7 - Inheritance & Ecology

Question 1

What’s a population

Answer 1

A group of organisms of the same species, living in the same habitat at the same time

Question 2

What’s a community

Answer 2

All the populations of different species living in the same habitat at the same time

Question 3

What’s an ecosystem

Answer 3

A community, plus all the non living (abiotic) conditions of their environment.

Question 4

What are abiotic conditions

Answer 4

Non-living
Eg temperature and pH

Question 5

What are Biotic conditions

Answer 5

Living features
Eg inter/intraspecific competition, predation, food supply, disease

Question 6

Describe and explain how succession works (5m)

Answer 6

• colonisation by pioneer species
• pioneer species change the environment eg forms soil
• environment becomes more suitable for new species
• increase in biodiversity
• to climax community

Question 7

How could you do sampling

Answer 7

• use a grid
• get random coordinates using a random number generator
• count number in quadrat
• large sample and calculate average number per quadrat
• calculate the total number (mean number x no. Of quadrats)

Question 8

Give two features of a climax community

Answer 8

• same species present over long time
• abiotic factors constant over time

Question 9

What are 3 actions to achieve balance between conservation and breeding

Answer 9

• provide less food to the species so their populations don’t grow large enough to cause competition
• do not breed similar animals as they share the same habitat and food so will compete
• keep the species in separate areas as they occupy the same habitat

Question 10

Describe the mark release re capture method

Answer 10

• capture the sample, mark and release
• leave time for species to disperse before second sample
• population = (no. in first sample x no. in second sample) /no. recaptured (in 2nd sample)

Question 11

Describe the equation for calculating population in the mark release recapture method

Answer 11

(Total No. in first sample x total no. In second sample) divided by no. Marked in 2nd sample

Repeated at least 10 times

Question 12

What is interspecific competition

Answer 12

• biotic factor
• competition between different species
• for limited resources eg food

Question 13

What is intraspecific competition

Answer 13

• biotic factor
• competition between the same species
• for resources & a mate to reproduce

Question 14

What is predation

Answer 14

Interaction between predators and prey

Question 15

How does conservation effect succession

Answer 15

• climax community is prevented
• so wider variety of habitats
• so higher species diversity

Question 16

What are the assumptions made in proportional sampling

Answer 16

• they know the size of the area where a population lives
• the organisms are evenly distributed

Question 17

What are the assumptions made in mark release recapture

Answer 17

• there’s enough time for organisms to distribute themselves
• no migration
• no births or deaths

Question 18

What is an autosome

Answer 18

Any chromosome that isn’t a sex chromosome

Question 19

What’s the typical ratio for dihybrid crosses when crossing over occurs

Answer 19

9:3:3:1

Question 20

What’s the typical ratio for dihybrid crosses when crossing over does not occur

Answer 20

3:1

Question 21

In genetic crosses why are observed phenotypes not the same as expected ratios

Answer 21

• small sample size
• fertilisation of gametes is random

Question 22

What’s the hardy Weinberg equation

Answer 22

P^2 + 2pq + q^2 = 1
p+ q = 1

Question 23

What does each letter stand for in the hardy Weinberg equation

Answer 23

p = frequency of dominant allele
q = frequency of recessive allele
P2 = frequency of homozygous dominant genotype
2pq = frequency of heterozygous genotype
q2 = frequency of homozygous recessive genotype

Question 24

What is a homologous pair of chromosomes

Answer 24

Two chromosomes that carry the same genes

Question 25

Describe Allopatric speciation

Answer 25

• geographical isolation eg mountains or rivers
• Separate gene pools, no interbreeding
• Mutations create genetic variation in each population
• Different selection pressures act on each population
• Leading to natural selection of different favourable alleles
• Different survival and reproductive success
• Leads to change of frequencies over many years
• Members of different populations cannot interbreed
• New species arise from existing species

Question 26

Describe directional selection eg antibiotic resistance

Answer 26

• Selection pressure act on one side of the mean
• one extreme phenotype more likely to survive and produce organisms with the gene for resistance
• mean Phenotype changes

Question 27

Describe stabilising selection, e.g. human birthweights

Answer 27

• stable environment
• Selection and pressure act either side of the mean
• Both extremes of phenotype less likely to survive and produce eg very small or very large
• mean Phenotype remains the same

Question 28

Describe disruptive selection

Answer 28

• Selection against the mean
• both extremes of phenotypes are favoured
• Could result in two separate species

Question 29

What is speciation?

Answer 29

The development of a new species from an existing species when population can cannot interbreed

Question 30

Describe Sympatric speciation

Answer 30

• Population in the same area
• Individuals reproductively isolated due to different mating seasons or different courtship behaviour
• different selection pressures
• Lead to change of allele frequencies within gene pools
• Members of different populations cannot interbreed
• New species arise from existing species

Question 31

What is a niche

Answer 31

The role of a species within a habitat eg where it eats or what it eats