Classification & Biodiversity (Edexcel International AS Biology)

Exam Questions

2 hours9 questions
1a
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3 marks

Sehuencas water frogs are endemic to Bolivia.

It was once believed that this frog was extinct in the wild.

This was due to human activity and a disease caused by a fungus.

Suggest how human activity could cause the extinction of the Sehuencas water frog in the wild.

1b
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4 marks

In 2008, there was only one Sehuencas water frog in captivity.

In 2018, five Sehuencas water frogs were discovered in a Bolivian mountain forest.

Three of these frogs were male.

Scientists suggested that these five frogs were resistant to the fungal disease.

Explain how resistance to this fungus could develop in a population of Sehuencas water frogs. 

1c
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2 marks

One way of studying the genetic diversity within a species is to calculate the heterozygosity index.

Describe how the scientists could calculate the heterozygosity index for a population of Sehuencas water frogs.

1d
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6 marks

Describe the role of zoos in the conservation of endangered Sehuencas water frogs.

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2a4 marks

The illustration shows a Tristan albatross.

q8-unit-2-oct-2020-edexcel-ial-biology

The Tristan albatross is endemic to a few small islands in the South Atlantic Ocean.

The adult birds nest on these islands and fly long distances in search of food.

They feed on fish, octopus and squid.

The Tristan albatross is critically endangered, with 4 500 of these birds left in the wild.

(i)

Describe two anatomical adaptations of the Tristan albatross that enable it to occupy its niche.

Use the information in the illustration to support your answer.

(2)

(ii)

It has been predicted that the population will continue to decline by 5.3 % per year.

Calculate the predicted albatross population after one year.

(2)

2b1 mark

The Tristan albatross (Diomedea dabbenena) was once classified as the same species as the wandering albatross (Diomedea exulans).

The illustration shows a wandering albatross.

q8b-unit-2-oct-2020-edexcel-ial-biology

Suggest why the Tristan albatross and wandering albatross were once classified as the same species.

2c4 marks

Tristan albatross chicks in nests on one island have been found to be at risk of predation from mice.

The diagram shows an albatross chick and two mice on this island.

q8c-unit-2-oct-2020-edexcel-ial-biology

Over a long period of time, mice on this island have become 50 % larger than normal mice.

It has been suggested that the mice from this island are a new species.

Suggest how the mice on this island have evolved to become a new species.

2d6 marks

Scientists have suggested that the Tristan albatross could be conserved.

Some suggestions are conservation strategies on the island where the mice are found.

Some suggestions involve zoos in other countries.

Explain how the Tristan albatross could be conserved.

Use the information in Question 8 to support your answer.

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3a4 marks

Methanobrevibacter smithii (M. smithii) is a single-celled microorganism found in the human intestine.

The photograph shows a microorganism that is similar in appearance to M. smithii.

untitled-27

Centers for Disease Control and Prevention CC0 1.0 <https://creativecommons.org/publicdomain/zero/1.0/>, via Raw Pixel

(i)

Calculate the magnification of this photograph.

Give your answer in standard form to two significant figures.

(2)

(ii)
Explain which type of microscope was used to take this photograph.

(2)

3b5 marks

Scientists classified M. smithii as a species in the domain Archaea.

(i)

Describe the information the scientists would have used to classify M. smithii into the Archaea domain.

(2)

(ii)

Scientists have identified a similar microorganism in the human mouth.

This microorganism is called Methanobrevibacter oralis (M. oralis).

Explain how the scientists could confirm that M. smithii and M. oralis are different species of Archaea.

(3)

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4a
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6 marks

The photograph shows a moose.

moose

Rufus46, CC BY-SA 3.0, via Wikimedia Commons

Moose are large mammals that eat grass and the shoots of plants.

The number of moose is declining in parts of America.

The graph shows the number of moose in one part of America from 1994 to 2016.

q9a-unit-4-oct-2020-edexcel-ial-biology

(i)

In 2016, the moose were not counted. The value shown on the graph is an estimate.

Describe how these data were used to estimate the number of moose in 2016.

(1)

(ii)

Calculate the percentage decrease in the number of moose from 1994 to 2016.

(2)

It has been suggested that global warming is responsible for the decrease in the number of moose from 1994 to 2016.

Sketch a graph to show this relationship.

(3)

q9aiii-unit-4-oct-2020-edexcel-ial-biology

4b
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8 marks

Ticks are parasites that live in the fur of moose.

Ticks are thought to be responsible for the decline in the number of moose.

The table shows the frequency distribution of ticks in a population of moose.

Number of ticks Number of moose
1 to 9 999 32
10 000 to 19 999 46
20 000 to 29 999 41
30 000 to 39 999 32
40 000 to 49 999 22
50 000 to 59 999 15
60 000 to 69 000 9
70 000 to 79 999 4
80 000 to 89 999 4
90 000 to 99 999 3
100 000 or more 6

(i)

Calculate the percentage of moose that have 50 000 or more ticks on their bodies.

(2)

(ii)

The diagram shows the life cycle of the tick.

q9bii-unit-4-oct-2020-edexcel-ial-biology

The ticks feed on the blood of the moose. One tick can remove 200 to 600 times its body mass.

The ticks irritate the moose. The moose will scratch against trees causing large clumps of fur to fall off.

Explain how global warming might affect the life cycle of ticks and result in the decline in the number of moose.

Use all the information in the question to support your answer.

(6)

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5a3 marks

The Galapagos Islands are located off the west coast of South America.

The biodiversity on these islands has changed over the past 40 years due to human activity.

One of these islands is called Santa Cruz.

The population of Santa Cruz increases by approximately 6.4 % per year.

The majority of the population, 85 %, live in urban areas.

The population of Santa Cruz living in urban areas in 2020 was 17 000.

Predict the total population of Santa Cruz in 2025.

Assume that the rate of increase stays constant.

5b1 mark

Non-endemic species have been introduced to the Galapagos Islands.

The graph shows the number of tourists to all the islands and the number of recorded non-endemic species.

q7b-unit-2-june-2021-edexcel-ial-biology

State the relationship shown in the graph.

5c8 marks

The wild blackberry was introduced to Santa Cruz in 1970 and has since spread over much of the island.

This has resulted in the reduction of the native endemic forest.

In 1960, the number of species in an area of the native forest was measured.

The table shows these results.

Species Number of individuals (n) (n – 1) n(n – 1)
A 21 20  
B 2 1 2
C 4 3 12
D 13 12  
E 54 53  
F 15 14 210
G 6 5 30
H 32 31  
    Total (N) =     Σn(n – 1) =

(i)

Calculate the index of diversity (D) for this area of the forest using the formula

screenshot-2022-11-29-10-30-26

Use the table to help you.

Give your answer to one decimal place.

(3)

(ii)

Explain why the spread of the wild blackberry affects the biodiversity of the island.

(5)

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6a
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4 marks

The common wombat is endemic to Australia and Tasmania.

The photograph shows a common wombat.

common-wombat



magnification × 0.1
JJ Harrison ([email protected]), CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

Common wombats mark areas of their habitat to signal to other wombats of the same species that they are living there. These marked areas are called territories.

Common wombats produce cube-shaped faeces. It is thought that these cubes can be stacked to mark territory without rolling away.

(i)
Calculate the surface area : volume ratio of one cube with a length of 2.5cm.
(2)

Answer ..........................................

(ii)
State what is meant by the term habitat.

(1)

(iii)
State what is meant by the term species.

(1)

6b
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1 mark

The height of a wombat is a result of polygenic inheritance.

State what is meant by the term polygenic inheritance with reference to wombat height.

6c
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2 marks

Common wombats dig burrows to live in. They have adaptations to help them to do this successfully.

Describe two anatomical adaptations of a common wombat that help it to dig burrows to live in.

Use the information in the photograph to support your answer.

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

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

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7a
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3 marks

Organisms can be classified using the three-domain system.

Molecular evidence is used to place an organism into one of the three domains.

(i)
Give one example of the molecular evidence used to support the three-domain system.

(1)

(ii)
Describe the role of the scientific community in evaluating the evidence for this system of classification.

(2)

7b
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4 marks

The table shows some features of living organisms.

Place an X in each row to show whether the feature is found in these domains.

Feature Archaea only Archaea and
Bacteria only
Archaea and
Eukarya only
Archaea and
Bacteria and
Eukarya
absence of a
nuclear envelope
presence of
circular DNA
presence of a cell
membrane
presence of
ribosomes

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8a
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1 mark

The photograph shows a titan arum plant (Amorphophallus titanum).

titan-arum-plant

Credits: US Botanic Garden., Public domain, via Wikimedia Commons

This plant is native to Sumatra, Indonesia, and is critically endangered.

There are fewer than 1000 individuals in the wild and 500 in botanical gardens around the world.

Sumatra is described as having a high species richness.

State what is meant by the term species richness.

8b
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2 marks

Seed banks often conserve endangered plants by storing samples of their seeds.

The seeds are dried and then frozen.

Explain the advantages of drying seeds before storage.

8c
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8 marks

Scientists have stated that more than a third of critically endangered plant species cannot be saved from extinction by storing seeds in seed banks.

The titan arum is one of these plants.

This plant flowers once every 10 years and the flowers last for two to three days.

The plant can reproduce asexually or sexually. In order to reproduce sexually it relies on insects to transfer pollen to other titan arum plants.

Scientists are developing ways to conserve this plant without losing genetic diversity.

Some of the suggestions include:

    • Grow more plants produced by asexual reproduction in botanical gardens
    • Collect pollen when an individual plant flowers and store it in a seed bank
    • Create a studbook for the species
    • Artificially pollinate plants in the wild and in botanical gardens.
(i)

The heterozygosity index can be calculated using an equation.

Write this equation.

(1)

(ii)

The heterozygosity index of the 500 titan arum plants in botanical gardens was found to be 0.166. 

Calculate the number of heterozygotes in this population.

(1)

(iii)

Discuss the suggestions, proposed by these scientists, for conserving the titan arum.

(6)

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9a
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1 mark

The Hood Island giant tortoise (Chelonoidis hoodensis) is only found on one of the Galapagos Islands.

The photograph shows two Hood Island giant tortoises fighting over territory.

two-galapagos-tortoises

https://www.flickr.com/photos/lightmatter/, CC BY 2.0 <https://creativecommons.org/licenses/by/2.0>, via Wikimedia Commons

Which of the following is a term that would be used to describe the fact that this species of giant tortoise is found only on the Galapagos Islands?

  A Diversity
  B Endemic
  C Isolation
  D Linkage
9b
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4 marks

The Hood Island giant tortoise has adaptations to its environment.

Two features are:

  • Long neck
  • Shell that arches above the neck.

When there is a dispute over territory, the tortoises use these features to make themselves look as large as possible.

(i)

Complete the table to show the type of adaptations shown by this tortoise.

(3)

Feature Type of adaptation
Long neck  
Shell that arches above neck  
Making themselves look as large as possible  


(ii)

Suggest one selection pressure that results in the development of one of these features.

(1)

9c
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6 marks

In 1963, there were only three males and 12 females of C. hoodensis left in the wild.

These 15 tortoises were used in a breeding programme.

The diagram shows the number of offspring from each female tortoise and the fathers of these offspring.

q9c-unit-2-january-2022-edexcel-ial-biology
(i)

Calculate the percentage of female 10’s offspring that were fathered by male B.

(1)

(ii)

The wild population of C. hoodensis is now 1800 individuals.

Calculate the percentage increase in the wild population of C. hoodensis tortoises.

Give your answer to one decimal place.

(2)

(iii)

A zoo tested its captive‐bred giant tortoise and determined that it was a C. hoodensis tortoise.

Explain how the zoo determined that its giant tortoise was a C. hoodensis tortoise.

(3)

9d
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2 marks

Scientists thought that a recessive allele was changing in frequency in the tortoise population.

Explain how the change in frequency of this allele could be determined.

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