Patterns Of Inheritance And Variation

Question 1

what are the two types of variation

Answer 1

genotype
phenotype

Question 2

what is genotype and what is it caused by

Answer 2

it is the genetic makeup of an organism caused by GENETIC factors

Question 3

what is a phenotype and what is it caused by

Answer 3

it is the expression of a genotype caused by GENETIC AND ENVIRONMENTAL factors

Question 4

what are the sources of genetic factors

Answer 4

• mutations
• crossing over during meiosis
• independent assortment during meiosis
• random fusion of gametes at fertilisation

Question 5

what are the sources of environmental factors

Answer 5

• diet
• etiolation in plants (chlorosis)
  this occurs due to lack of light, mineral deficiencies and virus infections

Question 6

what are the two types of reproduction

Answer 6

1. asexual
   produces genetically identical offspring
2. sexual
   random fusion of gametes producing genetic variation in offspring produced by meiosis

Question 7

continuous variation

Answer 7

polygenic
environmental and genetic
normal distribution
larger standard deviation, more variation

Question 8

discontinuous variation

Answer 8

genetic
bar chart

Question 9

what is a gene

Answer 9

the base sequence of DNA which codes for the amino acid sequence of an polypeptide

Question 10

what is an allele

Answer 10

different versions of the same gene

Question 11

recessuve allele

Answer 11

allele which requires 2 copies to be expressed

Question 12

dominant allele

Answer 12

allele which is expressed when there is one copy

Question 13

homozygous

Answer 13

2 identical alleles

Question 14

hetrozygous

Answer 14

2 different alleles where the dominant allele is always expressed

Question 15

what is monogenic inheritance

Answer 15

inheritance of a characteristic coded for by one gene
#f1 gen

Question 16

codominance

Answer 16

this is when both alleles are expressed in the phenotype if they are inherited tgether

Question 17

what is multiple alleles

Answer 17

when there are more than two alleles for the same gene

Question 18

female chromosomes
male chromosomes

Answer 18

xx
xy

Question 19

how many alleles does a female need to express a RECESSSIVE characteristic

Answer 19

2 recessive alleles on each X chromosome

Question 20

how many alleles does a male need to express a RECESSSIVE characteristic

Answer 20

1 recessive allele on one x chromsome

Question 21

if women only have one recessive allele are they a carrier or do they have the disease

Answer 21

carrier

Question 22

what is dihybrid inheritance

Answer 22

this is inheritance of 2 characteristics which is controlled by 2 different genes

Question 23

how to work out dihybrid inheritance

Answer 23

FOIL if 4 different alleles are present
punnet square

Question 24

what is haemophilia

Answer 24

blood which clots extremely slowly due to the absence of the protein blood clotting factor

Question 25

what makes a gene linked

Answer 25

when the loci of two different genes are on the same chromosome, they are likely to be inherited together

Question 26

what way will genes not be inherited together

Answer 26

if crossing over separates them during meiosis

Question 27

what is autosomal linkage

Answer 27

it is if two genes are on the same pair of homologous chromosomes they are kinked, alleles on the same chromosome are more likely to be inherited together. they go on tp the same daughter cell and is only separated if crossing over takes place

Question 28

what is epistasis

Answer 28

this is the interactions of genes at different loci, alleles of one gene masks the expression of alleles of another gene

Question 29

what is the chi squared test

Answer 29

shows if there is a significant difference between the observed phenotypic ratio and expected phenotypic ratio

Question 30

what iss evolution

Answer 30

it is the change in allele frequency which is affected by natural selection

Question 31

what are the factors which affect evolution

Answer 31

1. muations 2. gene flow 3. genetic drift 4. natural selection 5. sexual selection

Question 32

what is gene flow

Answer 32

the movement of alleles between populations

Question 33

what is the gene pool

Answer 33

describes all the alleles in a population

Question 34

higher genetic diversity ...... gene pool

Answer 34

larger

Question 35

what is population genetics

Answer 35

it is the investigation of how allele frequencies within a population change over time

Question 36

what limits the size of a population

Answer 36

1. density independent factors dependent on population size 2. density dependent factors affect populations of all sizes in the same way

Question 37

what is the founder effect

Answer 37

this is when small groups split to form new populations ' organisms start a new colony' low number of different alleles and there is low genetic diversity leading to a higher rate of genetic disease

Question 38

what is the genetic bottleneck

Answer 38

this when a population has been reduced due to external factors it reduces the gene pool and the genetic diversity

Question 39

what are the 3 types of selection

Answer 39

1. directional 2. stabilising 3. disruptive

Question 40

directional selection

Answer 40

alleles for an extreme phenotype is most likely to be selected for triggered by the environment genetic variation occurs

Question 41

stabilising selection

Answer 41

this is when the alleles for an average phenotype is selected occurs when environmental factors remain stable

Question 50

disruptive selection

Answer 50

extremes are selected for norms are selected against results in sympatric speciation

Question 50

what is speciation

Answer 50

it is the formation of new species through the process of evolution

Question 50

what is the two types of speciation

Answer 50

1. allopatric 2.sympatric

Question 51

allopatric speciation

Answer 51

species is seperated due to geographical isolation variations occur due to random mutations different areas have different selection pressures they are reproductively isolated

Question 51

what is sympatric speciation

Answer 51

occurs in populations within the same habitat mutations result in reproductive isolation separate gene pools disruptive selection cannot interbreed

Question 51

what is reproductive isolation

Answer 51

when populations cannot interbreed succesfully

Question 52

hardy weinberg theory