Genetics : Mendelian and Population Genetics
Study concepts, example questions & explanations for Genetics
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Example Questions
Example Question #71 : Genetics
If a tall pea plant with the genotype Tt is crossed with a short pea plant with the genotype tt (homozygous recessive), what should the F1 progeny consist of?
1/4 tall Tt
3/4 short tt
1/4 tall TT
1/4 tall Tt
1/2 short tt
1/2 tall Tt
1/2 short tt
1/2 tall TT
1/4 short Tt
1/4 short tt
1/2 tall Tt
1/2 short tt
Using a punnett square one can see we get 1/2 with genotype Tt and half with genotype tt.
T t
t Tt tt
t Tt tt
Example Question #72 : Genetics
Which definition below defines allelic variation?
different mutations can lead to the same disease
the percent of people with a mutation that develop a disorder
a mutation in the same genes causes different diseases
the varying degrees of disaese with the same gene mutated
a mutation in the same genes causes different diseases
Allelic variation is a mutation in the SAME gene causing different diseases. Genetic heterogeneity is when different mutations can lead to the same disease. Variable expressivity is the varying degrees of disease with the same gene mutated. Penetrance refers to the percentage of people with a mutation that develop a disorder.
Example Question #73 : Genetics
A color-blinded man is married to a female carrier.
What percentage of female children born to this couple with be colorblind?
50%
100%
25%
0%
50%
Since colorblindness is a sex-linked gene, female children need to have the sex-linked gene from both their mother and father in order to be colorblind. In this case, the mother will donate a colorblinded gene to half of all offspring, while the dad will give his colorblind gene to all his female children. This means that one out of every two female children will have this trait.
Example Question #74 : Genetics
Human birth size is an example of __________.
divergent selection
stabilizing selection
oppositional selection
directional selection
stabilizing selection
Human birth weight is an example of stabilizing selection, because babies that are too heavy or too light are selected against babies that are typically close to the average weight.
Example Question #74 : Genetics
What is the probability of a red flower (RR) and a white flower (rr) having offspring with pink flowers (Rr)?
0
100
25
50
100
Each parent only carries one type of the allele, so when they give the alleles to their children they would have one allele from each parent. This gives them an genotype of Rr for all of their children. The Rr phenotype is pink.
Example Question #74 : Genetics
Which of the following is not a condition of Hardy-Weinberg population?
Mates are selected for traits that are better for survival.
no organisms enter or leave the population
no mutation
The population size remains large.
Mates are selected for traits that are better for survival.
Hardy-Weinberg is the set of populations that maintain a certain distribution of alleles in a population. In order to maintain this, mating can't choose traits, as that would cause the allele frequency to change over time.
Example Question #81 : Genetics
Which of the following is an example of directional selection?
human babies having a birth weight around seven pounds
an Okapi's color
moths going from mostly white to mostly black
fish that are either 5oz or 50 oz
moths going from mostly white to mostly black
Directional selection is a process of natural selection when a single phenotype is chosen over another, and thus, many of the organisms in the population are phenotype instead of another extreme.
Example Question #82 : Genetics
How is an allele different from a genotype?
An allele is the combination of genotypes.
A genotype is the combination of two or more alleles.
An allele refers to the physical trait, whereas the genotype refers to the DNA sequence.
there is no difference
A genotype is the combination of two or more alleles.
An allele is the specific gene out of many for a given trait. The genotype is the combination of alleles that are present in the individual.
Example Question #83 : Genetics
What is a homozygous individual?
An individual that does not appear physically uniform for a given trait throughout its entire body (such as, spotted hair coat).
An individual that appears physically uniform for a given trait throughout its body (such as, solid brown hair coat).
An individual that expresses the same two alleles for a given trait.
An individual that expresses different alleles for a given trait.
An individual that expresses the same two alleles for a given trait.
A homozygous individual expresses the same two alleles for a given trait. An example would be a person with blue eyes would have two recessive alleles for that eye color, bb.
Example Question #84 : Genetics
If you cross a pea plant that is tall and has genotype Tt with another pea plant that is tall and has genotype Tt, what should their F1 progeny look like?
3/4 tall
1/4 short
1/4 tall
3/4 short
1/2 tall
1/2 short
1/4 medium
1/4 tall
1/2 short
3/4 tall
1/4 short
Using a pungent square, one can determine that 1/2 will have genotype Tt and will be tall, 1/4 will have genotype TT and will also be tall, 1/4 will have genotype tt and will be short.
T t
T TT Tt
t Tt tt
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