WHOLE7.Autosomal Linkage And Epistatis

Question 1

With dihybrid cross and two heterozygous parents what is the ratio you will receive for the Phenotype?
What will affect this ratio?

Answer 1

Normal Ratio 9:3:3:1
Autosomal Linkage OR(and) Crossing over in meiosis will affect ratio

Question 2

What is the definition of autosomal linkage? And how does this affect Ratio?

Answer 2

Autosomal Linkage is two genes located on same chromosome (Not X or Y sex chromosome)
ALLELE FOR EACH GENE LINKED ON SAME CHROMOSOME will be inherited together

Question 3

What are Sex Linkage?

Answer 3

Sex Linkage is some characteristics coded for BY GENES only found on sex chromosome so are sex linked.

Question 4

What is unique to females about Sex Linkage?

Answer 4

Females have two copies of X-Chromosome so 2 copy of every X-Linked gene.
Unless you have two copies of recessive Allele wont be expressed.
THEY will always have DOMINANT ALLELE which will be expressed.

Question 5

Where and What is crossing over?

Answer 5

Crossing over is sections of chromatids break and exchange SISTER chromatids on HOMOLOGOUS CHROMOSOME occurs during prophase 1.

Question 6

What is Independent Segregation?
[3 STEPS]

Answer 6

Homologous chromosome line up a the equator randomly.
Chromosome Separate Randomly so GAMETES receive different combination of MATERNAL and PATERNAL CHROMOSOME

Question 7

Another way in which increases Genetic Variation?

Answer 7

Random Fertilisation of Gametes further increase genetic variation within species.

Question 8

Give 2 characteristics of Sex Linkage for Males.

Answer 8

Males only have one copy of X-Chromosome so 1 allele of each sex linked gene so always be Expressed even if recessive.
All Y chromosome are inherited from Father-Males Must always inherit x-chromosome from mother.

Question 9

What is the definition of Epistasis?

Answer 9

When one gene influences the expression of another gene.

Question 10

What is the definition of Population?

Answer 10

A group of Organism of the SAME SPECIES (occupying particular space at particular time)

Question 11

What is the Definition of Gene Pool?

Answer 11

TOTAL NUMBER OF GENES OF EVERY INDIVIDUAL in an interbreeding Population.

Question 12

What is the definition of Allele Frequency?

Answer 12

Allele Frequency is how often an allele occurs in a population.

Question 13

What is Hardy-Weinberg principle used for?
[Type of what… fre…]

Answer 13

HWP us used to predict allele frequency such as frequency of genotype,phenotype and alleles

Question 14

What are the Assumption Hardy-Weinberg Principles based on?
[Hint:5]

Answer 14

1.Mating is random
2.No natural selection occurs
3.No mutations
4.No gene flow (Populations moving to different location)
5.Population size infinite

Question 15

What is Hardy-Weinberg Principle equation for alleles and Individuals?

Answer 15

HWP for Alleles: p+q=1
HWP for individuals: P2+2PQ+q2=1

Question 16

What does p and q stand for In Hardy-Weinberg principle?

Answer 16

p=Frequency of 1 dominant allele.
q=Frequency of the other allele.recessive

Question 17

What does 2pq p2 and q2 stand for in Hardy-Weinberg principle?

Answer 17

2pq=Frequency of Heterozygous
p2=Frequency of homozygous DOMINANT.
q2=Frequency of homozygous RECESSIVE .

Question 18

[AS] What is directional Selection and where does the curve shift?

Answer 18

Directional selection favours Extreme Phenotype
In directional Selection curve shifts in direction of phenotype

Question 19

[AS] What is Stabilising Selection?
Where does the curve shift?

Answer 19

Stabilising selection favours the Average Phenotype that has the advantage.
Curve shift to middle and narrow.

Question 20

What is disruptive Selection?
Where does the curve shift?
[A-LEVEL]

Answer 20

Disruptive Selection favours both extreme phenotype/allies BUT at different time due to environmental factors
Causes a m-shaped curve-Frequency of individuals of average phenotype decreases and both extreme phenotypes increases overtime.

Question 21

What is the definition of Variation?

Answer 21

Variation is the phenotypic variation within every population due to COMBINATION OF GENETIC+ENVIRONMENTAL FACTORS

Question 22

What is the definition of Speciation?
How does it occur?
What are the types of Speciation?

Answer 22

Speciation is the evolution of new species from existing ones.
It occurs due to SELECTION leads to an inability of members of population to interbreed+produce fertile offspring.
The two types are Allopatric ad Sympatric.

Question 23

What are the first thing that occurs in Allopatric Speciation?

Answer 23

In Allopatric population becomes Geographically Separated.

Question 24

What is the definition of Genetic Drift?
Give an example of Genetic Drift

Answer 24

Genetic Drift is the CHANGE in ALLELE FREQUENCY WITHIN a POPULATION between generations.
An example of Genetic Drift is by chance certain allele passed on by chance.

Question 25

In Allopatric Speciation why can’t Population reproduce and how will they survive.

Answer 25

In Allopatric speciation reason why population can’t reproduce is due to PHYSICAL BARRIER.
SEPARATED Population have different ENVIRONMENT so will gain different BENEFICIAL MUTATIONS over time to help them survive.

Question 26

In Allopatric Speciation what causes them
to speciate.

Answer 26

In Allopatric Speciation
TWO POPULATIONS eventually become SO GENETICALLY DIFFERENT that they can’t reproduce to produce FERTILE offspring so classed as different species.

Question 27

What is Sympatric speciation?
(Explain Everything)

Answer 27

Sympatric Speciation is populations become REPRODUCTIVELY ISOLATED due to DIFFERENCE IN BEHAVIOUR.
1.First thing that happens Random Mutation could influence REPRODUCTIVE behaviour.
2.Individuals will not reproduce Together so overtime DNA become so difficult so individuals can’t reproduce to produce fertile offspring (so classed as 2 different species)

Question 28

What is the definition of Genotype?

Answer 28

Genotype is the genetic Constitution of an organism.

Question 29

What is the definition of Phenotype?

Answer 29

Phenotype is the expression of the genotype and its interaction with the environment

Question 30

What is the definition of an Allele?

Answer 30

Allele is the variation of a gene