Populations in Ecosystems

Define population (1)

Group of organisms of the same species living in the same area at the same time that can interbreed together make fertile offspring

Define specie

A group of similar organisms that can reproduce to give fertile offspring

Define gene pool

Collection of genes within an interbreeding population at a particular time

Define allele frequency

How often different alleles occur in the gene pool of a population

Define phenotype (1)

An organisms observable characteristics

How can phenotype variation arise (3)

1. Genetic factors

2. Environmental factors

3. Both genetic and environmental factors

Which factors cause genetic variation (4)

1. Mutations

2. Crossing over

3. Independent segregation

4. Random fertilisation

Explain how independent segregation causes genetic variation (2)

1. Radom alignment of chromosomes result in different combinations of chromosomes

2. And different allele combinations in each gamete

Explain how crossing over causes genetic variation (1)

Exchange of genetic material between non-sister chromatids leads to new combinations of alleles on chromosomes

Explain how random fertilisation causes genetic variation (1)

Any male gamete can fuse with any female gamete

Define evolution (2)

1. The formation of new species from pre-existing species over time,

2. as a result of changes to gene pools and allele frequencies from generation to generation

Explain how mutation can cause genetic variation (1)

Random changes in the DNA base sequence results in generation of new allele

Define habitat (1)

Part of an ecosystem where a particular organism lives

Define community (1)

All the populations of different species in the same area at the same time

Define ecosystem

A community and non living components of the environment

Define niche

Organisms role within an organism

Define carrying capacity

The maximum population size an ecosystem can support

Define Abiotic factors

Non-living conditions of an ecosystem

Define biotic factors

Impact of interactions between organisms

Name some biotic factors

1. Competition for food

2. Competition for mates

Name abiotic factors

1. Temperature

2. Oxygen and CO2 concentration

3. Light intensity

4. pH

5. Soil conditions

name the two types of competitions (2)

1. Interspecific competition

2. Intraspecific competition

Define inter specific competition

When members of different species are in competition for the same resources that are in limited supply

Define intraspecific competition

When members of the same species are in competition for resources and a mate

Explain the predation cycle

1. Prey numbers rise

2. Predators number rise

3. Prey numbers fall

4. Predator number falls

5. Prey number rises again

What sampling techniques would we use for slow moving / still organisms ? (2)

1. Sample using a quadrant

2. Transects

What type of sampling method will we use for motile organisms (1)

Sample using the mark-release-recapture method

Describe how to do quadrat sampling (3)

1. Lie two tape measures at a right angle to create a gridded area

2. Use a random number generator to generate 2 co ords

3. Place quadrat to collect data

4. Repeat at least 30 times and calculate a mean

Describe how to use the line transect method (4)

1. Place tape measure at a right angle to the shore line

2. Place quadrat at every 5 metres

3. Collect data

4. Repeat by placing another 30 transects along at right angles

Describe the mark-release-recapture method (6)

1. Initial sample of the population is captured

2. Individuals are marked, then released back into the wild, and a number caught is recorded

3. These marked individuals are released and are left for a period of time to allow them to randomly dispersed

4. A second sample is captured

5. The total number captured in second sample and number recaptured with the marking is recorded

6. Size of population is estimated

what is the formula for estimating total population (2)

(Number of organisms initially caught X number of organisms initially second sample) / number of marked organisms recaptured

What considerations must you take when marking organisms (3)

1. Not toxic

2. Not increase chances of predation

3. Not reduce chances of reproduction

State reasons why the estimate may not be accurate (2)

1. Assumes that the Population size is constant

2. Assumes that animals always redistribute evenly

Describe primary succession (5)

1. Initially colonised by pioneer species

2. Pioneer species change the environment

3. The environment becomes less hostile for new species

4. Increase in biodiversity

5. Climax community

What is succession (1)

Natural process where ecosystems change over time , often leading to a climax community

What are some human activities that may interrupt succession and how (4)

1. Mowing -

2. preventing shrubs and trees from establishing

3. Grazing -

4. Livestock eat new shoots, halting succession

Define what conservation is (1)

Halting succession to protect species diversity

What are some sustainable methods to prevent succession (2)

1. Grazing

2. Managed burning

What is conservatism (1)

Involves managing species and habitats sustainably, meeting present needs without compromising the future

Name and explain the 6 methods of conservatism (12)

1. National and marine parks

2. Protect habitats with legal restrictions on access, development and hunting

3. Public engagement

4. Generates income through tourism, providing more jobs

5. Captive breeding

6. Helps restore species populations and supports research

7. Botanic gardens

8. Conserves rare plants using lab techniques and enables reintroductions

9. frozen zoos

10. Preserves genetic material for future reintroduction, reduces pressure on wild populations

11. Seed banks

12. Stores plant diversity safely, allowing future crop reservation