IB HL Bio Evolution Test

What are the two parts of a binomial name?

Genus and species.

What does the first word of a binomial name identify?

The genus.

What does the second word of a binomial name identify?

The species.

How should a scientific name be written?

The genus is capitalized, the species is lowercase, and both are italicized when typed.

What is the biological species concept?

A species is a group of organisms that can interbreed and produce fertile offspring.

Why is the biological species concept difficult to apply to bacteria?

Bacteria reproduce asexually and can exchange genes through horizontal gene transfer.

What is one limitation of the biological species concept?

It cannot easily be applied to asexual organisms or fossils.

What is evolution?

A change in the heritable characteristics of a population over generations.

Do individuals or populations evolve?

Populations evolve.

What is the diploid chromosome number of humans?

46.

What is the diploid chromosome number of chimpanzees?

48.

Why is the diploid chromosome number always even?

Chromosomes occur in homologous pairs, with one chromosome inherited from each parent.

What is a karyogram?

A diagram showing chromosomes arranged into homologous pairs.

What three features are used to arrange chromosomes in a karyogram?

Size, centromere position, and banding pattern.

What is the chromosome 2 fusion hypothesis?

Human chromosome 2 formed when two ancestral chromosomes fused together.

What evidence supports the chromosome 2 fusion hypothesis?

Human chromosome 2 has telomere sequences in the middle and evidence of a second inactive centromere.

What is genome variation within a species?

Differences in DNA sequences between individuals of the same species.

What is genome variation between species?

Differences in DNA sequences between different species.

Which organism on the study guide has the largest genome?

Paris japonica.

How large is the Paris japonica genome compared with the human genome?

Approximately 48 times larger.

Is genome size a reliable indicator of organism complexity?

No. Genome size does not necessarily correspond to organismal complexity.

What is one current use of whole genome sequencing?

Identifying genetic diseases or mutations.

What is one potential future use of whole genome sequencing?

Personalized medicine based on an individual's genome.

How can DNA sequences provide evidence for evolution?

More similar DNA sequences generally indicate a more recent common ancestor.

How can amino acid sequences provide evidence for evolution?

More similar amino acid sequences generally indicate a more recent common ancestor.

How is selective breeding evidence for evolution?

Humans select organisms with desirable inherited traits, causing populations to change over generations.

What is a homologous structure?

A structure with a similar underlying anatomy due to common ancestry, even if it has a different function.

Give an example of homologous structures.

The forelimbs of humans, bats, and whales.

What is an analogous structure?

A structure with a similar function that evolved independently and does not have the same evolutionary origin.

Give an example of analogous structures.

A bird wing and an insect wing.

What is the difference between homologous and analogous structures?

Homologous structures have common ancestry; analogous structures have similar functions but evolved independently.

What is convergent evolution?

When unrelated organisms independently evolve similar adaptations due to similar environmental pressures.

Why do dolphins and sharks have similar streamlined bodies?

They independently evolved similar adaptations because they live in similar aquatic environments.

What is speciation?

The formation of new species.

What is reproductive isolation?

When populations can no longer successfully reproduce with each other and exchange genes.

How does reproductive isolation contribute to speciation?

It prevents gene flow, allowing populations to become genetically different.

What is geographical isolation?

The physical separation of populations by a geographic barrier.

What is allopatric speciation?

Speciation caused by geographical isolation.

What is sympatric speciation?

Speciation occurring without geographical isolation.

What is behavioral isolation?

Differences in mating behavior prevent reproduction between populations.

What is temporal isolation?

Populations reproduce at different times, preventing interbreeding.

What is mechanical isolation?

Physical differences prevent successful mating or transfer of gametes.

What is adaptive radiation?

The formation of multiple species from one ancestral species as populations adapt to different ecological niches.

How does adaptive radiation increase biodiversity?

Populations specialize in different vacant niches and can eventually form different species.

What effect does speciation have on the total number of species?

It increases the total number of species.

What effect does extinction have on the total number of species?

It decreases the total number of species.

What is a clade?

A common ancestor and all of its descendants.

What is cladistics?

A method of classifying organisms based on evolutionary relationships and common ancestry.

What type of evidence is especially useful for determining evolutionary relationships?

Molecular evidence such as DNA or amino acid sequences.

Why can traditional classification sometimes be misleading?

Similar physical features can evolve independently through convergent evolution.

What is one advantage of evolutionary classification?

It reflects evolutionary relationships and common ancestry.

What is parsimony?

The principle that the best evolutionary tree requires the fewest evolutionary changes.

What is a molecular clock?

A method used to estimate when species diverged based on genetic differences and mutation rates.

Why does a molecular clock only give an estimate?

Mutation rates are not perfectly constant over time.

What is the root of a cladogram?

The common ancestral lineage.

What is a node on a cladogram?

A point representing a common ancestor where lineages branch.

What are sister taxa?

Two groups that share the most recent common ancestor.

What are the three domains of life?

Bacteria, Archaea, and Eukarya.

What evidence was used to establish the three domains?

Comparisons of ribosomal RNA sequences and other molecular evidence.

What is DNA barcoding?

Using a short standardized DNA sequence to identify species.

What is one advantage of DNA barcoding?

It can quickly identify organisms that may be difficult to identify from appearance alone.

Why can different chromosome numbers cause hybrid sterility?

Chromosomes may not pair properly during meiosis.

How many chromosomes does a horse have?

64.

How many chromosomes does a donkey have?

62.

How many chromosomes does a mule have?

63.

Why are mules usually sterile?

Their odd number of chromosomes makes proper chromosome pairing during meiosis difficult.

What is polyploidy?

Having more than two complete sets of chromosomes.

What is hybridization?

The crossing of individuals from different species or genetically distinct populations.

How can hybridization and polyploidy cause speciation in plants?

Chromosome doubling can restore fertility in a hybrid and produce a new reproductively isolated species.

What is rapid plant speciation?

The formation of a new plant species in a short period, sometimes one generation, often through polyploidy.

What are three processes that can cause isolated populations to become genetically different?

Mutation, natural selection, and genetic drift.

What happens when gene flow between populations is reduced?

The populations can accumulate genetic differences.

What is a dichotomous key?

A tool for identifying organisms using two contrasting choices at each step.

What is a scientific theory?

A well-supported explanation based on extensive evidence, not simply a guess.

What evidence supports evolution?

Fossils, DNA sequences, comparative anatomy, embryology, biogeography, and observed natural selection.