Biodiversity & Evolution (DP IB Environmental Systems & Societies (ESS): HL): Exam Questions

The Pyrenean desman (Galemys pyrenaicus) is a small, semi-aquatic, globally threatened mammal related to moles and shrews. It lives in the Pyrenees, a mountain range between France and Spain, and can be seen in the image below.

Outline two adaptive features of the Pyrenean desman.

During a study that lasted many years, scientists found that the number of desman travelling from the northern population to the southern side of the mountain range was extremely low. The scientists suspect that the original desman species may have split into two different species.

Explain how the original desman species may have split into two separate species.

Describe the overall changes in global rates of extinction over time.

The apple maggot fly (Rhagoletis pomonella) is a species of fruit fly that lay their eggs on apples. As a result of this, they are often found in apple orchards where they can cause much damage to apple yields. Scientists studied two populations of apple maggot flies from orchards that were separated by a busy highway. They found that flies from the two populations had difficulty breeding successfully when kept in close confinement.

Suggest a reason for this observation.

Explain the non-human factors contributing to the overall biodiversity of an ecosystem.

Compare and contrast species diversity and species richness.

Distinguish between species diversity and genetic diversity.

A biology teacher investigated the different species of insects found in a grassy meadow and in a nearby farmed field.

The insects were collected using traps at randomly chosen sites both in the grassy meadow and in the farmed field.

The table below shows the data collected.

Predict whether the species diversity of the grassy meadow will be higher or lower than the species diversity of the farmed field.

Explain your answer.

A student stated that the experiment suggested farming caused a reduction in species diversity.

Evaluate this statement.

Fertilisers are commonly used today by most farmers as they help to increase crop yield and profit. If it rains shortly after fertilisers are applied to a field then some of the fertiliser can enter nearby water sources as runoff.

A conservationist investigated the effect that runoff fertiliser from a nearby farm had on the distribution of organisms living in a stream. At the point where fertiliser had entered the stream, she found a high density of specific organisms but a low index of diversity.

Suggest how fertiliser contaminating the stream could explain their findings.

The conservationist moves further away from the farm to take further samples.

Predict how the index of diversity will change.

Justify your answer. 

The conservationist wanted to use their findings to take action against the local farm. However, the farmer’s lawyer argued that the scientific methods of the conservationist were not rigorous enough to conclude that runoff fertiliser was affecting species richness in the nearby stream. He demanded that more samples at random locations needed to be taken.

Explain the importance of taking a large number of samples at random sites.

A group of biologists conducted an investigation on a remote archipelago (a collection of islands) in the Pacific Ocean. A species of mouse lives on these islands without any natural predators. The biologists measured the claw length of a large number of these mice.

On half of the islands, a species of snake was accidentally introduced that preys on the mice but that cannot climb trees. Several years after the snakes were introduced the biologists returned and found that on the islands with snakes, the claw length of the mice had changed. Some had shorter claws, enabling them to run faster, while others had longer claws, enabling them to climb trees.

Suggest the benefit to the scientists’ investigation of there being islands without any snakes present.

When the biologists conducted the investigation in part a, flooding of the islands was very rare. Now, due to climate change, flooding of the islands occurs more regularly. This flooding can regularly wipe out large numbers of ground-living species.

Using this information and the information from part (a), explain how the claw length of the mice on the islands are likely to be changing now.

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Even though nylon wasn't invented until the 1940s, bacteria were soon discovered that could degrade nylon. The bacterium, Paenarthrobacter ureafaciens, has special enzymes that allow it to metabolise nylon and use it as an energy source. This is a very simple example of natural selection.

Describe how organisms can evolve through the process of natural selection.

The presence of an antibiotic can act as a selection pressure on bacterial populations.

Explain what selection pressure means in this context.

Discuss the economic, ecological and ethical arguments for conserving biodiversity.

Evaluate the usefulness of calculating diversity indices for understanding the nature of biological communities and the conservation of biodiversity.