Genetics Hardest Trivia Questions! Quiz

Bridges used the Drosophila sex determination system and nondisjunction to demonstrate that the gene for red/white eye color is on the X chromosome. By examining the chromosomes of the rare flies, he observed that the white-eyed females had two X chromosomes and one Y, while the red-eyed males had only one sex chromosome. The white-eyed females were XwXwY, indicating that they contained only recessive w alleles and were female due to their X:A ratio of 2:2 = 1.0. On the other hand, the red-eyed males were X+O, indicating that they had the dominant + allele and were male due to their X:A ratio of 1:2 = 0.5. This provided evidence that genes responsible for phenotypes are located on chromosomes.

Human males, with XY chromosomes, are heterogametic because they produce two different kinds of gametes (sperm) that carry either an X or Y chromosome. On the other hand, females with XX chromosomes are homogametic because they produce only one kind of gamete (egg) that carries an X chromosome.

An XO human is female because the absence of the SRY gene on the Y chromosome leads to the development of a female despite having only one X chromosome. On the other hand, an XO Drosophila is male because Drosophila is diploid and has two copies of each autosome. If there is a single X chromosome, the X:A ratio is 0.5, which is characteristic of a male.

The boy has an X-linked recessive condition that is not seen in either parent. This suggests that the mother must be a carrier of the allele for the condition because she passed it to the son without showing it herself. The father could not have been a carrier because he did not show the condition. If the son has the recessive condition, the recessive allele must be on both his X chromosomes, indicating that his two X chromosomes are the same and were inherited from his mother. The nondisjunction, where sister chromatids failed to separate, occurred in the mother's germline during meiosis II.

Dioecious is the correct answer because it refers to species where organisms have either male or female reproductive structures, but not both. In dioecious species, individuals are either male or female, and they require individuals of the opposite sex to reproduce. This is in contrast to monoecious species, where individuals have both male and female reproductive structures.

The presence of the SRY gene on the Y chromosome determines maleness in humans, so even though an XXY individual has two X chromosomes, they are still considered male. In Drosophila, an X: A ratio of 0.5 determines maleness, so an XXY individual would have two X chromosomes and one autosome, resulting in an X:A ratio of 1.0, which is considered female.

The sex determination system used by Drosophila is called the genic balance system. This system relies on the balance of genes on the sex chromosomes to determine the sex of the individual. In Drosophila, females have two X chromosomes, while males have one X and one Y chromosome. The presence or absence of certain genes on these chromosomes determines the development of male or female characteristics.

not-available-via-ai

The statement is true. In reptiles like turtles and alligators, the temperature during embryonic development plays a crucial role in determining the sex of the offspring. This phenomenon is known as temperature-dependent sex determination (TSD). The eggs of these reptiles are sensitive to the temperature of the environment, and specific temperature ranges can result in the development of either male or female individuals. This is an important adaptation for reptiles to ensure a balanced sex ratio in their populations and allows them to adjust to varying environmental conditions.

The statement is true because the SRY gene, located on the Y chromosome, is responsible for the development of male characteristics in humans. It codes for a protein called testis-determining factor (TDF), which triggers the development of testes and the production of male sex hormones. This gene is crucial for the differentiation of male reproductive structures and the determination of male sex.

Male mammals inherit an X chromosome from the maternal parent, the mother, because the mother is the only parent that can pass on an X chromosome. This is because females have two X chromosomes, while males have one X and one Y chromosome. The father can only pass on a Y chromosome to his male offspring, determining their sex as male. Therefore, the X chromosome that males receive comes exclusively from their mother.

Having no X chromosomes, such as in the condition YO, is indeed lethal in humans. This is because the presence of at least one X chromosome is necessary for normal development and survival. Without any X chromosome, the individual would lack the essential genetic information required for proper functioning of various bodily systems, leading to severe developmental abnormalities and ultimately resulting in death. Therefore, the statement "True" accurately reflects the fact that the condition of having no X chromosomes is lethal in humans.

In species where females are the homogametic sex, the gender of offspring is determined by the male. This means that the male contributes the sex-determining chromosome, such as the Y chromosome in humans, which determines the development of male offspring. In these species, the female always contributes an X chromosome, resulting in female offspring. Therefore, the statement "True" is correct.

Individuals with androgen insensitivity syndrome (AIS) have a genetic mutation that prevents their body from responding to male sex hormones called androgens. This condition is typically caused by mutations in the androgen receptor gene, which is located on the X chromosome. As a result, individuals with AIS may have XY sex chromosomes (typically associated with males) instead of the usual XX sex chromosomes (typically associated with females). Therefore, the statement that a female with androgen insensitivity may have XY sex chromosomes is true.

Dioecious species are characterized by having individuals that possess either male or female reproductive structures exclusively. This means that individuals of a dioecious species are either male or female, but not both. Therefore, the statement "Species in which individuals have only male or only female reproductive structures are called dioecious" is true.

Female mammals that are heterozygous for an X-linked gene have patches of cells that express one allele and patches of cells that express the other. This is due to a process called X-inactivation, where one of the X chromosomes in each cell is randomly inactivated during early development. As a result, some cells will express one allele while others express the other allele, leading to the presence of patches of cells with different gene expression patterns. This phenomenon is commonly observed in females with X-linked genetic disorders.

In X-linked recessive inheritance, the gene responsible for color blindness is located on the X chromosome. Since the woman's father is color blind, he must have passed on his X chromosome with the color blindness gene to his daughter. However, the woman has a child with a man with normal color vision, meaning the child will receive one X chromosome from the mother and one Y chromosome from the father. As a result, the child cannot inherit the color blindness gene from the mother and is therefore not expected to be a color blind female.

The statement is false because the condition XXXY is not always lethal in humans. XXXY is a chromosomal abnormality that occurs in males, where there are three extra sex chromosomes (XYY). While this condition can lead to certain physical and behavioral traits, it is not necessarily lethal. Lethality is determined by various factors and can vary depending on the individual's overall health and other genetic factors.

In haplodiploid species, the sex is determined by the number of chromosome sets. Males are haploid, meaning they have only one set of chromosomes, while females are diploid, having two sets of chromosomes. This type of sex determination is seen in certain insects, such as bees and ants, where unfertilized eggs develop into males (haploid) and fertilized eggs develop into females (diploid). Therefore, the correct answer is haplodiploid.

During meiosis I, anaphase, the homologous X chromosomes segregate. This is because during meiosis I, homologous chromosomes pair up and then separate, resulting in each daughter cell receiving one copy of each chromosome. In this case, the homologous X chromosomes will separate, with one going to each daughter cell. Meiosis II, anaphase is incorrect because during this stage, the sister chromatids of each chromosome separate, not the homologous chromosomes. The statement "they do not segregate; gametes contain a copy of X and a copy of Y" is also incorrect because in grasshoppers with XX-XO sex determination, females have two X chromosomes and males have one X and one Y chromosome. Therefore, the homologous X chromosomes do segregate.

A Barr body is a visible inactivated X chromosome in the nucleus of a cell from a female mammal. In female mammals, one of the two X chromosomes is randomly inactivated during early development. This inactivated X chromosome forms a condensed structure known as a Barr body, which can be observed in the nucleus of the cell. This phenomenon ensures dosage compensation between males and females, as males only have one X chromosome while females have two.

During meiosis I, anaphase, the X and Y chromosomes segregate. This is the stage in meiosis where homologous chromosomes separate and move to opposite poles of the cell. In the case of a germ-line cell from a human male, the X and Y chromosomes are the homologous pair that segregates during this phase. This process ensures that each gamete receives only one copy of either the X or Y chromosome, resulting in the production of sperm cells with either an X or Y chromosome.

X-inactivation is a process in which one of the two X chromosomes in female cells is randomly inactivated to equalize gene expression between males and females. It is not related to reducing the amount of nondisjunction during meiosis. Nondisjunction refers to the failure of chromosomes to separate properly during cell division, leading to an abnormal number of chromosomes in daughter cells. X-inactivation does not directly affect the occurrence of nondisjunction during meiosis. Therefore, the correct answer is False.

The given cell is from an organism with the XX-XO sex determination system, which means that the organism can be either male (XO) or female (XX). Since the cell has only one X chromosome, it indicates that the individual is a male. In this system, males have one X chromosome and no Y chromosome, while females have two X chromosomes. Therefore, the presence of only one X chromosome in the cell suggests that the individual is male.

In males, only one X chromosome is present, while females have two X chromosomes. Barr bodies are condensed X chromosomes that are inactive. Since the boy in the karyotype is male and has only one X chromosome, we would expect to find one Barr body per cell.

The X and Y chromosomes are not named after their characteristic shape. They are actually named based on the order in which they were discovered. The X chromosome was the first to be identified, and it was named after its distinct shape. The Y chromosome was later discovered and named after the next letter in the alphabet. Therefore, the statement that the X and Y chromosomes are named after their characteristic shape is false.

When a female Drosophila is heterozygous for a recessive X-linked mutation and is crossed with a wild-type male, the male offspring will receive the wild-type X chromosome from the father and the mutant X chromosome from the mother. However, the female offspring will receive one wild-type X chromosome from the father and one wild-type X chromosome from the mother, masking the mutant phenotype. Therefore, none of the female progeny will have the mutant phenotype, resulting in 0% of female progeny with the mutant phenotype.

In birds, the Z chromosome is the sex chromosome that determines the gender of the offspring. If the male bird is heterozygous for a recessive Z-linked mutation, it means that he carries one normal allele and one mutated allele on his Z chromosome. However, since the mutation is recessive, it will only be expressed if both alleles on the Z chromosome are mutated. When the male bird is crossed with a wild type female, who has two normal alleles on her Z chromosome, none of the offspring will inherit two mutated alleles on their Z chromosome. Therefore, the proportion of mutant males in the progeny will be 0%.

The given cell has a pair of sex chromosomes, Z and W. In the ZZ-ZW sex determination system, females have a pair of ZW chromosomes, while males have a pair of ZZ chromosomes. Since the cell in question has a W chromosome, it indicates that the individual from which the cell came is female.

The correct answer is "all of the above". This means that all of the mechanisms listed (chromosomal sex determination, haplodiploidy, genetic sex determination, and environmental sex determination) can be used to generate sexes in dioecious species.

Klinefelter syndrome is a genetic disorder that occurs in males when they have an extra X chromosome. The normal male genotype is XY, but individuals with Klinefelter syndrome have an additional X chromosome, resulting in genotypes such as XXY, XXYY, or XXXY. Therefore, all of the given options (XXY, XXYY, and XXXY) are associated with Klinefelter syndrome.

The answer is correct because these three strategies are commonly used to equalize the amount of sex chromosome gene products. Inactivation of one sex chromosome in the homogametic sex ensures that both males and females have the same number of active sex chromosomes. Halving the activity of genes on both sex chromosomes in the homogametic sex also helps to equalize gene expression. Increasing the activity of genes on the sex chromosome in the heterogametic sex compensates for having only one active sex chromosome.

The probability of a gamete from this individual having the genotype alleles A and b, chromosome X is 1/8. This is because the individual has two pairs of autosomes, which means there are four possible combinations of alleles for the autosomes (AA, Aa, aA, aa). Additionally, there is one X chromosome, which can have either the A or b allele. Therefore, the probability of getting the genotype alleles A and b, chromosome X is 1/4 x 1/2 = 1/8.

not-available-via-ai

The probability of a gamete from this individual having the genotype alleles A and b, and the chromosome Z is 1/8. This is because the individual is diploid and has two pairs of autosomes and a pair of sex chromosomes, Z and W. The genotype alleles A and b can be present on one of the autosomes. Since there are two pairs of autosomes, the probability of having alleles A and b on the same autosome is 1/4. Additionally, the probability of the chromosome Z being present in the gamete is 1/2. Therefore, the overall probability is (1/4) * (1/2) = 1/8.

The boy's X chromosomes can have any combination of the polymorphism alleles present in his mother's X chromosomes (7 and 14) and his father's X chromosome (5). Therefore, all of the above combinations are possible in the boy's X chromosomes.

In this question, we are given that the individual with the ZZ-ZW sex determination system has two pairs of autosomes and a pair of sex chromosomes, Z and W. We are also given that alleles A and B are dominant. When this individual is crossed with an individual of genotype Aa Bb, we need to find the probability of a female offspring with two dominant traits given by alleles A and B.

To determine the probability, we need to consider the possible combinations of alleles that can be inherited by the female offspring. The female offspring can inherit either the A allele or the a allele from the first parent, and either the B allele or the b allele from the second parent. Since both A and B are dominant alleles, the female offspring will have the two dominant traits if she inherits both the A and B alleles.

The probability of inheriting the A allele from the first parent is 1/2, as there is an equal chance of inheriting either the A allele or the a allele. Similarly, the probability of inheriting the B allele from the second parent is also 1/2.

To find the probability of both events happening, we multiply the probabilities together: (1/2) * (1/2) = 1/4.

Therefore, the probability of a female offspring with the two dominant traits given by alleles A and B is 1/4.

However, we need to consider that there are two pairs of autosomes, so the probability needs to be multiplied by 2. Therefore, the final probability is 1/4 * 2 = 1/2.

Therefore, the correct answer is 1/2, which is equivalent to 9/18 or 9/32.

In meiosis II, the sister chromatids separate, resulting in four haploid cells. In this case, the individual has two pairs of autosomes (A and B) and one X chromosome. During metaphase of meiosis II, the sister chromatids align at the equatorial plate. Option C suggests that one cell can have a pair of sister chromatids with the A allele and another pair with the B allele. Option D suggests that one cell can have a pair of sister chromatids with the a allele and another pair with the B allele, along with a pair of sister chromatids of the X chromosome. Both options C and D are possible combinations of chromosomes in one of the two cells during metaphase of meiosis II.

During meiosis II, the sister chromatids of each chromosome separate, resulting in two cells with half the number of chromosomes as the original cell. In this case, the original cell has two pairs of autosomes (A and B) and a pair of sex chromosomes (Z and W). In meiosis II, one possible combination of chromosomes in one of the two cells could be a pair of sister chromatids with the A allele, a pair of sister chromatids with the B allele, and a pair of sister chromatids with the W allele. Therefore, the correct answer is a pair of sister chromatids with a allele, a pair of sister chromatids with B allele, a pair of sister chromatids W.