IGCSE Biology (a) Food production Topic Practice

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

Coppicing

Coppicing is a traditional woodland management technique that was commonly used until about 70 years ago. Coppicing involves repeatedly cutting trees near to their base and allowing them to regrow. This provides a sustainable supply of timber. Coppicing has several benefits compared with replanting. Coppiced trees already have developed root systems, making regrowth quicker. They are also less likely to be eaten by species such as deer. Coppicing also reduces shading.

The demand for coppiced timber is beginning to increase again, as timber prices rise and other uses of coppiced timber develop. These uses include wood for biofuel. Much of this wood is used for heating schemes for homes and small factories. One exception is the huge Drax power station in North Yorkshire, United Kingdom, which has been using coppiced wood to generate electricity since 2004.
Coppicing is still a popular conservation practice because of the benefits it provides to trees and wildlife. Trees naturally lose their branches, which extends their lifespan. Coppicing is an artificial way of removing branches and increasing the lifespan of the tree.
Coppicing also increases woodland biodiversity, as greater amounts of light can reach the ground, allowing other plant species to grow. Many of these species are food sources for butterflies and other insects, providing food for birds and mammals such as bats.
In managed coppiced woodland the varied age structure of the vegetation also provides good habitat and shelter for different bird species.
Coppicing is a good way to ensure that there is a range of different light levels in a woodland, which leads to an increase in plant biodiversity.

This food web comes from a woodland ecosystem.

A farmer is using a pesticide in fields next to the woodland.

The pesticide is reducing the numbers of greenfly and caterpillars in the woodland.

Describe a different method the farmer could use to reduce the number of greenfly on his crops.

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

Offshore or freshwater fish farming

Fish farming in fresh water and in the sea offers the potential to increase the amount of fish harvested whilst protecting wild fish stocks. Offshore or fish farming at sea has less risk of serious injury or death to people than catching fish by deep sea fishing.

Some scientists predict that smart fish farming at sea could increase ocean fish production by an estimated 21 million tonnes from the 2020 value to 44 million tonnes by 2050 . Other estimates suggest that fish farming at sea, using an area the size of Lake Michigan, might produce the same amount of seafood as all of the world's wild-caught fisheries.

Fish farming at sea is done anywhere from three to 200 miles away from the coast. The fish produced are often Atlantic salmon, seabass and cobia. The aim is to reduce the environmental impact of fish farming near the coast by moving them further away from sensitive shorelines. This limits the impact of disease, pollution and pests such as sea lice. Further out to sea, and at deeper depths, the water movement is often faster.

Fish farm at sea

Freshwater fish farm

Critics of fish farming at sea claim that it will be more difficult to monitor and regulate any environmental impact and that pollution, disease and pests would still impact the surrounding waters. A major risk of farming at sea is the exposure to high winds and water speeds, increasing the risk of all the fish escaping. In 1997, 300000 farmed Atlantic salmon escaped into the Pacific Ocean. Wild fish are attracted to the farms by the scent of fish food. These wild fish are at risk of being hit by ships travelling to and from the large fish farms.

In contrast, other scientists support the development of fish farming in fresh water. Freshwater fish farms have increased in numbers steadily in the past 30 years. Asia is the main part of the world where this has happened. It is relatively cheap and easy to grow freshwater fish in small ponds. Fish farming provides incomes for many family farms, workers and small businesses, as well as jobs.

The main species produced by freshwater farming are carp, tilapia and catfish. These fish are herbivores or omnivores. In the farms they are fed small amounts of fish to

speed up growth, but their main diet is the by-products of crops like rice, groundnut and soy. Farmed freshwater fish are an affordable food for millions of low- and middle-income consumers.

Yeast cells can be genetically modified to produce the proteins found on the outside of viruses.

Biologists classify organisms into different groups. One group of organisms is fungi.

Insulin is a hormone produced in the human body.

An industrial fermenter is used to grow the genetically modified bacteria.

Explain why the fermenter is cleaned using steam before the genetically modified bacteria are added.

Aphids are a type of insect that are pests of many crops.
The photograph shows an aphid.

Pesticides are often used to control aphid populations.

Scientists investigate the effect of using two different pesticides, P and Q, on aphid populations.

This is the scientists' method.
- grow tomato plants in two glasshouses
- place aphids into both glasshouses
- record the number of aphids in both glasshouses for two weeks
- immediately after recording the numbers of aphids in week two, spray pesticide P in one glasshouse and pesticide Q in the other glasshouse
- record the number of aphids for another eight weeks

The graph shows the scientists' results.

Comment on the effectiveness of pesticide P and pesticide Q in reducing aphid numbers.

The diagram shows a yeast cell.

The passage describes the process used to produce yoghurt.

Complete the passage by writing a suitable word or words in each blank space.

Yoghurt is made by heating to a high temperature.

This heating process is known as .

This ensures that bacteria present in the liquid are

。

The liquid is then cooled to between $40^{\circ} \mathrm{C}$ and $46^{\circ} \mathrm{C}$.

A type of bacteria called is then added.

These bacteria use a sugar called for respiration.

The pH of the yoghurt decreases because this respiration produces a substance called .

The diagram shows a yeast cell.