Populations In An Ecosystem

Front 1

Ecosystem

Back 1

All the organisms living in a community plus all the non living (abiotic) conditions in the area in which they live

Front 2

Community

Back 2

A group of interacting populations of different species living in the same place at the same time.

Front 3

Population

Back 3

A group of organisms belonging to the same species found in the same area at the same time and potentially able to interbreed.

Front 4

Habitat

Back 4

The environment of which an organism or population of organisms usually lives.

Front 5

Abiotic

Back 5

The non living features of an ecosystem such as the temperature and the soil.

Front 6

Biotic

Back 6

The living features of an ecosystem for example the presence of predators or food

Front 7

Niche

Back 7

The role of a species within a habitat, for example what it eats when and where it feeds.

Front 8

What happens if two species try to occupy the same Niche? What is this known as?

Back 8

A niche can only be occupied by one species. If they tried, they will be in competition. With one another. One will eventually be more successful until only one is left.

Competitive conclusion

Front 9

What is an Adaption?

Back 9

A feature that members of a species have that increases their chance of survival and reproduction.

Front 10

What is Natural selection?

Back 10

Organisms with better adaptations are more likely to survive, reproduce and pass on advantages alleles. increases frequency of these alkenes in the population so adaptations become more common.

Front 11

What is Population size?

Back 11

Total numbers of organisms of one species in a habitat

Front 12

What is Carrying capacity?

Back 12

The maximum population size that can remain sustainable in an ecosystem

Front 13

How do abiotic factors affect population size? Give examples

Back 13

Ideal= faster growth and reproduction

Eg. Plant in higher temperatures ( less energy maintaining temp)

Not ideal= slower growth and reproduction. Population size sometimes decreases.

Eg. Mammals in cold conditions (more energy maintaining temp)

Front 14

What is Interspecific Competition? And how does it link to the Competitive exclusion principle?

Back 14

Competition between different species.

For same resources.

Reduces pop size as less food.

One will have competitive advantage,

So one will increase and other decrease

Which is CEP.

Front 15

What is Intraspecific Competition?

Back 15

Competition between members of the same species.

Fluctuation in pop size.

Cycle: large pop, red food availability, smaller pop. Now more food available, pop starts to increase. Cycle repeats.

Front 16

How does predation affect population size?

Back 16

Pop size of predators and prey is interlinked. As one changes=change in other.

It creates a Selection pressure meaning members of species better adapted at evading predators more likely survive and reproduce .

Each new species better adapted for survival.

Front 17

Investigating bacteria population. What does low absorbance of light mean?

Back 17

There aren't many bacteria present.

High absorbancd of light shows lots of bacteria present.

Front 18

How many ways can you measure abundance of a population?

Back 18

Frequency and Percentage cover

Front 19

What is abundance?

Back 19

Number of individuals of one species in a particular area.

Frequency - number of samples recorded

% cover- how much area is covered by species

Front 20

What is distribution?

Back 20

How a species is spread across a habitat.

Clumped - favour specific areas

Even

Random

Front 21

How to carry out random sampling?

Back 21

1. Choose an area

2. Split into grid. Random coordinate generator

3. take as many samples as possible (MIN 15)

4. Carry out statistical tests

Front 22

Why randomly sample?

Back 22

Prevent any bias, the larger the more reliable

Front 23

What methods can you use to investigate population sizes?

Back 23

Quadrat

Transect

Front 24

What is a quadrat?

Back 24

A square frame divided into smaller squares.

It's placed at random in the investigated area.

Front 25

What is Species Frequency?

Back 25

The likelihood of a particular species occuring withing the quadrat.

Eg 15/30 squares. Frequency is 50%

Front 26

What is percentage cover?

Back 26

Count number of squares that's covered by species. (More than half covered is one square) calculate percentage.

Front 27

What are transects?

Back 27

Lines through study area. Samples taken along it.

Useful if change in abiotic factors across area (eg shade to light). Shows DISTRIBUTION

Front 28

Two types of transects

Back 28

Belt transects and interrupted belt transects

Front 29

What is a belt transect?

Back 29

Quadrats next to each other in a line.

Front 30

What is interrupted belt transect?

Back 30

Quadrats at regular intervals

Front 31

What is the mark release recapture method?

Back 31

Harmless marking after capture. Released to environment. Allow mixing with population. Recapture and count how many marked.

Front 32

What is mark release recapture equation?

Back 32

Total pop size = No. 1st sample X no. 2nd sample

DIVIDED BY

No. marked in 2nd sample

Front 33

Comment on the accuracy of the mark release recapture method.

Back 33

Depends on a few assumptions:

Marked sample has time to mix with non marked

Marking doesn't affect survival

Mark is still visible

No change in population size die to births deaths or migration

Stress can lead to reduction in survival.