Week 9: Questions Flashcards
What is the advantage of the method of sex determination found in clownfish, i.e., how does it lead to successful reproduction in these fish?
The clownfish turns into a female after certain time and even if the dominant female is killed, the dominant male quickly becomes female and the hierarchy can advance and they can reproduce
What is the advantage of the method of sex determination found in the green spoonworm, Bonillia, i.e., how does it lead to successful reproduction in these worms?
When the hatchling falls anywhere besides the female body, it will develop as a female and if it falls on the female body, it will be male
The advantage is that genetics do not play a role in this reproduction
In social insects like ants and honeybees, males are haploid and females are diploid. Are males or females more likely to display traits determined by recessive alleles? What about traits displayed by dominant alleles?
For ants, the females will get the recessive alleles since they were produced through proper fertilization so they have both genes from each parent.
In humans and other mammals, the father determines the sex of the offspring. Explain why this is so.
The father holds the XY chromosome and the mother only holds the XX chromosome and if there are 2 XX chromosomes, its a girl, if its an XY chromosome, its a boy so it depends on the father with a 50/50 chance
What was the biological mistake in the portion of the video showing sex determination in ants? Hint: Follow the DNA!
The male ants are produced without fertilzation so they only carry one set of genes which they need 2 as 1 from each parent.
Explain the difference between primary and secondary sex determination.
Primary: the step in sexual development that determiens whether ovaries or testes form
Secondary: the step in sexual development that governs the development of sex-related body characteristics such as external genitals, structure of pelvic bone, voice tone, and locations of body fat and hair
Explain the role of the sex hormones in development of male or female secondary sex characteristics.
Testostrone promotes the development of wolffian ducts, prostate gland and penis.
It also inhibits breast formation and regualtes the descent of testes into a pouch callled the scrotum
Estrogren is produced by XX embryos and develop mullerian ducts, oviducts, uterus and the upper end of the vagina.
As males know and females may have observed, male testes are very sensitive and a blow to the testes is extraordinarily painful. Why is the high pain sensitivity of the testes adaptive? Would you expect that female ovaries would be as sensitive to pressure or a blow as male testes? Why or why not?
Because it is a vital organ that is located on the outside of the body and contains many nerves that cause it to be highly sensitive.
What is the role of the stem cells in the seminiferous tubules of the testes? Are these cells haploid or diploid?
The seminiferous tubules make up the bulk of the testes in male humans and are the location of sperm production. This process is also known as spermatogenesis, and it functions to convert diploid primary germ cells into haploid mature sperm cells.
It’s a self renewing cell and when they undergo mitosis, tbe daughter cells replenshies the stem cell population, the other cell, called the primary spermatocyte, begins the long journey of becoming a sperm cell
What is the difference between a spermatid and a sperm?
During meiotic maturation, sperm precursors reduce their DNA and chromosome content. After the completion of meiotic division they are called spermatids. Spermatids are therefore the first precursors of sperm with haploid chromosome content.
The primary spermatocytes undergo meiosis 1 to form secondary spermatocytes, which are haploid.
Secondary spermatocytes undergo meiosis 2 to form spermatids.
A single, primary spermatocyte may produce four spermatids.
These spermatids then undergo spermiogenesis, differentiating into mature sperm cells.
Hence, spermatids can be considered as the precursors of sperm cells.
Semen is a complex fluid. What are the roles of the secretions of the bulbourethral glands, the prostate gland, and the seminal vesicles in semen?
Two bulbourethral glands secrete a clear fluid into the urethra to neutralize any urine resisiue that might be present
The prostate gland secretes a milky white fluid that neautralizes the acidity of the vagina so that the sperm could survive
Two semincal vesicles secrete the sugar fructose, which serves as an energy source for sperm.
How many primary oocytes are present in the ovaries of a newborn baby girl? How many secondary oocytes are released during the reproductive life of a woman?
700,000 when born, fewer then 500 are ever released for possible fertilziaton
Compare the roles of FSH and LH in human male and female reproductive systems.
FSH stimulates sperm production, LH triggers testorsetrone production in men
FSH causes the follicle to grow, FSH and LH also stimulate estrogen secretion
AIS
Individuals are XY and SRY gene functions correctly and they develop testes, which causes the Mullerian ducts to disappear
But do not have the right testosterone receptors for male genitals to form
Results in individual presenting as female with internal testes
Pseudohermaphroditism
Individuals are XY with a missing enzyme that enables testosterone to send the right signals
External genitals are female, but Mullerian disappears so no internal female organs
At puberty, testosterone is produced and cause male primary/secondary characteristics
