Unit 4

Variation, classification and adaptation

Variation  All living things vary in the way they look or behave.  Living things that belong to the same species are all slightly different.  Living things that belong to different species are so different that they cannot reproduce together.  Inheritance, the environment or a combination of both may cause these differences.

Classification  Living things are divided into kingdoms.  There are six main kingdoms – virus, bacterium, protist, fungus, plant and animal.

Keys Use of keys is an important feature of work on variation and classification, e.g.: Use of keys is an important feature of work on variation and classification, e.g.:animals backbone no backbone hairno hair legsno legs dogfrog ladybirdworm dogfrog ladybirdworm

Which of these is an animal? cowgrassboyspiderelephantworm

Characteristics  Every person is unique.  Each person has characteristics which make them distinguishable from other human beings.  Even identical twins, human clones, will acquire scars and behaviours which will distinguish them from each other.

Variation  We vary partly because of the random way our characteristics are inherited.  The environment can affect most of our characteristics.  It is usually a combination of genetics and environment that determines how we look and behave.  Some characteristics are not affected by the environment, e.g. eye colour, natural hair colour, blood group, ability to roll the tongue, certain inherited diseases.

Databases Using a simple database: Using a simple database:  Data can be collected  Data can be organised  Data can be analysed  Data can be represented in a number of different ways

Ecology  Plants and animals interact with their environment to create habitats.  Ecology is the study of these interactions.  The world is divided into a number of large regions called biomes.  Each biome is characterised by a particular climate.

Biomes  Tundra biomevery cold  Coniferous forest biomecold  Temperate forest biomevaried but cool  Grassland biomedry  Savannahdry  Desertvery dry  Tropical rainforesthot and wet

Habitats  The place where a plant or animal lives is its habitat.  Some habitats are very small and are called microhabitats.  A habitat has to supply all the needs of the animals and plants that live in it.  The animals and plants that share a habitat are locked together in an interdependent community. They form a food web which is dependent on the energy from the sun.

Adaptation  In a community, the animal or plant best adapted to its surroundings will survive.  Predators have adapted to survive by being strong, agile and fast. They have good vision and often a camouflaged body. They may also hunt in packs, have a variety of prey, and frequently hunt the young, sick and old.  Prey have also adapted: the best adapted escape and breed. Prey may be able to run, swim or fly fast. They often stay in large groups. They may have a horrible taste. They may have warning colours or camouflage.

Competition  Populations cannot keep growing out of control.  Animals have to compete for space, food and water in their struggle to survive.  Only those fitted to the opportunities and limitations of their environment will survive – survival of the fittest.  Plants compete for space, light, water and nutrients.  If a living organism can adapt to its environment then it will survive and breed.

Limiting factors Factors which keep a population from becoming too large are called limiting factors: Factors which keep a population from becoming too large are called limiting factors:  Amount of food and water available  Predators or grazing  Disease  Climate, temperature, floods, droughts, storms  Competition for space, mates, light, food and water  Human activity such as pollution or destruction of habitat.