Limiting factors in photosynthesis

A student investigated the effect of temperature on the rate of photosynthesis in pondweed. Figure 2 shows how the student set up the apparatus.

This is the method used.

1. Prepare six tubes of pondweed as shown in Figure 2.

2. Place one tube into each of six water baths set at different temperatures.

3. Wait two minutes.

4. Measure the time taken for each piece of pondweed to release 10 bubbles.

What is the independent variable in the investigation?

Tick () one box.

Table 2 shows the results.

Complete the sentences.

Choose answers from the box.

Describe the effect of increasing temperature on the time taken for the pondweed to release 10 bubbles.

Calculate the rate of photosynthesis at 50 °C.

Use the equation:

Use Table 2.

Give your answer to 1 decimal place.

Which temperature had the fastest rate of photosynthesis?

Tick () one box.

Table 2 is repeated below.

The student repeated the investigation at 80 °C.

What would be the time taken for the pondweed to release 10 bubbles at 80 °C?

Tick () one box.

Which two factors could affect the rate of photosynthesis in this investigation?

Tick () two boxes.

A student investigated the effect of temperature on the rate of photosynthesis in pondweed.

Figure 4 shows how the student set up the apparatus.

This is the method used.

1. Prepare five tubes of pondweed as shown in Figure 4.

2. Place one tube into each of five water baths set at different temperatures.

3. Wait two minutes.

4. Measure the time taken for each piece of pondweed to release 10 bubbles.

What is the independent variable in the investigation?

Table 4 shows the results.

Calculate the rate of photosynthesis at 20 °C.

Give your answer to 3 significant figures.

Give the unit.

Explain the difference in the rate of photosynthesis at 40 °C compared with the rate of photosynthesis at 10 °C.

Give two other factors that affect the rate of photosynthesis.

Do not refer to temperature in your answer.

Describe one way the method could be changed to obtain more accurate results for the rate of photosynthesis.

A gardener noticed that some plants were not growing as well as usual.

Describe two ways the gardener could identify a plant disease.

One of the plants had purple spots on its leaves and the leaves fell off.

What disease is the plant most likely to have?

A different plant had yellow leaves, but no spots.

Explain why plants may develop yellow leaves.

A student investigated the effect of different factors on photosynthesis.

The student used three leaves growing on the same plant.

Each leaf was treated in a different way.

After 48 hours the student tested each leaf for starch.

Table 3 shows the results.

Explain the results for the three leaves.

In another investigation the student used a different type of plant.

The plant was left uncovered in the light for 48 hours.

After 48 hours the student tested a leaf from the plant for starch.

Figure 6 shows the leaf before it was tested for starch.

Complete Table 4 to show the results you would expect for the starch test on the leaf in Figure 6.

Explain the results you gave in Question 07.2.

In some leaves, the green parts become yellow because of an ion deficiency.

Which ion is deficient in a plant with yellow leaves?

Give the scientific term that describes the yellow colour of the leaves.

The rate of photosynthesis is affected by different factors.

How could the oxygen produced during photosynthesis be used to measure the rate of photosynthesis?

Light, carbon dioxide and temperature are limiting factors of photosynthesis.

Figure 7 shows how the rate of photosynthesis is affected by light, carbon dioxide and temperature.

At point A on Figure 7, light is a limiting factor.

What is meant by a ‘limiting factor’?

Explain the effect of increasing temperature and increasing carbon dioxide concentration on the rate of photosynthesis shown in Figure 7.

Photosynthesis investigations often use a light source.

The spreading out of light from a source obeys the inverse square law.

The inverse square law links light intensity to distance from the light source.

Which of the following shows the inverse square law?

Tick (✓) one box.

Photosynthesis produces oxygen.

Complete the word equation for photosynthesis.

Choose answers from the box.

_____________________ + _____________________ → _____________________ + oxygen

Explain how oxygen is used in cells.

A student investigated the effect of light from different coloured light bulbs on photosynthesis.

The student:

• used pondweed in a beaker of water

• used different coloured light bulbs in a lamp

• counted the number of bubbles of oxygen the pondweed produced in 2 minutes for each colour of light bulb.

Give one hazard the student would need to consider when using the apparatus in this investigation.

Give the risk the hazard would cause.

The student needed to keep the temperature of the water in the beaker the same throughout the investigation.

Describe how the student could keep the temperature of the water the same.

The beaker of water contained the pondweed.

Explain why the temperature of the water in the beaker needed to be kept the same throughout the investigation.

Table 3 shows the results.

Which colour of light caused the highest rate of photosynthesis in the pondweed?

Tick (✓) one box.

What is the best way to display the data in Table 3 ?

Tick (✓) one box.

The student wanted to measure the volume of oxygen the pondweed produced in 2 minutes.

Name one piece of apparatus the student could use to measure the volume of oxygen.

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

Figure 1 shows the results.

Describe what Figure 1 shows about the relationship between light intensity and the rate of photosynthesis.

This question is about photosynthesis.

Complete the symbol equation for photosynthesis.

Figure 8 shows how the rate of photosynthesis changes with light intensity.

Which part of the graph could be represented by the equation y = mx + c ? Tick (✓) one box.

A student investigated the effect of colour of light on the rate of photosynthesis

in leaves. Figure 9 shows how the investigation was set up.

Table 5 shows the results.

Give one way the student could change the colour of the light shining on the leaf discs.

Give the independent variable and the dependent variable in this investigation. Independent variable

Dependent variable

All of the air had to be removed from the leaf discs before placing them in the beaker. Suggest one reason why.

The leaf discs were placed in a beaker of sodium hydrogencarbonate

Explain why sodium hydrogencarbonate solution was used instead of water.

Explain why the leaf discs moved to the surface of the solution during the investigation.

There are two types of chlorophyll in leaves.

Figure 10 shows the percentage of different wavelengths of light that the two types of chlorophyll absorb.

Table 6 shows the colour of different wavelengths of light.

Suggest the advantage to a plant of having two types of chlorophyll.

Table 5 is repeated below.

The leaf discs in the investigation are green. Explain the results in Table 5 for blue light and for green light. Use data from Figure 10 and Table 6.

A scientist investigated the rate of photosynthesis of one type of tomato plant.

The tomato plants were grown in a greenhouse.

Table 2 shows the results.

Give two control variables the scientist should have used in the investigation.

Which range of carbon dioxide concentrations caused the rate of photosynthesis to change the most?

Tick (✓) one box.

How could the scientist have improved the validity of the results?

Tick (✓) one box.

Explain the change in the rate of photosynthesis when the concentration of carbon dioxide increased between 0.00% to 0.08%.

A farmer decided not to use a concentration of carbon dioxide higher than 0.08% to grow tomato plants.

Suggest two reasons for the farmer’s decision.

Use information from Table 2 and your own knowledge.

Viruses cause disease.

What name is given to microorganisms that cause disease? Tick (✓) one box.

How do viruses cause the symptoms of disease? Tick (✓) one box.

Figure 4 shows a virus and an animal cell.

Suggest one reason why viruses are not classed as cells.

A vaccine can protect humans from a viral disease.

What does the vaccine contain? Tick (✓) one box.

In some cases, a first vaccination needs to be followed by a second vaccination some time later.

Which graph shows how the concentration of antibodies in a person’s blood changes after the first and second vaccinations? Tick (✓) one box.

Tobacco mosaic virus (TMV) causes disease in plants.

TMV affects the rate of photosynthesis in plants.

Which part of a plant shows discolouration caused by TMV? Tick (✓) one box.

Table 1 shows the rate of photosynthesis in four different tobacco plants.

Complete Figure 5. You should:

• label the y-axis

• add the correct scale to the y-axis

• plot the data from Table 1

• label each bar.

What conclusion can be made from the data in Table 1 ?

Explain why a high level of TMV infection reduces growth in a plant.

This question is about photosynthesis.

Complete the word equation for photosynthesis.

Describe how energy for the photosynthesis reaction is gained by plants.

Students investigated the effect of temperature on the rate of photosynthesis. The students shone light from a lamp onto pondweed and measured the volume of oxygen produced per hour. Table 3 shows the results.

Calculate mean value X.

The students identified one anomalous result in Table 3.

Draw a ring around the anomalous result in Table 3.

Suggest one possible cause of the anomalous result.

How did the students deal with the anomalous result?

Give one factor the students should have kept constant in this investigation.

Table 3 is repeated below.

Why did the rate of photosynthesis decrease from 35 °C to 45 °C?

Complete Figure 10 using data from Table 3. You should:

• label the y-axis

• use a suitable scale for the y-axis

• plot the mean data from Table 3 for temperatures from 25 °C to 45 °C

• draw a line of best fit.

This question is about photosynthesis.

Complete the word equation for photosynthesis.

Describe how energy for the photosynthesis reaction is gained by plants.

Students investigated the effect of temperature on the rate of photosynthesis. The students shone light from a lamp onto pondweed and measured the volume of oxygen produced per hour. Table 1 shows the results.

Calculate mean value X.

The students identified one anomalous result in Table 1.

Draw a ring around the anomalous result in Table 1.

Suggest one possible cause of the anomalous result.

How did the students deal with the anomalous result?

Give one factor the students should have kept constant in this investigation.

Table 1 is repeated below.

Why did the rate of photosynthesis decrease from 35 °C to 45 °C?

Complete Figure 1 using data from Table 1. You should:

• label the y-axis

• use a suitable scale for the y-axis

• plot the mean data from Table 1 for temperatures from 25 °C to 45 °C

• draw a line of best fit.

This question is about photosynthesis.

Complete the word equation for photosynthesis:

A student investigated photosynthesis using pondweed.

Figure 14 shows the apparatus the student used.

This is the method used.

1. Set up the apparatus as shown in Figure 14.

2. Switch on the lamp.

3. After 20 minutes, record the volume of oxygen collected in the measuring cylinder.

4. Repeat steps 1–3 using bulbs of different power output.

What was the independent variable in the investigation?

Tick (✓) one box.

Suggest two ways the method could be improved so the results would be more valid.

Table 9 shows the student’s results.

Calculate value X in Table 9.

Complete Figure 15.

You should:

• label the x-axis

• use a suitable scale

• plot the data from Table 9 and your answer to Question 09.4

• draw a line of best fit.

Determine the expected rate of photosynthesis with a bulb of power output 75 watts.

Use Figure 15.

Which graph shows the effect of temperature on the rate of photosynthesis?

Tick (✓) one box.

This question is about photosynthesis.

Complete the word equation for photosynthesis:

A student investigated photosynthesis using pondweed.

Figure 3 shows the apparatus the student used.

This is the method used.

1. Set up the apparatus as shown in Figure 3.

2. Switch on the lamp.

3. After 20 minutes, record the volume of oxygen collected in the measuring cylinder.

4. Repeat steps 1–3 using bulbs of different power output.

What was the independent variable in the investigation?

Tick (✓) one box.

Suggest two ways the method could be improved so the results would be more valid.

Table 3 shows the student’s results.

Calculate value X in Table 3.

Complete Figure 4.

You should:

• label the x-axis

• use a suitable scale

• plot the data from Table 3 and your answer to Question 03.4

• draw a line of best fit.

Determine the expected rate of photosynthesis with a bulb of power output 75 watts.

Use Figure 4.

Which graph shows the effect of temperature on the rate of photosynthesis?

Tick (✓) one box.

Plants can be infected by fungi, viruses and insects.

Aphids are small insects that carry pathogens.

Figure 6 shows an aphid feeding from a plant stem.

An aphid feeds by inserting its sharp mouthpiece into the stem of a plant.

Give the reason why the mouthpiece of an aphid contains a high concentration of dissolved sugars after feeding.

Plants infected with aphids may show symptoms of magnesium deficiency.

Magnesium deficiency symptoms include:

• yellow leaves

• stunted growth.

Explain how a deficiency of magnesium could cause these symptoms.

A farmer thinks a potato crop is infected with potato virus Y (PVY).

The farmer obtains a monoclonal antibody test kit for PVY.

To make the monoclonal antibodies a scientist first isolates the PVY protein from the virus.

Describe how the scientist would use the protein to produce the PVY monoclonal antibody.