Sister Taxa and Homologous Structures

Sister taxa

Groups of organisms sharing a common ancestor

Shared ancestral character

Character originated in ancestor of two taxa

Homologous structures

Bones in bat wing and human forelimb

In Figure 20.6 below, which similarly inclusive taxon descended from the same common ancestor as Canidae?

Mustelidae

Based on the tree below, which statement is not correct?

Lizards are more closely related to salamanders than to humans.

Evolution is best defined as which of the following?

a change in genetic composition of a population from generation to generation

During a study session about evolution, one of your fellow students' remarks, "The giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result." Which statement is most likely to be helpful in correcting this student's misconception?

Characteristics acquired during an organism's life are not passed on through genes.

Which of the following is an example of artificial selection?

a farmer cultivating sweet watermelons

What are adaptations?

inherited characteristics of organisms that enhance their survival and reproduction in specific environments

Two plant species live in the same biome but on different continents. Although the two species are not at all closely related, they may appear quite similar because of

convergent evolution

Natural selection changes allele frequencies because some ________________ survive and reproduce better than others

individuals

Analogous features share ________ function but not ________ ancestry.

similar; common

Which of the following is NOT TRUE about viruses?

They are comprised of cells.

Which situation is not an example of a prezygotic barrier?

Two species of insects produce infertile offspring

A lion and tiger will produce hybrids ___________.

when members of closely related species reproduce

Which of the following is a mechanism of evolution?

Genetic flow

.Which following associated with random changes in the allele frequencies of a population?

Genetic drift

"Organisms evolve on purpose" is:

An inaccurate statement because variation that selection acts on is already in a population and doesn't arise in response to the environmental change.

Genes are_______________.

Basic units of heredity, DNA, Units that determine phenotype.

A animal that is heterozygous for a trait will have

Two different alleles for the same trait

Which of the following descriptions correctly identifies a main structural difference between viruses with envelopes and viruses without envelopes?

Only viruses with envelopes have their contents enclosed by a layer containing lipids

.Which of the following statements best supports the argument that viruses are nonliving?

They do not carry out metabolic processes.

The host range of a virus is determined by whether ________.

the proteins on virus surface can bind with proteins on the host surface

Which of the following characteristics, structures, or processes is common to both bacteria and viruses?

genetic material composed of nucleic acid

Which of the following statements best describes evolution?

Natural selection favors the most abundant trait.

Schooling by fishes is what time of adaptation.

Behavioral

Mimicry of leaves by insects is what kind of adaptation.

Structural

Which is true about microevolution?

Adaptations lead to variation in the same species

Hybrid in viability

Is a post-zygotic isolating mechanism where hybrids fail to reach reproductive maturity

A key difference between acclimation and adaptation is:

Acclimations are reversible changes in phenotype, adaptations are not reversible.

Genetic Drift

• Changes in allele frequencies due to the chance events

• Random events; not based on characteristics

• More likely to impact small populations

Natural Selection

• More adapted individuals survive and pass genes

• The more prolific reproduction of individuals with favorable traits that have survived environmental change because of those traits

• Increase in frequency of a particular allele

• Resulting in decrease of other alleles because individuals with the FAVORABLE allele are more likely to survive and reproduce

• Allowing the passing of allele on to their offspring in a particular environment

• Variation in a trait

• Fitness difference relationship between trait and some aspect od reproduction or survivorship

• Heritability of trait must be at least

Gene Flow

• The movement of different alleles into or out of a population

• Such a movement may be due to the migration of individual organisms that can reproduce in their new population

Mutation

• A change in DNA; change in the DNA sequence

• The ultimate source of new alleles

most common way to introduce genotypic and. Phenotypic variability

1. Harmful/ unfavorable and will eventually be eliminated

2. Beneficial and will eventually spread

3. Neutral- no effect

• The usefulness of a mutation is dependent on whether it helps the organism survive and reproduce

Heterozygosity

• Heterozygous refers to having different alleles for a particular trait

• Gene diversity(heterozygosity), defined as the chance that two DNA segments drawn randomly from a group are different.