MCQ-4: Human Influences on Ecosystems

Over-use of fertilisers on farmland causes the chemicals in the fertilisers to be washed into ponds and lakes.
This causes eutrophication resulting in the following events.

1. algae grow
2. fish die
3. bacteria grow
4. oxygen decreases

What is the correct sequence of these events?

The concentration of a pesticide in the tissues of the organisms in the following food chain was measured.
plants → small fish → large fish → birds of prey
Which bar on the chart represents the large fish?

Which activity will be least likely to lead to the extinction of species?

The diagram shows the age structure of a human population.

Which age group has the largest number of people?

What is a reason for conserving plant species?

What is reduced after deforestation?

The graphs show the number of carnivores in a habitat over a period of time. At time X the herbivores in their food chain are removed from the habitat.
Which graph shows the effect of this on the number of carnivores?

Which statement describes the effect of predation and disease on a population?

What is not a reason for having conservation programmes?

When raw sewage is discharged into a stream, what is a result of eutrophication?

Some examples of the waste products of human activity are discarded household rubbish, excess fertiliser, industrial chemicals and untreated sewage.
Which of these can both cause increased growth of aquatic plants?

The action of which type of bacteria would cause soil to be lacking in nitrates?

What is used to help sustain fish stocks?

What is a direct result of deforestation?

The table shows the ability of three species of fish and their eggs to survive in water at different pH levels.
If the eggs do not survive offspring cannot be produced.

key
✓= survive
x = do not survive
A lake at pH 6.0 contains breeding populations of all three fish.
If acid rain causes the pH to fall to 5.0, which outcome would be likely to occur?

Pieces of plastic between 1 μm and 1 mm in size are called microplastics. Microplastics are put into some face creams and are produced during clothing manufacture. They can now be found in increasing quantities in oceans all over the world.
As well as their small size, which other property of microplastics make them dangerous to living organisms?

In 1991 there were only fourteen Daviesia cunderdin plants.
What happens to a plant population that becomes very small?

The diagram shows a food web in a woodland.

What is most likely to happen if all of tree type X is removed by humans?

The increased availability of nitrates in rivers and lakes can result in the death of fish.
Which statement explains why fish die in rivers and lakes containing a high concentration of nitrates?

What are the possible effects of deforestation?