1. 5.3 Populations IB SL & HL I Biology

2. 5.2 Homework 5.2.4 Outline the precautionary principle Concept that someone wishing to take an action should prove that the action does not cause serious or irreversible harm to the public Simpler terms: If we are not certain of the results of a change in behaviour, people must prove that is will not be harmful

3. Uses of Precautionary principle Shifts the burden of proof away from those people that need protection towards those proposing an action may be harmful Entertainment, health, food and medicine Eg. Drug manufacturer must prove that a medicine will do what it promises, and that is has no serious/lasting side effects Eg. Companies must prove to FDA that food additives are safe

4. UN and Montreal Protocol (1987) International treaty to protect the ozone layer Reduce/stop the production of CFCs (lead to greenhouse gases in the environment) Atmospheric [CFCs] have leveled off or decreased Potential to recover the ozone layer by 2050

5. 5.2.5 PP & Climate Change Not sure what the exact effects of increasing CO2 levels are – this is a GLOBAL issue Economic harm of limiting global warming now vs more harm for future generations if nothing is done. ▫Should we solve immediate problems first? Should we knowingly damage ecosystems, habitats and species populations by doing nothing? Inequality between people contributing most to the problem, and the people who will be most harmed. ▫Who should pay for this?

6. Populations

7. Definitions Population size – the number of individuals in a population at a given time Natality – the birth rate Mortality – the death rate Immigration – individuals entering a population Emigration – individuals leaving a population

8. Population Size Population size = (natality (N) + immigration (I)) – (mortality (M)+ emigration (E))

9. Population Growth Curve Sigmoid (S-shaped) curve Shows the changes in population size over time. What do you think each stage represents?

10. Stages of Population Growth Curve Exponential growth phase ▫Unlimited growth of population (N+ I > M + E) ▫No limiting factors ▫Exp = 1, 2, 4, 8, 16, 32…etc Transitional phase ▫Limited growth of population (due to limiting factors Plateau phase ▫No more increase in growth ▫N+I = M + E ▫Has reached the carrying capacity

11. Carrying Capacity (K) The maximum number of individuals of a species that can be sustainably supported by the environment Add “K” to your S-curve

13. Limiting Factors Factors that control a process such as population growth Animals ▫Amount of food available ▫Presence of parasites/disease ▫Amount of predation/competition ▫Available nesting sites ▫Environmental change Plants ▫Amount of light, water and CO2 available ▫Temperature ▫Environmental change ▫http://www.brainpop.com/science/ourfragileenviron ment/populationgrowth/http://www.brainpop.com/science/ourfragileenviron ment/populationgrowth/

14. Spaceship Earth Activity Read handout “Spaceship Earth” Get into assigned regions and obtain resource cards Complete Activity 1 and Activity 2 Complete 5 questions individually and hand in

15. Homework Paramecium Simulation (25 lab marks) ▫See handout ▫You must hand in: handout, printed table and printed graph