4.7 Energy Efficiency

The diagram is a pyramid of energy.
- of the 100 percent of the producer, only 10 percent make it to the primary consumer
- of the 100 percent of the producer, only 1 percent make it to the secondary consumer.
Question: what are the causes of the losses that we are seeing?

Simple food chain (e.g.)
1) producer ( grass ) 100 Kj eaten by the herbivore
2) primary consumer ( mouse ) since 10% - only 10 Kj of the original will become part of the mouse's body and tissues.
Why? = The mice have to walk around and find their food - carry the process of respiration. Not  all of the 100 Kj of energy is available to the mouse e.g. mice cannot digest cellulose so the plant cell wall cannot be digested and the energy is lost in the form of feces. Therefore, 90Kj of the energy is lost through respiration and undigested food
3) secondary consumer ( owl ) - will only be able to assimilate 1Kj. When the owl eats the mouse, only one percent will make it this far. The losses to the owl are = respiration, energy for movement, energy for flight, energy for digestion. However, some energy is also lost in the form as feces.

All organisms will finally die.
They will be broken by the micro-organisms = decomposers

4.6 Energy and Substances in Food Chains

Bush Grass = Producer
Impala = Primary Consumer
Leopard = Secondary Consumer
Lion = Tertiary Consumer

- Producer: converts light energy into chemical energy. The chemical energy takes the form of organic molecules including: carbohydrates, proteins and lipids. These molecules, which are called food, are composed of:
C-H
C-O
C-C
O-H
C-N
bonds.
- These bonds all represent energy
- Carbon, Hydrogen, Nitrogen and Oxygen 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 fixed from sunlight, now in the form of chemical energy.
- The impala consumes this for: respiration, growth and life processes
- When the leopard eats the impala, these molecules are passed on and re-organized into leopard form, and so on...

Substances/Matter and the energy which is in the bonds between the elements are passed from each stage in the food chain.

4.5(a&b) Food Chains and Food Webs

4.5a Food Chains 



Food Chains link together:
Producer ----> Primary Consumer ------> Secondary Consumer -----> Tertiary Consumer

• Only one organism per trophic level
• You cannot show an organism being an omnivore / cannot show organisms feeding at more than 2 trophic levels
• Food Chains show the flow of matter and flow of energy

4.5b Food Webs




The food web allows us to provide a better description of the ecosystem (ecosystems are community of organisms interacting) In this case interacting = feeding

Feeding at different trophic levels:
consequences
- organisms can have multiple predators
- may be feeding on multiple pray
- resulting to the food chains becoming linked.

4.4 Trophic Levels

- Tropic = feed
- In the example:

• the carrot plant is doing the photosynthesis - - - - - in ecology terms - - - - - Producer (light energy and turning it into chemical energy)
• the carrot fly is eating the plant = herbivore - - - - - in ecology terms - - - - - Primary Consumer (chemical energy of the plant into chemical energy of the fly - change in the form of the chemical energy)
• the flycatcher eats the fly = carnivore - - - - - in ecology terms - - - - - Secondary Consumer (again, changing the chemical energy from one form to another)
• another carnivore eating another carnivore = top carnivore. - - - - - in ecology terms - - - - - Tertiary Consumer (Chemical energy from one form to another)

At some stage, they all die.

At this point, decomposers break the complex molecules down into nitrates and phosphates. 

fungi and bacteria are an example of decomposers.

4.3 Quadrates Samples

For this example, the habitat is sandunes:
The sample has to be:
- Random - so it is not biased
- Representative - have to take a sample large enough that the estimated population is as close to the true population as possible.

How to do this:
1) Set up a grid system across the field which will work like the x, y co-ordinates of a graph. The grid has to be equal sizes.
2) Place the quadrates into the squares. Using random numbers. (The random number generates a number for the x co-ordinate and the y co-ordinate
3) Count the number of daises in that square

Representative Sample
- the bigger the better.
- Around 10 quadrates / 10% actual area
- Draw a table with two columns consisting of Quadrate and Number of Daises
- Add up the column: number of daises
- Divide by the number of quadrates
= this will give us the number of daises per m-squared

Using this technique we can estimate the population of daises in the field and also use this technique to compare the number of daises in two or more different areas.

4.2 Quadrates

Sand-dune Ecosystem - it is made up of a number of populations which form the community and the habitat

The fence line running in the middle splits the sand-dune area into: GRAZED and UN-GRAZED by cattle. Therefore, there are two different areas within an ecosystem.

How to study the populations in the different sides: Count the number of individuals in the population.

Quadrating - when you separate land into squares using metal, wood and string (From 0.25m x 0.25m up to 1m x 1m)

It is used to sample the area and count the number of individuals inside the grid. This will be repeated a number of times = Estimate of the population size

"Quadates are a method of sampling different locations so that populations can be compared in the two different locations"

4.1 Ecosystems

Ecosystem: 

Community of organisms:

It is made up of population of difference species and they are interacting.

Population: Number of individuals of a particular species

Species: Organisms that reproduce to give fertile offspring

Habitat (Abiotic - non biological factors):
1. Daylight / Dark
2. Temperature
3. Rainfall
4. Humidity
5. Slope of the land

All of these factors are non biological factors.


- the common interaction is feeding


"A ecosystem is a community of organisms in a particular habitat. Community is made up of different populations of the different species interacting within that habitat"