Which of the following statements is true regarding the SRY gene? SRY is an X-linked gene. SRY is located on an autosome. SRY is involved in human sex determination. Two copies of SRY are normally present in human males. All of these choices are correct. Question 26 (1.25 points) All of the phenotypes listed below are determined at least partially by genotype. Which trait is most likely to be influenced by the environment as well? body weight sex Klinefelter syndrome eye color hair color
The Correct Answer and Explanation is :
Correct Answer to Question 1:
SRY is involved in human sex determination.
Explanation:
The SRY (Sex-determining Region Y) gene is crucial for human sex determination. It is located on the Y chromosome and plays a vital role in initiating male sex differentiation. During early embryonic development, the SRY gene triggers the formation of the testes, which produce male hormones such as testosterone, leading to the development of male secondary sexual characteristics.
The other statements about SRY are incorrect:
- SRY is an X-linked gene – This is false because SRY is located on the Y chromosome, not the X chromosome.
- SRY is located on an autosome – This is false because it is not on an autosome; it is specific to the Y chromosome.
- Two copies of SRY are normally present in human males – This is incorrect because males typically have one Y chromosome and, therefore, only one copy of the SRY gene.
- All of these choices are correct – Since the other statements are false, this cannot be correct.
Correct Answer to Question 2:
Body weight
Explanation:
While many traits are influenced by genotype, body weight is particularly influenced by environmental factors, such as diet, physical activity, and socioeconomic conditions. Genetics do play a role in determining a person’s predisposition to obesity or leanness through the regulation of metabolism, appetite, and fat storage. However, environmental factors like caloric intake and exercise levels significantly impact body weight.
The other traits are much less influenced by the environment:
- Sex – Determined almost entirely by the presence or absence of the SRY gene.
- Klinefelter syndrome – Caused by a chromosomal abnormality (XXY karyotype), independent of the environment.
- Eye color – Determined primarily by genetic inheritance and not significantly affected by external factors.
- Hair color – Genetically determined, though it may be slightly influenced by environmental factors like sun exposure (e.g., lightening in the sun).
Thus, body weight is the trait most influenced by the environment.