Variation, Alleles and Mutations

Question 1

What’s the difference between alleles and genes?

Answer 1

A gene is the length of DNA that encodes for a protein and an allele is the different forms of gene that encode for different forms of protein.

Question 2

What are spontaneous and induced mutations?

Answer 2

spontaneous mutation arises for no apparent reasons and induced mutations have an identifiable cause such as radiation or chemical mutagens.

Question 3

Explain the difference between point mutations and block mutations

Answer 3

Point mutations only affect one base, they can also be silent mutations, missense mutations and nonsense mutations. The latter two will cause a frameshift mutation.

Block mutations affect multiple genes. They can be deletions, inversions, duplications and translocations.

Question 4

Explain a silent mutation

Answer 4

silent point mutation is when a single base is changed however it has no effect on the amino acid produced.

Question 5

Explain a missense mutation

Answer 5

A missense mutation is where a single base is changed and it does change the amino acid produced possibly altering the function of the resulting protein.

Question 6

Explain a nonsense mutation

Answer 6

A nonsense mutation is where a single base is changed resulting in a stop codon causing a protein to terminate or end its translation earlier than expected.

Question 7

Explain frameshift mutation

Answer 7

A frameshift mutation is the insertion or deletion of a single nucleotide base causing the reading frame to shift

Question 8

Explain what a duplicate block mutation is

Answer 8

A duplicate block mutation is where part of a chromosome is copied, resulting in duplicate sections potentially increasing gene expression

Question 9

Explain what a deletion block mutation is

Answer 9

A deletion changes the DNA sequence by removing at least one nucleotide in a gene. The deleted DNA may alter the function of the affected protein or proteins

Question 10

Explain what an inversion block mutation is

Answer 10

Inversion mutations occur when a section of DNA breaks away from a chromosome during the reproductive process and then reattaches to the chromosome in reversed order. This changes the genetic code and can make it more difficult to read.

Question 11

Explain what a translocation block mutation is

Answer 11

Many genes may be transferred between chromosomes. Such translocation mutations can cause disorders of growth, development, and function of the body’s cells and systems.

Question 12

Explain location and heritability of a mutation (somatic and germline mutations)

Answer 12

Mutations that happen in body cells and cannot therefore be on to offspring are called somatic mutations. Mutations that happen in the gonads and are therefore heritable are germline mutations.

Question 13

What are regulatory genes?

Answer 13

regulatory genes are genes that affect the expression of other genes, genes that are not regulatory are structural genes.

Question 14

What is a selecting agent?

Answer 14

A selecting agent is a thing in the environment that tends to kill individuals with one phenotype more than it kills individuals with another phenotype. The action of a selecting agent is called a ‘selection pressure’.

Question 15

Provide examples of selection pressures

Answer 15

Question 16

Explain the concept of biological fitness

Answer 16

Biological fitness measures an individual’s contribution to the next generation’s gene pool compared to others. phenotype fitness can change with environmental shifts or new mutations, making them less fit.

Question 17

Where does variation come from?

Answer 17

Variation comes from mutations

Question 18

What’s the effect of selective breeding (artificial selection) on gene pools

Answer 18

Like natural selection artificial selection reduces genetic diversity by allowing certain individuals to have much greater reproductive success than other individuals, whose phenotypes and the alleles that encode them, are eventually eliminated from the population.

Question 19

Explain gene flow

Answer 19

gene flow is the movement of genes from one population into another population by interbreeding between members of that population. could happen in migration.

Question 20

What is the founder effect?
(example of genetic drift)

Answer 20

The founder effect is when a new population starts from a very small number of individuals, and the alleles of the founder population will determine a large extent of the population’s allele frequency.

Question 20

Explain genetic drift

Answer 20

Genetic drift is where there is a change in allele frequency due to chance events. in each case, the population will grow but leave the gene pool relatively small

Question 21

What is a genetic bottleneck?
(example of genetic drift)

Answer 21

The genetic bottleneck is where the majority of the population is killed leaving only a few individuals, who then reproduce leaving rise to a larger population.

Question 22

Explain allopatric speciation

Answer 22

Allopatric speciation is the most common way in which a species gives rise to two species.

isolation- when a population is isolated from the rest of the species by a barrier it prevents genetic flow between two populations.

mutations- Over time due to mutations arising independently in each population and natural selection favouring phenotypes in each population the two populations evolve to become so different that they cannot interbreed and produce fertile offspring.

Question 23

Explain sympatric speciation

Answer 23

sympatric speciation occurs in plants where one species diverges into two normally due to mistakes in meiosis that result in polyploidy can also be due to soil conditions.

Question 24

List the order of species classification

Answer 24

Kingdom - Phylum - Class - Order - Family - Genus - Species

Question 25

Explain the ‘biological species concept’

Answer 25

Places two individuals in the same species if they can mate with each other and produce viable offspring

Question 26

Explain the ‘phylogenetic species concept’

Answer 26

Relies on DNA and the taxonomy of living things, basically significant genetic difference justifies the status of different species

Question 27

Explain the ‘morphological species concept’

Answer 27

is based on the shapes and sizes of anatomical structures.