Q: Which equation correctly represents the calculation of recombination frequency ($$RF) in a $$genetic cross?

$$RF = \frac{\text{Number of recombinant offspring}}{\text{Total offspring}} \times 100$$

Question 1

In a dihybrid testcross involving Drosophila, the genes for body color (b) and wing shape (vg) are found on the same chromosome. If the recombination frequency between these genes is 17%, what does this indicate about their physical relationship on the chromosome?

Accepted Answer

They are located on the same chromosome but can be separated by crossing over, with a 17% chance of recombination.

Question 2

If the F1 dihybrid female (b+ vg+/b vg) is crossed with a double mutant male (b vg/b vg), which of the following phenotypes would be considered recombinant offspring?

Accepted Answer

Gray body, vestigial wings

Question 3

Which equation correctly represents the calculation of recombination frequency ($$RF) in a $$genetic cross?

Accepted Answer

$$RF = \frac{	ext{Number of recombinant offspring}}{	ext{Total offspring}} 	imes 100$$

Question 4

A deletion mutation occurs in a chromosome. Which of the following best describes this event?

Accepted Answer

A segment of the chromosome is removed.

Question 5

Which chromosomal alteration is most likely to result in the Philadelphia chromosome, associated with chronic myelogenous leukemia?

Accepted Answer

Reciprocal translocation between chromosomes 9 and 22

Question 6

A woman over the age of 40 is statistically more likely to have a child with Down syndrome. What is the primary biological reason for this increased risk?

Accepted Answer

Increased likelihood of nondisjunction during oogenesis

Question 7

Which of the following karyotypes is associated with Turner syndrome?

Accepted Answer

XO

Question 8

Genomic imprinting results in the expression of only one allele of a gene, depending on its parental origin. Which molecular mechanism is most commonly associated with this phenomenon?

Accepted Answer

DNA methylation

Question 9

A mouse inherits a mutant $$IGF2$$ allele from its father and a normal $$IGF2$$ allele from its mother. If only the paternal allele is expressed due to imprinting, what will be the phenotype of the mouse?

Accepted Answer

Dwarf, because only the mutant paternal allele is expressed

Question 10

Which of the following statements about mitochondrial inheritance is correct?

Accepted Answer

Mitochondrial genes are inherited only from the mother.

Question 11

If two genes are 50 map units apart on the same chromosome, what is their expected recombination frequency?

Accepted Answer

$$50\%$$

Question 12

Which of the following best explains why genes that are close together on the same chromosome tend to be inherited together?

Accepted Answer

There are fewer opportunities for crossing over to occur between them.

Question 13

A duplication mutation in a chromosome can have which of the following effects?

Accepted Answer

It can increase gene dosage and potentially cause developmental disorders.

Question 14

Which of the following is a real-life example of a disorder caused by aneuploidy of an autosome?

Accepted Answer

Down syndrome

Question 15

A patient is diagnosed with mitochondrial myopathy. Which of the following symptoms is most likely to be observed?

Accepted Answer

Muscle weakness and exercise intolerance

Question 16

Which of the following best describes a translocation mutation?

Accepted Answer

A segment of a chromosome is moved to a different, non-homologous chromosome.

Question 17

If a gene is imprinted such that only the maternal allele is expressed, what would be the result if the maternal allele is mutated and the paternal allele is normal?

Accepted Answer

The offspring will show the mutant phenotype because only the maternal allele is expressed.

Question 18

Which of the following is NOT a possible outcome of nondisjunction during meiosis?

Accepted Answer

Duplication of a gene segment

Question 19

Which of the following statements about the relationship between recombination frequency and gene distance is correct?

Accepted Answer

As the distance between genes increases, the recombination frequency increases.

Question 20

Which of the following best explains why some chromosomal alterations have no observable effect on phenotype?

Accepted Answer

The alteration occurs in a region of the chromosome that does not affect gene expression.

Bio 100 LEC Chapter 15 Module 3-5

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드