All AP Biology Resources
Example Questions
Example Question #11 : Understanding Genetic Drift, Bottleneck Effect, And Founder Effect
For natural selection to occur, which of the following must be true of a population?
Food is not available
Having many populations in one area
The population must be isolated
Must be capable of sexual reproduction
Phenotypic variations must be based on genetic variations
Phenotypic variations must be based on genetic variations
Example Question #12 : Understanding Genetic Drift, Bottleneck Effect, And Founder Effect
Which type of isolation between populations is due to barriers related to time, such as differences in mating periods or differences in the time of day that individuals are most active.
Geographic isolation
Two of these
Reproductive isolation
Behavioral isolation
Temporal isolation
Temporal isolation
Temporal isolation is between populations due to barriers related to time, such as differences in mating periods or differences in the time of day that individuals are most active. Geographic isolation between populations is due to physical barriers, not time. It wouldn't be both of them because only temporal isolation deals with time, versus geographic isolation is based on the physical barrier between populations such as mountains, rivers, or, for example, insects living on different trees in the jungle. Reproductive isolation is the inability to interbreed between species for various reasons like sterile offspring, physical incompatibility, or different mating rituals.
Example Question #13 : Understanding Genetic Drift, Bottleneck Effect, And Founder Effect
Which of the following is an example of genetic drift?
An organism is born with traits not attributed to the alleles of its parents, but a brand new allele.
Individuals from one population move and mate with members of a different population.
All of these are examples of genetic drift.
An allele increases in frequency due to the increase in fitness it provides the organism.
A massive storm randomly kills many individuals in a population, changing the frequency of alleles in that population.
A massive storm randomly kills many individuals in a population, changing the frequency of alleles in that population.
Genetic drift occurs when the frequency of alleles in a population change by random chance. Change in allele frequency based on biological fitness is natural selection, not genetic drift. The change in allele frequency due to members moving from one population to another describes migration. A brand new allele that did not exist in the parents is the result of mutation.
Example Question #44 : Population Genetics
A population of wolves is living in an area when a tornado strikes and kills most of the wolves. The population of the wolves has been greatly reduced. Which of the following best describes the impact of the disaster on the genetic makeup of the population of wolves?
Cannot be determined from the information
Gene flow
Hardy-Weinberg principle
Bottleneck effect
Founder effect
Bottleneck effect
The Bottleneck effect happens when an event occurs that drastically reduces the population of a species. The remaining individuals most likely do not represent the genetics of the population before the catastrophic event, since it becomes a much smaller sample size.
Example Question #21 : Understanding Genetic Drift, Bottleneck Effect, And Founder Effect
There was once a population on planet M311, called the Freg, who lived on a planet not unlike Earth. At the height of the Fregs technology and evolution, a collection of asteroids bombarded the planet and the devastation was so great that the planet was split in two, as was the Freg population. Much of the Freg population died, but many still survived on both pieces of M311.
The asteroid was an enormous catastrophe that drastically reduced the Freg population. As a result, their gene pool will be significantly smaller. What is this phenomenon called?
The Extinction Example
The Bottleneck Effect
Radical Genetecism
The Dinosaur Hypothesis
The Darwin Conundrum
The Bottleneck Effect
The bottleneck effect is the correct answer here. The effect is defined as a sharp reduction in a populations size due to an environmental effect. In this scenario, the asteroids were the environmental effect and it caused the Freg population to decrease significantly. Also, none of the other answers are real theories.
Example Question #241 : Evolution And Genetics
Which of the following is true of genetic drift?
None of these statements are true
Genetic drift involves the random change of allele frequencies in a population
The effects of genetic drift are negligible in smaller populations
Genetic drift only occurs in populations at Hardy-Weinberg equilibrium
Genetic drift helps reduce the frequency of harmful alleles in a population
Genetic drift involves the random change of allele frequencies in a population
Genetic drift is a direct result of independent assortment. Since genes are not inherited by any organized mechanism, there are random fluctuations during which certain alleles experience an increase in frequency over others.
Genetic drift results in random changes in allele frequency; these changes are not a cause of genetic drift. In smaller populations and extreme cases, random changes can result in the loss of an allele entirely within the population. The results of genetic drift are more prominent in smaller populations due to their already reduced gene pool. Since genetic drift is random, both beneficial and harmful alleles can be promoted or eliminated.
Genetic drift cannot increase genetic diversity. The only way to increase genetic diversity is by the introduction of new traits and alleles. Genetic drift can reduce genetic diversity by eliminating alleles from a population, but is incapable of creating new traits. This can only be done through mutation.
Example Question #1 : Perform Chi Squared Test
In a population of flowers, red is dominant to white. A true-breeding white flower is crossed with a heterozygous flower. Determine the expected ratios of this cross. Given observed values: 63 white flowers, 37 red flowers, determine:
1) The chi squared value
2) The degrees of freedom
3) The p-value
1) 14.44
2) 2
3) p>0.005
1) 6.76
2) 1
3) p>0.025
1) 3.35
2) 4
3) p=0.25
1) 6.76
2) 2
3) p=0.05
1) 6.76
2) 1
3) p>0.025
First, determine the expected ratios using a Punnet Square. Given that red is dominant to white, the genotype of a true-breeding white flower can be denoted rr, and the genotype of a heterozygous flower can be denoted Rr. This cross will produce 50% Rr, 50% rr. Then, converting these percentages to decimals (50%= 0.50), and multiplying by the total population size of the observed population (0.50*100), gives expected values of 50 Rr (red flowers) and 50 rr (white flowers). These expected values and the observed values can then be plugged into the chi square equation . The equation will be . Degrees of freedom is n-1, so 2-1= 1. To determine p-value, use critical values table. The chi square value of 6.76 with 1 degrees of freedom will fall between a critical value corresponding with a p-value of 0.05 and 0.025. Thus, p>0.025
Example Question #1 : Perform Chi Squared Test
In a chi squared test, the greater the difference between the observed and expected frequencies of a trait, the ___ the p-value.
more positive
more negative
greater
lower
lower
A larger difference between observed and expected values will result in a larger chi square value. Using the critical values table, for a given degrees of freedom, as chi square value increases, p-value decreases.
Example Question #1 : Perform Chi Squared Test
If the p-value determined by a chi-square test is low, which is possible
The null hypothesis is accepted
The alternative hypothesis is rejected
The null hypothesis is rejected
The chi square value is also low
The null hypothesis is rejected
When the p-value is equal to or below the significance level (alpha), the null hypothesis is rejected. For the p-value to be low, the chi square value would need to be large (large difference between observed and expected values). The null hypothesis would not be accepted (under no circumstance is a null hypothesis “accepted”; onlay rejected or failed to reject). The alternative hypothesis would be accepted if the p-value is equal to or below the significance level (alpha).
Example Question #1 : Perform Chi Squared Test
Which of the following chi square values would likely result in rejection of the null hypothesis?
1.97
7.36
13.8
0.35
13.8
A larger difference between observed and expected values will result in a larger chi square value. Using the critical values table, for a given degrees of freedom, as chi square value increases, p-value decreases. A small p-value results in rejection of the null hypothesis.