B3 – Life On Earth

1. B3 – Life On Earth

2. Food Webs / Competition • Living organisms are dependent on the environment and other species for their survival • Competition for resources between different species that are part of the same food web

3. Rapid Change may cause Extinction • Environmental Change • New species introduced (competitor, predator, disease organism) • A species in the food web becomes extinct

4. Extinction due to Human Activity • Hunting • Deforestation • Poaching

5. Grey Wolf • 1740 – Great Britain • Deforestation and hunting • Martinique Amazon Parrot • 1722 – America • Habitat cleared for agriculture • Bali Tiger • 1937 - Indonesia • Habitat loss and hunting • Caribbean Monk Seal • 1952 – Mexico • Hunted for meat and oil

6. Biodiversity • Biodiversity provides high variety of crops, livestock, forestry, and fish, which are important sources of food and medicine for humans. • Important for sustainable development

7. Evolution • All species that have ever lived evolved from very simple living things. • Life on Earth began about 3500 million years ago • If conditions on Earth at any stage were different, natural selection could have produced different results

8. Evidence for Evolution • Fossils • Similarities and Difference in DNA

9. The Begining of Life • The first living things developed from molecules that could copy themselves. • These molecules were produced by conditions on Earth or have come from elsewhere (asteroid)

10. Natural Selection • How evolution happens. • The natural genetic variation within a population of organisms means that some individuals will survive and reproduce more successfully than others in their current environment. • This means that more of this organisms genes will be passed on to the next generation

11. Environmental and Genetic Variation • Variation is cause by both of these, but only genetic variation can be passed on to offspring.

12. Selective Breeding • Selective breeding is the process of breeding plants and animals for particular genetic traits.

13. Mutations • Mutations are changes in DNA caused by radiation, viruses or other factors. • Mutations that occur in sex cells (sperm or egg cells) can be passed onto offspring and may produce new characteristics (eg: 4 wings instead of 2, red eyes, etc)

14. Creating a New Species • The combined effects of: • Environmental Changes • Mutations • Natural Selection • Can product a new species over time

15. Evolution of Multi-cellular Organisms • Led to nervous and hormonal communication systems

16. Receptor and Effector Cells • Neurones (Nerve Cells) link receptor cells to effector cells

17. Central Nervous System • In vertebrates, the nervous system is coordinated by the CNS • The Nervous System uses electrical impulses for fast, short-lived responses. It doesn’t make permanent, long lasting changes

18. Hormones • Chemicals which travel in the blood and bring about slower, longer-lasting responses.

19. Examples • Nervous Communication • Blinking • Muscle Control • Heart Beat • Hormonal Communication • Puberty (Testosterone, Oestrogen) • Mood, appetite, sleep (Serotonin) • Increase heart rate and blood pressure (Dopamine)

20. Homeostasis • Nervous and Hormonal systems are involved in maintaining a constant internal environment

21. Larger Brain • Evolution of larger brain gave early humans a better chance of survival • Smarter • Quicker • More social • More artistic • Language

22. Human Evolution • Common Ancestor • Divergence (Separation) of Hominid Species • Extinction of all but one of these species