Question

Which of the following is FALSE about dominant alleles?

Question 9 options:

	For a given gene, a dominant allele can be common or rare in a population.
	For some genes, there is no allele that is completely dominant to all others.
	Dominant alleles can be adaptive, harmful, or neutral for an organism.
	Dominant alleles are more likely to be inherited than recessive alleles
	A dominant allele affects the phenotype of the organism, whether or not a recessive allele is present. In the life cycles of sexually reproducing organisms, there is a transition from diploid to haploid. This is most similar to which of Mendel's hypotheses? Question 10 options: Genes are discrete units of heredity that do not blend together For a gene with two alleles, one allele is dominant An offspring inherits two alleles of each gene, one from each parent The "law of segregation" The "law of independent assortment"

Answer 1

Question 9

Option a is correct. When people hear the word “dominant”, often they incorrectly believe that the majority of the population expresses this trait. Describing a trait as dominant does not mean it is the most common; it means that it is expressed over the recessive trait. For example, tongue rolling is a dominant trait, controlled by the dominant version of a particular gene (R). Individuals with one or two copies of R will exhibit tongue rolling. Only individuals that have two recessive versions of the gene (r) will lack the ability to tongue roll. But what does this tell us about the relative commonness or rareness of tongue rolling in a population?
How frequently a trait is observed in a population is not related to whether or not it is dominant or recessive. Instead, it is a reflection of how frequently the gene responsible for causing a trait is found in people. For example, polydactyly, the presence of extra fingers and/or toes, can be caused by a dominant mutation. However, polydactyly only occurs in 0.31-6.18 births in 1,000, depending on ethnic background. This means it is very rare for a person to have the gene mutation that causes polydactyly, even though it is dominant.

Option B is also correct. Dominance affects the phenotype derived from an organism's genes, but it does not affect the way these genes are inherited. Complete dominanceoccurs when the heterozygote phenotype is indistinguishable from that of the homozygousparent. However, sometimes the heterozygote displays a phenotype that is an intermediate between the phenotypes of both homozygote parents (one of which is homozygous dominant, and the other of which is homozygous recessive). This intermediate phenotype is a demonstration of partial or incomplete dominance. When partial dominance occurs, a range of phenotypes is usually observed among the offspring. Although the offspring may show a variety of phenotypes, each one will lie along a continuum bracketed by the homozygous parental phenotypes.

Option c is also correct. Two types of dominant alleles can cause damage and may be selected against. The first is a gain-of-function allele, which causes the individual to exhibit a trait it would not exhibit normally. In our flower example, this would mean that the flowers are generally white, but this gene causes a strange color (purple) to be produced. In humans, an example of this phenomenon is dwarfism, during which the FGFR3 gene causes the bones to stop growing before they generally do.. The other type of dominant allele that may be harmful is known as a dominant negative allele because it produces proteins that prevent other proteins from doing their jobs. Thus it has a negative effect. If our purple flowers were produced because the dominant gene blocked the white from exhibiting, this dominant gene would be a dominant negative allele.

Option D is false. No, recessive alleles are equally likely to be inherited (if your dealing with only those two types of alleles). BUT, dominant alleles are the ones that show up. That is precisely why they are called dominant. Compared to recessive alleles, dominant ones will overrule the others, making it the one inherited.

Option E is correct. , dominance may change according to the level of organization of the phenotype. Variations of dominance highlight the complexity of understanding genetic influences on phenotypes.

Question 10

Option D is correct. The law of segregation beause this transition marks the anaphase of mesois 1 and that a marks the mechanistic behavior of chromosomes during mesois 1