18 Questions
What is the primary sex ratio?
The proportion of males to females conceived in the population
What is the assumed basis for the theoretical sex ratio of 1:1?
All of the above
What is the purpose of dosage compensation in humans and other mammals?
Both a and b
Based on the 1969 worldwide census data, which population had the highest secondary sex ratio?
Korean population
What does a secondary sex ratio of 1.06 for the Caucasian population in the United States indicate?
There were more males than females born
What is the difference between primary and secondary sex ratio?
Primary sex ratio reflects the proportion of males to females conceived, while secondary sex ratio reflects the proportion of each sex born
What determines the sex of an individual in Drosophila?
The ratio of X chromosomes to the number of haploid sets of autosomes
What is the normal ratio of X chromosomes to haploid sets of autosomes in female Drosophila?
2X:2A
What happens when the ratio of X chromosomes to haploid sets of autosomes exceeds unity in Drosophila?
An inviable female (metafemale) is produced
How does Drosophila achieve dosage compensation for X-linked genes in females?
Increased transcription rate of X-linked genes in males
What is the role of the Sxl (Sex-lethal) gene in Drosophila?
It induces female differentiation during sex determination
Which of the following statements about Caenorhabditis elegans is true?
Hermaphrodites have both testes and ovaries, while males have only testes
What is the primary reason for the deviation of the sex ratio from 1.0 in humans?
Differential survival rates of male and female embryos
Which of the following statements about dosage compensation is correct?
It ensures equal expression of X-linked genes in males and females
What is the primary determinant of sex in humans?
The presence or absence of the Y chromosome
Which of the following statements about sex chromosomes is correct?
The X and Y chromosomes are heteromorphic (dissimilar)
Which of the following factors can influence the secondary sex ratio (at birth) in humans?
All of the above
In which group of organisms is sex determination primarily influenced by temperature variation?
Many reptiles
Learn about sex ratios in populations, including primary and secondary sex ratios. Explore the concept of sex ratio and its implications through examples from worldwide census data.
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