Biodiversity

A group of students investigate the biodiversity in two fields, A and B. Field A is grazed by cattle and field B has no cattle.

Explain what is meant by the term biodiversity.

The students investigate the plant species in each field. They counted the number of each species in five 0.5 m × 0.5 m quadrats. They repeated this for each field. Table 1 shows their results.

Describe how the quadrats should be placed to obtain unbiased species numbers for each field.

For the most frequently occurring plant species in field B, calculate the number of plants in one square metre.

number of plants =_........

Name the species with the greatest variation in number of plants recorded in quadrats for field B.

Table 1 is repeated here.

The students conclude that grazing affects the species in field A. Using information in Table 1 and your own knowledge, discuss the students’ conclusion.

Megalodon was an animal.

Which of these features does megalodon share with the fungus yeast?

1 nuclei present in cells

2 nervous coordination

3 stores carbohydrate as glycogen

Scientists think that the giant, predatory toothed whales that replaced the extinct megalodon consumed the same sources of food.

Explain how the evolution of giant, predatory toothed whales may have caused the extinction of megalodon. (lines 5 to 7)

Volcanoes release sulfur dioxide into the atmosphere.

Describe the biological consequences of sulfur dioxide release. (lines 10 to 12)

The release of large amounts of dust into the atmosphere reduced light intensity.

Explain why this would cause a loss of food chains. (lines 9 to 11)

Explain why the cells in cryozoos are put in salt and sugar solution rather than pure water. (lines 16 to 18)

Describe how scientists could clone a banteng. (lines 18 to 20)

Explain why releasing cloned mammoths could have negative and positive effects on Arctic biodiversity. (lines 22 to 28)

Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow.

Tissue culture and plants

In micropropagation, plant tissues are grown in vitro on plant tissue culture media, under aseptic conditions in a controlled environment. This technique is possible because plant cells can differentiate and become specialised cells. This allows them to change their metabolism, growth and development to form a whole plant.

Plant tissue culture media contain substances to support the normal growth and development of plants. The media are mainly composed of minerals, vitamins, and plant hormones. The pH of the media is kept constant.

Plant hormones play an essential role in determining how cells and tissues develop in culture media. Plant cells can differentiate into different tissues and cell types. The concentration of hormones can determine the tissue that develops. Auxins and cytokinins are the most widely used. A balance of both auxin and cytokinin leads to the development of a mass of undifferentiated cells known as a callus.

In vitro cell culture offers an alternative method for conserving endangered species and varieties. Tissue culture can be used when the plant species produce seeds that do not germinate or have seeds that cannot be stored for a long period of time. These can be successfully preserved using in vitro techniques for the maintenance of gene banks.

Embryo culture is a type of plant tissue culture that is used to grow embryos from seeds in nutrient media. In embryo culture, the plant develops directly from the embryo or indirectly through the formation of a callus and then subsequent formation of shoots and roots. The technique has been developed to break dormancy in seeds, and to reproduce rare species and haploid plants.

Scientists are also using cell suspension culture systems from which products can be extracted. A suspension culture is developed by transferring a portion of the callus into liquid media. The media are maintained under suitable conditions of agitation, light and temperature. This system can provide a continuous, reliable source of natural products independent of climate and soil conditions. The first commercial application of large‑scale suspension cultivation of plant cells was carried out to produce shikonin. Shikonin is used in traditional Chinese medicine and is a potential anti‑cancer treatment.

State what is meant by the term in vitro. (line 1)

Explain how plant cells differ from human cells in their ability to differentiate and specialise. (lines 2 and 3)

Give the function of two named minerals included in the culture media. (line 6)

Explain why the pH of the media needs to be kept constant. (line 7)

Auxin also controls the response of plants to light.

Describe a simple experiment you could do to show the phototropic response of plant stems to light.

Explain why scientists want to conserve endangered plant species and varieties. (lines 13 and 14)

Explain why plant cell suspension culture media are maintained under suitable conditions of agitation, light and temperature. (lines 24 and 25)

Scientists study the populations of plants in two fields, X and Y, in southern England.

They investigate the numbers of three different wildflower species, A, B and C, so that they can compare the biodiversity in each field.

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(Source: © Patrick Guenette/
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Species A
Species B
Species C

The table shows the numbers of plants of each species per m² counted in each field.

Calculate the mean number of plants of species B in Field Y.

mean number =_........ per m

Describe how the scientists could determine the number of each plant species per m² in each field.

Discuss what the results show about the distribution of species in each field and the difference in biodiversity between the two fields.

Name an abiotic factor that could affect the distribution of the plant species.

The graph shows the change in area of rainforest on the Earth from 1990 to 2015.

Determine the mean rate of decrease of rainforest area, in km² per year, from 1990 to 2015.

mean rate of decrease =_........ km² per year

Loss of rainforests causes an increase in atmospheric carbon dioxide gas.

Explain the negative effects of an increase in atmospheric carbon dioxide gas.

Scientists investigated the effect of deforestation on a river. The river flows through a forest, part of which has been deforested.

The graphs show the changes in nitrate concentration and the biodiversity of animals in the river as it flows through the forest.

Describe the role of microorganisms in the conversion of organic waste into nitrate ions in the river.

The number of different animal species living in the river was recorded as a measure of the biodiversity of animals.

Give a reason why this may not be a complete measure of biodiversity.

Explain the change in the biodiversity of animals along the river.

Use information from the graphs in your answer.

Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow.

Plastic pollution

A mass of 12.7 million tonnes of plastic is dumped into our oceans every year. This is equivalent to the mass of 1.8 million adult elephants. This plastic pollution is a concern because of its harmful effect on living organisms.

Turtles eat plastic bags, mistaking them for jellyfish, and sea birds have been found with stomachs full of plastic. Researchers have reported 800 kg of plastic found in the carcass of a stranded whale in France. The stomach of another whale in Australia contained six square metres of plastic sheeting and 30 plastic carrier bags. Plastic items can block the tubes leading from the mouth to the stomach and to the lungs in some animals. This can cause death because it affects digestion and gas exchange.

Whale sharks are the largest fish in the world, yet feed on microscopic plankton that photosynthesise. The plankton is also eaten by crustaceans, which are then eaten by fish. These fish are eaten by humans. Many whales are filter feeders. They swallow hundreds of cubic metres of water a day to capture plankton and may take in microplastics during the process. The microplastics are produced from the breakdown of larger pieces of plastic. Microplastics are similar in size and mass to many types of plankton. These microplastics are not biodegradable and build up in the bodies of organisms that occupy higher trophic levels in food chains. This is called 20 bioaccumulation.

Plastic pollution may be responsible for putting filter feeding whale sharks and other filter feeders at risk of extinction. The whale shark, for example, is listed as being endangered.

Studies have found toxic chemicals associated with plastics in the bodies of large filter feeders. Scientists think these chemicals might reduce the population sizes of the large filter feeders. This is because the toxins might affect many biological processes involving hormones that regulate the body’s growth and development, metabolism, and reproduction.

Whale sharks feeding in the Sea of Cortez near Mexico, an important breeding ground, ingest 200 microplastic particles per day. Fin whales in the Mediterranean Sea ingest 2000 microplastic particles per day. Any reduction in the reproduction of these species will have consequences for biodiversity.

Attempts are being made to reduce the use of plastic. Coffee companies are being encouraged to use wooden spoons and straws rather than plastic ones. Also, shoppers are being given biodegradable plastic bags, or paper bags.

Which organism named in the passage is a producer?

Which organism named in the passage is a tertiary consumer?

Explain how blocked tubes leading from the mouth can lead to death in some animals. (lines 8 to 10)

Suggest why bioaccumulation of microplastics is a problem for humans. (lines 17 – 20)

Calculate the difference between the number of plastic particles ingested in a year by a fin whale and a whale shark. (lines 29 – 31)

Give your answer in standard form.

Explain the effects of reduced reproduction on biodiversity. (lines 31 – 32)

Suggest a benefit of using biodegradable plastic bags. (line 35)

Suggest what is meant by the term sustainable (line 3).

Explain why having a developed root system makes regrowth quicker (lines 4 to 5).

Coppiced wood can be used as a biofuel (lines 8 to 9).

Give similarities and differences in the use of biofuel compared with the use of fossil fuels.

New growth in woodland is often destroyed by species such as deer (lines 5 to 6).

Suggest one way to protect woodland from this damage.

Coppicing increases biodiversity in woodland ecosystems (line 17).

Describe a method to investigate the effect of coppicing on the biodiversity of plants in a woodland.

Coppicing increases the number of insects in woodland.

A farmer owns a field next to a coppiced woodland.

Give one reason why more insects in the woodland might be an advantage for the farmer.

Give one reason why more insects in the woodland might be a disadvantage for the farmer.

Explain why a range of different light levels in a woodland leads to an increase in plant biodiversity (lines 23 to 24).