Energy Flow UNIT 2: ENVIRONMENTAL BIOLOGY AND GENETICS

Transcription

1 Energy Flow UNIT 2: ENVIRONMENTAL BIOLOGY AND GENETICS

2 Learning Objectives Components of an Ecosystem Give the meanings of the words; habitat, population, community and ecosystem

3 What is Ecology / Environmental Biology? Watch the video clip to get an idea What is an Ecosystem? David Attenborough often explains it the best why not watch some episodes at home they are educational and SQA often use examples in their exam papers In planet Earth each episode is on a different ecosystem In Madagascar it looks at the unique ecosystems and specific adaptations to those ecosystems In frozen planet the focus is on the Arctic and Antarctic Ecosystems Watch the selected DVD and make notes on the following terms Ecosystems, community, habitat, populations Any key words or ideas mentioned.

4 Components of an Ecosystem An ecosystem contains Community Habitats Each community contains several interacting populations

5 Components of an ecosystem Ecosystem The interaction between the members of a community and their physical habitat Habitat Place where an organism lives Community All populations living in the same area at the same time Population A groups of organisms of the same species living in the same place at the same time

6 Learning Objectives Food Chains and Food Webs State the meanings of the words; producer, primary and secondary consumer, herbivore, carnivore, predator and decomposer. Give an example of each of these from a given food web. State that the arrows in a food web show the direction of energy flow Describe how energy can be lost from a food chain/web. Describe pyramids of energy, numbers and biomass

7 Energy Flow Producers and Consumers The SUN provides the energy for an Ecosystem Producers convert the sun s light energy into chemical energy by photosynthesis Consumers must consume other organisms in order to obtain the energy they need Herbivore- eats plant material Omnivore eats plant and animal material Carnivore eats animal material only Predators hunt their prey

8 Energy flow - decomposers Bacteria and fungi are decomposers They obtain energy supply by using enzymes to breakdown waste material, dead and decaying matter recycle chemical nutrients in the ecosystem e.g. Carbon Cycle

9 Energy Flow Energy is transferred through organisms in a food chain The arrow indicates the energy flow Heather Mountain hare Eagle Producer primary consumer secondary consumer

10 Food Webs A food web shows the complex relationships in an ecosystem by containing inter-connecting food chains

11 Energy Loss Energy is lost as it flows through a food chain or web because An organism uses energy to build its body, some parts of the body are uneaten or undigested Energy gained by a consumer is used To maintain body temperature Movement Heat lost during respiration On average only 10% of energy taken in by an organism makes its body tissues and becomes available to the next stage in the food chain

12 Pyramids of Number A pyramid of numbers represents the number of organisms at each trophic level in a food chain E.g. Algae water flea stickleback pike Some pyramids are inverted E.g oak tree caterpillar shrew owl

13 Pyramids of Biomass Biomass total mass of living matter Normally calculated as dry mass per unit area Biomass decreases at each trophic level and can be represented as a pyramid E.g brown seaweed limpet crab

14 Problems with pyramids of biomass In some ecosystems, plants have a high turnover rate and the standing crop at any given time may give an underrepresentation of biomass Chemical composition of an organism Fat contains twice as much the energy in protein and carbohydrate per unit mass

15 Pyramids of Energy Most reliable comparison between orgamisms in a food chain Based on productivity Dry mass (g) per square metre per year converted into kj m 2 year -1 Pyramid of energy always takes the form of a true pyramid