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Ch12 Ecology

This text explores the essential abiotic and biotic environmental factors affecting organisms. Abiotic factors include light, temperature, water, oxygen, mineral salts, and pH. Each of these elements plays a crucial role in the survival and behavior of organisms, influencing their habitats and adaptations. The biotic environment consists of interactions among living organisms, forming populations and communities. Key concepts include food chains, food webs, and energy pyramids, all integral to understanding ecology and the interdependence of life forms in various ecosystems.

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Ch12 Ecology

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  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.

  25. Example of food web:

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

  27. 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.

  28. Example of pyramid of energy:

  29. Pyramid of numbers: Oak tree Caterpillar Bluetit Sparrowhawk

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

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