4.7 Energy Efficiency

explain why only about 10% of the energy is transferred from one trophic level to the next

-pyramid of energy  ->

-out of 100% of producers only 10% makes it to the primary consumer level and only 1% (out of the 100%) makes it to the secondary consumer level.

-causes of losses:

-100kj of grass energy eaten by herbivore.

-of 100kj of energy eaten by the mouse only 10kj (of the original 100kj) will be part of the mouse body and tissue (bones, eye, muscles, skin, fur etc..)

-REASON- mice has to walk around and find food. they need to respire.

-energy will be lost by respiration.

-not all 100kj of energy is available to the mice. mice cannot digest cellulose (cell wall) but cellulose contains energy- energy lost by feces.

-since 10kj is gained from mice eating 100kj of grass, 90kj of energy is lost by respiration and undigested food.

-when the owl eats the mouse only 1% of the original 100% will make it this far, so the owl gets 1kj out of 100kj (10% rule)

-losses are from respiration, producing energy for flight, movement, digestion etc.

-not all of the mouse is available to the owl. can't digest all- lost by feces.

-all organisms will die at some point- they will broken down by micro-organisms which live by the dead and decaying remains of other organisms- called decomposers.

4.6 Energy and substances in food chains.

understand the transfer of substances and of energy along a food chain.
-bush grass being eaten by the impala.
-bush grass- producer
-impala- primary consumer
-leopard- secondary consumer
-lion- tertiary consumer (if the lion eats the leopard)

-producer- converting light energy to chemical energy - chemical energy takes the form of organic molecules (carbohydrates, protein, lipids) molecules are food.

-molecules are composed of:
C-H  (carbon to hydrogen bonds)
C-O  (carbon to oxygen bonds)
C-C  (carbon to carbon bonds)
O-H  (oxgen to hydrogen bonds)
C-N  (carbon to nitrogen bonds)
-these bonds all represent energy.

-C, H, O, N (carbon, hydrogen, oxygen, nitrogen) are the substances/matter.
-as bush grass carries out photosynthesis it creates the organic molecules which are the substances and contain the energy which was from sunlight- in form of chemical energy.
-impala consumes this for growth, respiration and life processes.
-the leopard consumes the impala and passes on the same molecules reorganize into leopard form and if the lion eats the leopard it would be reorganized into lion form.
- what passes from each stage in the food chain are the substances or matter (C, H, O, N) and the energy which is in the bonds between the elements. (eg. bond [-] between C-H)

4.5b Food Webs

understand the concepts of food chains, food webs, pyramids of number, pyramids of biomass and pyramids of energy transfer.


-food web allows us to provide a better description of the ecosystem.
-the ecosystem is composed of the community of organisms which are interacting (feeding)
-the advantages of the food web is that it allows us to show organisms feeding at different trophic levels.
-feeding at different trophic levels has consequences

•  organisms can have multiple predators.
•  organisms may be feeding on multiple pray.
•  results in food chain becoming linked.

-PRODUCER- grass.
-PRIMARY CONSUMER- rabbit, beetle, slugs mice, wood lice.
-SECONDARY CONSUMER- small birds, badger, hawk.
-TERTIARY CONSUMER- hawk

-grass eaten by rabbit, rabbit eaten by the hawk- ( in this case hawk is also a secondary consumer)
-grass eaten by beetles, beetles eaten by small birds, small birds eaten by the hawk- (in this case the hawk is a tertiary consumer)

4.5a Food Chains

understand the concepts of food chains, food webs, pyramids or number, pyramids of biomass and pyramids of energy transfer.


- food chain links together the producer to the primary producer to the secondary consumer to the tertiary consumer.
-one organism shown at each trophic level
-in food chain you cannot show a food chain being an omnivore.
-cannot show organisms feeding at more than 2 trophic levels.
-food chains show the flow of matter and they show the flow of energy.

4.4 Trophic Levels

recall the names given to different trophic levels to include producers, primary, secondary and tertiary consumers and decomposers.


-trophic- to feed.
-carrot plant- doing photosynthesis    PRODUCER
-carrotfly- eating carrot plant- herbivore  PRIMARY CONSUMER
-flycatcher- eating the carrotfly- carnivore  SECONDARY CONSUMER
-sparrow hawk- eating the flycatcher- top carnivore  TERTIARY CONSUMER

-producer turning light energy to chemical energy.
-primary consumer takes in the chemical energy of the plant and turns it into chemical energy of the fly. changing the form of the chemical energy
-secondary consumer changing the chemical energy from one form to the other.
-tertiary consumers eat the secondary consumer, taking in the molecules of the fly catcher and turning them into the molecules suitable for the sparrow hawk.

- all of the organisms die at some stage.
-they are broken down by special organisms called decomposers. eg. fungi and bacteria.
-important in the recycling of molecules.
-often breaking down complex molecules into nitrates and phosphates.

4.3 Quadrat Samples

describe the use of quadrats as a technique for sampling the distribution of organisms in their habitat.
-use quadrat technique for sampling the distribution of organisms in their habitat.
-sample has to be random so there is no bias introduced and
-sample needs representative.
-sample needs to be large enough, so that the estimate of population is close enough to the true population as possible.

-set up grid system in area, it works like an x,y coordinates on a graph (grid must be equal sie)

-random numbers are needed to place quadrat in the squares.

-random numbers can be generated online or in tables.

-use of random numbers- generate number in x and y coordinate.

-random numbers generated -> 3 and 3. so grid will be at 3,3 (shown below)

-(assume that) each quadrat is one by one meter 

-count the number of daisies inside there.

-we need a representative sample- the bigger the better

                                                    - 10 quadrats or 10% of the area

-record data in a table (shown below)

-quadrat number & number of daisies for heading

-add up number of daisies divide number of quadrats.

-answer would give us the the number of daisies per meter square.

-this technique can be used to estimate the population of daisies in the field 

-we can also compare the number of daisies in many areas.

4.2 Quadrats

recall the use of quadrats to estimate the population size of an organism in two different areas.
-ecosystem is made up of a number of populations which forms the community and the habitat.
- fence separating two different areas of the sand dune. grazed by cattle and ungrazed by cattle.
-we can study both of the sides by counting the number of individuals in the population in each side.
-we can use the technique quadrating -> squares made of any material to form a square grid. (quadrats range from half a meter by half a meter to one meter by one meter)
-quadrats are used to sample the area and count the number of individuals inside the area and will be repeated a number of times to get and estimate of the population size.
- quadrats can be sampled in different locations and they can be compared.

4.1 Ecosystems

understand the terms: population, community, habitat and ecosystem.

- ecosystems are branched into 2 sections.
- community of organisms and habitat.
- habitat includes all abiotic factors (non biological factors) daylight/dark, temperature, humidity, rainfall and slope.
- community of organisms is made out of organisms of different species  and are interacting.
-population is the number of individuals of a particular species.
-species is the organisms that reproduce to give fertile off spring.
-the common interaction is feeding with in the habitat.

Seeds & Fruit

-fruits and seeds we cut in the lesson.