Biodiversity and the distribution o f life on planet earth

1. Biodiversity and the distribution of life on planet earth

2. Previously we learnt about Niches Collect and complete the find me sheet. You have 5 minutes (or the first person to finish) to get round the class finding someone to sign your sheet if they can explain a word or phrase in a box. Only one person per box The teacher will review it with you by asking around the class and the next slide.

3. We have been learning about Niches What is a niche? A niche is the role that an organism plays within a community. What kind of resources will organisms be using in their ecosystem? Light, temperature and nutrient availability. What types of interactions occur between organisms in A community? Competition, parasitism and predation.

4. In this section we are learning more about specific factors affecting biodiversity. • Biotic and abiotic factors affect biodiversity in an • ecosystem • Grazing and predation are biotic factors • pH and temperature are abiotic factors • Human activities can have an impact on biodiversity • Natural hazards can have an impact on biodiversity At the end of the section you should have an improved understanding of these factors and how they affect biodiversity

5. Biotic factors • These are factors that are living including diseases, • predation, competition (space, light, nutrients, reproduction) • and grazing. • How would predation and competition affect organisms? • (Remember you already discussed this in a previous lesson). • How might these affect biodiversity?

6. Grazing What is grazing? • Animals that eat plants to gain their energy are called grazers. • Commonly sheep, deer and rabbits are thought of as grazers. • How can these animals affect biodiversity by grazing? • It depends on the type of grazer. • Sheep are selective grazers. They select the more dominant • competitive grasses to eat. • How might this help the other plants growing in the area? • The other weaker species get the opportunity to grow more • so biodiversity is kept high. • However too many sheep would over graze the area and reduce biodiversity.

7. Rabbits are relatively unselective grazers. What does this mean? • By eating almost all types of plants on grassland • they maintain a high diversity. • The more vigorous plants are kept in check. • Obviously a massive population of rabbits overgrazing • an area would decrease the biodiversity.

8. Abiotic factors • These are factors that are non living including light, • moisture, pH, temperature, O2 and CO2. • How might these factors affect organisms? • How might this affect biodiversity? • Temperature would affect the growth rate of organisms. • Why would temperature affect growth rate? All organisms rely on enzymes to control chemical reactions. • As the temperature increases reactions happen faster, • up to a certain point so growth could increase. • At lower temperatures there will be slower growth.

9. pH is another factor that can affect organisms especially living in aquatic environments. Why would pH affect organisms in aquatic environments? • Organisms work at their best in a small pH range. • If the pH changes then the biodiversity may • be affected as an organisms chances of survival may be • affected. • Examples of this include fish and corals growing in • aquatic environments.

10. The affect of human activities on biodiversity • How are humans affecting the survival of plants and animals on the planet? • If animal and plant numbers decrease, biodiversity decreases. • Watch Episode 2 from State of the Planet DVD. • Make a note of the 5 ways humans are affecting biodiversity (with examples) as the DVD is playing.

11. Review of Biodiversity and the distribution of life on planet earth Here are 2 short clips to recap some of the work on Biodiversity vimeo.com/14105623 http://www.youtube.com/watch?v=HA3xNMJnFuo