Topic 5:Ecology and Evolution

5.1 Communities and Ecosystems

5.1.1 Define species, habitat, population, community, ecosystem and ecology.

Species: a group of organisms that can interbreed and produce fertile offspring.

Habitat: the environment in which a species normally lives or the location of a living organism.

Population: a group of organisms of the same species who live in the same area at the same time.

Community: a group of populations living and interacting with each other in an area.

Ecosystem: a community and its abiotic environment.Ecology: the study of relationships between living

organisms and between organisms and their environment.

5.1.2 Distinguish between autotroph and heterotroph

How would you separate these into 2 groups?

5.1.2 Distinguish between autotroph and heterotroph

Autotrophs (producers) are able to make their own organic molecules as food from inorganic molecules (i.e. via photosynthesis: light energy + H2O + CO2 C6H12O6)

Heterotrophs (consumers) obtain an organic food source from other organisms (i.e. autotrophs or from other heterotrophs)

5.1.3 Distinguish between consumers, detritivores and saprotrophs.

We are consumers! This means we ingest living organisms or recently killed organisms as a source of food. But what happens to waste?

Detritivores eat non-living/dead organic matter

5.1.3 Distinguish between consumers, detritivores and saprotrophs.

Saprotrophs live on or in non-living organic matter. They secrete digestive enzymes and absorb the products of digestion. They break down waste material

5.1.4 Describe what is meant by a food chain, giving three examples, each with at least three linkages (four organisms).

Food chain uses arrows () to show the direction of energy flow from one species to another based on feeding relationships

energy energy energy energy

Task: In your notes, create a food chain with at least four organisms. You will share with the class in 5min.

5.1.5 Describe what is meant by a food web.

Food web is an interconnecting series of food chains. This better represents the variety of food that an organism eats.

5.1.6 Define trophic level

A trophic level refers to its position in the food chain.

Trophic level What are they?

T5 Quaternary consumer Eat tertiary consumers

T4 Tertiary consumer Eat secondary consumers

T3 Secondary consumer Eat primary consumers

T2 Primary consumer Eat producers

T1 Producer Plants/photosynthetic organisms

T1 T2 T3 T4 T5

5.1.7 Deduce the trophic level of organisms in a food chain and a food web.

A trophic level refers to its position in the food chain.

Trophic level Example

T5 Quaternary

T4 Tertiary

T3 Secondary

T2 Primary

T1 Producer

Task: Give at least 1 example of each trophic level using the food web given.

Green plant/tree

Goat, rabbit, mouse

Jackal, wild cat, owl

Lion, kite

Lion or None

5.1.8 Construct a food web containing up to 10 organisms, using appropriate information.

Task: Create a food web using the information below:

•Plants are eaten by mice and grasshoppers•Tree leaves are eaten by rabbits, squirrels, and grasshoppers•Grasshoppers are eaten by mice and frogs•Fox eats mice and rabbits•Owls and snakes eat frogs•Snakes eat rabbits

*Remember, the arrows () show direction of energy flow

5.1.8 Construct a food web containing up to 10 organisms, using appropriate information.

Task: Label the diagram as T1, T2, T3, T4, and T5

5.1.9 State that light is the initial energy source for almost all communities.

The most important organisms are the producers because they are the source of all food for consumers. Sunlight is the original source of energy for almost all communities.

energy energy energy energy

5.1.10 Explain the energy flow in a food chain.

Producers absorb sunlight and it is transformed into chemical energy in the form of organic molecules (i.e. glucose). This energy becomes available to consumers when producers are consumed. Producers that are not eaten will be fed on be decomposers (i.e. fungi). Consumers lose energy as heat during cellular respiration.

5.1.11 State that energy transformations are never 100% efficient..

Task: With a partner think of as many reasons as you can why heat transfer is not 100% between trophic levels

5.1.11 State that energy transformations are never 100% efficient..

Energy

producer1°consumer2°consumer

Energy transfer is so inefficient that the energy available from

consuming a T3 consumer will be too little to support a T4 consumer

5.1.12 Explain reasons for the shape of pyramids of energy.

Pyramid of energy shows use how much and how fast energy flows from one trophic level to another.

*Don’t confuse this with a pyramid of numbers which only shows how many individuals there are in each trophic level.

5.1.13 Explain that energy enters and leaves ecosystems, but nutrients must be recycled.

The sun is a continuous source of energy for all living things. Once heat is lost to the environment it cannot be recycled.

Nutrients like carbon and nitrogen must be recycled since they are limited. Organisms obtain nutrients through consumption and return them back to the environment through decomposition.

ENERGY Nutrients

5.1.14 State that saprotrophic bacteria and fungi (decomposers) recycle nutrients.

Decomposers help unlock the nutrients stored in once living organisms through the process of decay. Organic matter is converted to more useful forms (i.e. protein to ammonia)

PROGRESS CHECK

Task: For each statement, is it True or False? If false, write the correct statement

1.Food chains show the movement of organic molecules2.Energy is lost between trophic levels in the form of heat through cell respiration, faeces, tissue loss and death.3.Energy is recycled by constantly being supplied to the ecosystem through light energy.4.Nutrients must be recycled as there is only a limited supply of them. 5.In order for a food chain to function, there must be a large number of consumers in each successive trophic level.