Final answer:
The correct option is 3. A trait that is expressed in only one sex is an example of sex-linked inheritance, which involves genes on the sex chromosomes. Male offspring need to inherit only one copy of the recessive allele on the X chromosome to express the trait, while females must inherit two copies. The question related to the phenotypes of offspring from a yellow male and a black female cat cannot be answered without information about the dominance of the alleles involved.
Step-by-step explanation:
Sex-linked Inheritance
A trait that is expressed in only one sex and not seen in the opposite sex shows sex-linked inheritance. This pattern of inheritance involves genes located on the sex chromosomes (X or Y chromosomes). For example, color blindness and hemophilia are common sex-linked disorders that are mostly seen in males. This is because males (XY) only have one X chromosome, and a single recessive allele on the X chromosome will result in the expression of the trait. Females (XX), on the other hand, would need two copies of the recessive allele to express the trait. Due to their genetic makeup, females can be carriers of sex-linked traits without expressing them.
Addressing the second question, the coat color of cats is an example of a sex-linked trait carried on the X chromosome. If a yellow male cat (XY, where the yellow color is X-linked) is crossed with a black female cat (XX, where one X carries the black color allele), the question regarding the offspring phenotypes cannot be answered definitively because the genetic information regarding which allele is dominant is not provided. Without knowing the dominance relationship between the black and yellow alleles, we cannot predict the phenotypes of the offspring.