Interdependence

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

Figure 7 shows part of a food web from one ecosystem.

Define the term ‘ecosystem’.

Describe the difference between a population and a community in one habitat.

Humans kill narwhals for meat and skin.

Killing more narwhals can cause the number of seals to increase or decrease.

Explain why killing more narwhals can have two different effects on the number of seals.

The algae in Figure 7 store a mass of 68 arbitrary units of carbon in 1 year.

8.4% of the carbon in each stage of the food web is passed to the next stage.

Calculate the mass of carbon stored in tertiary consumers in 1 year.

Mass of carbon = _____________________ arbitrary units

Mineral ions are at: a low concentration in sea water

a high concentration in algae.

Name the process algae use to absorb mineral ions from sea water.

Algae and plants are producers.

Explain how not having enough magnesium ions and nitrate ions can limit the mass of carbon stored in producers.

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 a managed forest:

tree seedlings are regularly planted

some trees are regularly removed.

Figure 12 shows information about the managed forest.

Name the processes X, Y and Z in Figure 12.

Choose answers from the box.

The dead trees are broken down during process Z.

What type of organism breaks down the dead trees?

A farmer removes some of the young trees from the managed forest every year.

Explain why removing some of the young trees allows the remaining trees to grow faster.

Suggest one advantage to the farmer if the remaining trees grow faster.

Explain how growing trees reduces climate change.

You should refer to carbon dioxide in your answer.

A scientist investigated the number of tree species in two forests in 1970 and 2000.

Table 4 shows the results.

Give two conclusions about the number of tree species in the forests in 1970 and 2000.

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.

Figure 10 shows a rock pool on a sea shore.

Rock pools are flooded twice a day with fresh sea water.

What is the community of the rock pool?

Tick (✓) one box.

The living organisms and abiotic factors in the rock pool

The number of different species in the rock pool

The number of predators and prey in the rock pool

The populations of all the species that live in the rock pool

Starfish are animals that live in rock pools.

A scientist investigated the effect that starfish had on the number of species in rock pools.

This is the method used.

1. Count the number of species in rock pool A and in rock pool B.

2. Regularly remove all the starfish from rock pool B.

3. Count the number of species in rock pool A and in rock pool B each year for 10 years.

Figure 11 shows the results.

Figure 12 shows a food web in the rock pools.

Starfish usually prefer to feed on mussels.

Mussels reproduce and grow more quickly than limpets, chitons, and barnacles.

After 10 years the only species left in rock pool B was mussels.

Explain the results shown in Figure 11 for rock pool B.

Use Figure 11 and Figure 12.

Explain the results shown in Figure 11 for rock pool A.

Some species of starfish can reproduce by cloning (asexual reproduction) and also by sexual reproduction.

Figure 13 shows what happens when starfish P reproduces by each type of reproduction.

During cloning a small piece of the starfish develops into a new starfish.

Before cell division, chromosomes replicate and the number of organelles increases.

Describe the stages in the process of cell division that produces offspring X.

Explain one advantage to the starfish of reproducing by cloning rather than reproducing by sexual reproduction.

Figure 1 shows part of a food web.

What is the source of energy for the nettle plants?

Tick (✓) one box.

Caterpillars

Soil

Sun

Which term describes the caterpillars in the food web?

Tick (✓) one box.

Primary consumer

Secondary consumer

Tertiary consumer

What is the name of one producer in the food web?

Tick (✓) one box.

Blue tits

Greenflies

Sparrowhawks

Wheat plants

Mice eat wheat plants and are eaten by sparrowhawks.

Complete the food web in Figure 1 by adding mice to Figure 1.

A sparrowhawk competes with other sparrowhawks for food.

Give one other factor sparrowhawks will compete for.

Do not refer to food in your answer.

The nettle plants were removed.

Explain how removing the nettle plants will affect the number of caterpillars.

Use Figure 1 on page 2.

Algal cells can photosynthesise.

A student investigated the effect of light intensity on photosynthesis in algal cells.

Figure 8 shows the apparatus used.

Describe the relationship between light intensity and distance, as the distance of the algal cells from the lamp is doubled.

You must include calculations of light intensity at 20 cm and 40 cm in your answer.

Use the equation:

The student recorded the pH of the water at the start and after one hour in each beaker.

Table 7 shows the results.

The method produced valid results.

Carbon dioxide is an acidic gas.

Explain the results in Table 7.

Corals are animals that live in the sea.

Corals: cannot move from one place to another place feed on tiny animals that float past in the water have algal cells living inside their own cells.

Figure 9 shows a coral and an enlarged coral cell.

Algal cells photosynthesise to produce glucose (C₆H₁₂O₆).

Write the balanced symbol equation for photosynthesis.

Explain one way the algal cells use glucose for growth.

Suggest one advantage to the algal cells of living inside the coral cells.

An increase in water temperature can cause coral to release the algal cells.

Releasing algal cells can result in the death of coral.

Suggest why coral may not survive without the algal cells.

Scientists investigated how the concentration of oxygen in the water around one coral changed during the day.

Figure 10 shows the results.

Explain the changes in oxygen concentration between A and B.

At C the rate at which oxygen is being produced equals the rate at which oxygen is being used.

Give the reason why.

Figure 7 shows part of a food web.

There are four levels of feeding relationship shown in the food web in Figure 7.

Algae are at level 1 in the food web.

Why is it difficult to identify the level of the loggerhead turtle in the food web?

Explain the effects a decrease in the population of clams could have on the other organisms in Figure 7.

Female loggerhead turtles lay their eggs in nests on sandy beaches.

Table 3 shows how the temperature of the nest affects the sex of the loggerhead turtles.

Explain how the continued use of fossil fuels could affect the population of loggerhead turtles.

Use information from Table 3.