Sampling and fieldwork

In 2018, all the plants were removed from the soil in a 1000 m² area.

A wall was built around this area to keep people out.

In 2019, three species of plants were recorded growing in this area.

Two of these species were indigenous.

State what is meant by the term ’indigenous’.

Name one piece of equipment that could be used to sample the number of indigenous plants in this area.

The area was surveyed every year and the number of plants of each species (A to H) was estimated.

Figure 20 shows the results.

State the trend shown by the data in Figure 20 for plant species C from 2019 to 2023.

A scientist suggested that the decrease in the number of plants of species B in 2021 was caused by competition from one of the other species of plant.

Which species is most likely to have out-competed species B in 2021?

Explain one way that this species could have out‑competed species B.

Give one way that species H could have moved into the area.

*(c) Figure 21 shows some plants growing in a small area of a 1000 m² field.

Devise a plan to estimate the number of named plant species growing in this field.

In 2018, all the plants were removed from the soil in a 1000 m² area.

A wall was built around this area to keep people out.

In 2019, three species of plants were recorded growing in this area.

Two of these species were indigenous.

State what is meant by the term ’indigenous’.

Name one piece of equipment that could be used to sample the number of indigenous plants in this area.

The area was surveyed every year and the number of plants of each species (A to H) was estimated.

Figure 6 shows the results.

State the trend shown by the data in Figure 6 for plant species C from 2019 to 2023.

A scientist suggested that the decrease in the number of plants of species B in 2021 was caused by competition from one of the other species of plant.

Which species is most likely to have out-competed species B in 2021?

Explain one way that this species could have out‑competed species B.

Give one way that species H could have moved into the area.

Plants also need water to grow.

Explain how water is absorbed into the plant.

5 (a) A scientist decided to study the variety of living organisms in a garden.

(i) The scientist wanted to use a random sampling technique. Devise a plan the scientist could use to randomly sample the number of plant species in the garden.

(ii) The scientist also measured abiotic factors in the garden. The pH of the soil was measured using a pH meter. Describe how three other abiotic factors could be measured in the garden.

(iii) Mistletoe is a parasite that grows on some trees. Figure 6 shows a tree with mistletoe growing on it.

(Source: © NagyDodo/Shutterstock)

Figure 6

Describe the feeding relationship between the mistletoe and the tree.

(b) Nitrate fertilisers are used in the garden. Explain why nitrate fertilisers are used in gardens.

6 In 2000, a council planted indigenous trees as part of a reforestation programme.

(a) Why were indigenous trees used instead of non-indigenous trees?

(b) The animal biodiversity in this reforested area was measured from 2004 to 2017. Biodiversity is measured on a scale from 0 to 1. 0 = low biodiversity 1 = maximum biodiversity Figure 12 shows the results.

2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 2020 2022

Figure 12

(i) Draw a straight line of best fit on Figure 12 to show the main trend in this data.

(ii) Estimate the animal biodiversity of the reforested area in 2022.

(c) (i) The data to calculate animal biodiversity was collected using the following method.

• a 100 m² area was chosen

• three 1 m² quadrats were placed randomly on the ground

• animals inside the quadrat were counted

• the number of each species of animal was recorded

State two ways that the quality of the results from this method could be improved.

(ii) State why point A on Figure 12 was ignored when considering the trend in animal biodiversity.

(iii) The data shown in Figure 12 was collected during the summer. Explain why animal biodiversity would be different if the data had been collected in the winter.

(d) A scientist observes that trees at the edge of a forest shade part of a field. Describe how a belt transect could be used to see how light intensity affects the biodiversity of plants growing in the field.

9 (a) Scientists use a technique called mark and recapture to estimate animal populations in a habitat. A sample of the population is captured and a harmless mark is added to each animal. These animals are released and after a period of time the population is sampled again. This second sample includes some recaptured animals that have marks on them. The population can be estimated using this equation number marked in the first sample × size of the second sampl e number marked in the first sample size of the second sample population size = number recaptured in the second sample A scientist used this technique to determine the change in the population size of snails in a pond from March to July. Figure 14 shows the results.

Figure 14

(i) Using data from Figure 14, calculate the difference in the population size from March to July.

Difference in the population size_{..............................................................}

(ii) State two factors the scientist should control when sampling the habitat in March and July.

(b) This pond is affected by eutrophication. Explain one possible cause of eutrophication.

*(c) Reforestation has a beneficial effect on air composition and biodiversity. Animal conservation projects can also have a beneficial effect on biodiversity. Explain the beneficial effects of reforestation and animal conservation projects.

Figure 16 shows an area of woodland with some small plants growing in the ground between the trees.

(Source: © Maksym Holovinov/Shutterstock)

Figure 16

The leaves of the small plants are green.

Describe how these plants make glucose.

Name a group of organisms that break down the dead leaves and release mineral ions into the soil.

The mineral ions are absorbed from the soil into the roots of plants.

Describe how these mineral ions are transported from the roots to the leaves of the plants.

A scientist recorded the mean light intensity and the mean number of small plants per m² for six 25 m² areas of the woodland.

Figure 17 shows the results.

Explain the effect of light intensity on the number of small plants per m².

State one variable the scientist should have controlled to make sure the light intensity measurements could be compared.

The scientist selects an area near the edge of the woodland where many stinging nettles are growing.

This area is partly shaded by the trees.

Describe how the scientist should use a belt transect to investigate how light intensity affects the growth of stinging nettles.

Figure 2 shows an area of woodland with some small plants growing in the ground between the trees.

(Source: © Maksym Holovinov/Shutterstock)

Figure 2

Name a group of organisms that break down the dead leaves and release mineral ions into the soil.

The mineral ions are absorbed from the soil into the roots of plants.

Describe how these mineral ions are transported from the roots to the leaves of the plants.

A scientist recorded the mean light intensity and the mean number of small plants per m² for six 25 m² areas of the woodland.

Figure 3 shows the results.

Explain the effect of light intensity on the number of small plants per m².

State one variable the scientist should have controlled to make sure the light intensity measurements could be compared.

The scientist selects an area near the edge of the woodland where many stinging nettles are growing.

This area is partly shaded by the trees.

Describe how the scientist should use a belt transect to investigate how light intensity affects the growth of stinging nettles.

A scientist investigated the distribution of invertebrates found in a garden.

Figure 9 shows an invertebrate about to fall into a pitfall trap.

The steps the scientist used to set up the pitfall trap are shown below.

The steps are not in the correct order.

1. put some sand around the beaker

2. put a beaker, baited with food, in the hole

3. place a flat stone on pebbles over the beaker

4. check the pitfall trap each day

5. dig a hole in the garden

Complete the steps in the correct order, from left to right.

The first number has been written in for you.

5

Figure 10 shows 30 invertebrates that the scientist collected.

Complete the table by filling in the tally and number for the spiders and worms.

The scientist selected an invertebrate at random to observe it in more detail.

State the probability that the invertebrate selected is an ant.

Give your answer in its simplest form.

State how the type of food used to bait the pitfall trap could affect the number of different invertebrates caught.

The scientist also counted the number of snails in four 1m² areas of the garden.

The garden had a total area of 40 m².

Describe how the scientist can use this information to estimate the number of snails in the garden.

(a) A student was investigating the populations of organisms in a garden.

Figure 15 shows the estimates of the number and biomass of some of the organisms in the garden.

Calculate the biomass of the population of earthworms in the garden.

Hedgehogs eat slugs and earthworms. Slug pellets were used to kill the slugs.

Explain how killing the slugs would affect the population of earthworms in this garden.

Describe a method that could be used to estimate the population of slugs in the garden.

Explain how cabbages, earthworms and squirrels contribute to the carbon cycle.

State three ways the concentration of nitrates in soil can be increased.

(a) A student was investigating the populations of organisms in a garden.

Figure 2 shows the estimates of the number and biomass of some of the organisms in the garden.

Calculate the biomass of the population of earthworms in the garden.

Hedgehogs eat slugs and earthworms. Slug pellets were used to kill the slugs.

Explain how killing the slugs would affect the population of earthworms in this garden.

Describe a method that could be used to estimate the population of slugs in the garden.

Explain how cabbages, earthworms and squirrels contribute to the carbon cycle.

Figure 11 shows a British glow-worm.

Read the following extract before answering the questions.

Female glow-worms produce bright lights in the summer to attract males. Glow-worm larvae are predators of slugs and snails, but adult glow-worms do not feed. Females only have a few weeks to attract a mate and lay eggs, before the females die.

What will happen if the population of snails decreases?

Female glow-worms have an enzyme called luciferase. The glow is produced when this enzyme catalyses a reaction between oxygen and a protein.

A scientist devised a plan to investigate the effect of oxygen concentration on this reaction.

The scientist had:

• five flasks of water each with a different concentration of dissolved oxygen

• a solution of the protein

• a solution of the enzyme.

The first step of this plan is:

Step 1. Add some of the protein solution to each of the five flasks.

Describe the next two steps that should be in this plan to obtain results for this investigation.

Which procedure would improve the investigation?

The enzyme luciferase works best at pH 8.

Explain why the activity of the enzyme decreases at pH 5.

Female glow-worms are found attached to grass plants in a large field.

Describe a sampling technique to find the mean number of female glow-worms in 1 m² of the field.

The mean number of female glow-worms in 1 m² of the field is 5.

The field has a total area of 800 m².

Estimate the number of female glow-worms in the whole field.