Energy & Feeding Relationships (Cambridge (CIE) IGCSE Biology)

Exam Questions

3 hours33 questions
1a
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2 marks

Rabbits are herbivores.

Define the term herbivore.

1b
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2 marks

The size of a rabbit population can increase and decrease from year to year, as shown in Fig. 1.

097031-may-2019-paper-3-q5b-rabbit-population---sq

Fig. 1

State two factors that could cause an increase in a rabbit population. 

1c
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3 marks

Since 1800 the population of humans in the world has increased dramatically.

State three ways in which this increase in the human population has affected marine ecosystems.

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2
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5 marks

The boxes on the left contain the names of processes from the carbon cycle.

The boxes on the right contain some descriptions of processes.

Draw one straight line from each process to link the process to its description.

An example has been done for you.

i~WdXYG7_061032-oct-2018-paper-3-q1-carbon-cycle---sq

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3a
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5 marks

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Fig. 1 shows an Arctic wolf, Canis lupus. These wolves are one of the few mammals adapted to the extreme cold of the tundra in the Canadian Arctic and in Alaska.

cie-igcse-2018-s3-p4-q2

Fig. 1

(i)

State two features, visible in Fig. 1, that identify Arctic wolves as mammals.

[2]

(ii)

Arctic wolves show many adaptive features to a cold environment.

Explain what is meant by the term adaptive feature.

[3]

3b
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3 marks

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The food available to animals in the Arctic tundra is limited. There is a short growing season for plants and the environmental conditions do not favour high rates of photosynthesis and growth compared with temperate and tropical ecosystems.

State three conditions that limit plant growth rates.

3c
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6 marks

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Arctic wolves are the top carnivores in the food web in the tundra.

Explain why the number of Arctic wolves is so small in this ecosystem.

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1a
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5 marks

Fig. 1 represents the carbon cycle.

cie-igcse-2020-specimen-p3-q9a-carbon-cycle

Fig. 1

Use Fig. 1 to answer the following questions.

(i)

Name the process labelled U.

[1]

(ii)

Name a group of organisms that are responsible for the process labelled W.

[1]

(iii)

 List two letters that identify respiration.

[2]

(iv)

 State which letter identifies photosynthesis.

[1]

1b
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2 marks

State the word equation for aerobic respiration.

1c
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3 marks

Suggest reasons why the mean percentage of carbon dioxide in the atmosphere has increased during the last 100 years.

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2a
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3 marks

The dominant grass species in an African grassland ecosystem are star grass and red oat grass.

  • Star grass is eaten by antelope species, such as topi and Thomson’s gazelle.

  • Smaller animals such as mice and grasshoppers feed on red oat grass.

  • Topi and Thomson’s gazelle are eaten by predators such as cheetahs, lions and serval cats.

  • Grasshoppers and mice are eaten by serval cats and tawny eagles.

  • Vultures feed on dead mammals.

Fig. 1 shows part of the food web for this ecosystem.

cie-igcse-2020-specimen-p4-q1a-food-web

Fig. 1

Complete the food web by writing the names of the correct organisms in the boxes in Fig. 1.

2b
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2 marks

Name the trophic level of the following species.

(i)

Star grass

[1]

(ii)

Topi

[1]

2c
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2 marks

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(i)

State the principal source of energy for the food web shown in Fig. 1.

[1]

(ii)

State what happens to energy when it leaves a food web.

[1]

2d
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3 marks

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Explain why there are no more than four trophic levels in the food web shown in Fig. 1.

2e
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3 marks

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Fish such as salmon can be reared intensively in fish farms. They are fed on high protein food made from animals. When eating this food, the fish are feeding as secondary consumers.

Describe the disadvantages of intensive farming, such as salmon farming, for producing human food.

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3
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7 marks

Fig. 1 shows a simple food web.

cie-igcse-2023-specimen-q7c

Fig. 1

(i)

Table 1 shows some of the terms that can be used to describe the organisms in the food web in Fig. 1.

Place ticks (✓) in the boxes to show the terms that can be used to describe each organism.

Table 1

organism

producer

herbivore

secondary consumer

corn plant

 

 

 

vole

 

 

 

grasshopper

 

 

 

hawk

 

 

 

[3]

(ii)

State the number of trophic levels in the food web in Fig. 1.

[1]

(iii)

Identify one organism that feeds at more than one trophic level.

[1]

(iv)

State the term used to describe an organism that gets its energy from dead or waste organic material.

[1]

(v)

State the principal source of energy for food webs.

[1]

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4a
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3 marks

Wetlands are important ecosystems. Researchers studied the feeding relationships between the organisms in an area of coastal wetland.

Fig. 1 shows part of the food web that they studied.

screenshot-2022-10-03-15-15-04

Fig. 1

Complete Table 1 by giving the name of one organism from the food web in Fig. 1 for each row.

Table 1

 

name of organism from Fig. 1

producer

 

secondary consumer

 

an animal that feeds at two trophic levels

 

4b
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7 marks

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The functioning of ecosystems relies on the cycling of nutrients.

Fig. 2 shows part of the nitrogen cycle.

screenshot-2022-10-03-15-26-59

Fig. 2

(i)

State the name of process A in Fig. 2 and give the type of organism that converts ammonium ions to nitrate ions.

[2]

(ii)

Describe how the nitrate ions used in process C enter the roots of plants.

[3]

(iii)

State the name of the structure in plant cells where process D occurs.

[1]

(iv)

State the process that occurs at B.

[1]

4c
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3 marks

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A pyramid of numbers for the wetland ecosystem showed that there were very large numbers of organisms at the base of the pyramid and very few at the top.

Explain why.

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5a
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5 marks

(i)

The sentences in the box describe the feeding relationships between four organisms. 

  Hawks obtain their energy from blackbirds.

  A fig tree carries out photosynthesis.

  Blackbirds are secondary consumers. 

  Caterpillars are herbivores.

Use the information in the sentences to write a food chain containing these four organisms.

Do not draw pictures of the organisms.

[3]

(ii)

State the principal source of energy for this food chain.

[1]

(iii)

State the type of organism that gains its energy from dead organic material.

[1]

5b
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5 marks

(i)

A species becomes endangered when it is at risk of extinction.

Explain two ways in which a species could become endangered.

[4]

(ii)

State one way in which endangered species can be conserved.

[1]

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6a
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1 mark

Adaptive features are defined as the inherited features of an organism that increase its fitness.

State what is meant by fitness in this context.

6b
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4 marks

Rodents are the most common mammals in many hot deserts.

Fig. 1 shows the lesser Egyptian jerboa, Jaculus jaculus, which lives in North Africa and the Middle East in areas that have high daytime temperatures and very little rainfall.

061041-may-2018-paper-4-q2a-jerboa---sq

Fig. 1

Like many desert-living mammals, jerboas are active at night.

Suggest two features of J. jaculus that adapt it to each of the following challenges of living in desert ecosystems:

(i)

very high daytime temperatures

1...............................

2...............................

[2]

(ii)

very little or no light at night

1...............................

2...............................

[2]

6c
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8 marks

A scientist studied communities in different parts of a desert and estimated the biomass of the organisms in each area.

He divided the organisms into four groups according to their roles in the food web as shown in Table 1.

Detritivores are animals that eat dead organisms or parts of organisms.

Table 1

groups of organisms in the food web

biomass / g per m2

 producers

480

 herbivores

220

 detritivores

120

 carnivores

40

Some of these results are shown as a pyramid of biomass in Fig. 2.

061041-may-2018-paper-4-q2c-pyramid-of-biomass---sq

Fig. 2

(i)

Use the information in Table 1 to complete the pyramid of biomass in Fig. 2.

[2]

(ii)

The scientist observed the detritivores and decided to include them with herbivores in this pyramid of biomass. 

Suggest what the scientist discovered about the detritivores that made him make this decision.

[1]

(iii)

Explain why there are rarely more than four or five trophic levels in ecosystems.

[2]

(iv)

Explain the advantages of presenting information about food webs as a pyramid of biomass and not as a pyramid of numbers.

[3]

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7a
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6 marks

Fig. 1 shows a pyramid of biomass and part of the carbon cycle.

cie-igcse-2018-s1-oct-p4-q1a-carbon-cycle

Fig. 1

(i)

State the principal source of energy required for trophic level D of the pyramid of biomass in Fig. 1. 

[1]

(ii)

State the letter that represents the primary consumers in Fig. 1.

[1]

(iii)

State how carbon is transferred from producers to primary consumers.

[1]

(iv)

Explain why trophic level A is smaller than trophic level B in the pyramid of biomass in Fig. 1.

[3]

7b
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2 marks

Some fungi and bacteria are decomposers

(i)

Define the term decomposer.

[1]

(ii)

Arrow X on Fig. 1 indicates the transfer of carbon from decomposers to the atmosphere. State the name of process X

[1]

7c
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5 marks

Describe how human activities are affecting the carbon cycle.

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8a
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3 marks

Fig. 1 shows part of the carbon cycle.

cie-igcse-2018-s3-may-p3-q5a-carbon-cycle

Fig. 1

Identify the processes shown by arrows A, B and C on Fig. 1.

Choose words from the list.

combustion      decomposition      excretion      feeding      fossilisation

8b
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2 marks

(i)

On Fig. 1 draw one arrow to represent photosynthesis.

Label this arrow with a letter D.

[1]

(ii)

On Fig. 1 draw one arrow to represent respiration.

Label this arrow with a letter E.

[1]

8c
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5 marks

The concentration of carbon dioxide in the atmosphere is increasing.

(i)

Describe two possible causes of the increased carbon dioxide concentration in the atmosphere.  

[2]

(ii)

State two adverse effects of the increase in carbon dioxide concentration in the atmosphere.

[2]

(iii)

Carbon dioxide is a greenhouse gas.

State the name of one other greenhouse gas.

[1]

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9a
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6 marks

Fig. 1 shows a food chain that is found in the sea.

screenshot-2022-10-05-16-42-04

Fig. 1

(i)

State the name of the producer in this food chain.

[1]

(ii)

Define the term producer.

[2]

(iii)

State the name of the secondary consumer in this food chain.

[1]

(iv)

State the name of the herbivore in this food chain.

[1]

(v)

State what the arrows in a food chain represent.

[1]

9b
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3 marks

In some countries humans eat crabs.

Explain how the over-harvesting of crabs could affect the other organisms in the food chain shown in Fig. 1.

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1a
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4 marks

Ecologists studied an area of woodland and estimated the biomass of each trophic level for one of the food chains in the woodland.

Some students wanted to use the data to draw a pyramid of biomass for the food chain.

Table 1 shows the students’ table.

The students added a column to calculate the width of the bars they would need to draw.

Table 1

trophic level

biomass / g m-2

width of bar / cm

1

producer

120

12.0

2

primary consumer

48

4.8

3

secondary consumer

16

1.6

4

tertiary consumer

2

 

(i)

Complete Table 1 by calculating the missing value and writing it in the table.

[1]

(ii)

Using the information in Table 1, draw a pyramid of biomass.

Label each bar with the trophic level.

[3]

1b
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1 mark

A type of organism gains energy from waste organic material from all trophic levels.

State the name of this type of organism.

1c
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6 marks

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(i)

Outline how organisms in the first trophic level of the woodland food chain produce biomass using energy from the Sun.

[3]

(ii)

Explain why the fourth trophic level has the least biomass in this food chain.

[3]

1d
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3 marks

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The woodland is a conservation area.

Outline the possible benefits of conserving this specific area of woodland.

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2a
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1 mark

In the Arctic, snowy owls are predators of lemmings. The lemmings eat Arctic plants.

Draw the food chain for this Arctic ecosystem.

2b
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9 marks

Fig. 1 shows changes in the populations of snowy owls and lemmings over a three year period.

cie-igcse-2020-specimen-p3-q5b-lemmings-and-owls

Fig. 1

During the first 10 months of year 1, the lemming population increases slowly at first and then more rapidly.

(i)

Suggest why the rate of increase becomes greater.

[1]

(ii)

Suggest why the lemming population falls during year 2.

[2]

(iii)

Use Fig. 1 to describe and explain how changes in the lemming population affect the snowy owl population.

[3]

(iv)

If all the snowy owls were removed from the Arctic ecosystem, suggest and explain what effect this would have on the lemming population in the following years.

[3]

2c
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2 marks

Lemmings and snowy owls get their energy from the food they eat.

(i)

State the principal source of all the energy in this ecosystem.

[1]

(ii)

Name the process that first traps this energy.

[1]

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3a
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2 marks

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Mangrove trees are hydrophytes because they grow in water.

Fig. 1 shows a young mangrove tree.

screenshot-2022-10-12-15-23-18

Fig. 1

Mangrove trees have many aerial roots and floating seeds.

Suggest how these adaptive features allow mangrove trees to survive in water.

3b
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9 marks

Fig. 2 shows a food chain in a mangrove forest.

mangrove tree → fiddler crab → seagull

Fig. 2

Table 1 gives the number of organisms and their biomass in a mangrove forest.

Table 1

organism

number of organisms

biomass of organisms / kg

mangrove tree

1 000

450 000

fiddler crab

7 500 000

8 000

seagulls

150 000

1 200

(i)

Estimate the biomass of one fiddler crab in grams.

Write your answer to two significant figures.

Show your working.

[2]

(ii)

Sketch a pyramid of numbers, using the information in Table 1, for the food chain shown in Fig. 2.

Write the number of each trophic level on the appropriate part of your pyramid. 

[3]

(iii)

Explain why the shape of a pyramid of biomass, for the information given in Table 1, would be different from the shape of your pyramid of numbers.

[4]

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4a
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3 marks

Wetlands are important ecosystems. Researchers studied the feeding relationships between the organisms in an area of wetland on the coast of Texas.

Fig. 1 shows part of the food web that they studied.

screenshot-2022-10-12-10-52-23

Fig. 1

Complete Table 1 by giving the name of one organism from the food web in Fig. 1 for each row.

Table 1

 

name of organism from Fig. 1

producer

 

secondary consumer

 

an animal that feeds at two trophic levels

 

4b
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2 marks

Extended only

The functioning of ecosystems relies on the cycling of nutrients.

Fig. 2 shows part of the nitrogen cycle.

screenshot-2022-10-12-10-55-32

Fig. 2

State the name of process A in Fig. 2 and give the type of organism that converts ammonium ions to nitrate ions.

4c
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3 marks

Extended only

Describe how nitrate ions enter the roots of plants shown by arrow C on Fig. 2.

4d
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1 mark

Extended only

State the name of the structure in plant cells where process D occurs.

4e
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1 mark

Extended only

State the process that occurs at B.

4f
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3 marks

Extended only

A pyramid of numbers for the wetland ecosystem showed that there were very large numbers of organisms at the base of the pyramid and very few at the top.

Explain why.

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