Biology 2 Exam 1

Question 1

If two species eat a different diet but one of the food sources is eliminated and both species are forced to eat the same foods, what change in the hybrid zone is most likely to occur?

Answer 1

Fusion is most likely to occur because the 2 species will interact more and similar traits in food acquisition will be selected.

Question 2

Describe the difference between punctuated equilibrium and gradual speciation. How does this affect the population of species?

Answer 2

Punctuated equilibrium- A new organism changes quickly from the parent species and goes unchanged for a long time.

Gradual speciation- A new organism gradually diverges over time. (small steps)

Question 3

What concept did Charles Darwin and Alfred Wallace discover independently

Answer 3

Natural selection

Question 4

Describe the difference between genotype and phenotype.

Answer 4

Phenotype- Physical characteristics (tall, blue eyes, etc.)
Genotype- Genetic makeup (alleles, or Tt, TT, or tt.)

Question 5

Natural selection takes place when there is variation in the population. What is meant by this?

Answer 5

For natural selection to occur there must be variation which allows competition between organisms. The best “fitted” organisms pass on their genes to the next generation.

Question 6

Describe the difference between divergent and convergent evolution.

Answer 6

Divergent Evolution- a type of evolution in which organisms are thought to have the same ancestor, but separated over time.
Convergent Evolution- a type of evolution in which similar traits evolve independently in species that don’t share a common ancestor.

Question 7

What was the evidence that Charles Darwin used to support his theory of evolution by natural selection? Describe each.

Answer 7

fossil evidence, biogeographical evidence, and anatomical evidence.

Question 8

Homologous vs. vestigial structures.

Answer 8

Homologous structures- anatomically similar structures(looks similar)
Vestigial structures- Unused structures without function

Question 9

What is the difference between allopatric and sympatric speciation?

Answer 9

Allopatric speciation- A population forms a new species while geographically isolated from its parent species.
Sympatric speciation- A population forms a new species while remaining in the same location as the parent species.

Question 10

What is reproductive isolation? Describe the different types.

Question 11

Explain the Hardy-Weinberg principle of equilibrium theory.

Answer 11

The Hardy-Weinberg principle assumes an infinitely large population and conditions with no mutations, migration, emigration, or selective pressure for or against genotype.

Question 12

Describe a situation in which a population would undergo the bottleneck effect and explain what impact that would have on the population’s gene pool.

Answer 12

Bottleneck effect- Where a large portion of a population dies from a natural event (earthquakes) which wipes out a large portion of the gene pool.

Question 13

List the ways in which evolution can affect population variation and describe how they influence allele frequencies.

Answer 13

Gene flow
Genetic drift
Mutations
Natural selection

Question 14

Describe natural selection and give an example of natural selection at work in a population.

Answer 14

Natural selection- the process in which organisms adapt and survive to their environment and pass on favorable traits to their offspring
Ex. A population of tortoises with long necks can reach more leaves and have better chances of survival

Question 15

Explain what a cline is and provide examples.

Answer 15

A cline is a type of geographic variation that is seen in populations of a given species that vary gradually across an ecological gradient.
Ex 1. Warm-blooded animals tend to have larger bodies in the cooler climates closer to the earth’s poles, allowing them to better conserve heat. This is considered a latitudinal cline.
Ex 2. Flowering plants tend to bloom at different times depending on where they are along the slope of a mountain. This is known as an altitudinal cline.

Question 16

Give an example of a trait that may have evolved as a result of the handicap principle and explain your reasoning.

Answer 16

The feathers of a peacock may have evolved as a result of the handicap principle. This is because it increases the chances of mating in males.
Handicap principle- Traits that increase mating but reduces survival chances.

Question 17

What is the study of population genetics?

Answer 17

It’s the study of changes in allele and genotype frequencies in a population

Question 18

Microevolution vs. macroevolution.

Answer 18

Microevolution- Organisms change in small ways over time.
Macroevolution- Larger evolutionary changes that result in new species
The processes that gave rise to new species and higher taxonomic groups with widely divergent characters (macroevolution).

Question 19

Which of the following evolutionary forces can introduce new genetic variation into a population?

Answer 19

Mutation and gene flow, nonrandom mating

Question 20

Which type of selection results in greater genetic variability in a population?

Answer 20

Disruptive or Diversifying selection

Question 21

What is used to determine phylogeny?

Answer 21

Evolutionary History

Question 22

On a phylogenetic tree, which term refers to lineages that diverged from the same place?

Answer 22

Sister taxa

Question 23

Describe the process of horizontal gene transfer. Can this be seen only in prokaryotes? explain.

Question 24

Why is it so important for scientists to distinguish between homologous and analogous characteristics before building phylogenetic trees?

Answer 24

Phylogenetic trees are based on evolutionary connections. If an analogous similarity were used on a tree, this would be incorrect and would cause the subsequent branches to be inaccurate.

Question 25

Dolphins and fish have similar body shapes. Is this feature more likely a homologous or analogous trait?

Answer 25

Analogous. Dolphins are mammals and fish are not. Dolphins evolved their bodies like fishes to adapt to the aquatic lifestyle similar

Question 26

Some organisms that appear very closely related on a phylogenetic tree may not actually be closely related. Why is this?

Answer 26

This can be due to convergence and how they appear similar but aren’t

Question 27

Compare the obvious body structure of the two fish above. Assume these two fish came from the same original ancestor. Why might the cavefish have evolved without eyesight? Is there any kind of sensory adaptation? If so, hypothesize how the cave fish has to be able to navigate in a cave, including catching and eating food.

Answer 27

The cavefish might have evolved without eyesight due to the survival of the parents. Since they are harder to find without eyes they survived and passed on their traits. They probably use vibration as their sensory adaption.

Question 28

View the dragons above. The winged trait is considered a dominant trait. Calculate the following using the Hardy-Weinberg equilibrium equation.

Answer 28

q2(aa) = 0.33
q(a) = 0.57
p(A) = 0.43
P2 (AA) = 0.18
2pq(Aa) = 0.49

Question 29

What is the frequency of heterozygote dragons in your population?

Answer 29

0.49

Question 30

List the different levels of the taxonomic classification system. (from most broad to most specific)

Answer 30

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 31

What does the phylogenetic model propose that all three domains of life evolved from a pool of primitive prokaryotes?

Answer 31

Ring of life