Genetics Test 3

 How is biological sex defined across living organisms (not just humans)? What core

biological criteria are used to classify an individual (across species) as one sex or another?

.

How many distinct sexes exist in nature? Support your answer with explanations and

examples from multiple types of organisms.

,

What is the default developmental pathway of a human embryo at the moment of conception?

b

 What is the SRY gene, where is it located, and what role does it play in human sex

determination?

g

What happens when a person is born with an atypical number of sex chromosomes? For each major syndrome, identify the chromosomal composition, its cause, and its effects on

Phenotype.

b

What sex-determination systems exist in nature beyond the human XX/XY model? For each

system, describe how sex is determined and provide at least one example organism.

g

How do incomplete dominance and codominance each challenge the assumptions of

Mendelian inheritance? What makes them distinct from each other? For both incomplete

dominance and codominance, how do the genotypic and phenotypic ratios compare to

Mendel’s predictions?

g

. Define sex-influenced and sex-limited traits. How does each differ from sex-linked traits in

terms of chromosomal location and expression patterns? How do the genotypic and

phenotypic ratios of sex-influenced and sex-limited traits deviate from standard Mendelian

predictions? Provide examples for each.

g

What are lethal alleles? Explain how they arise and how they distort expected genotypic and

phenotypic ratios in a cross.

f

 Distinguish between penetrance and expressivity. How does each concept explain why

individuals with the same genotype can look different? How do they modify expected

Mendelian ratios? Give examples of each.

g

 In your own words, what is epistasis, and how is it fundamentally different from simple

dominance? Identify and describe at least three types of epistasis, providing an example for

each.

g

How do environmental factors interact with an organism’s genotype to shape its

phenotype? Choose at least two specific traits and explain the environmental influence on

each.

g