Global warming

Farmers can increase crop yield by controlling the conditions the plants grow in.

Maize is a crop plant.

A variety of maize has been genetically modified (GM) to be resistant to a herbicide.

Explain how growing GM herbicide-resistant maize can produce a larger yield than growing non-GM maize.

Explain how growing a GM herbicide-resistant crop can decrease the biodiversity of animals.

Bees are a type of insect.

The number of insects near a crop can be increased by planting hedgerows.

Increasing the number of bees and other insects increases crop yield.

Suggest two reasons why increasing the number of insects can increase crop yield.

Hedgerows provide habitats for insects.

Give one reason why increasing hedgerow habitats increases insect numbers.

Some farmland contains areas of peat.

When peat is dug up:

• the oxygen levels in the peat increase

• the peat decays quickly.

Explain why increasing the level of oxygen in peat contributes to climate change.

Potatoes are a food crop.

Potato plants are classified as eukaryota.

What type of classification group is eukaryota?

Tick () one box.

Potato plants can reproduce by asexual reproduction.

Which statement is true for asexual reproduction?

Tick () one box.

Flowers of potato plants contain gametes for sexual reproduction.

How is a gamete different from other cells in a potato plant?

Tick () one box.

Plants in the same genus as potatoes have been studied by scientists.

Describe one way a new plant species could be identified as being in the same genus as potatoes.

Scientists have collected and stored seeds from species in the same genus as potatoes.

In the future, these seeds may be used for genetic modification of potato plants.

Genetically modified potato plants could help supply food to the human population as the climate changes.

Explain why genetic modification of crop plants may be important for the human population to survive climate change.

A student investigated how the distance from a river affects the number of different plant species. Figure 3 shows a river between two fields.

A, B and C show the positions of three transects. Where should the student position another transect for this investigation? Draw the extra transect line on Figure 3.

The student recorded the number of different plant species at 1 m intervals along each transect.

Which piece of equipment should be used at 1 m intervals along the transect? Tick (✓) one box.

Figure 4 shows the results.

What was the mean number of different plant species 5 m from the river?

What is the effect of increasing distance from the river on the mean number of different plant species?

The minimum and maximum values on Figure 4 show the range of results at each distance from the river. Why is it useful to know the range of results? Tick (✓) one box.

Cows are kept in the fields. Fewer plants are found where the cows often walk on the ground. The number of cows is one biotic factor that affects the number of plants. Which two factors are abiotic factors? Tick (✓) two boxes.

Explain why a decrease in the number of plants across the world increases global warming.

The polar bear is a mammal that lives in arctic habitats.

Complete Table 2 for the classification of the polar bear, Ursus maritimus.

Scientists have been measuring the area of sea ice in the Arctic since 1980. Figure 5 shows the area covered by sea ice every September.

Determine the annual rate of loss of sea ice between 1985 and 2017. A trend line has been drawn on Figure 5 to help you.

The total number of polar bears living on the arctic ice is not known. The hunting of polar bears has been banned or reduced in some areas. In some populations the average mass and height of polar bears has decreased. Polar bears eat seals. Seals live on the sea ice in winter and raise their pups there in early spring. In the summer seals live mainly in the sea catching fish to eat. Polar bears spend much of the year hunting seals on the sea ice and in the sea nearby. The sea ice area is at its lowest each year in September at the end of summer. The polar bears feed mainly in early spring, and again in autumn to build fat stores to survive the next winter. During the winter of 2017 scientists measured the metabolic rates of nine female polar bears and found them to be much higher than expected. Cameras attached to the female polar bears showed they had to swim long distances to find seals to eat.

Suggest why polar bears find it harder to catch seals in autumn than in spring.

Evaluate what might happen to the population of polar bears in the Arctic in the future.

Increased carbon dioxide levels in the atmosphere contribute to climate change.

Give one way deforestation can increase carbon dioxide levels in the atmosphere.

Name one other gas that contributes to climate change.

Do not refer to carbon dioxide in your answer.

Meat is produced for humans to eat.

Give two ways the production of meat releases carbon dioxide.

The mass of carbon dioxide released during the production of food varies depending on the type of food.

Figure 4 shows the mass of carbon dioxide released as a result of three different diets.

Compare the mass of carbon dioxide released as a result of the three diets shown

in Figure 4.

Use data from Figure 4 in your answer.

There has been a rapid increase in the percentage of carbon dioxide in the atmosphere since 1960.

Carbon dioxide is a greenhouse gas that contributes to global warming.

Name one other greenhouse gas.

Global warming causes climate change.

Give two effects of climate change.

Plants take in carbon dioxide from the atmosphere.

Figure 7 shows part of the carbon cycle.

Describe how carbon from the atmosphere is cycled through living organisms.

There has been a rapid increase in the percentage of carbon dioxide in the atmosphere since 1960.

Carbon dioxide is a greenhouse gas that contributes to global warming. Name one other greenhouse gas.

Global warming causes climate change. Give two effects of climate change.

Question 2 continues on page 10

Plants take in carbon dioxide from the atmosphere. Figure 2 shows part of the carbon cycle.

Describe how carbon from the atmosphere is cycled through living organisms.

Every year scientists have recorded the date when migrating birds arrived at summer breeding grounds in the UK.

The records show that for every 1 C increase in mean global temperature, the birds arrived one day earlier.

What will the birds be competing for when they arrive at their UK breeding grounds?

Tick two boxes.

Birds that arrive early might survive better than birds that arrive later.

Suggest one reason why.

Global temperatures are increasing every year.

This is because of an increase of greenhouse gases in the atmosphere.

Name one greenhouse gas.

Global warming affects the migration of animals.

Give one other effect of global warming.

Which two human activities cause global warming?

Tick two boxes.

Which gas in the atmosphere causes acid rain?

Tick one box.