you have performed a genetic cross, and in the final results, you get 3/4 dominant phenotype and 1/4 recessive phenotype. what other info would you need to know to determine if the characteristics is normal or sex influenced? in addition explain why you would need this info.

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Once YOU have come up with attempted answers to YOUR questions, please re-post and let us know what you think. Then someone here will be happy to critique your work.

=)

a) need to know what species b/c some have more than 2 sex
b) need to know if its all females, all males, or a mix of the two in the group
c) the breakdown of each in both of the phenotypes

am i on the right track with this?

yes, and also you need to know if the traits are governed by more than one genetic loci

genetic loci? what do you mean by that?

some traits you observe are more complicated that Dd, they have two loci, DdEd , or worse, many more. You probably are dealing with one loci, if you havent studied more. One trait I am familar with in Honeybees requires 13 loci, the same trait in humans is one loci.

oh ic. thanks. can you help me with the reasoning to my answers? i always have difficulty explaining =T

Certainly! Here's an explanation for each answer choice:

a) Species: Knowing the species is important because some species have more than two sexes. For example, some plants have male, female, and hermaphrodite sexes. In such cases, the determination of whether a trait is normal or sex influenced would depend on the presence or absence of specific gene combinations in each of the sexes.

b) Sex composition: Knowing the sex composition of the group is essential because some traits may be influenced by the sex of the individual. In some species, certain genetic traits are expressed differently based on the sex of the organism. By determining whether the group consists of all females, all males, or a mix of both, we can better understand if the observed trait is influenced by sex or not.

c) Phenotype breakdown: Analyzing the breakdown of each phenotype helps to determine if the observed trait follows a normal pattern or if it is influenced by sex. If the trait exhibits a 3:1 dominant-recessive ratio in both males and females, it suggests that the trait may be normal and not influenced by sex. However, if there is a difference in the phenotypic ratio between males and females, it indicates that the trait might be sex influenced.

In addition, determining if the trait is governed by more than one genetic locus is important because some traits are more complex and involve multiple genes and genetic loci. If a trait is controlled by multiple loci, it can affect the inheritance pattern and make it more difficult to determine whether the trait is normal or sex influenced based solely on phenotype ratios.

Remember, further analysis and experimentation may be needed to conclusively determine if a characteristic is normal or sex influenced, especially if the trait under investigation is more complex.