Ecology

Question 1

What is a population?

Answer 1

A group of individuals of the same species

Question 2

What is a community?

Answer 2

All of the organisms within an ecosystem

Question 3

What is a habitat?

Answer 3

Where an individual species lives. Each has specific physical characteristics.

Question 4

What is an ecosystem?

Answer 4

The interaction of all of the organisms within an area and the environment around them. Including biotic and abiotic factors.

Question 5

Give examples of biotic factors

Answer 5

They affect the population sizes of organisms and their distribution.
- predation of animals and grazing of plants
- competition for limited resources, such as food and shelter or light and water

Question 6

Give examples of abiotic factors

Answer 6

They affect the population size and distribution of organisms.
- light is needed by plant to photosynthesise and grow
- temperature affects organisms as extreme temperatures will kill them by stopping their enzymes from working, however some are adapted to live in extreme conditions
- water is needed by all living things, so lack of water will limit pop size of organisms or determine which will survive.

Question 7

Investigate the population size of an organism using quadrats

Answer 7

1. Measure a square with side of 10m by placing a tape measure on the ground and use a random number generator to provide co-ordinates,to make the results representative of the whole sample area
2. Place the quadrat on the ground
3. Count all organisms you are interested in
4. Repeat many times and calculate a mean for the area
5. Repeat this whole process again in a second sample area and compare the two means

Question 8

How do you estimate population size from a small sample area?

Answer 8

1. Calculate mean number of organisms per m^2
2. Multiply by the total area (in m^2) of the sample area

Question 9

What is biodiversity?

Answer 9

The variety of different species of organisms on Earth or within an ecosystem

Question 10

Investigate the distribution of organisms in their habitats

Answer 10

1. Mark out a line in the area of study
2. Collect data along the line by using quadrats placed next to each other (or at intervals) and count all of the organisms of interest
3. You could record other data such as mean height of the plants
4. Repeat several times and find the mean number of organisms or mean percentage cover for each quadrat
5. Could then plot a graph

Question 11

What are the trophic levels?

Answer 11

Tertiary consumers eat secondary consumers, who eat primary consumers, who eat producers
Decomposers break down (decompose) dead material and waste.

Question 12

Describe how energy is transferred along a food chain

Answer 12

1. Energy from the Sun is the source of energy for nearly all life on Earth
2. Plants use the energy from the Sun during photosynthesis, which then transfers through the food chain as animals and plants eat each other
3. Most of the material and energy available to each trophic level is lost

Question 13

Why is only 10% of energy transferred from one trophic level to the next?

Answer 13

Some parts of the food, e.g. roots or bones aren’t eaten by the organisms so the energy isn’t taken in. Some parts of the food is indigestible so pass through organisms and come out of waste.
A lot of the energy taken in is used for respiration, powering all life processes. Most of the energy is transferred to the surrounding by heat, so only 10% of the total energy available becomes biomass.