4.7 Energy efficiency

(Kilojoules)

In the producer, only 10% of the energy is transferred to primary consumer, and so on

Causes of losses

Producer -> Primary consumer -> Secondary consumer

100 kJ -> 10 kJ -> 1 kJ

1) Respiration (energy lost by primary consumer)

2) Plant cell wall cannot be digested (not all of the plant can be digested) -> Faeces

-- 90 kJ loss --

3) Not all of primary consumer is available to secondary consumer

All eventually die

Broken down by decomposers

4.6 Energy and substances in food chains

Producer

Light energy -> Chemical energy

Organic molecules

Carbohydrates

Proteins

Lipids

(Food molecules)

C-H

C-O

C-C

O-H

C-N

(Bonds that represent energy)

CHON (substances/matter)

Producer is consumed for life processes, growth, respiration

Same molecules (substances/matter) are passed on through the food chain

Energy is in between the bonds of the elements

4.5c Pyramids

Food chain (diagram of feeding relationships)

Producer -> Primary consumer -> Secondary consumer -> Tertiary consumer

Description of interaction between community = Feeding

quantify (trophic levels) and develop the idea of food chains

1) Pyramid of number - count number of organisms at each trophic level

4.5a Food Chains, 4.5b Food Webs

Food Chains

1 organism per trophic level

In food chains no omnivores or more than 2 trophic levels

Show flow of matter and energy

Food Webs

Better description of ecosystem (community of organisms which are interacting -> feeding)

Organisms feeding at different trophic levels

1) Multiple predators

2) Multiple prey

3) Food chains becoming linked

Producer -> Grass

Primary consumer -> Rabbit, beetle, slug, mice, woodlice

Secondary -> Small birds, badger

Hawk can be secondary consumer or tertiary consumer

Food chains are linked (2 or 3 links)

4.4 Trophic Levels

Trophic => To feed
Names given to different feeding levels

Plant (Photosynthesis) -> Herbivore -> Carnivore -> Top Carnivore
Producer -> Primary consumer -> Secondary consumer -> Tertiary consumer

1) Light energy -> Chemical energy
2) Chemical energy (of plant) -> Chemical energy (of fly)
3) & 4) Chem energy -> Chem energy

After death -> broken down by decomposers (fungi, bacteria)
Recycles molecules into nitrates and phosphates

4.3 Quadrats

4.3

Using quadrats to sample distribution of organisms in their habitat

Sample - random (no bias introduced)
- representative (large/as close to the true population as possible)

Setting up grid system across field
- Like xy coordinates of graph
Grids equal sizes
Use random numbers (generated online or from tables) - use for x, y coordinates
Draw quadrat is red
Find out area then count amount of organism

Representative sample - bigger = better
- 10 quadrats/10% of actual area

Make a table - find average
Find number of daisies per m²

This technique also used to compare populations with other areas

4.2 Quadrats summary

Quadrats - estimating population size of an organism

Eg sand dune ecosystem - some populations -> community -> habitat

Fence - splits area into two regions
Grazed - ungrazed (cattle)
2 areas of ecosystem - study the populations in grazed/ungrazed
Then count the population

Quadrating
Quadrats based on squares - square grids
Up to 1m x 1m
Sample -> counting populations
and estimating the population size

Quadrats -> method of sampling different locations - populations can be compared

4.1 Ecosystems

Ecosystem
eg. forest with waterfalls/tree etc

Ecosystem > Habitat (Abiotic - non-biological factors)
v
Community of organisms

Habitat
- Cycle of daylight/dark
- Temperature
- Rainfall
- Humidity
- Slope

Community of Organisms
- Populations of different species/interacting
- No. of individuals of particular species
- Species -> Organisms that reproduce to give fertile offspring
- Interactions -> eg, feeding