Concept explainers
To explain: The individual which shows heterogametic sex.
Introduction: The mechanism of sex determination differs from one species to another. Secondary sexual characteristic of an individual helps in the determination of its sex. Various environmental factors are responsible for the determination of sex as interaction between the environment and genes provides the criteria in the production of male and female.
To explain: The alien sex (female or male) is heterogametic.
Introduction: The mechanism of sex determination differs from one species to another. Secondary sexual characteristic of an individual helps in the determination of its sex. Various environmental factors are responsible for the determination of sex as the interaction between the environment and genes provides the criteria in the production of male and female.
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Chapter 7 Solutions
Human Heredity: Principles and Issues (MindTap Course List)
- A tortoiseshell cat, such as the cat pictured, is likely to be female. Why do tortoiseshell coats occur primarily in female cats? Testosterone suppresses the tortoiseshell gene in males, so tortoiseshell coats appear more often in females, who have less testosterone than males. Tortoiseshell coloring is an X-linked recessive trait, so females with two X chromosomes are more likely to express the trait than males. One of a female's two X chromosomes is randomly inactivated in each cell, so each cell may express different alleles. O The X chromosome is disabled in males, so a tortoiseshell coat, which is an X-linked recessive trait, does not occur in males.arrow_forwardIn certain salamanders, the sex of a genetic female can be altered, changing her into a functional male; these salamanders are called sex reversed males. When a sex-reversed male is mated with a normal female, approximately 23 of the offspring are female and 13 are male. How is sex determined in these salamanders? Explain the results of this crossarrow_forwardIn rabbits, the gene that codes for a spotted coat is dominant over the gene that codes for a solid coat, and the gene for the coat's black color is dominant over the gene for the coat's brown color. If a spotted, black-coated rabbit mates with a solid, brown-coated rabbit, what are the genotypes and phenotypes of their offspring?arrow_forward
- we discuss various mechanisms of sex determination, including the XX/XY system of placental mammals, and the ZZ/ZW system of birds. Monotremes, the most primitive mammals, have a very intriguing sex determination scheme that shares elements of both of these systems. Please use the internet to learn more about how sex in monotremes is determined. Then write a short essay (300-400 words) describing this system and comparing/contrasting it to the XX/XY and ZZ/ZW systems.arrow_forwardIn reptiles, sex determination was thought to be controlled by sex-chromosome systems or by temperature-dependent sex determination without an inherited component to sex. But as we discussed in section 7.6, in the Australian lizard, Pogona vitticeps, it was recently revealed that sex is determined by both chromosome composition and by the temperature at which eggs are incubated. What effects might climate change have on temperature- dependent sex determination in this species, and how might this impact the sex ratio for this species in subsequent generations?arrow_forwardNLFN3, a gene in the X chromosome has been linked to Autism spectrum disorder ASD. Research has shown that the mutation R451C (represented by the allele X+) is recessive and causes ASD. Ear lobes in humans are coded by a single gene which displays simple dominance. E results in free earlobes, and e corresponds to attached earlobes. What is the probability of having a female offspring with ASD symptoms and attached earlobes from X+Y Ee and X+X ee parents? 25% O 100% 0% O 75% O 12.5% O 50%arrow_forward
- Sex determination in birds is different from that in humans. The sex chromosomes in birds are called Z and W, because males have two of the same chromosome (ZZ), whereas females have two different chromosomes (ZW). There is a Z-linked allele in some birds that causes the death of the embryo when the normal dominant allele is not present. What would be the sex ratio in the living offspring of a cross between a male heterozygous for the lethal allele and a normal female? A) What are the genotypes of the parents? Male____ Female____ B) Which gametes would each form? Male____ Female____ C) Draw your Punnett square below and determine the sex ratios of living offspring.arrow_forwardIn fruit flies, red-eyes are dominant to white-eyes. In addition, eye color is a sex-linked trait. A red-eyed male Drosophila mates with a red-eyed female Drosophila. One of the female's parents had white eyes. What proportion of the male offspring will have white eyes? Check if my answer is correctarrow_forwardAssume that a single gene determines coat coloration in cats, with the B allele resulting in orange coloration, and b allele results in black coloration. This gene exists on the X chromosome (recall that cats have XX/XY system of sex determination). My cat Pepper is a female tortoiseshell, and my cat Hobbes is an orange male. (i) What is the probability that Hobbes and Pepper have three kittens, Hopper (male), Pepsi (female), and Hippie (female)? What is the probability that they have three kittens, and that Hopper (male), and Hippie (female) are both orange, and that Pepsi (female) is a tortoiseshell? (ii) Distribution of % of Barr Bodies in each body part 120 100 100 80 100 60 40 50 50 20 Head Body Tail Black Orangearrow_forward
- Drosophila have XX/XY sex determination systems just like mammals. In Drosophila, loci for both eye color and body color are on the X chromosome. Red eye color (R) is dominant to white eye color (r), and tan body color (T) is dominant to yellow body color (t). Which of the following is the genotype for a female with a yellow body and red eyes, who is homozygous for eye color? Group of answer choices XRT XrT XRt XRT XRt XRt XRt XRTarrow_forwardA species of centipede has a haploid chromosome number of 2. Leg length is controlled by a single gene with two alleles: the long leg allele (L) is dominant to the short leg allele (l). Body coloration is controlled by a single gene with two alleles: the dark allele (D) is dominant to the light allele (d). Leg length and body coloration are encoded by genes on separate chromosomes. Assume the traits obey Mendel’s Law of Independent Assortment. a) A centipede that is homozygous for the recessive allele at both loci mates with a centipede that is homozygous for the dominant allele at both loci. They produce 100 offspring. What fraction of the offspring would you expect to have short legs and light body coloration? Show your calculations and reasoning. b) Two centipedes that are each heterozygous for both leg length and body coloration mate and produce 100 offspring. What fraction of the offspring would you expect to have long legs and light body coloration? Show your work using a…arrow_forwardA species of centipede has a haploid chromosome number of 2. Leg length is controlled by a single gene with two alleles: the long leg allele (L) is dominant to the short leg allele (l). Body coloration is controlled by a single gene with two alleles: the dark allele (D) is dominant to the light allele (d). Leg length and body coloration are encoded by genes on separate chromosomes. Assume the traits obey Mendel’s law of Independent Assortment.arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning