Environmental Biology (Edexcel International A Level Biology)

The photograph shows two zebras.

Stano Novak, CC BY 2.5 <https://creativecommons.org/licenses/by/2.5>, via Wikimedia Commons

The stripes of zebras are thought to reduce attack by biting flies.

Biting flies cause stress and disease to cattle, reducing food production and causing financial losses for farmers.

Farmers use chemicals to kill the flies.

Flies often evolve resistance to a new chemical within about 10 years.

Explain how flies evolve resistance to new chemicals.

(3)

(ii)

Suggest why the evolution of resistance to these chemicals occurs so quickly in flies.

(1)

An investigation was carried out to see if the presence of stripes on cattle reduced the number of biting flies on their bodies.

Three groups of black cattle were compared:

• Unpainted cattle
• Cattle painted with black and white stripes
• Cattle painted with black stripes only.

Cattle repel flies by flicking their tails, stamping their feet and skin twitching.

The frequencies of these fly-repelling behaviours were recorded.

The graph and tables show some of the results of this investigation.

Table 1

Table 2

Determine the effectiveness of painting stripes on cattle in reducing the number of biting flies on them.

Use the information in the graph and both tables to support your answer.

Madagascar is a large island off the southeast coast of mainland Africa.

Lemurs are endemic to Madagascar.

There are many different species of lemur, all of which evolved from one common ancestor. This common ancestor is thought to be a primate that was carried across the sea from mainland Africa on a raft of vegetation.

The photographs show two different species of lemur, Sifaka and Indri, found in the same region of Madagascar.

The diet of Sifakas is mostly seeds but also includes fruits, flowers and some types of leaves. The diet of Indri is mainly leaves.

Explain the types of speciation that have taken place in the evolution of Sifakas and Indri in this region of Madagascar.

Lemurs have been found on another island close to Madagascar.

Scientists have used DNA profiling to show that these lemurs originated from those on Madagascar.

(i)

Explain the role of the polymerase chain reaction (PCR) in DNA profiling.

(2)

(ii)

Explain how DNA profiling could show that these lemurs originated from the lemurs on Madagascar.

(2)

The diagram shows part of the carbon cycle.

Carbon is found in carbohydrates.

The table shows some carbohydrates that may be found in plants and animals.

For each carbohydrate, put one cross ☒ in the appropriate box, in each row, to show where these carbohydrates are produced.

The mass of carbon recycling between the atmosphere and the plants, and the atmosphere and the oceans, are roughly balanced.

(i)

State how carbon is exchanged between the atmosphere and the oceans.

(1)

(ii)

Calculate the increase in the mass of carbon in plants as a result of carbon exchange between the plants and the atmosphere in one year.

Give your answer in kilograms.

(1)

(iii)

Describe how the carbon present in sugars in the plants is returned to the atmosphere in the carbon cycle.

(3)

Anthropogenic climate change is a result of an increase in the mass of carbon in the atmosphere.

(i)

State what is meant by the term anthropogenic climate change.

(2)

(ii)

Explain one way in which the effects of anthropogenic climate change can be reduced.

(2)

As the human population in the world has increased, the demand for food has increased.

The production of food has an impact on the environment, unless it can be done in a sustainable way.

State the meaning of the term population, as it has been used in this context.

(1)

(ii)

State the meaning of the term sustainable, as it has been used in this context.

(1)

The diagram shows the impact of food production on three environmental factors.

Explain how food production could contribute to the greenhouse effect.

(3)

(ii)

Land occupies 149 million km² of the surface of the Earth.

Habitable land is 71 % of this area and some of it is used for food production.

Calculate the area of the surface of the Earth used in food production.

Express your answer in standard form.

(3)

(iii)

Estimate the effect of food production on the ratio of biodiversity of mammals.

(1)

The diagram shows the area of land used to produce one kilogram of some food products.

Explain how food production could be made more sustainable.

Use the information in the diagram and your own knowledge to support your answer.

The photograph shows a ground squirrel.

Frank Schulenburg, CC BY-SA 4.0, via Wikimedia Commons

Ground squirrels feed on a variety of foods including nuts.

Ground squirrels have evolved food pouches.

The photograph shows the food pouches of a ground squirrel.

Colorado State University Libraries, CC BY-SA 4.0, via Wikimedia Commons

The table shows some information about three types of nut: acorns, hazelnuts and walnuts.

Type of nut	Photograph	Description	Energy content / kJ per 100 g
acorn		1.0 to 3.0 cm long 0.8 to 2.0 cm wide	1619
hazelnut		1.5 to 2.5 cm long 1.0 to 1.5 cm wide hard covering	2788
walnut		3.0 to 5.0 cm long 2.0 to 4.0 cm wide hard shell	2822

Alias 0591 from the Netherlands, CC BY 2.0; Horst Frank, CC BY-SA 3.0; Horst Frank, CC BY-SA 3.0, all via Wikimedia Commons

The volume of the smallest walnut is approximately 50 cm³.

Calculate the approximate volume of the largest hazelnut, using the formula:

where π = 3, l = length of the hazelnut and w = width of the hazelnut.

A student investigated the feeding preferences of ground squirrels.

(i)

Design a laboratory investigation to find out which of these three types of nut ground squirrels prefer to eat.

(3)

(ii)

Predict the results of this investigation, giving reasons.

Use the information in the table to support your answer.

(3)

Suggest how ground squirrels evolved pouches.

Redwood trees are the tallest living organisms on Earth. Some of the older trees are more than 2000 years old.

Dendrochronology can be used to work out how old a tree is and how much it has grown each year.

A sample of the tree trunk core can be taken using an increment borer.

The photograph shows an increment borer being used to take a sample of a tree trunk core.

Bureau of Land Management Oregon and Washington from Portland, America, Public domain, via Wikimedia Commons

The diagram shows an increment borer pushed into the trunk of a large Redwood tree.

An increment borer 1 m long was inserted into a Redwood tree. The borer did not reach the middle of the trunk. The distance from the end of the borer to the middle of the trunk is T cm.

Calculate the radius (r) of a tree with a circumference (C) of 8 m.

Use the formula: r =

(1)

(1)

To calculate how old a tree is and how much it has grown, core samples are taken at different heights up the tree.

These core samples are then aligned by matching the rings, as shown in the diagram.

(1)

Explain how these core samples can be used to calculate the age of this tree.

Use the information in the question and the diagram to support your answer.

(3)

Describe how the growth rate of this tree can be calculated.

(2)