Unit 7 - Genetics, populations, evolution and ecosystems

Question 1

species

Answer 1

Group of similar organisms that breed and produce fertile offspring

Question 2

population

Answer 2

All the organisms of the same species in a habitat that can interbreed

Question 3

community

Answer 3

Populations of different species in a habitat

Question 4

ecosystem

Answer 4

All organisms in a community interacting with biotic and abiotic factors

Question 5

habitat

Answer 5

place where an organism lives in an ecosystem

Question 6

niche

Answer 6

How the organism fits into the environment – where it lives/what it does

Question 7

abiotic

Answer 7

Non-living factors that affect organisms so affect communities

Question 8

biotic

Answer 8

Living factors that affect organisms so affect communities

Question 9

Interspecific competition

Answer 9

Different species competing for the same resources

Question 10

Intraspecific competition

Answer 10

same species competing for the same resources.

Question 11

Carrying capacity

Answer 11

An ecosystem supports a certain size of a population

Question 12

competitive exclusion principle

Answer 12

Organisms cannot share the same ecological niche

Question 13

gene

Answer 13

sequence of DNA bases that code for a polypeptide

Question 14

genome

Answer 14

all of the genes in an organism/ cell

Question 15

proteome

Answer 15

all the proteins that can be expressed by a cell/ organism

Question 16

allele

Answer 16

different versions of the same gene

Question 17

locus

Answer 17

specific position on the chromosome where the allele of the gene is found

Question 18

homozygous alleles

Answer 18

two copies of the same allele

Question 19

heterozygous alleles

Answer 19

two different alleles for a gene

Question 20

genotype

Answer 20

genetic constitution of an organism

Question 21

phenotype

Answer 21

the expression of the genetic constitution and its interaction with the environment

Question 22

codominant alleles

Answer 22

both alleles are expressed in the phenotype, neither allele is recessive

Question 23

What is the Hardy-Weinberg principle?

Answer 23

the frequency of alleles in a population remain constant over time

Question 24

What are the 5 conditions that need to be met for the Hardy-Weinberg principle?

Answer 24

• no mutations
• no migration
• no selection
• mating is random
• large population

Question 25

What are the two equations for the Hardy-Weinberg principle?

Answer 25

p+q=1 p2+2pq+q2=1

Question 26

What does p represent in the Hardy-Weinberg equation?

Answer 26

frequency of dominant allele

Question 27

What does q represent in the Hardy-Weinberg equation?

Answer 27

frequency of recessive allele

Question 28

What does p2 represent in the Hardy-Weinberg equation?

Answer 28

frequency of the homozygous dominant genotype

Question 29

What does 2pq represent in the Hardy-Weinberg equation?

Answer 29

frequency of the heterozygous genotype

Question 30

What does q2 represent in the Hardy-Weinberg equation?

Answer 30

frequency of the homozygous recessive genotype

Question 31

What is a sex-linked gene?

Answer 31

a gene which occurs on one of the sex chromosomes

Question 32

Epistasis defintion

Answer 32

one gene influences the expression of another gene

Question 33

What is autosomal linkage?

Answer 33

when two genes are found on the same chromosome

Question 34

What causes intraspecific variation?

Answer 34

mutations, independent segregation, crossing over, random fertilisation

Question 35

Species definition

Answer 35

a group organisms capable of interbreeding to produce fertile offspring

Question 36

Speciation definition

Answer 36

the process by which two new species are formed from one original species

Question 37

What are the three types of selection?

Answer 37

directional, stabilising, disruptive

Question 38

What is directional selection?

Answer 38

one of the extreme phenotypes has the selective advantage

Question 39

What is stabilising selection?

Answer 39

the modal phenotype has the selective advantage

Question 40

What is disruptive selection?

Answer 40

the two extremes of a phenotype have the selective advantage

Question 41

What are two types of speciation?

Answer 41

allopatric and sympatric

Question 42

What is allopatric speciation?

Answer 42

populations of the same species are geographically isolated and differences in gene pools develop leading to reproductive isolation

Question 43

What is sympatric speciation?

Answer 43

random mutations within a population prevent individuals that carry the mutation from breeding with other members of the population that don’t carry the mutation

Question 44

What are the two main processes of evolution?

Answer 44

natural selection and genetic drift

Question 45

What is evolution by genetic drift?

Answer 45

it is down to chance which alleles survive and are passed to the next generation

Question 46

Gene pool

Answer 46

the complete range of alleles present in a population

Question 47

Succession

Answer 47

the process by which an ecosystem changes over time. The biotic conditions change as the abiotic conditions change.

Question 48

What happens at each stage of succession?

Answer 48

new species colonises the area which may change the environment and make it less hostile

Question 49

Primary succession

Answer 49

Takes place in an area which is empty of life (no soil present)

Question 50

Secondary succession

Answer 50

Occurs in area where life once existed but has been destroyed (soil is already present)

Question 51

What is stage one of succession?

Answer 51

pioneer species - asexually reproduce moss and lichen grow

Question 52

What is stage two of succession?

Answer 52

Larger plants grow once soil is established

Question 53

What is stage three of succession?

Answer 53

Fast growing colonisers outcompete the grasses

Question 54

What is stage four of succession?

Answer 54

a climax community is reached

Question 55

give 3 features of a climax community

Answer 55

- same species present over long time - abiotic factors constant - populations stable