Environmental Biology & Genetics

1. Environmental Biology & Genetics Energy Flow Mr G Davidson

2. Ecosystems • An ecosystem is a natural unit composed of living organisms and their non-living environment, e.g. a woodland. • A habitat is the place where an organism lives, e.g. greenfly live on the leaves of the trees. • An organism’s niche is the role it plays within the ecosystem e.g a tawny owl is top predator in a woodland. Mr G Davidson

3. Ecosystems Mr G Davidson

4. Ecosystems • A population is the total number of organisms of one species living in a habitat, e.g. the total number of greenfly in the woodland. • A community is made up of all the living organisms in a habitat, e.g. all the trees, grass, insects, birds, etc.. Mr G Davidson

5. Ecosystems Mr G Davidson

6. Ecosystems • A species is a group of organisms which can interbreed to produce fertile offspring. Donkey Horse Horses and donkeys can mate to produce a mule – but mules are not fertile so horses and donkeys are separate species Mule Mr G Davidson

7. Ecosystems • All of the energy required by all living organisms in an ecosystem comes from the sun. • Light energy from the sun is converted to chemical energy by plants in a process called photosynthesis. Mr G Davidson

8. Producers & Consumers • Producers are organisms which can produce their own food by photosynthesis – usually green plants. • Consumers are animals which consume (eat) other organisms. They cannot make their own food. Mr G Davidson

9. Producers & Consumers • A primary consumer is an animal which eats plants, and is also known as a herbivore. • A secondary consumer is an animal which eats primary consumers, and is also known as a carnivore. Mr G Davidson

10. Producers & Consumers • An omnivore can eat both plants and animals. • Decomposers are bacteria and fungi which break down dead plants and animals for energy and release their nutrients back into the ecosystem. Mr G Davidson

11. Producers & Consumers • An animal which hunts other animals for food is called a predator. • An animal which is hunted by other animals as food is called prey. Mr G Davidson

12. Food Chains & Webs • A FOOD CHAIN shows a feeding relationship. It is usually written as: Green plant herbivore carnivore • The arrows in a food chain point from food to feeder and show the direction of energy flow. • A food chain always starts with a producer (green plant). Mr G Davidson

13. Food Chains & Webs • Energy is transferred in the form of chemical energy in food from plants to animals and then to other animals. • A green plant (producer) can be eaten by a herbivore. • The herbivore in turn can be eaten by a carnivore. Mr G Davidson

14. Food Chains and Food Webs ENERGY ENERGY Fox SECONDARY CONSUMER (CARNIVORE) Rabbit PRIMARY CONSUMER (HERBIVORE) Green Plant PRODUCER Mr G Davidson

15. Food Chains & Webs • Feeding relationships are more complicated than food chains suggest. • Food chains interconnect at many points. • This interconnection of food chains is called a food web. Mr G Davidson

16. Food Chains & Webs OWL WEASEL FOX HEDGEHOG RABBIT VOLE FROG SNAIL PRIMROSE PLANT OAK Mr G Davidson

17. Oak leaf Caterpillar Shrew Badger Energy Flow and Loss • Every time one organism eats another, energy is transferred from the food to the feeder. • The arrow indicates the direction of energy flow. • E.g. Mr G Davidson

18. Energy Flow and Loss • Not all the energy available at each step in a food chain is passed onto the next step. • Only about 10% is passed on. • 90% of the energy is lost e.g. as: • Movement • Heat production • Waste. Mr G Davidson

19. Pyramid of Numbers • A pyramid of numbers is a diagram which represents the number of organisms at each stage in a food chain. • A pyramid of numbers can look like: Mr G Davidson

20. Size of organisms increase Number of organisms decrease Thrush Ladybird Greenfly Grass Pyramid of Numbers Mr G Davidson

21. Thrush Ladybird Greenfly Grass Pyramid of Numbers Mr G Davidson

22. Pyramids of Energy • A pyramid of energy is a diagram which represents the amount of energy available at each level of a food chain. • It is usually measured in kilojoules of dry mass per square metre per year. Mr G Davidson

23. 100 kJ 1 000 kJ 10 000 kJ 100 000 kJ Pyramid of Energy Mr G Davidson

24. Pyramid of Biomass • A pyramid of Biomass is a diagram which represents the total mass of organisms at each level of a food chain. Mr G Davidson

25. Sparrows Caterpillars Oak leaves Pyramid of Biomass The energy available to the caterpillars is less than the energy available to the sparrows, and therefore, the caterpillars produce a greater biomass than the sparrows. Mr G Davidson

26. Vocabulary ecosystem carnivore habitat predator niche prey population decomposer community species producer pyramid of numbers primary consumer pyramid of biomass secondary consumer pyramid of energy herbivore Mr G Davidson