1. What is a "population" ?
Answer
A group of organisms of the same species that live in the same area at the same time.
2. State what abiotic factors are and give some examples.
Answer
Non-living parts of the environment; for example, light intensity, temperature, moisture levels, soil pH and mineral content, wind intensity and direction, carbon dioxide levels for plants, oxygen levels for aquatic animals.
3. Give the meaning of the word "ecosystem", and give some examples of ecosystems.
Answer
An ecosystem is the interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment; for example, coral reef, desert, marine, rainforest, tundra.
4. Explain what "extremophiles" are and give an example.
Answer
Organisms that live in environments that are very extreme, such as at high temperature, pressure, or salt concentration. For example, bacteria living in deep sea vents are extremophiles.
5. Give some resources that animals compete with each other for.
Answer
Food, water, mates and territory.
6. Explain what makes a stable community.
Answer
All the species and environmental factors are in balance so that population sizes remain fairly constant.
7. A disease kills all of the rabbits. Removing the rabbits from the food web might affect the mouse population. Suggest one reason why the mouse population might increase and one reason why the mouse population might decrease.
Answer
The mouse population would increase because more grass is available for them to eat. However, the population might later decrease since hawks will consume more mice when there are no rabbits to prey on.
8. A scientist investigates the effect of sulfur dioxide concentration on the number of species of lichen that grow on trees. Give some conclusions that can be reached from the graph in the figure below.
Answer
As the concentration of sulfur dioxide increases, the number of different lichen species decreases. The number of species remains constant when SO2 concentration is between 0 and 4, but no lichens are present when the concentration exceeds 180. The rate of decrease in species number declines sharply above 70 arbitrary units. Lichens can only grow at low sulfur dioxide concentrations, and they cannot survive when concentrations are above 180 arbitrary units. An increased concentration of sulfur dioxide in the air reduces the number of lichen species growing on trees.
9. Give some examples of the features of extreme environments.
Answer
High temperature, high pressure, high salt concentration, high acidity, etc.
10. Another adaptation of camels is that they avoid sitting in the Sun if possible. State whether this is a structural, behavioural or functional adaptation.
Answer
It is a behavioural adaptation.