OCR

GCSE
BIOLOGY
Community Level Systems
Ecosystems 1

Time allowed
61 minutes

QUESTION PAPER

Score Percentage

/51 %
4.1 | CELL BIOLOGY | QUESTION PAPER 1 1
1 Look at the food web.

peregrine falcons bald eagles cormorants humans

small birds sea lions baleen whales

worms small fish krill

phytoplankton

(a) (i) This is one of the food chains from the food web.

It shows the relative biomass at each stage.

phytoplankton small fish cormorants

dry biomass 8000 800

A pyramid of biomass can be drawn to describe this food chain.

Finish the pyramid of biomass to include the small fish and the cormorants.

Make sure the bars are drawn to scale and labelled.

The bar for phytoplankton has been drawn for you.

phytoplankton

[2]
 (ii) Here is another food chain in this food web.

phytoplankton krill baleen whales humans

Biologists would have great difficulty in collecting the data for the pyramid of biomass for
this food chain.

Explain why.

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(b) The bald eagle was an endangered bird in the USA.

It has had legal protection since 1940.

From 1963 until 2006, surveys of bald eagle breeding pairs were done.

In 2007 the bald eagle was removed from the USA list of endangered species.

Look at the graph.

bald eagle breeding pairs from 1963 to 2006

10 000 9789

8000

6471
breeding 6000 5748
pair 5094
numbers 4449
4000 3749
3035
2475
2000 1757 1875
1188
791
487
0
1965

1970

1975

1980

1985

1990

1995

2000

2005

year

Use the evidence in the graph to suggest why the bald eagle was at risk of extinction and why
it has now been removed from the endangered list.

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[Total: 7]
2 There are many types of microorganisms.

(a) Some are useful to humans and some are harmful to humans.

Draw straight lines to join each type of microorganism to its impact on humans.

type of microorganism impact on humans

Lactobacillus bacteria used in biogas production

bacteria that rot organic

used in yoghurt making
material releasing methane

bacteria that produce used in production of

toxins antibiotics

cause diseases such as

fungus producing penicillin
cholera or food poisoning
[2]

(b) Some bacteria live deep in the ocean near hot volcanic vents.

gas vent

There are similarities and differences in the way that these bacteria get their food compared
to the way that green plants get their food.

Write about one similarity and one difference.

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[Total: 4]
3 Soil contains different components.

These include mineral particles and dead material.

(a) Write down the name for partially decomposed dead material in soil.

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(b) Percy reads about different soils.

He finds out that mineral particles in soil can be sand, silt or clay.

Each particle is a different size.

Sand particles are largest and clay particles are smallest.

Percy gets some soil from his garden and shakes it up in a beaker of water.

He then lets it settle.

Look at the diagram of his results.

water

clay

silt

sand

(i) Suggest why the sand, silt and clay form separate layers as shown in the diagram.

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 (ii) Percy uses his ruler to measure the height of the clay layer.

The height of the clay layer is 20 mm.

The total height of the three mineral layers is 50 mm.

He calculates that 40% of the mineral content is clay.

Use a ruler to measure the height of the sand layer.

Use this to calculate what percentage of the mineral content is sand.

sand = ........................... % [2]

(iii) Percy uses information in this table to work out the type of soil in his garden.

Type of soil Range of clay content Range of sand content

% %

clay >50 <50

loam 10–45 30–70

sandy <45 >55

Work out what type of soil Percy has in his garden.

Use the percentages in (b)(ii) and the table.

Percy’s soil type is ........................... [1]

[Total: 6]
4 Look at the food web.

killer whale
seal

salmon

herring

zooplankton

phytoplankton

Look at the diagram.

It shows the energy flow in part of one food chain from the food web.

1500 kJ 225 kJ 22.5 kJ

phytoplankton zooplankton herring salmon

12500 kJ 1275 kJ 202.5 kJ

energy transferred out of the food chain

(a) The energy efficiency between zooplankton and herring in this chain is 15%.

Calculate the energy efficiency between the herring and salmon in the food chain and use
this value to explain why there are no more trophic levels after killer whales.

The quality of written communication will be assessed in your answer to this question.

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(b) Captivity can be used as a way to conserve endangered species.

Some killer whales are kept in captivity.

Some people are concerned about keeping killer whales in captivity. Describe reasons why.

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5 The venus flytrap is a plant that lives in very wet ground, such as bogs.

Bogs contain very low levels of minerals, such as nitrates, that plants need for growth.

The venus flytrap catches insects which it digests to get minerals.

fly

traps

(a) Venus flytraps digest insects by extracellular digestion.

What does extracellular mean?

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(b) Bogs contain very low levels of minerals because the rate of decay is very slow.

This is because very low levels of oxygen mean there are very low numbers of the
microorganisms that cause decay.

Explain why very low levels of oxygen mean there are very low numbers of these
microorganisms.

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(c) The way the traps close to catch insects involves osmosis.

The cells on the outside of the trap become turgid and swell more than the cells on the inside.

This causes the trap to close.

inside

outside
open trap closed trap

Suggest how the cells on the outside become more turgid than those on the inside.

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(d) The outside of each trap is green because these cells contain chlorophyll a.

The inside of each trap is red because these cells contain a red pigment called anthocyanin.

The red colour attracts insects.

The diagram shows how chlorophyll a absorbs light of different wavelengths.

chlorophyll a

light absorption

400 500 600 700

blue green red

wavelength of light in nanometres

Draw a line on the graph to show the absorption of light by anthocyanin. [1]
6 Aphids are small insects that feed on plants and damage crops.

Lacewings are insects that can be used for biological control.

aphid lacewing

(a) A seed company wants to sell buckwheat seeds to cotton farmers. Look at their advert.

Planting buckwheat seeds increases your cotton crop yield

Planting buckwheat alongside your cotton plants
will increase your cotton yield.

Buckwheat attracts lacewings because they feed

on buckwheat nectar.

Lacewings are also predators and will control the

aphids that damage your cotton plants.

The graphs show the effect of planting buckwheat:

Graph A Graph B
No buckwheat With buckwheat
mean 45 mean 45
number 40 number 40
of insects of insects
35 35
found per found per
30 30
sample sample
25 25
20 20
15 15
10 aphids 10
5 5 lacewings
lacewings aphids
0 0
15 30 14 28 15 15 30 14 28 15
Jan Jan Feb Feb Mar Jan Jan Feb Feb Mar
date date
 (i) Look at graph A.

Describe and explain the relationship between the numbers of aphids and lacewings
when there is no buckwheat.

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(ii) The advert claims that growing buckwheat attracts lacewings and increases crop yield.

Discuss whether the graphs support this claim.

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(b) To produce the graphs in the advert, scientists needed to collect aphids and lacewings.

They did this several times and calculated the mean (average) number per sample.

Increasing the number of samples increases the accuracy of the mean.

Explain why.

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[Total: 6]
7 This question is about microorganisms that cause disease.

Flu (influenza) is caused by a virus.

Salmonella food poisoning is caused by bacteria.

(a) Describe the structure of a virus.

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(b) Look at the graph.

It shows the number of people who tested positive each month for salmonella bacteria.

It also shows the number of people with flu-like symptoms visiting their doctor each month.

80

70
number of
people who 60
tested
positive for 50
salmonella salmonella
and 40
number of flu
people seeing
30
doctors with
flu-like
symptoms / 20
100 000
of the 10
population
0
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
month

(i) Discuss whether the graph gives the true numbers of people actually having salmonella
or flu.

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(ii) It is thought that the way the diseases are spread will affect when people are more likely
to get the disease.

Flu is spread by airborne droplets, usually indoors or on crowded buses or trains.

Salmonella is spread through food that is not cooked thoroughly or stored at incorrect
temperatures.

Write about how the way the microorganisms are spread can explain the patterns in the
graph.

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[Total: 7]
8 Look at the woodland food web.

wolf spider

beetle larva ground beetle

snail woodlouse earwig millipede

dead leaves

(a) (i) Look at one food chain in this web showing the numbers at each level.

100 dead leaves 4 snails 10 beetle larvae 1 wolf spider

Would you expect the pyramid of numbers and pyramid of biomass to be the same shape
for this food chain?
Explain your answer.

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(ii) The woodlouse and earwig are in the same trophic level.
Some energy from this trophic level does not pass into the next trophic level.
Write down reasons why.

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(b) The efficiency of energy transfer between trophic levels can be calculated.

Look at the data on energy flow through four trophic levels.

producers primary consumers secondary consumers tertiary consumers

97 000 kJ 7000 kJ 600 kJ 50 kJ

The efficiency of energy transfer between producers and primary consumers is 7.2%.

The efficiency of energy transfer between primary and secondary consumers is 8.6%.

(i) Calculate the efficiency of energy transfer between the secondary and tertiary consumers.

Secondary to tertiary consumers efficiency of energy transfer = ............................ % [1]

(ii) Use your answer to part (i) to explain why it is unlikely that there would be a fifth trophic
level.

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[Total: 6]