Abiotic & biotic factors

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.

Enlarge

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.

Figure 1 shows a food chain.

Which of the organisms in Figure 1 is the primary consumer?

Name the predator of the fish in Figure 1.

Draw one line from each term to the definition of the term.

Food chains and food webs can be used to predict the effect of a decreasing number of polar bears.

Why is a food web more useful than a food chain?

Tick (✓) one box.

Food webs show where energy is wasted.

Most animals eat more than one type of prey.

Producers are at the start of all food webs.

Krill eat algae.

Algae store a mass of 68 arbitrary units of carbon in 1 year.

8% of the carbon stored in algae becomes part of the carbon stored in krill.

Calculate the mass of carbon that becomes stored in krill.

Use the equation:

mass of carbon stored in krill = mass of carbon stored in algae ×

_ Mass of carbon stored in krill = _______________________ arbitrary units

The minerals in sea water are one abiotic factor that affects algae.

Which are two other abiotic factors that affect algae?

Tick (✓) two boxes.

Food availability

Light intensity

Pathogens

Prey

Temperature

Plants use root hairs to take in water and minerals from the soil.

Figure 7 shows a root hair cell.

Explain the advantage to a plant of having root hairs.

Use Figure 7.

Explain why root hair cells do not have chloroplasts.

Plants need minerals for healthy growth.

Minerals in the soil are an abiotic factor that affects plant growth.

What is one other abiotic factor that affects plant growth?

Tick (✓) one box.

Fungal disease

Predators

Water

Soil contains magnesium ions.

Which substance in plants contains magnesium?

Tick (✓) one box.

Chlorophyll

Glucose

Starch

Fertilisers contain minerals.

Fertilisers can be added to the soil.

Table 3 gives information about two different fertilisers.

Both fertilisers can be used on the same plants and contain the same minerals.

Evaluate which fertiliser would be best for a gardener to buy and to use.

Use Table 3.

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.

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.

Enlarge

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

In 1986 an accident at a nuclear power station released radioactive isotopes into the environment.

Radioactive isotopes have a half-life.

What is meant by ‘half-life’?

During the accident, 28 kg of caesium-137 was released into the environment.

Caesium-137 has a half-life of 30 years.

Calculate the mass of the caesium-137 released in 1986 that will still be present in the environment in 2136.

Give your answer in grams.

After the accident scientists investigated the effect of ionising radiation on the population of dragonflies.

Dragonflies are insects.

The scientists placed transects in different directions from the site of the nuclear power station.

The scientists recorded the number of dragonflies and the ionising radiation dose along the transects.

Figure 7 shows the results.

Describe the relationship between the ionising radiation dose and the number of dragonflies.

Suggest one abiotic factor that could affect this investigation.

Do not refer to ionising radiation dose in your answer.

Explain how the ionising radiation dose can affect the dragonfly population.

Figure 3 shows a food chain.

Draw one line from each description to the organism in the food chain.

Which word describes the total number of crabs in this habitat?

Tick (✓) one box.

Explain what will happen to the number of loggerhead turtles if there are fewer crabs.

Use information from Figure 3.

What type of factor is a new predator?

Tick (✓) one box.

Female loggerhead turtles lay their eggs on sandy beaches.

Scientists recorded data about turtles on one beach.

Figure 4 shows:

• the number of eggs each turtle laid

• the length of the turtle that laid the eggs.

Describe the trend in the data on Figure 4.

Female loggerhead turtles return to the same beach each year to lay their eggs.

Global warming is causing the sea level to rise.

Explain the effect that sea levels rising might have on the number of loggerhead turtles.

Greenhouse gases are one cause of global warming.

Methane is a greenhouse gas.

The concentration of methane in the atmosphere was:

• 720 arbitrary units in 1840

• 1872 arbitrary units in 2018.

How many times greater was the concentration of methane in the atmosphere in 2018 than in 1840?

Which two human activities cause an increase in greenhouse gases in the atmosphere?

Tick (✓) two boxes.