Question 1

Alleles for genes located on mitochondrial DNA are said to be maternally inherited.What is the reason for this pattern of inheritance?

Accepted Answer

Mitochondria, which contain the mitochondrial DNA, are only present in the cytoplasm of the egg cell and not in the sperm cell. Thus, during fertilization, the resulting zygote inherits all of its mitochondrial DNA from the mother's egg.

Question 2

White eyes is a recessive sex-linked trait in fruit flies.If a white-eyed female fruit fly is mated to a red-eyed male,their offspring should be

Accepted Answer

In fruit flies, the gene for eye color is located on the X chromosome. A white-eyed female (XwXw) crossed with a red-eyed male (X+Y) will produce all white-eyed males (XwY) and all red-eyed females (X+Xw).

Question 3

Which statement about plasmids is false?

Accepted Answer

Plasmids do not have the same function as the mitochondria in eukaryotic cells. Mitochondria are organelles involved in energy production, while plasmids are small, independent DNA molecules that may carry extra genes that can confer advantageous traits to the bacterial cells.

Question 4

Use the following to answer questions :
Egg and Fluffy are two linked bird genes that are 16 map units apart.The E allele of Egg produces large eggs and the e allele produces small eggs (E is dominant).The F allele produces fluffy feathers and the f allele produces nonfluffy feathers (F is dominant).
-If EeFf is crossed with eeff,what proportion of female offspring will produce small eggs and fluffy feathers?

Accepted Answer

The genes are 16 map units apart, indicating a 16% recombination frequency. The recombinant offspring will have the genotypes EeFf and eeff. Since we want small eggs and fluffy feathers (eeFf), this is one of the recombinant types, which will occur in 8% of the offspring (half of the 16% recombinants).

Question 5

Humans have 46 chromosomes and _______ autosomes.

Accepted Answer

Humans have 22 pairs of autosomes, which are non-sex chromosomes, making a total of 44 autosomes. The 23rd pair consists of the sex chromosomes.

Question 6

Which organelle does not contain DNA?

Accepted Answer

Ribosomes do not contain DNA as they are composed of RNA and proteins. The nucleus, chloroplasts, and mitochondria all contain DNA.

Question 7

When reciprocal crosses produce identical results,one can conclude that the trait is

Accepted Answer

When reciprocal crosses produce identical results, it indicates that the trait is not dependent on the sex of the parent, meaning it is not sex-linked. Therefore, option A is the correct answer. The other options are not necessarily true and cannot be concluded solely from the fact that reciprocal crosses produce identical results.

Question 8

Bacteria engage in genetic transfers after a thin projection called a _______ extends from one cell to another.

Accepted Answer

The thin projection that extends from one bacterial cell to another during genetic transfers is called a sex pilus. The other options are not accurate descriptions of this process.

Question 9

In humans,spotted teeth are caused by a dominant sex-linked gene.If a man with spotted teeth whose father had normal teeth has children with a woman with normal teeth,

Accepted Answer

The man with spotted teeth must have inherited the dominant sex-linked gene from his mother. Since the gene is on the X chromosome, all daughters will inherit the spotted teeth gene from their father.

Question 10

Use the following to answer questions :
Egg and Fluffy are two linked bird genes that are 16 map units apart.The E allele of Egg produces large eggs and the e allele produces small eggs (E is dominant).The F allele produces fluffy feathers and the f allele produces nonfluffy feathers (F is dominant).
-If EEFF is crossed with eeff,what proportion of female offspring will produce large eggs and fluffy feathers?

Accepted Answer

The EEFF x eeff cross produces EeFf offspring. Since the genes are linked and 16 map units apart, 16% of offspring will be recombinant (EeFf or eeff), and 84% will be parental (EEFF or eeff). Thus, 84% will have large eggs and fluffy feathers.

Question 11

A human male carrying an allele for a trait on the X chromosome is

Accepted Answer

Since males only have one copy of the X chromosome, they are hemizygous for any trait carried on that chromosome.

Question 12

The genes contained in bacterial plasmids can be involved in

Accepted Answer

Bacterial plasmids may contain genes that can help break down hydrocarbons and clean up oil spills, they are also known to be carriers of antibiotic-resistant genes and are capable of spreading those genes to other bacteria, making them more difficult to treat with antibiotics. Plasmids can also carry genes that enable bacteria to express virulence factors, which can make them more pathogenic. Furthermore, plasmids can be used as vectors for genetic engineering, allowing scientists to insert new genetic information into cells. Therefore, all of the above options are possible with the genes contained in bacterial plasmids.

Question 13

Very few genes have been located on the Y chromosomes of humans.Y-linked genes include a gene called testis-specific protein Y.A male with this gene will

Accepted Answer

Y-linked genes are present exclusively in males and are passed down only from father to son. Therefore, a male with the Y-linked gene testis-specific protein Y will pass it on only to his sons.

Question 14

Morgan demonstrated that white eye color in Drosophila is carried recessively on the X chromosome (recall that females are XX and males are XY).Which of the following best describes the offspring of a heterozygous (carrier)female and a white-eyed male?

Accepted Answer

A heterozygous female (X^RX^r) crossed with a white-eyed male (X^rY) results in half of the daughters (X^rX^r) and half of the sons (X^rY) having white eyes.

Question 15

When a dihybrid black,normal-winged fly is crossed with a double-recessive gray,vestigial-winged fly,the frequency with which black vestigial-winged and gray normal-winged flies are seen in the progeny is called the _______ frequency.

Accepted Answer

The frequency with which black vestigial-winged and gray normal-winged flies are seen in the progeny is due to the recombination of alleles during meiosis. Therefore, the correct term is recombinant frequency or recombination frequency. Options A, B, C, and D do not accurately describe this phenomenon.

Question 16

Use the following to answer questions :
Cleft chin is an X-linked dominant trait.Assume that a man with a cleft chin marries a woman with a round chin.
-What percent of their female progeny will show the cleft chin trait?

Accepted Answer

Since cleft chin is an X-linked dominant trait and the man has a cleft chin, he will pass the dominant allele to all his daughters, resulting in 100% of the female progeny having a cleft chin.

Question 17

Use the following to answer questions :
Egg and Fluffy are two linked bird genes that are 16 map units apart.The E allele of Egg produces large eggs and the e allele produces small eggs (E is dominant).The F allele produces fluffy feathers and the f allele produces nonfluffy feathers (F is dominant).
-If EeFf is crossed with eeff,what proportion of female offspring will produce small eggs and nonfluffy feathers?

Accepted Answer

When EeFf is crossed with eeff, the Punnett square for their offspring would be:
EF   Ef   eF   ef
EeFf | EF | Ef | eF | ef
eeff | eF | ef | eF | ef

From this Punnett square, we can see that 2 out of 4 possible offspring combinations (eF and ef) will have both small eggs and nonfluffy feathers. Therefore, the proportion of female offspring that will produce small eggs and nonfluffy feathers is 2/4 or 0.5 or 50%. However, since the question specifically asks for female offspring, we need to divide this proportion by 2, because half of the offspring will be male and therefore won't have the traits we are looking for. Therefore, the final proportion of female offspring that will produce small eggs and nonfluffy feathers is 0.5/2 or 0.25 or 25%, which is equivalent to 42% rounded to the nearest whole number. Therefore, the best choice is C.

Question 18

Organelles such as mitochondria and the genes that they contain display _______ inheritance and are _______ inherited.

Accepted Answer

Organelles such as mitochondria and the genes that they contain are inherited exclusively from the maternal parent and therefore display non-Mendelian or maternal inheritance.

Question 19

Use the following to answer questions :
Cleft chin is an X-linked dominant trait.Assume that a man with a cleft chin marries a woman with a round chin.
-What percent of their male progeny will show the cleft chin trait?

Accepted Answer

The answer of Use the following to answer questions :
Cleft...

Question 20

In tomatoes,tall is dominant to short and smooth fruits are dominant to hairy fruits.A plant that is homozygous for both dominant traits is crossed with a plant that is homozygous for both recessive traits.The F₁ progeny are tested and crossed with the following results: 78 tall smooth fruits;82 short hairy fruits;22 tall hairy fruits;and 18 short smooth fruits.These data indicate that the genes are

Accepted Answer

The data indicate that the two traits are linked, as the expected ratio of F2 offspring based on independent assortment would be 9:3:3:1 (tall smooth : tall hairy : short smooth : short hairy). The observed ratio of 78:22:18:82 indicates that the tall and smooth traits are linked together on one chromosome, while the short and hairy traits are linked together on the other chromosome. The recombination frequency between the two linked genes can be calculated as (22+18)/(78+22+18+82) = 0.2, or 20 percent. Therefore, choice D is the best answer.

Quiz 8: Inheritance, Genes, and Chromosomes