Ch12 Ecology

1. Ch12 Ecology Bio- Miss Loke/ Miss Chng

2. Environment Everything surrounding an organism that affects how it lives

3. Abiotic Environment Factors that affect: • Light (photosynthesis/some animals) • Temperature (affect activity of enzymes in plants and animals) • Water (cytoplasm of cells have 90% water) (Xerophytes vs hydrophytes)

4. Abiotic Environment • Oxygen (survival) • Mineral salts and salinity (freshwater vs saltwater) • pH (alkaline or acidic)

5. Light • Light is a physical feature that affects the activities and behaviour of living things • Some animals, like bats and earthworms, stay away from light completely

6. Light • Plants can only survive where there is enough sunlight • The presence of light enables plants to make food • Green plants in turn provide food and shelter for other living organisms • Some plants, like chrysanthemum, grows well in bright sunlight while most ferns prefer shady places

7. Temperature • Most organisms cannot tolerate extreme fluctuations in temperature • But many organisms have developed special features to adapt to extreme temperatures

8. Temperature • In tropical regions, the temperature usually ranges from 20°C to 30°C where the animals and plants are active throughout the year • E.g. The bird, whimbrel found in Sungei Buloh Nature Park in Singapore between September and March

9. Temperature • In temperate regions, animal hibernate or migrate (to warmer regions) during winter. • Hibernation • A period of long and deep sleep of an animal during a cold season • Its body temperature drops and its heart beat and breathing slow down • E.g. polar bear

10. Water • The amount of water found in a place is determined by the amount of rainfall throughout the year • Water is a basic necessity for survival.

11. Water • Xerophytes: The cactus plant is well adapted for life in hot desert areas. • It has a thick stem to store water and a strong skin which reduces the loss of water. • The leaves are just sharp spines which protect the plant from predators

12. Water • Hydrophytes: Plants live in water or very wet places. - completely submerged e.g. Hydrilla - partially submerged e.g. water-lily - free floating e.g. water hyacinth

13. Water • A frog lives in wet places. • It has a a thin , moist skin through which it is able to breathe. • A camel live in desert produces little sweat and urine.

14. Oxygen • On land, trees produce most of the oxygen in the air through photosynthesis. • In aquatic life, oxygen produced by water plants is dissolved in the water. • The concentration of oxygen in the water can be greatly affected.

15. Oxygen • Water pollution harms aquatic plants, resulting in a decrease in oxygen levels in the water. • The decomposition of the dead plants and animals increases the number of bacteria in the water. • These bacteria respire and use up the oxygen in the water. • More aquatic animals will die as a result.

16. Oxygen • There are organisms that are adapted to living in an environment with a low oxygen content. • For example, the mangrove plant has breathing roots that stick out of the oxygen –poor mud to absorb oxygen in the air. • The fishes, like the guppy, can swim up to the water surface to breathe. • Air breather

17. Mineral salts and salinity • Mineral salts • Important in manufacture of proteins, vitamins and chlorophyll • Freshwater vs Saltwater

18. pH • The pH value of water in soil, ponds or the sea affects the kind of organisms that live in these habitats, • Marine organisms live in the soil, which is slightly alkaline, with a pH of 8. • Most land plants(e.g. hibiscus)grow best in neutral soils. • Sweet pea plant grows best in slightly alkaline soil. • Cotton plant grows best in slightly acidic soil.

19. Biotic Environment • Includes the other living organisms that an organism comes in contact with. • An environment where an organism lives is called HABITAT. • Eg:ocean, forest, pond, trees

20. Biotic Environment • A group of organisms of the same kind is called a POPULATION. • Eg: mudskippers, squirrels, humans • Different populations or organisms living together in the same habitat makes up a COMMUNITY. Populations Community = + Habitat

21. Ecosystem Primary Consumers Secondary Consumers Tertiary Consumers

22. Food Chain • What is a food chain? • It is a series of organisms which energy is transferred in the form of food.

23. Example of food chain:

24. Food Web • What is a food web? • It occurs in a community where foodchains are linked to form a food web. • They are complex food relationships that occur in natural ecosystem.

26. Example of food web:

27. Website • http://library.thinkquest.org/28343/foodchan.html

28. Pyramid of energy • It is a way of expressing the energy present in each level of the food chain. • A lot of energy is loss to the environment as food is transferred from one trophic level to the next. • Energy is lost as • heat during respiration • In excretory matter and undigested food from consumers • The total energy decreases progressively along a food chain. • 90% of energy is lost as food is transferred along a food chain.

29. Example of pyramid of energy:

30. Pyramid of numbers: Oak tree Caterpillar Bluetit Sparrowhawk

31. TASK:Draw the pyramid of numbers and pyramid of energy