Maintaining biodiversity

Biodiversity is the variety of species within an ecosystem.

A student investigated the biodiversity in a field.

In part of the field, the living grass had been replaced with plastic grass.

Other plants grow between living grass plants and between pieces of plastic grass.

Figure 1 shows the field.

Figure 1

Living grass

Plastic grass

The student used quadrats to randomly sample the biodiversity of plants in:

the area with living grass

the area with plastic grass.

Describe how the student could decide where to randomly place the quadrats in the area with plastic grass.

How would a greater number of different plant species affect the biodiversity of animals in the area?

Another student used a transect to place quadrats in the field.

Figure 2 shows the position of the transect.

The student placed a quadrat every 5 metres from point A to point B.

Table 2 shows the results.

Describe the relationship between the type of grass and the number of plant species.

Which of the following are two improvements to the investigation that used a transect?

Tick (✓) two boxes.

Decrease the length of the transect to 20 metres.

Increase the distance between quadrats from 5 metres to 10 metres.

Record the number of plants of each species as well as the number of species.

Repeat three times at different times of the same day.

Repeat using three different transects that cross the two types of grass.

Small pieces of plastic break off plastic grass and enter rivers and oceans.

Leaves from trees take longer to decompose on plastic grass than on living grass.

Other plants can grow between pieces of plastic grass.

Plastic grass cannot be recycled.

Explain how plastic grass affects biodiversity of ecosystems.

Ecosystems with low biodiversity may have small populations of some species.

Why are small populations more likely to become extinct than large populations?

Tick (✓) one box.

A small population may be more varied genetically than a large population.

Large populations in the same habitat interact to form communities.

Less genetic variation is a greater risk if the ecosystem changes.

Suggest two ways biodiversity in and around fields can be increased.

Do not refer to plastic grass.

In managed forests:

tree seedlings are regularly planted

some trees are regularly removed.

Some of the young trees in a managed forest are removed every year.

The biomass of wood produced by the remaining trees in the forest is increased by removing the young trees.

Explain why.

Explain how the processes of photosynthesis and respiration in a tree are involved in the production of new biomass for the tree.

Planting trees to maintain forests is good for the environment.

Explain the environmental and biological benefits of maintaining forests.

A student investigated the number of plants in two fields.

Figure 12 shows the fields.

This is the method used.

1. Place a quadrat randomly in field A.

2. Count the number of plants in the quadrat. Do not count grasses.

3. Repeat steps 1 and 2 another five times.

4. Repeat steps 1 to 3 in field B.

The student used a quadrat to count the number of plants.

What is a quadrat?

Tick (✓) one box.

An identification chart

A square frame

A tape measure

Table 4 shows the results.

Calculate mean value X in Table 4.

The area of the quadrat used was 1 m².

Field B was 100 m long and 90 m wide.

Calculate the total number of plants in field B.

You should calculate:

the total number of plants.

Use the data in Table 4.

The mean number of plants in field A is greater than in field B.

Suggest one reason why.

A student did a different investigation in field A.

Figure 13 shows the areas sampled.

The student sampled:

an area at the edge of the field next to the hedge, P

an area at the edge of the field with no hedge, Q.

Table 5 shows the results.

Give three conclusions from the results in Table 5.

Suggest one way to increase biodiversity in field A.

A student investigated the number of plants in two different fields.

This is the method used.

1. Place a quadrat randomly in field A.

2. Count the number of plants of each species in the quadrat. Do not count grasses.

3. Repeat steps 1 and 2 another 19 times.

4. Repeat steps 1 to 3 for field B.

Figure 6 shows the two fields.

Why should a random sampling method be used to sample the plants?

The student counted dandelion plants.

The student used a 0.5 m × 0.5 m quadrat.

The mean number of dandelion plants in field A in Figure 6 was 2.8 per quadrat.

Determine the total number of dandelion plants in field A.

The student placed insect traps in the ground in field A and in field B.

The insect traps were used to estimate the total number of insects in each field.

Figure 7 shows the position of the insect traps in each field.

Figure 8 shows the insect trap the student used.

This is the method used.

1. Place the insect traps in the fields as shown in Figure 7 and Figure 8.

2. Leave for 12 hours.

3. Count the number of insects of each species in each trap.

4. Repeat every 2 days for 6 days.

The method for estimating the total number of insects in field A and field B may not give valid results.

Suggest two reasons why.

Table 5 shows the results for all the plants and insects sampled.

A student concluded:

‘There is greater biodiversity in field B than in field A.’

Give the reason why.

There has been a decrease in the total number of birds in the UK since 1970.

Explain how planting more hedges would affect the number of birds.

This question is about greenhouse gases.

Methane is a greenhouse gas.

Name one other greenhouse gas.

Greenhouse gases cause global warming.

Global warming can cause a decrease in biodiversity.

What is biodiversity?

Tick (✓) one box.

The differences in sunlight in an area

The range of temperatures in an area

The variety of organisms in an area

Destruction of peat bogs decreases biodiversity.

Give one reason why peat bogs are being destroyed.

Which two human activities can increase biodiversity?

Tick (✓) two boxes.

Building more roads

Growing hedgerows between fields

Increasing the use of pesticides

Planting more woodlands

Selective breeding of farm animals

Methane (CH₄) is a small molecule.

A small molecule has a diameter of 1.0 nm.

1 m = 1 000 000 000 nm

What is the diameter of the small molecule in metres?

Tick (✓) one box.

1.0 × 10¹⁰ m

1.0 × 10⁹ m

1.0 × 10^‒9 m

1.0 × 10^‒10 m

Which structure is larger than a methane molecule?

Tick (✓) one box.

A carbon atom

An electron

A neutron

A protein

Figure 1 shows the concentration of methane in the Earth’s atmosphere from 2015 to 2019.

What was the concentration of methane in the Earth’s atmosphere in 2016?

Use Figure 1.

Concentration = ___________________ arbitrary units

Give one conclusion from Figure 1.