topic 4a: organism in the environment

What is ecology?

Ecology is the branch of biology that studies relationships between living organisms and their environment.

Define ecosystem.

An ecosystem is all of the biotic organisms in an area and all the abiotic conditions.

What is a habitat?

A habitat is the place where an organism lives.

How is a population defined in ecology?

A population is all the organisms of one species in a habitat.

What constitutes a community in ecological terms?

A community is all the different species in a habitat.

What are biotic factors?

Biotic factors are the living components that affect population sizes and distribution.

List some examples of abiotic factors.

Sunlight, temperature, pH, water, minerals, soil type, salinity, and wind

Why might investigating population sizes be challenging for ecologists?

Due to the complexity of ecosystems and the need for accurate data.

What method do scientists commonly use to estimate population sizes?

Scientists use sampling techniques, such as quadrats, to estimate population sizes more quickly.

What is a quadrat?

A quadrat is a square metal frame, usually one meter in length, used by ecologists to take samples.

What is biodiversity?

Biodiversity is a measure of the variety of different species in an ecosystem

Quadrat practical 1: Compare the population of daisies in two areas of the school playing fields.

1. Mark out a 10 meter by 10 meter area using large tape measures in both locations A and B.

2. Use the random number generator function on your calculator to choose coordinates along the tape measures.

3. Place the bottom left corner of your quadrat and that point.

4. Count the number of daisies in the quadrat and record it in the table.

5. Repeat steps 2-4 for at least 9 further readings

6. Calculate the mean number of daisies per quadrat for each area.

7. Multiply mean number by the no. quadrats that could be placed in the field

Practical to investigate biodiversity and measuring distribution (Measure how the distribution of organisms changes across a woodland path)

• Lay your transect across the path

• Place a quadrat every meter next to the transect

• You could look at one species and see how it changes across the transect (or you could look at the number of different species in each quadrat to measure how biodiversiy changes)

• If you are counting grass or something similar then it’s easier to look at the percentage of the quadrat covered by the grass rather than count individual organisms

• For each quadrat you should also take some abiotic data e.g. light intensity, temperature, soil pH