Q: In a mapping experiment, 20 nonparental types are observed out of 200 total offspring. What is the map distance between the genes?

$$\frac{20}{200} \times 100 = 10 cM$$

Q: Which equation would you use to calculate the recombination frequency ($$\mu) in a $$test cross?

$$\mu = \frac{\text{number of nonparentals}}{\text{total}} \times 100$$

Question 1

If a diploid organism has a haploid number ($$n) of 8$$, how many chromosomes and chromatids are present in a cell during metaphase of mitosis?

Accepted Answer

16 chromosomes and 32 chromatids

Question 2

In a diploid cell where $$n = 5$$, how many chromosomes and chromatids are present after Meiosis I is complete?

Accepted Answer

5 chromosomes and 10 chromatids

Question 3

A pedigree shows affected children born to unaffected parents, with both males and females affected equally. What is the most likely mode of inheritance?

Accepted Answer

Autosomal recessive

Question 4

In the first pedigree image, what is the most likely mode of inheritance for the trait shown?

Accepted Answer

Autosomal recessive

Question 5

In the second pedigree image, the trait appears more frequently in males and is passed from unaffected mothers to affected sons. What is the most likely mode of inheritance?

Accepted Answer

X-linked recessive

Question 6

A cross between two mackerel tabby cats (Tt x Tt) produces both mackerel and classic tabby kittens. What is the probability of getting exactly 5 classic tabby kittens out of 8?

Accepted Answer

$$P = \frac{8!}{5!3!} (0.25)^5$ (0.75)^3$

Question 7

Which of the following best describes the result of F+ x F- bacterial conjugation as shown in the fourth image?

Accepted Answer

Both cells become F+

Question 8

In Hfr conjugation (fifth image), what is the main genetic outcome for the recipient cell?

Accepted Answer

It receives chromosomal genes but usually remains F-

Question 9

A dihybrid cross TtPp x TtPp produces which phenotypic ratio in the offspring?

Accepted Answer

9:3:3:1

Question 10

If a test cross is performed between a TtPp individual and a ttpp individual, what is the expected phenotypic ratio?

Accepted Answer

1:1:1:1

Question 11

Which formula would you use to calculate the probability of getting a specific number of a particular phenotype in a set of offspring, regardless of order?

Accepted Answer

$$P = \frac{n!}{x!(n-x)!} p^x q$$^{n-x}$$

Question 12

A geneticist observes that two mutations fail to complement each other in a complementation test. What does this indicate?

Accepted Answer

The mutations are in the same gene

Question 13

In a mapping experiment, 20 nonparental types are observed out of 200 total offspring. What is the map distance between the genes?

Accepted Answer

$$\frac{20}{200} 	imes 100 = 10 cM$$

Question 14

A lethal allele results in which of the following Mendelian ratios in the offspring of a heterozygote cross?

Accepted Answer

2:1

Question 15

Which of the following is true about X-linked recessive inheritance?

Accepted Answer

More males are affected, and the trait is passed through carrier females

Question 16

Which equation would you use to calculate the recombination frequency ($$\mu) in a $$test cross?

Accepted Answer

$$\mu = \frac{	ext{number of nonparentals}}{	ext{total}} 	imes 100$$

Question 17

Which of the following best describes the Lyon hypothesis?

Accepted Answer

Random inactivation of one X chromosome in females

Question 18

Which bacterial cell type can transfer chromosomal genes to a recipient during conjugation, as shown in the fifth image?

Accepted Answer

Hfr

Question 19

A test cross between a female XrXr and a male XRY will produce which phenotypes in the offspring?

Accepted Answer

All males recessive, all females dominant

Genetics Exam 1 Review: Chromosomes, Pedigrees, Probabilities, and Bacterial Genetics

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