1. What is a "community" ?
Answer
A group of two or more populations of different species that live in the same area at the same time.
2. State what biotic factors are and give some examples.
Answer
Living parts of the environment; for example, availability of food, new predators arriving, new pathogens, one species outcompeting another so the numbers are no longer sufficient to breed.
3. Explain what "adaptations" are, and give examples of adaptations to extremely cold conditions.
Answer
Structural, behavioural or functional features that enable organisms to survive in the conditions in which they normally live. Adaptations to extremely cold conditions include: small ears so smaller surface area for heat loss, huddling together to keep warm, or hibernating in winter.
4. Give some resources that plants compete with each other for.
Answer
Light, space, water and mineral ions.
5. Explain what the term "interdependence" means.
Answer
Each species depends on other species for food, shelter, pollination, seed dispersal, and so on. If one species is removed it can affect the whole community.
6. What defines a community, an ecosystem, and a population in the food web shown in the figure below ?
Answer
Community: all of the grass, grasshoppers, lizards, hawks, and so on in the grassland ecosystem
Ecosystem: grassland
Population: all of the lizards, rabbits, snakes, etc.
7. A student notices that there are less daisies growing in a shaded area under a tree than in an unshaded area. A student makes the hypothesis: "The number of daisies growing in a field is affected by light intensity." Describe an investigation to test this hypothesis.
Answer
Put two tape measures perpendicular to each other in the shaded area of the field, then use a random number generator to get coordinates. Put a quadrat down at the coordinates then count the number of daisies in the quadrat. Repeat this at least 10 times in the shaded area and find the mean number of daisies per quadrat. Repeat the sampling in the unshaded area of the field. Compare the mean number of daisies in the shaded and unshaded areas.
8. Explain why there might be fewer daisies in the shaded than unshaded area of the field.
Answer
Light intensity affects the rate of photosynthesis.
9. The table below gives information about grey and red squirrels. The grey squirrel was introduced into a habitat where red squirrels live. After a while, it was noticed that the population of red squirrels had decreased. Suggest three reasons why the population of red squirrels has decreased.
Answer
The red squirrel is smaller, about half the mass of the grey squirrel, so it cannot compete as successfully for food. It eats a smaller variety of foods than the grey squirrel, making it more difficult to find adequate resources. The red squirrel also has a smaller range of habitats available. As a result, the same area of land can support far fewer red squirrels—around five times fewer—than grey squirrels. In addition, the grey squirrel can spread the squirrelpox virus to red squirrels, and red squirrels have no immunity.
10. The camel is an animal that lives in hot, dry conditions, such as a desert. Camels can feed on thorny desert plants and can live without water for months. The figure below shows some of the adaptations that help the camel to survive. Suggest how each of the adaptations helps the camel to survive in the desert.
Answer
Their mouths are not damaged by the thorns or spines of desert plants. The fat stored in their bodies can be used in metabolic reactions, such as respiration, to produce water. Less water is lost in urine, so it is conserved within the camel's body.