Some populations of Atlantic tomcod fish have an allele that makes the fish resistant to toxic pollutants called PCBs.

Question

Tomcod populations in several rivers were analyzed for the presence of this allele. Each river had varying levels of PCB pollution.

Which of the following results would best support the conclusion that natural selection is influencing the presence of this allele in the tomcod populations?

Dioxins and DL-PCBs in Foods

(1 point)
Responses

The rivers with high PCB levels have larger percentages of tomcod with this allele than the rivers without PCBs.
The rivers with high PCB levels have larger percentages of tomcod with this allele than the rivers without PCBs.

Eggs from tomcod without this allele can hatch in rivers with or without PCBs, and eggs from tomcod with this allele can only hatch in rivers without PCBs.
Eggs from tomcod without this allele can hatch in rivers with or without PCBs, and eggs from tomcod with this allele can only hatch in rivers without PCBs.

All of the tomcod in each of the rivers have this allele.
All of the tomcod in each of the rivers have this allele.

The percentage of tomcod with this allele remains the same from year to year in each river.

Answer 1

The result that would best support the conclusion that natural selection is influencing the presence of this allele in the tomcod populations is:

The rivers with high PCB levels have larger percentages of tomcod with this allele than the rivers without PCBs.

This observation suggests that natural selection is favoring the allele in environments where PCBs are present, as fish with the allele are more likely to survive and reproduce in polluted conditions compared to those without the allele.

Answer 2

Stephen's woodrat can consume juniper plants (toxic to most animals) without harm due to its specialized liver enzymes. Which explanation best accounts for the prevalence of these enzymes in the woodrat population?

(1 point)
Responses

The enzymes reduce the genetic diversity and variety of traits of the woodrats.
The enzymes reduce the genetic diversity and variety of traits of the woodrats.

The enzymes increase the ability of the woodrats to survive and pass on their genes.
The enzymes increase the ability of the woodrats to survive and pass on their genes.

The enzymes allow the woodrats to grow much larger.
The enzymes allow the woodrats to grow much larger.

The enzymes make the woodrats poisonous to their predators.

Answer 3

The explanation that best accounts for the prevalence of these enzymes in the woodrat population is:

The enzymes increase the ability of the woodrats to survive and pass on their genes.

This is because the specialized liver enzymes enable the woodrats to consume juniper plants without harm, thus allowing them to access a unique food source and potentially outcompete other animals that cannot consume these toxic plants. As a result, woodrats with these enzymes are more likely to survive, reproduce, and pass on these advantageous traits to their offspring.

Answer 4

Which of the following statements regarding evolution is true?(1 point)
Responses

Evolution anticipates future changes in environment and allows organisms to adapt accordingly
Evolution anticipates future changes in environment and allows organisms to adapt accordingly

There is a distinct origin and end goal
There is a distinct origin and end goal

There is no overall direction, simply a response to local conditions
There is no overall direction, simply a response to local conditions

It is typically observable in a single generation

Answer 5

The true statement regarding evolution is:

There is no overall direction, simply a response to local conditions.

Evolution is a process that happens over long periods of time as populations adapt to their environments through natural selection, genetic drift, mutation, and other mechanisms. It does not have a specific direction or end goal; rather, it is shaped by the conditions present in an organism's environment.

Answer 6

What is the first major cause of genetic change in populations?(1 point)
Responses

Random mutation
Random mutation

Natural selection
Natural selection

Environmental change
Environmental change

Evolution

Answer 7

The first major cause of genetic change in populations is:

Random mutation.

Mutations are changes in the DNA sequence that can introduce new genetic variations into a population. These variations can then be subject to natural selection, genetic drift, and other evolutionary processes, but it is the random mutation that first generates the genetic diversity that evolution can act upon.

Answer 8

There was a prolonged drought on the Galapagos Islands and most plants died. The plants that survived the drought were mainly bushes that had large seeds. Only finches (birds) that had larger beaks are able to crack these large seeds. Below are three possible ways that the finch population might change in the generations after a drought. The solid line shows that range of beak sizes before the drought. The dashed line shows how the beak sizes might change after the drought. Using your understanding of natural selection, which change in the population is most likely to occur after a drought?(1 point)
Responses

Graph A
Graph A

Graph C
Graph C

Graph B

Answer 9

Without the specific graphs to reference, I can provide a general guideline for how to interpret the scenario you've described regarding the finch population after a prolonged drought.

In the scenario where only finches with larger beaks can effectively crack the larger seeds produced by the surviving bushes, natural selection would favor these finches. Over generations, you would expect to see a shift in the population's beak size towards larger sizes because these birds would have a higher survival and reproduction rate than those with smaller beaks.

Therefore, the change in the population that is most likely to occur after the drought would be represented by a graph showing a shift in beak size towards larger beaks (Graph B would be the most likely choice if it shows a similar trend).

If you have specific descriptions or patterns in the graphs, I can help you further narrow it down!

Answer 10

Please complete the sentences below by dragging the term into the sentence to make it correct. (2 points)
Put responses in the correct input to answer the question. Select a response, navigate to the desired input and insert the response. Responses can be selected and inserted using the space bar, enter key, left mouse button or touchpad. Responses can also be moved by dragging with a mouse.
Traits that appear in a population as a bell curve or normal distribution (a range) are referred to as Response area traits. These traits are controlled by multiple genes. Traits that appear in two forms (like purple or white pea plant flowers) are controlled by one gene and are called Response area. Response area is an example of a polygenic trait. Response area is either dark colored or light colored and this is an example of a monogenic trait.
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Answer 11

Here are the completed sentences with the appropriate terms filled in:

Traits that appear in a population as a bell curve or normal distribution (a range) are referred to as polygenic traits. These traits are controlled by multiple genes. Traits that appear in two forms (like purple or white pea plant flowers) are controlled by one gene and are called monogenic traits. Flower color is an example of a polygenic trait. Pea plant flower color is either dark colored or light colored and this is an example of a monogenic trait.

(Note: The specific words for the last two sentences are inferred based on common examples of polygenic and monogenic traits, but if there are specific terms you were provided with, please use those instead.)