3.7 Genetics, populations, evolution and ecosystems (A-level only) Flashcards
(20 cards)
1
Q
Genotype
A
- the genetic constitution of an organism
2
Q
Phenotype
A
- the expression of the genetic constitution
- and its interaction with the environment
3
Q
Homozygous
A
- two copies of the same allele for a gene
4
Q
Heterozygous
A
- two different alleles for the same gene
5
Q
Recessive allele
A
- An allele that is only expressed if there are no dominant alleles present
6
Q
Dominant allele
A
- An allele that is always expressed in the phenotype
7
Q
Codominance
A
- two alleles are both dominant
- both are expressed in the phenotype
8
Q
Multiple alleles
A
- More than two alleles for a gene
9
Q
Sex-linkage
A
- a gene located on the X chromosome
- in the non-homologous region
10
Q
Autosomal linkage
A
- genes located on the same chromosome (not the X or Y chromosome)
INSERT IMAGE HERE
11
Q
Epistasis
A
- When one gene masks/modifies with the expression of another gene
12
Q
Monohybrid
A
- The inheritance of one gene
13
Q
Dihybrid
A
- The inheritance of two genes
14
Q
Natural selection
A
- the process that leads to evolution in populations
- results in species becoming better adapted to their environment
15
Q
Selection pressure
A
- factors that affect the survival of an organism
- the driving force of natural selection
16
Q
Differential reproductive success
A
- not all individuals are equally
likely to reproduce - results in changes in allele frequencies within a gene pool
17
Q
Allele frequency
A
- The proportion of an allele in the population
18
Q
Disruptive selection
A
- Individuals with either extreme trait are more likely to survive and pass on their alleles
- the middling trait allele becomes less frequent
- leads to speciation
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19
Q
Reproductively isolated
A
- Two populations of the same species, but they cannot breed together
- there is no gene flow
20
Q
A
