Patterns of inheritance and Evolution

Question 1

what is interspecific variation

Answer 1

differences between different species

Question 2

what is intraspecific variation

Answer 2

differences between individuals of the same species

Question 3

what is continuous variation

Answer 3

• can be measured (quantitative)
• no categories
• controlled by genes/environment
• line graph

Question 4

what is discontinuous variation

Answer 4

• cannot be measured - qualitative
• categories
• controlled by genes only
• bar graph

Question 5

what are genetic factors that influence phenotypic variation

Answer 5

Polygenic
- controlled by many genes
Monogenic
- controlled by 1 gene

Question 6

what are the environment factors that influence phenotypic variation

Answer 6

• diet, climate, lifestyle, nutrients

Etiolation - plants grow abnormally due to lack of sunlight
Chlorosis - don’t produce enough chlorophyll due to lack of magnesium

Question 7

how can you create genetic variation

Answer 7

Crossing over
- chromatids twist around each other and swap alleles
- contain some genes but different alleles

Independent assortment
- chromosomes align on metaphase randomly
- one chromosome from each pair passes into a daughter cell

Random fertilisation
- any sperm can fertilise any egg

Question 8

what is sex linkage

Answer 8

• any gene that is carried on the X/Y chromosome
• recessive conditions on sex chromosomes are more likely to appear in men as there is no dominant allele on the X

Question 9

what are autosomal genes

Answer 9

• chromosome that is not a sex chromosome
• genes on the same chromosome are linked

Question 10

how are autosomal genes linked

Answer 10

• crossing over in meiosis prophase 1
• closer genes less likely they are separated
• independent assortment in meiosis 1
• genes on the same autosome are linked stay together during independent assortment

Question 11

what is epistasis

Answer 11

when one gene masks or supresses the expression of another

Question 12

example of epistasis

Answer 12

Humans
- widow’s peak controlled by one gene and baldness
- alleles that code for baldness it doesn’t matter if you don’t have the allele for Widow’s peak - already bald
- baldness gene masks the expression of the widow’s peak gene

Question 13

what is genetic bottleneck

Answer 13

• random reduction in population which changes gene pool
• original population
• large number of population die
• reduced population - some alleles lost from the original population
• reproduction
• new population - genetic diversity greatly reduced

Question 14

what is the founder effect

Answer 14

• small group leaves with varying genes
• migration

Question 15

what is the genetic drift

Answer 15

characteristics are passed on by chance rather than due to factors that affect the individuals ability to survive and reproduce

Question 16

what is speciation

Answer 16

• development of a new species
• occurs when population of the same species become reproductively isolated
• changes in alleles frequency leads to change in phenotype

Question 17

what is allopatric speciation

Answer 17

• geographic isolation
• separate gene pools and no interbreeding between the two populations
• variation due to mutations
• different abiotic/biotic factors
• selected organisms survive and reproduce
• leads to changes in allele frequency
• new species created
• cannot interbreed

Question 18

what is reproductive isolation

Answer 18

• changes in alleles and phenotypes of two populations to prevent them from breeding together successfully
• seasonal changes - flowering and mates
• mechanical changes - changes in genitalia prevent successful reproduction
• behavioural changes - different courtship

Question 19

what is sympatric speciation

Answer 19

• don’t have to be geographically isolated to become reproductively isolated
• occurs when members of two different species interbreed and from fertile offspring
• hybrid formed has different amounts of chromosomes
• can no longer interbreed
• stops gene flow
• random mutations

Question 20

what is artificial selection

Answer 20

• selectively breeding plants and animals for desirable characteristics
• humans select individuals with desirable characteristics

Question 21

dairy cow example of artificial selection

Answer 21

• female with high milk yield and male cow whose mother had a high milk yield
• breed them together
• select offspring with highest milk yield
• breed
• milk quality
• large udders
• calm temperature
• lactation period

Question 22

wheat example of artificial selection

Answer 22

• large ear plants bred with large ear plant
• offspring selected with large ears are breed
• process repeated over generations to produce very large ears
• tolerance to cold
• short stalks

Question 23

what are the problems with artificial selection

Answer 23

• health problems - traits may be exaggerated
• reduces genetic diversity / gene pool
• more susceptible to genetic disease

Pugs - small nasal passage and difficult to breathe