Classification & Biodiversity (Edexcel International A Level Biology)

The illustration shows a Tristan albatross.

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.

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)

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

The illustration shows a wandering albatross.

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

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.

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.

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.

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.

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

Calculate the magnification of this photograph.

Give your answer in standard form to two significant figures.

(2)

(2)

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)

The photograph shows a 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.

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)

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.

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

(2)

The diagram shows the life cycle of the tick.

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)

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.

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.

State the relationship shown in the graph.

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.

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

Use the table to help you.

Give your answer to one decimal place.

(3)

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

(5)

The common wombat is endemic to Australia and Tasmania.

The photograph shows a common wombat.

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.

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

(1)

(1)

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.

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.

Organisms can be classified using the three-domain system.

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

(1)

(2)

The table shows some features of living organisms.

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

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

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.

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.

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.

The heterozygosity index can be calculated using an equation.

Write this equation.

(1)

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)

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

(6)

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.

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?

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)

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

(1)

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.

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)

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.