. Figure 6 shows these test tubes at the start of the investigation.

Figure 7 shows the colour of the BTB solution after 5 hours.

Explain the results for tube A and tube B shown in Figure 7.

Figure 13 shows part of a food web of organisms found in the cold Antarctic Ocean.

Which term describes phytoplankton in this food web?

Humans are removing large numbers of cod from the Antarctic Ocean.

State why the removal of cod could lead to a decrease in the numbers of squid and penguins.

Explain why the removal of cod could lead to an increase in the numbers of squid and penguins.

Figure 14 shows information about the biomass of some organisms in one part of the Antarctic Ocean.

Draw and label a pyramid of biomass for this food chain.

Seals are mammals.

Explain why the conversion of biomass from phytoplankton to shrimps is more efficient than the conversion of biomass from cod to seals.

Cod are being overfished in the Antarctic Ocean.

Suggest two actions that could be taken by humans to increase the number of cod in the Antarctic Ocean.

6 (a) Figure 10 shows a method of investigating the rate of photosynthesis in a water plant.

(Source: © ghrzuzudu/Shutterstock)

Figure 10

(i) What are the products of photosynthesis?

(ii) The rate of photosynthesis can be measured by counting the number of bubbles of gas produced in one minute. Figure 11 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.

Figure 11

Describe the effect of light intensity on the rate of photosynthesis. Use information from Figure 11 to help you.

(iii) The bubbles are different sizes and can be difficult to count. Describe how the quality of the results from this investigation could be improved.

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

(b) Increased nitrates can cause eutrophication in lakes. Explain how eutrophication will affect the fish living in the lakes.

Figure 16 shows an area of woodland with some small plants growing in the ground between the trees.

(Source: © Maksym Holovinov/Shutterstock)

Figure 16

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 17 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) Photosynthesis occurs in leaves.

Which substance is needed for photosynthesis?

A leaf cell is 0.08 mm long.

Calculate the length of the image of this cell after it has been magnified 50 times using a microscope.

Pine trees can live in dry soil.

Use words from the box to complete the sentences.

The pine leaf has stomata in pits to reduce the loss of_........ .

The pine leaf is needle-shaped to reduce the surface_........ .

Figure 5 shows young tomato plants growing in a glasshouse.

The young tomato plants are growing towards the light.

Explain how a plant hormone causes these shoots to grow towards the light.

Figure 12 shows the global movement of carbon into or out of the atmosphere.

Calculate the net mass of carbon added to the atmosphere each year.

Joseph Priestley was a scientist who investigated how green plants and combustion affected the carbon cycle.

Figure 13 shows his first experiment.

in a bell jar
minutes

State why the candle was not burning after three minutes.

Joseph Priestley continued the investigation but placed a plant inside the bell jar as shown in Figure 14.

He observed that the candle stayed alight for two minutes more than the candle in the bell jar in the first experiment.

Explain his observation.

State two variables that would need to be controlled to compare these two experiments.

Nitrogen is cycled through the environment.

Describe the roles of bacteria in the nitrogen cycle.

(a) Figure 12 shows a cross section through a leaf.

What is the name of the part labelled R in Figure 12?

Figure 13 shows the mass of glucose produced in each layer of a leaf per hour.

Describe the difference in the mass of glucose produced per hour in the palisade mesophyll and the mass of glucose produced in the spongy mesophyll shown in Figure 13.

Figure 14 shows how light intensity changed during one day.

Use information in Figure 14 to explain why oxygen moved out of the leaf between 9 am and midday.

Glucose is produced in a leaf.

Glucose is a

Describe a test for glucose.

Figure 15 shows an enzyme and three substrates found in plant cells.

The enzyme will only break down one of these substrates.

State the name of this enzyme.