BIOB51 Practice Questions Quiz UTSC

UTSC BIOB51 Practise questions 

NATURAL SELECTION IN THE ROCK POCKET MICE

 Question 1

Define “mutation.”
Selected Mutation is a copying error that causes a change in the chemical letter that make up our Answer: genes.

  Question 2

Is the following statement true or false? Justify your answer in one or two sentences: “Mutations are caused by selective pressure in the environment.”
Selected False, mutations are not caused by selective pressure in the environment. Although mutations can help
Answer: in pressured environments, the mutation itself is caused be an error in the copying of the genetic code.

  Question 3

Is the following statement true or false? Justify your answer in one or two sentences: “The same mutation could be advantageous in some environments but deleterious in others.”

Selected Answer:

True, the same mutation could be advantageous in some environments but deleterious in others. For example, the white pocket mouse has a mutation that causes it fur to become darker. This dark fur can be advantageous in an environment with moulted rocks since the fur can be use to blend in with the surrounding rocks to avoid predators. However, this dark fur mutation can be deleterious in the desert where the sandy fields make the dark fur look like a bulls-eye target for predators.

 Question 4

Does the example of evolution of fur colour in the Rock Pocket Mouse fit Darwin’s postulates? State each postulate and briefly describe how this example relates to each postulate.

Selected Answer:

1. Indiviuals within populations are variable
There are pocket mouse that have white top fur or dark top fur.
Although both pocket mice have a white underbelly.

2. Some of these variations are passed on to offspring = heritable
The mutations causing dark fur mice allowed for these species to have a
higher survival rate in the moulted rock environment. These dark furred mice then produced offspring that also had dark fur (through copying their parent
gene). With a higher survival rate, these dark fur mice produced more offspring with the same mutation.

3. Many more offsprings are produced than can survive and reproduce
The owls, coyotes, and rattle snakes eat the pocket mice. Thus not
all of the offspring that are produced will survive to reproduce

4. Survival and reproduction are not random. Individuals with favorable traits will produce more
offspring over their life-time than individuals with less favorable traits.
In the moulted rock climates, the mutated dark top furred mouse had
a favourable trait since it was hard to see by predators, unlike the white colored mice. Since most of the predators perceive color, the dark-furred mice camouflaged with the rocks, whereas the white-colored mice stand out. Thus the dark-furred mice have a higher survival rate allowing them a longer time to live and produce offspring that have the same mutation. With this favorable trait more dark-furred mice are produced and survive to reproduce, whereas the white-furred mice as flushed out, since their color make them easy targets. 

 Question 5
As you saw in the film, rock pocket mice evolved to have dark-
colored fur in certain habitats. Inthree to five
sentences, explain how this trait increased in frequency in the population. Include the following key terms: “fitness” (or “fit”), “survival” (or “survive”), “selection” (or “selective”), and“evolution” (or “evolve”).

Selected Answer:

In a moulted rock environment where everything is black a white-furred mouse is like an "eat me" sign. Having a mutation that made all the top fur of the mouse dark allowed for the dark-furred mouse to blend in with the surroundings and naturally camouflage with the rocks. These selective feature allowed the mutated mouse to survive and reproduce more mice with the same mutated genes for dark fur. As the fitness of the dark-furred mice rose, while the white-furred mice diminished, the pocket mice species evolved into mostly having dark-fur.


  Question 6
Near the end of the film, Dr. Sean B. Carroll states that “while mutation is random, natural s electionis not.” In your own words, explain how this is possible. (also discussed briefly on p. 93 of your text).

Selected Mutation is an error in the genetic coding, which can happen anywhere in any gene, thus meaning Answer: mutation is random. On the other hand, natural selection occurs ONLY when the mutation in beneficial to the species environment. If this mutation allows the species to live and produce offspring that eventually produce more offspring with this mutation than natural selection has occurred. Thus Natural selection occurs under situations where mutation is a "winning" factor and is not random. 

Question 7

Suppose you are studying a recently discovered population of rock pocket mice with dark- colored fur that lives on volcanic rock. You take a DNA sample from a member of this new population and identify the DNA sequence of a gene known to play a role in fur color. The sequence you g et is identical to that of the same gene in another rock pocket mouse population with dark- colored fur that lives on a different patch of volcanic rock. Which of the following could explain this observation?

Ans. The volcanic rock caused the same mutation in each rock pocket mouse population, resulting in dark coloration. 


  Question 8

For rock pocket mice, which of the following contributes to selective pressure favoring dark-
colored fur? There may be more than one correct response.

• Genetic Mutations Rock Colour
  

 Question 9
Suppose you are studying a new population of rock pocket mice in Arizona. These mice li ve on arecently discovered patch of dark-
colored volcanic rock. This environment does not have nearly asmany visual predators as i n previously studied areas in New Mexico. You observed the followingnumbers of light- and
dark-colored mice on this new patch of rock.

Describe what the data shows in one or two sentences, then outline one possible hypothesis that could explain the observed

data. Be sure to include the following key words in your answer:“selection” (or “selective”) , “fitness” (or “fit”), and “survival” (or “survive”).

Selected From the data, we see that there is a comparable amount of light-mice and dark-mice in the population. This Answer: may be caused by the fact that not AS MANY predators are visual predators, making color not a selective trait

for the mice. As color doesn’t particularly effect their survival rate, the fitness between the two colored mice are similar.

 Question 10
You decide to move 50 of the newly discovered light-
colored rock pocket mice from Arizona to acolony in New Mexico (described in the
video) that also lives on dark-colored volcanic rock. Youalso move 50 dark-
colored mice from the New Mexico

colony to the Arizona colony. You monitor the populations for five years and observe the following. 

Summarize the data in two or three sentences. Then
provide an explanation for theseobservations in a few
sentences. Be sure to include the following key words in your answer:“selection” (or “sele ctive”), “fitness” (or “fit”), and “survival” (or “survive”).

Selected Answer:

From the chart for the mouse population in New Mexico, we see that the addition white-mice gradually die, whereas the dark-mice gradually overpopulates. This shows that with more white-furred mice as targets for the visual predators the longer period of time the dark-furred mice have to survive and reproduce. As the selective trait for white-fur is unfavorable in this environment, the fitness of the white-furred mice is far lower than that of the dark-furred mice. Then from the chart for the mouse population in Arizona, we see that the addition of dark-mice causes an overpopulation of dark-mice compared to white-mice, however, over time there is a very slight change in the population ratio of dark mice:white mice. This shows that the selection for color does not greatly affect the fitness of each colored mice, due to the fact that there are not many visual predators, thus resulting to similar survival rates for both colored mice. 

 Question 11
You are talking with your non-biologist friend on the bus after watching this video
together. The non-biologist turns to you and says
"It seems incredible that Rock Pocket mouse populations repeatedly evolve dark fur colour--the exact trait that is needed for crypsis on dark rock. If mutation is random, and can happen at any place in the mouse genome, then how can this particular mutation happen over and over again, just when it is needed?"
Provide an answer for your friend. It may help you to consider which parts of this statement are facts, which are incorrect assumptions, and how the facts can lead to the observation of repeated evolution of dark colouration. (Yes, this question is challenging--think about it and give it a shot!). 

Selected Answer:

"The mutation itself doesn't occur over and over again, it's that the this mutation is copied into the genetic coding of the mutated species' offspring, allowing it to have dark-fur. As the dark-fur is a morefavorable feature for survival, these offspring are more likely to survive and reproduce more mice with the same mutation. As more of the mutated offspring survive to reproduce there will be more dark-furred mice in that area; until the species evolves to be mostly dark-furred mice compared to white-furred mice."