Ecology & Evolution

1. AmitMishra - NES International School Mumbai Ecology & Evolution IB DP – CORE

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3. Amit Mishra - NES International School Mumbai Basic Concepts • Species : a group of organism that can interbreed & produce fertile offspring.(have a common gene pool). • Habitat: the environment in which species normally lives (location). • Population: a group of the organism of the same species ,living in the same area at the same time. • Community: a group of populations living & interacting with each other in an area. • Ecology: the study of relationships between living organisms & their environment.

4. Amit Mishra - NES International School Mumbai Environment • Its everything which surrounds an organism. • It has 4 main components • Hydrosphere (water) • Atmosphere (gases) • Lithosphere (rocks) • Biosphere (all living beings) • The first 3 are abiotic components while the 4th is the Biotic component

5. Amit Mishra - NES International School Mumbai Autotrophs & heterotrophs

6. Amit Mishra - NES International School Mumbai • Autotrophs are the organisms with the capacity to make their own food. • Eg.:cynobacteria, Algae,Grass, Trees. • Hetrotrophs are the organisms which do not have the capacity to produce their own food. • Eg.:animals,fish,zooplanktons. • Three types : • consumers • detritivore • saprotroph

7. Amit Mishra - NES International School Mumbai Detrivores & saprotrophs • Detrivores are the organism that consumes dead organic matter. • Eg.: earthworm, woodlice. • Saprotrophs are the organisms that live on, or in, dead organic matter. (digesting the food by secreting enzymes).

8. Amit Mishra - NES International School Mumbai Food chain & food web

9. Amit Mishra - NES International School Mumbai • A food chain is a sequence of relationships between trophic levels where each member feeds on the previous one. • A food web is a diagram that shows the feeding relationships in a community. The arrows indicate the direction of energy flow. • It’s the interlinking of the food chains.

10. Amit Mishra - NES International School Mumbai • Define trophic level. (1) • A trophic level is where an organism is positioned on a food web. • Producer • Primary consumer • Secondary consumer • Tertiary consumer

11. Energy flow • Each animal in the food chain eats another animal or a plant in order to gain energy. • The energy flow in the ecosystem keeps all of the animals alive. Amit Mishra - NES International School Mumbai

12. Amit Mishra - NES International School Mumbai • Sun is the principal source of energy in biological systems. • Green plants absorb only a very small fraction of (about 10%) of the light energy. • Light energy converts into chemical energy by plants.

13. Amit Mishra - NES International School Mumbai 10 % Law of energy flow • Of the total energy entering a particular trophic level, only 10% is available for the next higher trophic level. • Grass → Goat → Tiger • 200 Kg → 20Kg → 2Kg • Hence short food chains provide more energy to higher trophic level. • That’s the reason why vegetarians get more energy than meat eating people.

14. Amit Mishra - NES International School Mumbai Ecological pyramids • Pyramid of biomass • Biomass is the total dry mass of all organism in an unit area. • Total biomass = biomass of producers + biomass of consumers + biomass of decomposers. • The mass of all the organisms at each step of the food chain is measured. • On the basis of the measurement of the dry mass (at each trophic level) a diagram can be drawn. • This is known as pyramid of Biomass.

15. Pyramid of Number • This is drawn according to the number of organisms at each trophic level of the food chain. Amit Mishra - NES International School Mumbai

16. Amit Mishra - NES International School Mumbai Pyramid Of Energy • Energy pyramids are formed by measuring the amount of energy available at each trophic level in the food chain. • The energy is measured over a fixed period of time.

17. Amit Mishra - NES International School Mumbai Pyramid of Energy

18. Amit Mishra - NES International School Mumbai Explain that energy can enter and leave an ecosystem, but that nutrients must be recycled. Energy enters as light and usually leaves as heat. Nutrients do not usually enter an ecosystem and must be used again and again. Nutrients such as Carbon dioxide, Nitrogen, and Phosphorus

19. Greenhouse Effect Phenomenon • The mean global temperature has risen about 1 degree Celsius since 1856. • We saw an increase between 1910 and 1940, and from 1970 onwards. Amit Mishra - NES International School Mumbai

20. Amit Mishra - NES International School Mumbai Greenhouse Effect Human Activities • Increased burning of fossil fuels releasing Greenhouse gases • Deforestation – less trees to convert CO2 back to O2 • Other industrial activities that release other Greenhouse gases

21. Amit Mishra - NES International School Mumbai Greenhouse Effect Causes • Light from the sun has short wavelengths and can pass through most of the atmosphere. • This sunlight warms the earth which in turn emits long wave radiation. • This long wave radiation is bounced back by the greenhouse gases, such as carbon dioxide, methane, water vapour, and sulphur dioxide

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23. Amit Mishra - NES International School Mumbai Greenhouse Effect • Flooding of low –lying land • Melting of glaciers and polar ice • More frequent storms and hurricanes • Changes in weather patterns

24. Amit Mishra - NES International School Mumbai Greenhouse Effect Measures • Increase photosynthesis and reduce emissions by: • restoring ecosystems where there has been deforestation or desertification • spreading nutrients such as iron in nutrient-deficient oceans to encourage algal growth

25. Amit Mishra - NES International School Mumbai Greenhouse Effect • Reducing energy consumption; insulation, smaller vehicles, local grown food instead of transported • Changing from fossil fuels to solar, wind, or nuclear

26. Amit Mishra - NES International School Mumbai Carbon cycle • The carbon cycle includes the interaction of living organisms and the biosphere through the processes of photosynthesis, respiration, fossilization and combustion.

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28. Amit Mishra - NES International School Mumbai Populations Outline how population size can be affected by natality, immigration, mortality and emigration.

29. Amit Mishra - NES International School Mumbai Populations • Natality – offspring are produced and added to the population • Mortality – individuals die and are lost from the population • Immigration – individuals move into the area from somewhere else and add to the population • Emigration – indivuals move out of the area and are lost from the population

30. Populations Draw a graph showing the sigmoid (S-shaped) population growth curve. (1) Amit Mishra - NES International School Mumbai

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32. Amit Mishra - NES International School Mumbai Populations • Lag phase: population just begins to grow • Exponential Phase Population increases exponentially because the natality rate is higher than the mortality rate. This is because there is an abundance of food, and disease and predators are rare.

33. Amit Mishra - NES International School Mumbai Populations • Transitional Phase • Difference between natality and mortality rates are not as great, but natality is still higher so population continues to grow, but at a slower rate. • Food is no longer as abundant due to the increase in the population size. May also be increase predation and disease.

34. Amit Mishra - NES International School Mumbai Populations • Plateau Phase Natality and mortality are equal so the population size stays constant. • Limiting Factors: • shortage of food or other resources • increase in predators • more diseases or parasites • If a population is limited, then it has reached its carrying capacity

35. Amit Mishra - NES International School Mumbai Populations Define carrying capacity. The maximum population size that can be supported by the environment

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37. Amit Mishra - NES International School Mumbai Populations List three factors which set limits to population increase. Limiting Factors: • shortage of food or other resources • increase in predators • more diseases or parasites

38. Amit Mishra - NES International School Mumbai Evolution • Evolution—the process of cumulative change in the heritable characteristics of a population. • Macroevolution – the change from one species to another. i.e. – reptiles to birds • Microevolution – the change from one variation within a species to another. i.e. – a Chihuahua and a Great Dane

39. Amit Mishra - NES International School Mumbai Evolution State that populations tend to produce more offspring than the environment can support.

40. Amit Mishra - NES International School Mumbai Evolution Explain that the consequence of the potential overproduction of offspring is a struggle for survival. Populations tend to grow exponentially, but population sizes tend to remain constant. More offspring are produced than can be supported, therefore there is a struggle to survive, where some live and some die.

41. Amit Mishra - NES International School Mumbai Evolution State that the members of a species show variation.

42. Amit Mishra - NES International School Mumbai Evolution Explain how sexual reproduction promotes variation in a species. • Meiosis • fertilization

43. Amit Mishra - NES International School Mumbai Evolution Explain how natural selection leads to the increased reproduction of individuals with favourable heritable variations. • The Darwin–Wallace theory is accepted by most as the origin of ideas about evolution by means of natural selection

44. Amit Mishra - NES International School Mumbai • Since organism’s traits vary, some organisms are more adapted to survival than others. • When there is a struggle to survive those with favorable traits tend to survive long enough to pass them on. • Those that have less favorable traits die before being able to pass the traits on.

45. Amit Mishra - NES International School Mumbai Evolution • Discuss the theory that species evolve by natural selection. • There is evidence that the traits of populations change over time in relation to changes in their environment. • However, these recently observed changes are relatively small. • These observations do not prove that the different species evolved from other species. • Evolution is simply a theory. • There are other theories as well.

46. Amit Mishra - NES International School Mumbai Evolution • Two useful terms for discussion: • Micro-Evolution – changes within a species due to natural selection in response to environmental changes. Observed. Scientific fact. • Macro-Evolution – change from one species to another species through natural selection. Has not been observed. Still remains a theory.

47. Amit Mishra - NES International School Mumbai Evolution • Explain two examples of evolution in response to environmental change; one must be multiple antibiotic resistance in bacteria.

48. Amit Mishra - NES International School Mumbai Antibiotic resistance bacteria. • The bacteria becoming resistant to antibiotics, such as penicillin. Is an example of natural selection. • Penicillin works by stopping bacteria from forming cell walls. • When a infected person is treated with penicillin, the bacteria are unable to grow new cell walls, & they burst open. • However the population of bacteria in the person’s body may be several millions. • The chances are that any of the bacteria will get mutated & is not affected by penicillin.

49. Amit Mishra - NES International School Mumbai • This mutant bacteria will go on reproducing • Soon it may form a huge population of penicillin resistant bacteria. • If some bacteria becomes resistant to one, they may be treated with another antibiotic. • This happens quite frequently & hence there are so many different antibiotics available.

50. Amit Mishra - NES International School Mumbai Classification • Define • Species—a group of organisms which can interbreed and produce fertile offspring.