Question 1

What is the genotype of an individual that is lives in protection from both sickle cell disease and malaria?

Accepted Answer

The genotype of an individual with protection from both sickle cell disease and malaria would have one copy of the sickle cell allele (HbS) and one copy of the normal allele (HbA), as well as one copy of the trait for thalassemia (U1) and one copy of the trait for glucose-6-phosphate dehydrogenase deficiency (P1). This genotype is represented as Hb^AHb^S. Option B is the only one that fits this description. Option A has an additional copy of the HbA allele, which does not provide protection against malaria. Option C has two copies of the sickle cell allele, which can lead to sickle cell disease. Option D has an incorrect notation for the second trait. Option E has an incorrect notation for the thalassemia trait.

Question 2

Individuals who inherit sickle cell disease,a recessive disorder,tend to die at an early age while individuals who are homozygous for their blood cells survive.How does the recessive allele persist in the population?

Accepted Answer

Individuals who are heterozygous for the sickle cell trait have an advantage in certain environments. In areas where malaria is common, individuals with one copy of the sickle cell allele have a higher chance of surviving malaria infections. This results in the spread and persistence of the recessive allele in the population. This phenomenon is called heterozygote advantage or balanced polymorphism.

Question 3

Polydactylism (possessing more than five fingers per hand)within the Amish population in Pennsylvania is considered an example of founder effect.This is because the frequency of polydactylism among the Amish in Pennsylvania is identical to its frequency among the Amish population in Germany.

Accepted Answer

The frequency of polydactylism among the Amish in Pennsylvania is different to its frequency among the Amish population in Germany and therefore is an example of founder effect.

Question 4

If the survivors of an original population survived due to specific phenotypes that they possessed,then this event is an example of

Accepted Answer

Natural selection is the process by which specific traits or phenotypes become more prevalent in a population over time because they provide a survival advantage. In this case, the survivors of the original population possessed certain phenotypes that allowed them to survive, indicating that natural selection played a role in their survival. Genetic drift refers to random fluctuations in allele frequencies in small populations and would not necessarily explain the survival of specific phenotypes. The founder effect refers to a small group of individuals establishing a new population, which may have reduced genetic diversity, but does not necessarily involve specific phenotypes. Industrial melanism refers to the darkening of organisms in response to pollution and is not related to the scenario described.

Question 5

Microevolution is the term that applies to which of the following?

Accepted Answer

Microevolution refers to small-scale changes over a short period of time, such as changes in allele frequencies within a population. Large-scale changes over a long period of time are referred to as macroevolution. Option A is incorrect because it is too broad and does not accurately describe the term. Option B is incorrect because it only describes macroevolution. Option C is partially correct but does not include the time frame. Option E is incorrect because it is too narrow and only pertains to microorganisms.

Question 6

A fraction of the original green frog population survives to reproduce and generate the new population.If the survivors of the original population survived by chance,then this event is an example of

Accepted Answer

This scenario describes genetic drift, which is the random fluctuation of gene frequencies in a small population due to chance events such as a natural disaster or, in this case, only a fraction of the original population surviving. Natural selection refers to the process by which certain traits are selected for or against based on their survival or reproductive advantages. Founder effect refers to a small group of individuals starting a new population with a limited set of genetic variations. Industrial melanism refers to a specific example of natural selection where darker pigmentation is advantageous in polluted environments.

Question 7

Natural selection will favor directional,stabilizing and disruptive selection in the same population simultaneously.

Accepted Answer

Natural selection will favor only one type of selection at a time within a given population.

Question 8

A population of bacteria is in Hardy-Weinberg equilibrium.However,through repeated exposure to an antibiotic,the frequency of the recessive allele is rapidly increasing.What is the most likely explanation for this response?

Accepted Answer

The recessive allele is likely providing resistance to the antibiotic, leading to an increase in its frequency due to selective pressure.

Question 9

In what type of environment is being heterozygous in regards to the sickle cell trait an advantage?

Accepted Answer

Being heterozygous for the sickle cell trait provides an advantage in environments that have malaria. Individuals who are heterozygous have a lower risk of dying from malaria than individuals who are homozygous for either the normal hemoglobin or sickle cell hemoglobin genes. This is because the sickle cell trait provides some resistance to the malaria parasite, making it more difficult for the parasite to survive and reproduce in red blood cells. Therefore, in areas where malaria is common, the sickle cell trait is an advantage.

Question 10

British land snails primarily occur in two extreme phenotypes.This is an example of

Accepted Answer

This is an example of disruptive selection because the two extreme phenotypes (presumably light and dark colored snails) are being favored over the intermediate phenotype. This can lead to the evolution of different subspecies or even species if the two extremes become isolated from each other.

Quiz 15: Evolution on a Small Scale