4. Ecology and environment

Question 1

what is ecology?

Answer 1

the study of ecosystems

Question 2

what is an ecosystem?

Answer 2

An ecosystem is an easily described system or area where organisms interact with their physical environment.

Question 3

what is a population?

Answer 3

the total number of individuals of one species in a particular habitat at a particular time

Question 4

what is a community?

Answer 4

populations of all the species present in an ecosystem at a particular time.

Question 5

what is a habitat?

Answer 5

the places where specific organisms live

Question 6

What are consumers?

Answer 6

organisms whish eat other living things (e.g. animals)

Question 7

what are decomposers?

Answer 7

organisms which secrete digestive enzymes to decay (breakdown) dead organic matter to obtain their food; they help to recycle nutrients

Question 8

what are producers?

Answer 8

organisms which make their own food (e.g. photosynthesising plants)

Question 9

what does abiotic mean?

Answer 9

Non-living factors which affect growth and survival of living things. e.g. temperature, carbon dioxide and oxygen concentrations, minerals in the soil

Question 10

Method: population size of a species in an area - 5 marker

Answer 10

• tape measure placed at right angles to
  form a grid
• random number generator
• co-ordinates e.g. 2,11
• place quadrat ( known area)
• count the number of species in the
  quadrat
• repeat x10 –> calculate the mean
• scale up to the size of field/area

Question 11

Method: Comparing biodiversity differences between field A and B

Answer 11

Field A
- tape measure placed at right angles to
form a grid
- random number generator
- co-ordinates e.g. 2,11
- place quadrat ( known area)
- count the number of species in the
quadrat
- repeat x10 –> calculate the mean

Calculate biodiversity using equation
Then repeat for Field B and compare

Question 12

Pyramids of number

Answer 12

these are drawn to show the number of
each organism counted in the ecosystem. They can be odd shapes due to the different masses of organisms.

Question 13

Pyramids of biomass

Answer 13

these are drawn to show the total mass of the organisms in each trophic level (i.e. the mass of an individual x the number of individuals). These are a more accurate way of looking at the relative amounts of organisms.

Question 14

pyramids of energy

Answer 14

these are drawn to show the total energy available in each trophic level per
square metre per year. There should be a decrease in energy between each trophic level.

Question 15

why is the least efficient transfer is from light energy to the producer?

Answer 15

• Some light will miss the plant or miss the plant’s chloroplasts.
• Some light will be reflected by the cuticle
• Some light has the wrong wavelength to be absorbed by chlorophyll

Question 16

Why is approximately 10% of energy is passed from one trophic level to the next?

Answer 16

• Some parts of the organisms are not eaten (so the biological molecules are not available for respiration)
• Some parts are not digested and absorbed - they are egested as faeces (so the biological molecules are not available for respiration)
• Some materials are respired to release energy - the energy is used for:
  ○ Muscle contraction - e.g. movement and breathing
  ○ Maintaining a constant body temperature (in mammals and birds)
  ○ Synthesising biological molecules (including excretory products)
  ○ Movement of molecules (active transport)
  ○ Cell division