Question 1

Carriers of cystic fibrosis have some protection against intestinal infections such as cholera.However,people with two copies of the cystic fibrosis allele develop a life-threatening disease.The mutant allele is very common in people of northern European descent because of

Accepted Answer

The answer of Carriers of cystic fibrosis have some protection...

Question 2

The bottleneck effect

Accepted Answer

The bottleneck effect occurs when many members of a population die, resulting in a great loss of genetic diversity. This can happen due to natural disasters, disease outbreaks or other events that reduce the size of a population significantly. With fewer individuals, there is less genetic variability, and certain traits may be overrepresented in the surviving population. This can reduce the overall fitness of the population and make it more vulnerable to future challenges.

Question 3

Darwin obtained which of the following in the Essay on the Principle of Population by Malthus?

Accepted Answer

Darwin obtained the idea of "struggle for existence" from Malthus' Essay on the Principle of Population, which stated that more individuals of a population are born than can survive to reproduce. This idea was a crucial component of Darwin's theory of evolution by natural selection.

Question 4

Sexually dimorphic features do not include

Accepted Answer

Sexually dimorphic features are physical characteristics that differ between males and females of a species. Intelligence is not a physical characteristic and therefore does not fall under the category of sexually dimorphic features.

Question 5

Darwin made which observation while on his four-year voyage on the HMS Beagle?

Accepted Answer

Darwin observed that organisms are varied and some variations are inherited. This observation was a crucial foundation for his theory of natural selection, which explains how favorable variations in a population can lead to evolutionary changes over time. Although Darwin did make other important observations during his voyage on the HMS Beagle, such as the fact that more individuals of a population are born than can survive to reproduce, it was his observation about inherited variation that had the most profound impact on his thinking about evolution.

Question 6

Use the Hardy-Weinberg equations: p + q = 1 and p² + 2pq + q² = 1.If the dominant allele frequency is 0.8,then what percent of the population will be homozygous recessive?

Accepted Answer

The frequency of the recessive allele (q) is 1 - 0.8 = 0.2. The percentage of the population that is homozygous recessive is q^2 = (0.2)^2 = 0.04, or 4%.

Question 7

Ancestors of giraffes with shorter necks could not reach branches high up in trees for food.This led to ____ for giraffes with longer necks.

Accepted Answer

The situation described suggests that giraffes with longer necks are at an advantage because they are better able to access food sources that giraffes with shorter necks cannot reach. This is an example of directional selection, as the trait of a longer neck is being selected for, and is becoming more prevalent in the population over time.

Question 8

A male peacock has enormous tail feathers that it uses in mating displays to attract females.While the tail feathers are an advantage in mating,what is the potential disadvantage of these feathers to the male?

Accepted Answer

Producing and carrying around such large and ornate feathers requires a significant amount of energy, which could be a potential disadvantage for the male peacock.

Question 9

The North American bison was hunted to near-extinction in the 1800s.It has since recovered,but with decreased genetic diversity.This is an example of

Accepted Answer

The near-extinction of the North American bison in the 1800s caused a bottleneck effect, where the population was reduced to a small size and genetic diversity was lost. This can have long-lasting effects on the genetic makeup of a population.

Question 10

Alleles conferring red plumage to cardinal males are common because red plumage

Accepted Answer

Red plumage is preferred by female cardinals in choosing a mate. This preference leads to the selection and spread of alleles that confer red plumage in males.

Question 11

The founder effect

Accepted Answer

The founder effect occurs when a small group of individuals leave their home population and establish a new settlement, mating only among themselves. This can result in a loss of genetic diversity compared to the original population.

Question 12

In the section "Investigating Life: Size Matters in Fishing Frenzy",a population declines when

Accepted Answer

A population declines when the death rate exceeds the reproductive rate. This means that the number of individuals dying in the population is greater than the number of individuals being born and this leads to a decrease in population size. Therefore, option A is the best choice.

Question 13

The few ancestors of the Galapagos finches who colonized the islands is an example of

Accepted Answer

The few ancestors of the Galapagos finches who colonized the islands is an example of founder effect, which is a type of genetic drift that occurs when a small group of individuals colonizes a new area, resulting in a new population with decreased genetic variation compared to the original population.

Question 14

Farmers and horticulturalists bred broccoli,cauliflower,kale,and cabbage from the wild mustard plant through _____.

Accepted Answer

Farmers and horticulturalists purposefully selected and bred plants with desirable traits, such as larger heads or specific colors, through artificial selection. This process is different from natural selection, where environmental pressures and random genetic mutations determine which organisms survive and reproduce.

Question 15

Use the Hardy-Weinberg equations: p + q = 1 and p² + 2pq + q² = 1.If the dominant allele frequency is 0.8,then what percent of the population will be homozygous dominant?

Accepted Answer

Let p = 0.8 (frequency of dominant allele)
Then q = 0.2 (frequency of recessive allele)

To find the percent of the population that will be homozygous dominant (SS), we need to use the Hardy-Weinberg equation:
p^2 + 2pq + q^2 = 1
where:
p^2 = frequency of homozygous dominant (SS)
2pq = frequency of heterozygous (Ss)
q^2 = frequency of homozygous recessive (ss)

We want to find p^2:
p^2 + 2pq + q^2 = 1
0.8^2 + 2(0.8)(0.2) + 0.2^2 = 0.64 + 0.32 + 0.04 = 1
p^2 = 0.64

Therefore, 64% of the population will be homozygous dominant (SS).

Question 16

Darwin concluded from his observations of nature and readings that

Accepted Answer

The answer of Darwin concluded from his observations of nature...

Question 17

Ancestors of the Galapagos finches had two different types of seeds to eat on some islands.Some seeds were very small,and required small beaks to handle.Other seeds were very large and required large strong beaks to crack.This led to ____ among the Galapagos finches.

Accepted Answer

The existence of two different types of seeds selecting for birds with small beaks and birds with large, strong beaks respectively creates two distinct groups with higher fitness, leading to disruptive selection.

Question 18

Use the Hardy-Weinberg equations: p + q = 1 and p² + 2pq + q² = 1.If the dominant allele frequency is 0.8,then what percent of the population will be heterozygous?

Accepted Answer

Calculating 2pq gives the percentage of heterozygotes.Please see section 12.4 for more information.

Question 19

Babies that are at a low birth weight are more likely to have health problems,while women will have difficulty delivering babies with high birth weight.Together this leads to ______ for babies of average birth weight.

Accepted Answer

Stabilizing selection favors individuals with intermediate traits and selects against extremes on either end. In this scenario, low birth weight and high birth weight both have disadvantages, but average birth weight falls within the range of favorable traits. The presence of difficulties with either extreme birth weight leads to selection for an average birth weight, resulting in stabilizing selection.

Question 20

If an environment changes rapidly,organisms with ____ will be more likely to survive and reproduce.

Accepted Answer

Rapid change does not leave time for new mutations to arise,so existing advantages phenotypes win out evolutionarily.Please see section 12.3 for more information.

Quiz 12: Forces of Evolutionary Change