Topic 7 - Genetics, Populations, Evolution And Ecosystems

Question 1

Gene pool

Answer 1

All alleles in population

Question 2

Mark release recapture

Answer 2

• capture someplace and mark and release
• non harmful marks
• allow time for redistribution after release
• recapture
• est. pop. = total of 1st x total of 2nd / marked in 2nd

Question 3

Succession

Answer 3

• pioneer species colonise
• change in abiotic factor in environment
• less hostile extreme conditions
• increase biodiversity
• gets too climax community

Question 4

Est. Size of population

Answer 4

• grid
• random coordinates
• calculate frequency Per quadrant
• calculate % cover
• large sample
• calculate average

Question 5

Features of climax community

Answer 5

• consistent abiotic factors
• stable populations and community

Question 6

Inter/intraspecific competitions

Answer 6

• inter = between different species
• intra = between same species

Question 7

Species

Answer 7

Group of similar organism in same place at same time that can successfully breed to produce fertile offspring

Question 8

Allele frequency

Answer 8

Number of times allele appear in gene pool

Question 9

H-W principle

Answer 9

• calculate frequency of different alleles of a gene in a population
• assume frequencies of alleles in a population remain constant between generations

Question 10

Assumptions of H-W principle

Answer 10

• no selection - alleles all equal
• no mutation - no new alleles
• no migration - alleles not removed or changed
• large population - no genetic bottlenecking
• random mating

Question 11

Allele frequency equation

Answer 11

Dominant - p
Recessive - q
2 alleles = p+q=1

Question 12

Genotype equaiton
Dom homo
Rec homo
Hetro

Answer 12

• DH = P2
• rh = q2
• H = 2pq

P2+2pq +q2 = 1

Question 14

Define:
Gene
Allele
Genotype
Phenotype
Monohybrid

Answer 14

Gene - inherited instruction which codes for a polypeptide
Allele - alternate form of a gene. Can arise from mutation
Genotype - genetic constitution of an organism that determines characteristics
Phenotype - observable traits of an organism
Monohybrid cross - cross in which the allele of only one gene are inherited

Question 15

Monohybrid inheritance

Answer 15

The inheritance of a characteristic controlled by a single gene.
Show the likely hood of different alleles of that gene being inherited from parents.
HH + hh = 100% Hh offspring
Hh + hh = 50/50 Hh hh

Question 16

Codominance

Answer 16

• When alleles of a gene share dominance of characteristics
- both are expressed in the phenotype
• example of diagram is capital letters with smaller letters as powers and as the characteristic

Question 17

Dihybrid cross

Answer 17

RrYy RRYY rRyY rryy
Inheritance of two genes with 2 different alleles each on different chromosomes
Independent segregation = alleles on different chromosomes
so can pass into gametes in any combo

Question 18

Autosomal linkage

Answer 18

• non sex chromosomes
• if genes are on same chromosome it is assumed they are inherited together (linked and no crossing over)
• stay together during independent segregation
• ## closer they are together, the closer they are linked

Question 19

Sex-linked inheritance

Answer 19

• genes on sex chromosomes
• female is XX
• males is XY
• Y is smaller so carries less genes
• some genes like faulty only carried by X so more likely inherited by male offspring due to only one X

Question 20

Epistasis

Answer 20

• polygenetic characteristics
• when alleles of one gene mask expression of another
• dominant = mask expression of alleles at second gene
locus
• recessive - 2 recessive at one gene mask allies expression of another

Question 21

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

Answer 21

-random fertilisation of gametes
-mutation/crossing over
-small sample size
-linked genes
-epistasis
-lethal genotypes

Question 22

Test cross

Answer 22

Determines if an organism is homozygous dominant or heterozygous
Whether 2 genes are linked or not
Always cross homo rec

Question 23

Autosomal

Answer 23

Not sex chromosome

Question 24

ABO blood groups

Answer 24

I0 is allele for O (recessive)
IA is allele for A
IB is allele for B

IA and IB are codominant (AB)

Question 25

9:3:3:1

Answer 25

DD:Dr:Dr:rr

Question 26

XX and XY

Answer 26

XX = female XY = male Y = smaller so most genes go on X and no homologous pairs present of Y Characteristics caused by recessive alleles have greater chance of appearing in males

Question 27

Chi squared

Answer 27

- assess if observed if significantly different from expected - categorical raw values - null hypothesis = no significant difference between O and E - if calculated value is less that critical value then accept null

Question 28

Describe these phenotype frequencies: 1860,580,68,57

Answer 28

Larger number linked genes - smaller numbers means a mutation has occurred which means they are random, not linked and not expected but observed - smaller numbers caused by crossing over

Question 29

Assumptions to why expected and observed are not the same

Answer 29

- small sample size - random fertilisation of gametes - lethal genotypes

Question 30

Why is chai squared test used

Answer 30

- to show if differnce between observed and expected is significant or not - its categorical data

Question 31

Diploid

Answer 31

2 sets off chromosomes so 2 alleles for each gene

Question 32

Gametes

Answer 32

Sex cells Only one allele for each gene

Question 33

FOIL

Answer 33

FIRST OUTSIDE INSIDE LAST

Question 34

Phenotypic ratio

Answer 34

- ratio of different phenotypes in ratios Can predict ratios in F1 and F2

Question 35

Causes of genetic variation

Answer 35

Crossing over Random fertilisation Independent segregation Lethal alleles

Question 36

Locus

Answer 36

Position of gene on chromosome

Question 37

Recessive epistasis

Answer 37

2 copies of recessive epistasis allele masks or blocks expression of other gene 9:3:4

Question 38

Dominant epistasis

Answer 38

When dominant allele completely masks allele at 2nd locus 12:3:1

Question 39

Chi squared equation

Answer 39

X2 = sum of (O-E)2/E

Question 40

STATS OUTCOME

Answer 40

Equal or more = AND Less = RSN

Question 42

Allopathic speciation

Answer 42

- geographical isolation - different pressure once separated differentiate two groups into two different species - genetic drift - frequency of alleles in each population differs - reproductively isolated -

Question 43

Sypactric speciation

Answer 43

- without geographical isolation - random mutations occur that prevent members of population breeding with another member of the species - mutations occur to produce polyploidy when the chromosomes are increased ion number - individuals with different numbers of chromosomes can’t reproduce to produce fertile offspring - leads or asexual production - more common in plants