Plant disease & defence

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.

A root is a plant organ.

Plant roots contain many different types of tissue.

What is a tissue?

Tissue in the tip of a plant root contains stem cells.

Stem cells can differentiate into any type of cell.

Name the type of tissue in plants that contains stem cells.

In the past many drugs were extracted from plants.

Aspirin is a painkiller.

Which plant does aspirin originate from?

Scientists have extracted chemical A from the deadly nightshade plant.

Chemical A can be used as a painkiller.

Table 5 shows information about where chemical A is found.

The scientists usually extract chemical A from the berries of the deadly nightshade plant.

Suggest one reason why berries are used instead of leaves or roots.

A deadly nightshade plant has chlorosis (yellow leaves).

The mass of chemical A found in the leaves of the plant is 60% of the mass shown in Table 5.

Calculate the mass of chemical A in 200 g of the leaves with chlorosis.

Give your answer in mg.

Suggest one reason why the leaves of the deadly nightshade plant have chlorosis.

Chemical A has not been tested in large-scale clinical trials in the UK.

It is important for drugs to be tested in clinical trials before the drugs are approved for use by the public.

Give two reasons why.

There are many online reports making claims about the effects of chemical A.

Some of these reports are biased.

Suggest one reason why a report making claims about the effects of chemical A may be biased.

How can scientists be sure that claims about new drugs are valid?

Tick (✓) one box.

A root is a plant organ. Plant roots contain many different types of tissue.

What is a tissue?

Tissue in the tip of a plant root contains stem cells. Stem cells can differentiate into any type of cell. Name the type of tissue in plants that contains stem cells.

In the past many drugs were extracted from plants.

Aspirin is a painkiller. Which plant does aspirin originate from?

Scientists have extracted chemical A from the deadly nightshade plant. Chemical A can be used as a painkiller. Table 1 shows information about where chemical A is found.

The scientists usually extract chemical A from the berries of the deadly nightshade plant. Suggest one reason why berries are used instead of leaves or roots.

A deadly nightshade plant has chlorosis (yellow leaves).

The mass of chemical A found in the leaves of the plant is 60% of the mass shown in Table 1.

Calculate the mass of chemical A in 200 g of the leaves with chlorosis. Give your answer in mg.

Suggest one reason why the leaves of the deadly nightshade plant have chlorosis.

Chemical A has not been tested in large-scale clinical trials in the UK.

It is important for drugs to be tested in clinical trials before the drugs are approved for use by the public. Give two reasons why.

There are many online reports making claims about the effects of chemical A. Some of these reports are biased.

Suggest one reason why a report making claims about the effects of chemical A may be biased.

How can scientists be sure that claims about new drugs are valid? Tick (✓) one box.

Plants take up water from the soil through their roots.

Some of the water is used for photosynthesis.

Complete the word equation for photosynthesis.

Choose answers from the box.

Water and dissolved substances are transported through a plant.

Complete the sentences.

Choose answers from the box.

Water moves from the roots to the leaves in the

Water is lost from leaves through pores called

Dissolved sugars are transported in the.

Table 3 shows the rate of transpiration in four different plant species.

Calculate how many times greater the rate of transpiration of species A is than the rate of transpiration of species B.

Give your answer to 2 significant figures.

Which factor could cause species A to have a higher rate of transpiration than species B ?

Tick (✓) one box.

Which environmental change would cause an increase in the rate of transpiration?

Tick (✓) one box.

Which plant species in Table 3 is most likely to live in a dry desert?

Tick (✓) one box.

Some plants have adaptations that help them survive.

Figure 6 shows part of a gorse plant.

How will the sharp spines help the gorse plant survive?

Animals also have adaptations to help them survive.

Figure 7 shows two insects.

Hornets are insects that sting other animals and cause pain.

Hornet moths do not sting other animals.

Explain why animals avoid eating the hornet moth.

Plants and animals have many defence responses.

Table 5 shows some plant defences. Identify whether each defence is a chemical response or a physical response. Tick (✓) one box in each row.

Mimicry is a mechanical adaptation seen in both plants and animals.

Figure 5 shows two insects.

Hornets are insects that sting other animals and cause pain. Hornet moths do not sting other animals. Suggest how mimicry helps the hornet moth survive.

Adult hornet moths lay eggs that hatch into larvae.

Figure 6 shows the larvae of a hornet moth.

The larvae of the hornet moth:

• live inside the roots of trees

• use the tree roots as a source of food

• cause damage to the tree roots.

Explain why a tree might die if the roots of the tree are damaged.

The larvae of the hornet moth form when fertilised eggs divide by mitosis. Describe how mitosis produces two genetically identical cells.

The cells which are first formed from the fertilised eggs of the hornet moth are stem cells. Name the process by which these stem cells then form specialised cells.

A cactus is a plant that lives in a dry environment. Figure 6 shows part of a cactus plant.

Give one adaptation shown in Figure 6 that helps to prevent the cactus from being eaten by animals.

A plant may produce poisons that make animals unwell. What is this type of defence mechanism?

Tick (✓) one box.

Some desert plants only grow leaves after it has rained. As soon as the soil dries out, the leaves fall off. How could the leaves falling off the plant be an advantage to a plant that lives in a dry environment? Tick (✓) one box.

The stem of a cactus is green.

What causes the green colour in the stem?

What is the advantage to the cactus of having a green stem?

The stem of a cactus contains many different tissues.

What name is given to a group of tissues working together? Tick (✓) one box.

Name one substance transported through the xylem in the stem of the cactus.

Name the tissue that transports dissolved sugars through the stem of the cactus.

Figure 7 shows part of a deadly nightshade plant.

How will the poisonous berries help the deadly nightshade plant to survive?

Which type of defence mechanism are the berries? Tick (✓) one box.

Figure 8 shows part of a gorse plant.

Suggest how the gorse plant is adapted to defend itself.

The green leaves of the gorse plant make glucose for the plant to use. What are two uses of glucose in the gorse plant? Tick (✓) two boxes.

A student wanted to show that the leaves of a gorse plant contain glucose. The student crushed the leaves to extract the liquid from the cells. Describe the method the student could use to test the liquid from the cells for glucose. Include the result if glucose is present.

The roots of the gorse plant have bacteria that turn nitrogen gas into nitrate ions. Explain why nitrate ions are needed by the gorse plant.

The roots of gorse plants can be infected by honey fungus. The honey fungus produces tiny spores underground. Suggest how the honey fungus spores travel from the roots of an infected gorse plant to the roots of a healthy gorse plant.

A drug can be extracted from gorse seeds.

Doctors want to trial the drug from gorse seeds to see if it can treat diarrhoea.

Which two factors must the doctors test the drug for in the trial? Tick (✓) two boxes.

In the trial some patients will take tablets made from gorse seeds and some patients will take tablets made from sugar. What are the tablets made from sugar called? Tick (✓) one box.

Many plants have evolved defence mechanisms. Figure 8 shows part of a gorse plant and part of a deadly nightshade plant.

The gorse plant has evolved to have sharp thorns. What type of defence response are thorns?

How do thorns defend the gorse plant?

The deadly nightshade plant has poisonous berries. What type of defence response are poisonous berries?

A scientist noticed that in one area the gorse plants had yellow leaves and had stunted growth. One reason for yellow leaves and stunted growth is a deficiency of nitrate ions in the soil. Explain two other possible reasons for the yellow leaves and stunted growth. Do not refer to nitrate ions in your answer.

The gorse plant has nodules on its roots.

The nodules are part of the living root tissue. Bacteria which convert nitrogen gas into soluble nitrate ions live in the nodule tissue. Figure 9 shows the nodules on the roots.

Suggest how the nodules benefit the bacteria.

Explain how the nodules benefit the gorse plant.

For many years drugs have been extracted from plants. Which plant material was chewed as a painkiller? Tick (✓) one box.

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This question is about leaves.

Complete the sentences.

Choose answers from the box.

The layer of cells lining the upper surface and lower surface of a

leaf is the.

The part of the leaf where most photosynthesis occurs

is the.

Water is transported to the leaf in the

Water is lost through small openings on the lower surface of plant leaves.

These small openings are called stomata.

Figure 5 shows two stomata on the lower surface of a leaf.

The cells labelled X control the width of the stomata.

What are the cells labelled X ?

Tick (✓) one box.

What is the function of the stomata?

Tick (✓) one box.

How is water lost from a leaf?

Tick (✓) one box.

A student investigated the volume of water lost from two plants.

The plants were different species.

Figure 6 shows the student’s results.

Calculate the difference in the volume of water lost by plant A compared to plant B in the first hour.

What could cause plant A to lose water at a faster rate than plant B ?

Tick (✓) one box.

After the first 2 hours, both plants were moved to a new room.

Suggest one reason why both plants lost water at a faster rate in the new room.

Some plants have adaptations to stop them from being eaten by animals.

Figure 7 shows part of a holly plant.

Describe one way the holly plant is adapted to stop it being eaten by animals.

Aphids are small insects that carry pathogens.

Figure 7 shows an aphid feeding from a plant stem.

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

After feeding, the mouthpiece of an aphid contains a high concentration of dissolved sugars.

Which part of the plant was the aphid feeding from?

Tick one box.

What is the process that transports dissolved sugars around a plant?

Plants infected with aphids have stunted growth.

Explain one way the removal of dissolved sugars from the stem of the plant causes stunted growth.

Most aphids do not have wings when they hatch. After several generations, some aphids hatch which have wings and can fly.

Explain the advantage to the aphid of being able to fly.

The leaves of some plants release oils onto their surface.

Suggest how the production of oil on the surface of a leaf may protect the plant from aphids.

Figure 8 shows part of a rose plant.

Give one adaptation shown in Figure 8 that helps the rose plant defend itself.

Figure 9 shows a plan of a garden containing rose plants.

Plant A has the fungal disease rose black spot.

Which plant in Figure 9 is the fungus likely to spread to first?

Give a reason for your answer.

Suggest one way the gardener could reduce the spread of rose black spot to the other plants in the garden.

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.