Unit 3 Life on Earth - Evolution of Species Flashcards

Flashcards testing core concepts of evolution, natural selection, speciation, mutation, and antibiotic resistance based on past exam questions.

Based on this diagram representing four animal populations ($P$, $Q$, $R$, and $S$) and their areas of interbreeding, how many species may evolve over time?

$2$ species (Populations $P$, $Q$, and $R$ can interbreed with each other, while population $S$ is isolated by the mountain range).

What is the sequence of events leading to antibiotic resistance in bacteria?

Mutation \rightarrow use of antibiotic \rightarrow natural selection

What is the only source of new alleles in a population?

Mutation

What are the possible effects of a mutation on the survival of an organism?

A mutation can have no effect (neutral), give the organism an advantage, or disadvantage the organism.

What is the main outcome when selection pressures act on a population during natural selection?

Organisms with favourable alleles survive and reproduce.

In what chronological order do isolation, mutation, and natural selection occur during speciation?

1. Isolation
2. Mutation
3. Natural selection

Using the information in this diagram showing the stages in speciation, describe how new species are formed.

1. An initial population is separated by an isolation barrier into sub-populations.
2. Random mutations occur in each sub-population.
3. Natural selection selects for different favourable alleles in each environment.
4. Over time, sub-populations evolve until they become distinct species that cannot interbreed to produce fertile offspring.

Define the term 'mutation'.

A random change in an organism's genetic material.

Define the term 'species'.

A group of organisms that can interbreed to produce fertile offspring.

Why is variation important for the survival of a population?

It allows the population to adapt to changing environmental conditions.

If $7$ out of $20$ members of an extended family possess a mutation for high bone density, what percentage of the family does NOT have the mutation?

$65\%$ (since $13$ out of $20$ do not have the mutation: $\frac{13}{20} \times 100 = 65\%$).

When testing a family for a genetic mutation, why are tests also performed on a group of unrelated individuals without the mutation?

To act as a control for comparison.

Name environmental factors that can increase the rate of mutation.

Radiation (such as UV light or X-rays) and chemical agents (such as mustard gas).

In a moth mark-recapture investigation where $480$ light moths and $520$ dark moths were released, why is the recapture number calculated as a percentage?

Because different numbers of light and dark moths were originally marked and released, making percentage necessary for a fair comparison.

Why was the percentage of light moths recaptured higher than dark moths in a non-industrial woodland area?

Light moths were camouflaged against the light tree bark, making them less likely to be seen and eaten by bird predators.

What term is used to describe the role of an organism, such as the Scottish crossbill, within its community?

Niche

What feature of offspring produced by mating two organisms proves that the parent organisms belong to different species?

The offspring are infertile (sterile).

What three types of isolation barriers can divide populations during speciation?

Geographical, ecological (environmental), or reproductive barriers.

Why do antibiotics have no effect on the pathogen that causes the common cold?

The common cold is caused by a virus, and antibiotics are only effective against bacterial infections.

Place the stages of antibiotic resistance evolution in order: A (Mutation makes bacteria resistant), B (Next gen resistant), C (Surviving bacteria reproduce/pass alleles), D (Bacterial populations show genetic variation), E (Antibiotic kills non-resistant, resistant survive).

$$D \rightarrow A \rightarrow E \rightarrow C \rightarrow B$$

According to this graph, what is the minimum concentration of antibiotic required to kill all of the bacteria across both strains?

$$50\text{ units}$$

Based on the survival curves for the original and mutated bacterial strains, what advantage did the mutation give to the mutated strain?

The mutated strain was able to survive at higher concentrations of antibiotic compared to the original strain.

What term is given to micro-organisms, such as bacteria, that cause disease?

Pathogen