Patterns of Inheritance

Question 1

Gregor Mendel

Answer 1

Pea plant experiment

Question 2

Genotype

Answer 2

Genetic makeup
-describes all the alleles that an organism has

Question 3

Phenotype

Answer 3

Visual characteristic of an organism
due to genotype and environment

Question 4

Alleles

Answer 4

Different forms of a gene
eg different eye colour

Question 5

Physical mutagens

Answer 5

X-rays, gamma rays & UV

Question 6

Chemical mutagens

Answer 6

Benzopyrene - tobacco smoke

Question 7

Biological mutagens

Answer 7

Viruses and food contaminants

Question 8

Codominance

Answer 8

Blood groups
where 2 different alleles both contribute to the phenotype displayed
blend of both features

Question 9

Genetic causes of variation

Answer 9

Indel
Inversion
Translocation
Non disjunction (polyploidy&aneuploidy)

Question 10

hardy weinberg calculation

Answer 10

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

Question 11

what each letter means

Answer 11

p = frequency of dominant allele
q = frequency of recessive allele
p2 = % of homozygous dominant
q2 = % of homozygous recessive
2pq = % of heterozygous individuals

Question 12

discontinuous variation

Answer 12

individuals fall into a number of distinct classes/ categories
qualitative differences
-bar charts
-blood groups
-monogenic

Question 13

continuous variation

Answer 13

complete range of measurements from one extreme to another
-no definite categories
-quantitative differences
-line graph, polygenic

Question 14

chi squared

Answer 14

x2 = sum of (O-E)2 / E
finds out whether the difference is due to chance or a real effect
critical value found
uses degrees of freedom = n-1
then 0.05
if value is bigger than table reject null hypothesis
if lower than table accept

Question 15

how can meiosis bring about genetic variation

Answer 15

Random arrangement of chromosomes lining up
Crossing over of chromatids before first division

Question 16

monogenic inheritance

Answer 16

when one phenotypic characteristic is controlled by a single gene

Question 17

dihybrid inheritance

Answer 17

where 2 phenotypes are determined by 2 different genes present on 2 different chromosomes at the same time

Question 18

sex linkage

Answer 18

where an allele is located on one of the sex chromosomes
meaning its expression depends on the sex of the individual

Question 19

multiple alleles

Answer 19

a gene with more than 2 alleles
Xo Xa
eg blood groups

Question 20

autosomal linkage

Answer 20

where 2 or more genes are located on the same (NON SEX) chromosome
one homologous pair needed for all 4 alleles to be present
if not linked 2 homologous pairs needed

Question 21

epistasis

Answer 21

where 2 non linked genes interact and one masks the the expression of the other
eg black in colour but melanin gene not produced so the animal is white albino

Question 22

stabilising selection

Answer 22

occurs when environmental conditions stay the same
individuals closest to mean are favoured
any new characteristics are selected against
-low diversity

Question 23

Directional selection

Answer 23

Occurs when environmental conditions change
individuals with phenotypes suited to new conditions will survive and pass of their genes
over time mean of population will move towards these characteristics

Question 24

genetic drift

Answer 24

change in a populations allele frequencies that occurs due to chance

Question 25

genetic bottleneck

Answer 25

catastrophic event occurs reducing size of population
decreasing variety and diversity

Question 26

founder effect

Answer 26

when a small number of individuals become isolated and create a new gene colony
limited gene pool

Question 27

speciation

Answer 27

where a population is split and isolated
different selective pressures on 2 groups
2 groups can no longer interbreed if genetic makeup is changed to an extent

Question 28

allopatric speciation

Answer 28

speciation resulting from a physical barrier geographic

Question 29

sympatric speciation

Answer 29

speciation from a non physical barrier
eg a mutation that means the 2 individuals can no longer produce fertile offspring

Question 30

artificial selection

Answer 30

when humans pick the individuals to breed to produce desired offspring