Populations, ecosystems, evolution

Question 1

What is a population?

Answer 1

A group of organisms of the same species occupying a particular space at a particular time

Question 2

What is a gene pool?

Answer 2

Total number of alleles that are present in a population

Question 3

What is the Hardy Weinberg equation used for?

Answer 3

estimate the frequency of allles in a population

Question 4

What is assumed when using the Hardy-weinberg principle?

Answer 4

-No mutations occur
-No migration
-Population is large
-No selection pressures
-Mating is random

Question 5

What are the 3 reasons for variation in alleles or genes?

Answer 5

-Random fertilistaion
-Meiosis
-Mutation

could also be environmental influences

Question 6

What is a niche?

Answer 6

Species specific role within the environment, how it fits into the ecosystem

Question 7

What happens to species within the same niche?

Answer 7

Compete with each other, natural selection

Question 8

What are Abiotic factors?

Answer 8

Non-living aspects of an ecosystem e.g. temp, light intensity, moisture, soil pH, O2 levels

Question 9

What is an adaptation?

Answer 9

Feature of an organism that increases its chance of survival.

Question 10

What is Allopatric speciation?

Answer 10

When two populations become geographically isolated

Question 11

Define biodiversity

Answer 11

The variety of genes, species, and habitats within a particular area

Question 12

What are biotic factors?

Answer 12

The living components of an ecosystem e.g. pathogens, predators

Question 13

What is the ‘carrying capacity’?

Answer 13

The average size of a population that can be supported by an ecosystem over extended periods of time.

Anything above this is not sustainable

Question 14

What is the chi-squared test?

Answer 14

Stats test used to determine whether a pattern of inheritence is statistically significant

Question 15

What is a climax community?

Answer 15

The stable community of organisms that exists at the final stage of ecological succession

Question 16

What is a community?

Answer 16

All of the populations of different species living together in a habitat

Question 17

What is conservation?

Answer 17

Maintenance of ecosystems and biodiversity by humans in order to preserve the Earth’s resources

Question 18

What is directional selection?

Answer 18

Favours an extreme phenotype and selects against all other phenotypes

-Change in the environment
-e.g. resistant bacteria

Question 19

What is disruptive selection?

Answer 19

Favours both individuals with extreme phenotypes and selects against phenotypes close to the
mean

e.g. large animals survive due to increased body fat, and small animals also survivre as they dont need as much food

Question 20

What is an ecosystem?

Answer 20

Community of living and non-living components of an area and their interactions.

Question 21

What is evolution?

Answer 21

Gradual change in allele frequencies within a population over time

Question 22

What is genetic drift?

Answer 22

Change in the frequency of an existing allele in a population

-due to genetic bottleneck or founder effect

Question 23

What is genetic variation?

Answer 23

Differences in genotypes between members of a population which may occur due to meiosis, mitosis, or random fertilisation

Question 24

What is a habitat?

Answer 24

The region where an organism normally lives

Question 25

What is Interspecific competition?

Answer 25

Takes place between members of different species

Question 26

What is Intraspecific competition?

Answer 26

Takes place between members of the same species

Question 27

What is 'Mark-release-recapture'?

Answer 27

Method of estimating the population size of motile organisms. Involves capturing a sample, marking them, then releasing them. At a later date, another sample is captured

Question 28

What is a pioneer species?

Answer 28

Species that can survive in hostile environments and colonise bare rock or sand, e.g. lichens

Question 29

Define predator

Answer 29

An organism that eats other organisms

Question 30

Define prey

Answer 30

An organism that is eaten by predators

Question 31

What are selection pressures

Answer 31

Environmental factors that drive evolution by natural selection and limit population sizes e.g. competition

Question 32

Define Speciation

Answer 32

The formation of a new species due to population being separated and cannot interbreed 2 forms: allopatric sympatric

Question 33

What is a species?

Answer 33

A group of similar organisms that are able to breed with one another to produce fertile offspring

Question 34

What is stabilising selection?

Answer 34

A type of selection that favours individuals with phenotypes close to the mean, and selects against extreme phenotypes. -successful characteristics are preserved, does not occur due to a change in environment

Question 35

What is succession?

Answer 35

Describes changes in the community of organisms occupying a certain area over time.

Question 36

What is sympatric speciation?

Answer 36

Occurs when two populations within the same area become reproductively isolated.

Question 37

What is variation?

Answer 37

The differences between individuals due to genes, the environment, or a combination of both.

Question 38

What happens if organisms have an unsustainably large number of offspring?

Answer 38

They cannot all survive due to limited resources, so have to compete, natural selection

Question 39

Briefly summarise the process of evolution via natural selection

Answer 39

-Variety of phenotypes within a population -Environmental change occurs, selection pressures change -Some have advantageous alleles so a selective advantage, allow them to survive and reproduce -Advantageous alleles are passed onto offspring -Frequency of alleles in a population changes

Question 40

What is selection?

Answer 40

Process by which individuals who are better adapted to their environment are more likely to survive and breed.

Question 41

What is Predation?

Answer 41

When the prey is caught and eaten by the predator , the 'predator-prey relationship'

Question 42

What is primary succession?

Answer 42

When an area previously devoid of life is colonised by communities of organisms, for example the eruption of a volcano which would lead to the formation of a rock surface

Question 43

Explain the process of succession

Answer 43

-The area is first colonised by pioneer species such as lichens, on bare rock. -As organisms die, they are decomposed by microorganisms, which turns into soil, where more organisms can grow. -Over time the soil becomes more rich in minerals, so larger plants and shrubs survive. -Eventually, a climax community is established, a self-sustaining and stable community of organisms.

Question 44

What is secondary succession?

Answer 44

When a previously colonised area in which an existing community has been cleared e.g a forest fire, and a soil layer is already present