DNA & Gene Expression
What molecule stores hereditary information in most organisms?
DNA (deoxyribonucleic acid).
What is evolution at the population level?
A change in allele frequencies across generations.
What pattern occurs when unrelated species independently evolve similar traits?
Convergent evolution.
DOUBLE JEOPARDY
What is species richness?
The number of different species in a community
What is an allele?
An alternative/specific form of a gene
What is the process of making mRNA from a DNA template called?
Transcription
What is the name for random changes in allele frequencies, especially in small populations?
Genetic drift.
What is evolution in which related populations develop different traits called?
Divergent evolution.
What does species evenness describe?
How evenly individuals are distributed among the species in a community.
What genotype is heterozygous for a gene with alleles A and a?
Aa
Which RNA molecule carries amino acids to a ribosome?
Transfer RNA (tRNA).
DOUBLE JEOPARDY
What type of selection favours one extreme phenotype?
Directional selection
What is the term for interacting species exerting reciprocal selection pressures on each other?
Co-evolution
Calculate Simpson’s Diversity Index for a community with three species represented by 5, 3 and 2 individuals.
D ≈ 0.689
If T is dominant to t, what phenotype is expected from genotype tt?
the recessive phenotype
DOUBLE JEOPARDY
A DNA template strand is 3′–TAC GGA CTT–5′. What mRNA sequence is produced?
The 3' and 5' end must be labelled correctly
5′–AUG CCU GAA–3′.
Explain why antibiotic resistance can become more common in a bacterial populations that are exposed to antibiotics
Resistant bacteria survive antibiotic exposure more successfully and reproduce, passing resistance alleles to offspring. The resistance allele becomes more frequent over generations
Related species in separate environments independently evolve similar adaptations. What pattern is this?
Parallel evolution
Two habitats have equal species richness, but one has individuals distributed more evenly across species. Which usually has the higher Simpson’s Diversity Index when using the 1 − D formula?
The habitat with the more even distribution of individuals generally has the higher Simpson’s Diversity Index.
In a cross Aa × Aa, what is the expected genotype ratio?
1 AA : 2 Aa : 1 aa.
Explain how a base substitution can change a protein and phenotype.
A substitution may change an mRNA codon, which may change the amino acid incorporated during translation. This can alter protein structure or function and affect the phenotype. Some substitutions are silent and do not change the amino acid sequence.
A flood randomly leaves only a few individuals alive in a population. Explain how this can affect genetic diversity
The bottleneck reduces population size and may randomly remove alleles. The surviving population can have lower genetic diversity and different allele frequencies. This is an example of genetic drift
Explain how geographic isolation can lead to allopatric speciation.
A geographic barrier reduces gene flow between populations. Mutation, natural selection and genetic drift cause the populations to diverge. Reproductive isolation may eventually develop, resulting in separate species.
Explain why biodiversity can increase ecosystem resilience.
Greater species and functional diversity may mean different organisms respond differently to disturbances. This can help maintain ecosystem processes when environmental conditions change. However, the effect depends on the ecosystem and the species present.
A rare recessive genetic condition occurs only in individuals with genotype aa. Two unaffected carrier parents have a child. What is the probability the child has the condition?
25% (1 in 4), assuming simple Mendelian inheritance and independent allele segregation.