1. Select the statement that best describes the relationship between the terms “
ID: 65625 • Letter: 1
Question
1. Select the statement that best describes the relationship between the terms “allele” and “phenotype”.
Select one:
a. Every phenotype is determined by the dominant or recessive genes that make up the alleles.
b. Each allele of a gene encodes a different phenotype for the trait determined by that gene.
c. The alleles determine the phenotype when they are dominant.
d. The phenotype is a mixture of the alleles present for the genes on homologous chromosomes.
2.
Polydactyly is a genetic condition that results in people born with extra fingers and toes (see picture). In countries with advanced health care the extra digits are typically removed shortly after birth, but in less-developed countries people live with the extra digits.
Polydactyly is due to a mutation in a single gene. The allele that causes polydactyly is a GAIN-OF-FUNCTION allele. Pick the most accurate statement from the list below about the GENE associated with polydactyly.
Select one:
a. The gene promotes the formation of toes.
b. The gene inhibits the formation of toes.
c. The gene influences the formation of toes in the embryo.
3.
From the list below, select the most accurate statement about the law of segregation.
Select one:
a. Segregation occurs in heterozygotes but does not occur in homozygotes.
b. Segregation does not occur between genes located close together on the same chromosome.
c. Segregation occurs in meiosis I when homologous chromosomes are separated into the two daughter cells.
d. Segregation occurs during anaphase of mitosis, anaphase of meiosis I, and anaphase of meiosis II.sd
Explanation / Answer
Answer 1: Option B
b. Each allele of a gene encodes a different phenotype for the trait determined by that gene.
If a gene for eye color has two alleles, then it will have minimum two phenotypes.
Answer 2: Option C
The gene for polydactyly promotes the formation of toes and fingers. We have five fingers or toes, but if even one allele for polydactyly is active, it will lead to formation of extra finger or toe.
Answer 3: Option D
Segregation occurs in both homozygotes and heterozygotes, because its simply a process of separation of alleles of a gene. So option A is incorrect. Segregation occurs between alleles of a gene, not between two genes. Thus, option B is also incorrect. Segregation occurs in anaphase, thus option D is correct.
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