Bio 230 Exam 1

Which of the following best describes homologous structures?

Traits inherited from a common ancestor, though they may serve different functions

Which of the following is an example of homologous structures?

Flippers of a whale and arms of a human

The forelimbs of a bat, a what, and a human have different functions (flying, swimming, grasping). What does this illustrate?

Divergent evolution through homologous structures

Homologous structures are evidence for:

Common ancestry

Which of the following is the best distinction between homologous and analogous structures?

Homologous structures share a common ancestor, while analogous do not

Which of the following best explains why bird wings and insect wings are considered analogous?

They perform the same function but evolved independently

Analogous structures are the result of

Convergent evolution

Which of the following is an example of analogous structures?

Wings of a bat and wings of a butterfly

The forelimbs of humans, cats, whales, and bats are examples of:

Structural homology

The presence of pharyngeal (gill) pouches in embryos of fish, chicken and human is an example of:

Developmental homology

Which of the following is the best example of molecular homology?

Similar DNA sequences coding for hemoglobin in humans and chimpanzees

Which type of homology is easiest to observe directly without advanced technology?

Structural

Which of the following statements is true?

Developmental homology is seen in embryonic stages

Lamarck theory vs Darwins theory

Lamarck's theory proposed that organisms can pass on traits acquired during their lifetime to their offspring, while Darwin's theory of evolution by natural selection suggests that evolution occurs through the differential survival and reproduction of individuals with advantageous traits.

According to Lamarck, how are acquired characteristics passed to offspring?

Traits or modifications that an organism develops during its lifetime (like muscle strength or longer neck) are transmitted to its offspring

Darwin or Lamarck theory:

Elephants couldn’t reach resources with a smaller trunk so they stretch their trunk during their lifetime and pass it off to their offsprings.

Lamarck

Darwin or Lamarck theory:

Elephants with longer trunks survived more and were able to reproduce more allowing for longer trunks to be a characteristic of elephants now

Darwin

Darwin or Lamarck theory:

Muscles stretch their structures until they achieve desired length and pass it to their offspring

Lamarck

The differences in dog breeds such as bulldogs, poodles, and collies, are due to ______.

Selective breeding

Which event happened first in earth’s history?

Photosynthesis evolved

What type of homology is embryology?

developmental homology

What is part of structural homology?

a. homologous structure

b. analogous structure

c. embryology

d. universal genetic code

a and b

What are the three categories in homology?

structural, developmental, and molecular homology.

What is true of the protein used in different organisms?

They are comprised of the same 20 amino acids in all life forms

Which of the following is the ultimate source of all genetic variation?

Mutations

Which of the following is the best example of gene flow?

Pollen from one population of flowers fertilizes flowers in a nearby population.

Which process moves genes between populations rather than just shuffling or creating new variation within a single population?

Gene flow

Which is not part of forces of evolution

non random mating

Which one is a example of Alleles?

B and b

What is an example of genotype?

BB, bb, Bb

What are the four forces of evolution:

a. mutation

b. genetic drift

c, gene flow (migration)

d. natural selection

e. non-random mating

a,b,c,d

What are the mutations that can occur in DNA:

point mutation, gene duplication, chromosomal mutations

A change in a single base pair that causes sickle cell anemia is an example of:

Point mutation

Which type of mutation results in an extra copy of a gene?

Gene duplication

A mutation that deletes an entire chromosome would be classified as:

Chromosomal mutation

Which type of mutation is most likely to involve only a few nucleotides (bases)?

Point mutation

Which of the following best describes chromosomal mutations

They change the overall structure or number of chromosomes.

Which of the following best describes a synonymous (silent) mutation?

A mutation that changes a codon but does not alter the amino acid

A mutation that does NOT alter the protein production is called a ______.

none of the above (silent mutation)

A mutation changes GGT (glycine) to GGC. What type of mutation is this?

Synonymous

Nonsynonymous (missense) mutations:

Change the amino acid sequence and may have small or large effects depending on location and type of substitution

Which statement is true about the impact of nonsynonymous mutations?

Their effects depend on which amino acid is replaced and where in the protein the change occurs

Chromosome inversions are highly polymorphic in some species. Evolutionary biologist were wondering why and how chromosome inversion evolved and spread in a population.

Chromosome inversion often causes _______. Select the best answer.

Suppression of recombination

What is the main difference between gene duplication and point mutation?

Gene duplication involves larger segments of DNA than point mutations.

Which evolutionary role makes gene duplication especially important?

It provides a source of entirely new genes that can evolve new functions.

Retroposition differs from unequal crossing over because:

It uses mRNA as a template to make DNA, often lacking introns.

Unequal crossing over occurs because:

Homologous chromosomes or sister chromatids misalign during recombination.

A key result of unequal crossing over is:

One chromatid contains a duplication while the other has a deletion.

Retroposition differs from unequal crossing over because:

Retroposition creates gene copies from processed mRNA, often lacking introns.

Which process most directly causes whole-genome duplication?

Nondisjunction during cell division

Polyploidy is especially common and often beneficial in:

Plants

Which of the following statements is not true?

Duplicate genes always take on new functions

If a section of a chromosome breaks off an inserts into a different, nonhomologous chromosome, it is called a(n) _________

translocation/retrotransportation

A locus is polymorphic if:

Its most common allele has a frequency of 95% or less.

Which measure represents the fraction of loci that have more than one allele in a population?

Polymorphism (P)

Assuming that brown fur is a dominant trait in hamster, and this hamster population is under Hardy-Weinberg Equilibrium. If the gene pool for a population of hamsters has 40% allele B and 60% allele b, what fraction of hamsters are brown?

0.64

In the previous example (Q1), what fraction of hamsters are heterozygous in the population? (q=0.4 p=0.6)

0.48

Martison and colleagues tested 43 individuals: 26 with genotype +/+, 16 with genotype +/-, and 1 with -/-. What is the frequency of - allele?

0.209

If a population meets all HWE assumptions, which of the following is true?

The population does not evolve as long as these conditions hold

Assuming a population is under HWE. There are 60 red flowers and 40 white flowers in a population. White flower is the dominant trait. What is the frequency of the allele responsible for white flower?

0.23

Wet ear wax is a dominant trait in humans. If we survey BIOS 230 and find that 75 out of 170 students have wet ear wax, p (the frequency of wet ear was allele) is approximately:

0.25

A survey of 1210 people in Iceland finds 194 individuals are blood groups MM, 581 are MN, and 436 are NN. What is p (frequency of M)?

0.4

In the sandblossom example given above, with p = 0.2, q = 0.8, and violet flower is the dominant trait. How many violet flowers would you expect in a population of 650 plants?

234

If for AA, w = 1.0; for Aa, w = 1.0; and for aa, w = 0.8, then which of the following is predicted?

The a allele will decrease but not be eliminated entirely

If for AA, s = 0; for Aa, s = 0.25; and for aa, s= 0.5, then which of the following is predicted?

Genotype Aa has intermediate fitness

If for AA, w = 0.9; for Aa, w = 1.0; and for aa, w = 0.9, which of these predictions are correct?

An equilibrium where p=q=0.5

Why is selection against a recessive lethal allele fast at first?

Because many recessive alleles are in homozygotes where they are exposed to selection.

Will frequency of recessive alle reach zero in selection against recessive allele? Will dominant allele reach fixation?

no, no

Why is selection against a dominant deleterious allele more efficient than against a recessive one?

Because dominant alleles are expressed in both homozygotes and heterozygotes

If a dominant deleterious allele has selection coefficient s=1s = 1s=1 (lethal), which individuals are removed by selection?

Both homozygotes and heterozygotes carrying the allele

In a population where heterozygotes have higher fitness than either homozygote, this situation is called:

Overdominance

What is the long-term effect of heterozygote advantage on allele frequencies?

Both alleles are maintained in the population at a stable equilibrium

Sickle cell trait in humans provides resistance to malaria. Which genotype has the highest fitness in malaria-endemic regions?

Heterozygous (Aa)

Which of the following best describes selection in heterozygote advantage?

Selection is stabilizing, maintaining both alleles at intermediate frequencies

If allele A and allele a show heterozygote advantage and fitnesses are:

• wAA=0.8w_{AA} = 0.8wAA​=0.8

• wAa=1.0w_{Aa} = 1.0wAa​=1.0

• waa=0.9w_{aa} = 0.9waa​=0.9

Which of the following statements is true?

Both alleles will be maintained in the population

Selective Coefficient: S=0.3 and t=0.1. What will be p^?

0.25

Selective Coefficient: S=0.3 and t=0.1. What will be q^?

0.75

Relative fitness: AA=0.7, Aa=1, aa=0.9

What will happen in this population?

An equilibrium where p<q

When frequency of the normal hemoglobin allele p=0.88, frequency of the sickle cell allele q=0.12. Among 100,000 people in a HWE pop, how many people carry sickle disease?

22,560

In positive frequency-dependent selection:

Common phenotypes are favored

Which is a likely outcome of positive frequency-dependent selection?

Fixation of the common phenotype

In negative frequency-dependent selection, the advantage lies with:

Phenotypes that are rare

Which evolutionary effect is most associated with negative frequency-dependent selection?

Maintenance of genetic variation

Assuming the head symmetry of scale eating fish is controlled by a single gene. Dominant allele (R) is responsible for the right mouthed structure. Recessive allele (r ) is responsible for the left mouther structure. If the scale eating fish pop is under HWE and the frequencies of the two morphs maintain at 0.5 (there is a 50% chance of both alleles). What is the approximate frequency of allele R (p) in the population at equilibrium.

0.29

Vagility refers to:

The ability of organisms to move or disperse between populations

If two populations are separated by a barrier but individuals occasionally cross and reproduce, what will happen to gene flow?

Gene flow will occur, but at reduced levels compared to populations with no barrier

Outbreeding depression is most likely to occur when:

Two populations adapted to different environments interbreed

Outbreeding depression can occur because:

Co-adapted gene complexes are disrupted

Which scenario is least likely to produce outbreeding depression?

Crosses between neighboring populations in the same environment

What statement(s) about genetic drift is correct?

Genetic drift can sometimes be stronger than natural selection

Genetic drift has the greatest effect when:

Population size is small

A population of cheetahs experienced a sharp decline in numbers during the Ice Age and shows very little genetic variation today. This is an example of:

Bottleneck effect

Which of the following is the best example of the founder effect?

A small group of birds is blown by a storm to an isolated island and starts a new colony

One consequence of genetic drift is:

Rare alleles may be lost purely by chance

Both the bottleneck effect and the founder effect are forms of:

Genetic drift

Nonrandom mating can cause a population to deviate from HWE. Why nonrandom mating is not considered as a force of evolution?

Nonrandom mating changes genotype frequency, does not change  the allele frequency

Which of the following is true about positive assortative mating?

a. Increases heterozygous frequency in population

b. Mating among individuals that are different

c. Reduce homozygous frequency in population

d. A type of random mating

e. none of the above

e

What is the primary genetic consequence of inbreeding?

Increase in homozygosity, decrease in heterozygosity

Self-fertilization (selfing) in plants leads to:

A rapid decline in heterozygotes over generations

Compared to Hardy–Weinberg expectations, inbreeding populations show:

More homozygotes and fewer heterozygotes