Photosynthesis

Figure 5 shows a food chain.

What process allows algae to be producers for the food chain?

Adélie penguins are one species of penguin.

Adélie penguins:

feed in the ocean

make nests on the ground using stones.

The amount of snow is an abiotic factor which affects Adélie penguins.

Which are two biotic factors that affect the Adélie penguins?

Tick (✓) two boxes.

A new pathogen

Acidic soil

High light intensity

Lack of food

Low temperature

Figure 6 shows an Adélie penguin on a nest made of stones.

Adélie penguins steal stones from nearby nests to make their own nest higher.

A higher nest gives young penguins a better chance of surviving.

What is stealing stones for nests an example of?

Tick (✓) one box.

An ecosystem

Competition

Interdependence

Scientists calculated the mean area covered by one Adélie penguin nest.

The mean area of one nest is 18 000 cm².

Enlarge

An area of 122 400 m² was covered by nests.

Calculate the maximum possible number of nests in an area of 122 400 m².

Use your answer from Question 04.6.

There are many ways of sampling animal and plant populations.

Students sample a plant population.

Which piece of equipment can the students use to sample a plant population?

Tick (✓) one box.

A pH meter

A quadrat

A thermometer

Students sometimes use a transect.

When should a transect method be used?

Tick (✓) one box.

To investigate feeding relationships

To investigate the distribution of a population

To investigate the oxygen concentration in water

Photosynthesis produces glucose (C₆H₁₂O₆).

Write a balanced symbol equation for photosynthesis.

A student investigated the effect of light intensity on the rate of photosynthesis in three species of aquatic plant.

Figure 7 shows the apparatus used.

This is the method used.

1. Place species A in water in a test tube.

2. Leave the test tube containing species A in a dark room for 10 minutes.

3. Put the test tube containing species A 20 cm away from the lamp.

4. Record the number of bubbles produced by species A in 5 minutes.

5. Repeat steps 2 to 4 at different distances from the lamp.

6. Repeat steps 1 to 5 using species B and species C.

The student repeated the investigation several times.

Explain how two other improvements to the method would ensure the results are more valid.

When the distance between the lamp and the plant is 20 cm, the light intensity is 0.0025 arbitrary units.

Calculate how many times greater the light intensity is at 20 cm compared with the light intensity at 60 cm.

Use the equation:

The student collected valid results.

Figure 8 shows the results.

Predict the number of bubbles that would be produced by species B at 10 cm from the lamp.

You should extend the line on Figure 8.

Species A, B and C grow at different depths in ponds.

Which species is most likely to be found growing near the surface of the pond?

Give the reason for your answer.

Tick () one box.

A B C

Global dimming is a decrease in the sunlight reaching the Earth’s surface due to particulates in the atmosphere.

Enlarge

A species of grass has the binomial name Lolium perenne.

What is the genus of the grass?

Grass leaves look green because of a green pigment found in chloroplasts.

Name the green pigment found in chloroplasts.

Which mineral ion is found in the green pigment in chloroplasts?

Tick (✓) one box.

Magnesium ion

Nitrate ion

Sodium ion

An area of grass changed colour after being covered by a tent.

The colour of the grass changed from green to yellow.

Figure 13 shows the area of green grass and the area of yellow grass.

A student used paper chromatography to investigate the pigments in grass leaves from: the area of green grass the area of yellow grass.

Figure 14 shows the results.

Figure 14

Distance

Start line

Green Yellow grass grass leaves leaves

The student crushed the grass leaves.

Describe a method to separate the pigments in the crushed grass leaves using paper chromatography.

Figure 14 is repeated below.

Figure 14

Distance

Start line

Green Yellow grass grass leaves leaves

Determine the R_f value of the pigment that is found in green grass leaves but not found in yellow grass leaves.

Use the equation:

R = distance moved by pigment ^f distance moved by solvent

Use Figure 14.

There are fewer pigments in the yellow grass leaves than in the green grass leaves.

Suggest one reason why.

A species of grass has the binomial name Lolium perenne.

What is the genus of the grass?

Grass leaves look green because of a green pigment found in chloroplasts.

Name the green pigment found in chloroplasts.

Which mineral ion is found in the green pigment in chloroplasts?

Tick (✓) one box.

Magnesium ion

Nitrate ion

Sodium ion

An area of grass changed colour after being covered by a tent.

The colour of the grass changed from green to yellow.

Figure 2 shows the area of green grass and the area of yellow grass.

A student used paper chromatography to investigate the pigments in grass leaves from: the area of green grass the area of yellow grass.

Figure 3 shows the results.

Figure 3

Distance

Start line

Green Yellow grass grass leaves leaves

The student crushed the grass leaves.

Describe a method to separate the pigments in the crushed grass leaves using paper chromatography.

Figure 3 is repeated below.

Figure 3

Distance

Start line

Green Yellow grass grass leaves leaves

Determine the R_f value of the pigment that is found in green grass leaves but not found in yellow grass leaves.

Use the equation:

R = distance moved by pigment distance moved by solvent

Use Figure 3.

There are fewer pigments in the yellow grass leaves than in the green grass leaves.

Suggest one reason why.

In managed forests:

tree seedlings are regularly planted

some trees are regularly removed.

Some of the young trees in a managed forest are removed every year.

The biomass of wood produced by the remaining trees in the forest is increased by removing the young trees.

Explain why.

Explain how the processes of photosynthesis and respiration in a tree are involved in the production of new biomass for the tree.

Planting trees to maintain forests is good for the environment.

Explain the environmental and biological benefits of maintaining forests.

Some plants have leaves with white areas and green areas.

A student tested a leaf with white areas and green areas for starch.

This is the method used.

1. Boil the leaf in ethanol.

2. Rinse the leaf in water.

3. Add iodine solution to the leaf.

4. Record the colour of each area of the leaf.

Figure 2 shows the results.

The student boiled the leaf in ethanol to remove the green colour from the leaf.

Why does the green colour need to be removed from the leaf before the leaf is tested for starch?

Explain how the results in Figure 2 provide evidence that the white area of the leaf did not contain chlorophyll.

The student investigated the coloured pigments in the leaf.

Figure 3 shows the apparatus.

Chromatography involves a mobile phase and a stationary phase.

Draw one line from each phase to the identity of that phase in the investigation.

The student drew the start line in pencil.

Why did the student not draw the start line in ink?

Table 2 shows the results.

Calculate X in Table 2.

Use the equation:

The distance moved by the solvent was 121 mm.

Give your answer to 2 significant figures.

Table 3 shows the range of R_f values for known leaf pigments.

The student used Table 3 to identify the leaf pigments in their investigation.

Which colour is the leaf pigment phaeophytin?

Use Table 2 and Table 3.

Another student did the investigation using the same leaf pigments.

The R_f values for the same pigments were different.

What is the reason for the difference?

Tick (✓) one box.

A different solvent was used.

A greater volume of solvent was used.

The solvent moved further.

Figure 3 shows a tomato plant.

A leaf is a plant organ.

Name one other plant organ shown in Figure 3.

A student investigated the effect of different colours of light on the growth of tomato plant seedlings.

Figure 4 shows the apparatus used.

This is the method used.

1. Place three tomato plant seedlings under each colour of light.

2. Water each seedling every day.

3. Measure the height of each seedling after 30 days.

Give two control variables the student should have used in their investigation.

The student repeated the investigation using a valid method.

Table 2 shows the results.

Give two conclusions from the results in Table 2.

Another student investigated the effect of light intensity on the rate of photosynthesis.

The student counted the number of bubbles of oxygen produced by pondweed at different light intensities.

Figure 5 shows some of the apparatus used.

Describe how the student could change the light intensity.

The pondweed did not produce many bubbles.

How could the student change the investigation to increase the number of bubbles produced?

Tick (✓) one box.

Add more water to the test tube.

Use a smaller piece of pondweed.

Use water at a higher temperature.

The student calculated the rate of photosynthesis.

Which equation is used to calculate the rate of photosynthesis?

Tick (✓) one box.

rate of photosynthesis = number of bubbles × time

Figure 6 shows the rate of photosynthesis at different light intensities.

Describe the pattern in Figure 6.

Use data from Figure 6.

Algal cells can photosynthesise.

A student investigated the effect of light intensity on photosynthesis in algal cells.

Figure 8 shows the apparatus used.

Describe the relationship between light intensity and distance, as the distance of the algal cells from the lamp is doubled.

You must include calculations of light intensity at 20 cm and 40 cm in your answer.

Use the equation:

The student recorded the pH of the water at the start and after one hour in each beaker.

Table 7 shows the results.

The method produced valid results.

Carbon dioxide is an acidic gas.

Explain the results in Table 7.

Corals are animals that live in the sea.

Corals: cannot move from one place to another place feed on tiny animals that float past in the water have algal cells living inside their own cells.

Figure 9 shows a coral and an enlarged coral cell.

Algal cells photosynthesise to produce glucose (C₆H₁₂O₆).

Write the balanced symbol equation for photosynthesis.

Explain one way the algal cells use glucose for growth.

Suggest one advantage to the algal cells of living inside the coral cells.

An increase in water temperature can cause coral to release the algal cells.

Releasing algal cells can result in the death of coral.

Suggest why coral may not survive without the algal cells.

Scientists investigated how the concentration of oxygen in the water around one coral changed during the day.

Figure 10 shows the results.

Explain the changes in oxygen concentration between A and B.

At C the rate at which oxygen is being produced equals the rate at which oxygen is being used.

Give the reason why.

Plants absorb light to photosynthesise.

Complete the word equation for photosynthesis.

Light intensity affects the rate of photosynthesis.

Figure 13 shows some of the equipment used to measure the rate of photosynthesis.

Describe a method to investigate the effect of light intensity on the rate of photosynthesis.

Use the equipment in Figure 13 and other laboratory equipment.

Algal cells photosynthesise.

Scientists investigated the effect of light intensity on algal cells.

The algal cells were placed in different light intensities.

Table 8 shows the number of extra algal cells after two days.

The initial number of algal cells was 200 000

Calculate the total number of algal cells after two days when the light intensity was 500 lux

Plot the data from Table 8 on Figure 14.

The first two points have been plotted.

Draw a line of best fit.

Give two conclusions from the results.

Use information from Table 8.

Explain how an increase in temperature from 20 °C to 25 °C would affect the number of algal cells.

Plants absorb light to photosynthesise.

Complete the word equation for photosynthesis.

Light intensity affects the rate of photosynthesis.

Figure 3 shows some of the equipment used to measure the rate of photosynthesis.

Describe a method to investigate the effect of light intensity on the rate of photosynthesis.

Use the equipment in Figure 3 and other laboratory equipment.

Algal cells photosynthesise.

Scientists investigated the effect of light intensity on algal cells.

The algal cells were placed in different light intensities.

Table 2 shows the number of extra algal cells after two days.

The initial number of algal cells was 200 000

Calculate the total number of algal cells after two days when the light intensity was 500 lux

Plot the data from Table 2 on Figure 4.

The first two points have been plotted.

Draw a line of best fit.

Give two conclusions from the results.

Use information from Table 2.

Explain how an increase in temperature from 20 °C to 25 °C would affect the number of algal cells.