Sampling and fieldwork

Figure 5 shows a food chain.

What process allows algae to be producers for the food chain?

Adélie penguins are one species of penguin.

Adélie penguins:

feed in the ocean

make nests on the ground using stones.

The amount of snow is an abiotic factor which affects Adélie penguins.

Which are two biotic factors that affect the Adélie penguins?

Tick (✓) two boxes.

A new pathogen

Acidic soil

High light intensity

Lack of food

Low temperature

Figure 6 shows an Adélie penguin on a nest made of stones.

Adélie penguins steal stones from nearby nests to make their own nest higher.

A higher nest gives young penguins a better chance of surviving.

What is stealing stones for nests an example of?

Tick (✓) one box.

An ecosystem

Competition

Interdependence

Scientists calculated the mean area covered by one Adélie penguin nest.

The mean area of one nest is 18 000 cm².

An area of 122 400 m² was covered by nests.

Calculate the maximum possible number of nests in an area of 122 400 m².

Use your answer from Question 04.6.

There are many ways of sampling animal and plant populations.

Students sample a plant population.

Which piece of equipment can the students use to sample a plant population?

Tick (✓) one box.

A pH meter

A quadrat

A thermometer

Students sometimes use a transect.

When should a transect method be used?

Tick (✓) one box.

To investigate feeding relationships

To investigate the distribution of a population

To investigate the oxygen concentration in water

Adélie penguins are one species of penguin.

Adélie penguins feed in the ocean.

The penguins are part of a food web.

Which of the following is the producer in the food web?

Tick (✓) one box.

Algae

Fish

Fungi

Prey

Adélie penguins nest on the ground in large groups.

Figure 5 shows an Adélie penguin on a nest made of stones.

Describe how biotic factors could affect the population of the penguins.

Adélie penguin nests cover all the ground in one large circular area.

The number of Adélie penguin nests in the area was estimated to be 60 000

The mean area of an Adélie penguin nest is 2.0 m².

Calculate the radius of the large circular area covered by all of the penguin nests.

Use the equation:

area of circle = 3.14 × (radius)²

A scientist investigated the abundance and the distribution of a plant species near the penguin nests.

Explain why different methods are needed to sample abundance of a plant species and distribution of a plant species.

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.

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.

In 1986 an accident destroyed a nuclear power station.

Radioactive caesium-137 was released into the environment.

A nucleus of caesium-137 emits a high-speed electron when it decays.

What type of radiation does a nucleus of caesium-137 emit when it decays?

Tick (✓) one box.

Alpha

Beta

Gamma

Figure 2 shows how the percentage of caesium-137 nuclei remaining in a sample changes with time.

After one half-life, 50% of the caesium-137 nuclei remain in the sample.

What is the half-life of caesium-137?

Use Figure 2.

A sample of caesium-137 has a mass of 32 kg.

What mass of caesium-137 remains after two half-lives?

Tick (✓) one box.

4 kg 8 kg 16 kg 64 kg

Scientists investigated the effect of radiation on the dragonfly population near the nuclear power station site.

Dragonflies are insects.

The scientists recorded the number of dragonflies and level of radiation at different distances from the nuclear power station.

The scientists used a transect.

What is a transect?

Tick (✓) one box.

A line that is sampled along

A quadrat placed randomly

A sample at one location

Radiation from the nuclear power station caused the dragonfly population to decrease.

Nuclear radiation is an abiotic factor affecting the dragonfly population.

Which are two other abiotic factors that could affect the dragonfly population?

Tick (✓) two boxes.

Air temperature

Other insects

Predators

Prey

Water