BIOL 252 Final Exam and Already
Solved Solutions 2025-2026 Updated.
Why are the testes external to the body? - Answer Needs to be a cooler temperature for
proper sperm development. Since sperm are created at puberty they must be kept separate
from body or else immune system would destroy them
What are the hormonal and non-hormonal roles of the sertoli cells - Answer -supplies
nourishment to developing sperm during spermatogenesis
-creates barrier between sperm and rest of the body
-Secretes inhibin’s to regulate FSH levels. Increases testosterone levels in seminiferous tubules
in order to stimulate spermatogenesis.
FSH stimulate Sertoli cells to release accessory protein that helps testosterone and inhibin
(inhibits hypothalamus and posterior pituitary
What is the major role of the interstitial cells? - Answer -LH stimulates interstitial cells to
secrete testosterone (the major androgen), which then inhibits further LH release (negative
feedback)
-AKA Leydig cells
-adjacent to seminiferous tubules
What are the similarities and differences between sperm and oocyte development? - Answer
-Both start with 2n diploid cells with 46 chromosome, and divide to form and primary
oocyte/spematocyte also diploid with 46 chromosomes. Those then further divide into 2
secondary spermatocytes or oocytes that's haploid
-oogenia= 3 polar bodies and one egg
-Sperm= 4 haploid spermatids
How is the semen necessary for fertilization? - Answer Includes fructose which provides
energy to sperm, prostate gland which contract the smooth muscles of the female reproductive
tract, as well as buffers that protects the sperm from acidic female environment
What are the major roles of testosterone? How do we make sure not too much testosterone is
secreted? - Answer -Male primary sexual characteristics- the ability to produce sperm cells
and enlargement and differentiation of the male genitalia
-Male secondary sexual characteristics- structural and behavioral changes (hair distribution and
growth, reduced tension of the vocal folds, increased metabolism)
-Male sexual behavior: hypothalamus is responsible for sex drive; driven by testosterone
directly or through conversion of testosterone to other steroids
, -LH stimulates interstitial cells to secrete testosterone and FSH stimulates Sertoli cells to release
an accessory protein inhibin to inhibit testosterone production
-Testosterone inhibits further LH release: negative feedback
Erection - Answer -controlled by parasympathetic division
-Arterioles supplying blood to the erectile tissues are dilated in response to parasympathetic
signals
-Blood fills the spaces in the corpora cavernosa, leading to expansion of erectile tissue
Ejaculation - Answer Sympathetic nerves serving the genital organs cause:
-Reproductive ducts and accessory organs to contract and empty their contents
-The bladder sphincter muscles to constrict, preventing the expulsion of urine
-Rhythmic contractions of penis muscles, leading to propulsion of semen from the urethra
-Accompanied by pleasure sensation, rabid heart beat, high BP= orgasm
Imagine yourself as being a primary oocyte, one of the lucky ones that made it to puberty. Your
month had come and you were "chosen" to be one of the candidates for fertilization. Describe
your daily life in the next year and hopefully, if you are the one to be fertilized, describe your
whereabouts in the days following fertilization. What would you secrete to promote your own
implantation? - Answer - A primary oocyte is surrounded by a follicle of somatic cells and is
diploid with 46 chromosomes. It will then divide into a small polar body (which will die) and a
larger secondary oocyte that is haploid, with 23 chromosomes. It's surrounded by a protective
membrane called the zona pellucida as well as a primary follicle made of granulosa cells, which
will then thicken into a theca layer. Once the secondary oocyte is ovulated, it will develop an
atrium, and a thicker tertiary follicle. If not fertilized, it dies and bleeds into the atrium of the
follicle and is washed out with menstruation, and its corpus luteum degenerates.If fertilized, it
will produce another polar body, which dies, and will undergo meiosis with the sperm and
produce a zygote that will turn into an embryo. Its corpus luteum left behind will grow and
secrete HCG in preparation for embryo
Imagine yourself as part of the pituitary gland. When during life and specifically during the
ovarian cycle are you going to secrete LH and FSH and when are you not? - Answer -At
puberty, GnRH is released ; FSH and LH are released by the pituitary, which act on the ovaries
-Low estrogen levels inhibit secretion of LH from the pituitary gland
- Just before the 14th day, estrogen levels rise dramatically
-High estrogen levels stimulate secretion of LH
Estrogen levels increase and high estrogen levels have a + feedback on pituitary, causing a
sudden surge of LH
-LH spike- stimulates primary oocyte to complete meiosis 1, triggers ovulation, and transforms
the ruptured follicle into a corpus luteum, which produces inhibin, progesterone, and estrogen
Solved Solutions 2025-2026 Updated.
Why are the testes external to the body? - Answer Needs to be a cooler temperature for
proper sperm development. Since sperm are created at puberty they must be kept separate
from body or else immune system would destroy them
What are the hormonal and non-hormonal roles of the sertoli cells - Answer -supplies
nourishment to developing sperm during spermatogenesis
-creates barrier between sperm and rest of the body
-Secretes inhibin’s to regulate FSH levels. Increases testosterone levels in seminiferous tubules
in order to stimulate spermatogenesis.
FSH stimulate Sertoli cells to release accessory protein that helps testosterone and inhibin
(inhibits hypothalamus and posterior pituitary
What is the major role of the interstitial cells? - Answer -LH stimulates interstitial cells to
secrete testosterone (the major androgen), which then inhibits further LH release (negative
feedback)
-AKA Leydig cells
-adjacent to seminiferous tubules
What are the similarities and differences between sperm and oocyte development? - Answer
-Both start with 2n diploid cells with 46 chromosome, and divide to form and primary
oocyte/spematocyte also diploid with 46 chromosomes. Those then further divide into 2
secondary spermatocytes or oocytes that's haploid
-oogenia= 3 polar bodies and one egg
-Sperm= 4 haploid spermatids
How is the semen necessary for fertilization? - Answer Includes fructose which provides
energy to sperm, prostate gland which contract the smooth muscles of the female reproductive
tract, as well as buffers that protects the sperm from acidic female environment
What are the major roles of testosterone? How do we make sure not too much testosterone is
secreted? - Answer -Male primary sexual characteristics- the ability to produce sperm cells
and enlargement and differentiation of the male genitalia
-Male secondary sexual characteristics- structural and behavioral changes (hair distribution and
growth, reduced tension of the vocal folds, increased metabolism)
-Male sexual behavior: hypothalamus is responsible for sex drive; driven by testosterone
directly or through conversion of testosterone to other steroids
, -LH stimulates interstitial cells to secrete testosterone and FSH stimulates Sertoli cells to release
an accessory protein inhibin to inhibit testosterone production
-Testosterone inhibits further LH release: negative feedback
Erection - Answer -controlled by parasympathetic division
-Arterioles supplying blood to the erectile tissues are dilated in response to parasympathetic
signals
-Blood fills the spaces in the corpora cavernosa, leading to expansion of erectile tissue
Ejaculation - Answer Sympathetic nerves serving the genital organs cause:
-Reproductive ducts and accessory organs to contract and empty their contents
-The bladder sphincter muscles to constrict, preventing the expulsion of urine
-Rhythmic contractions of penis muscles, leading to propulsion of semen from the urethra
-Accompanied by pleasure sensation, rabid heart beat, high BP= orgasm
Imagine yourself as being a primary oocyte, one of the lucky ones that made it to puberty. Your
month had come and you were "chosen" to be one of the candidates for fertilization. Describe
your daily life in the next year and hopefully, if you are the one to be fertilized, describe your
whereabouts in the days following fertilization. What would you secrete to promote your own
implantation? - Answer - A primary oocyte is surrounded by a follicle of somatic cells and is
diploid with 46 chromosomes. It will then divide into a small polar body (which will die) and a
larger secondary oocyte that is haploid, with 23 chromosomes. It's surrounded by a protective
membrane called the zona pellucida as well as a primary follicle made of granulosa cells, which
will then thicken into a theca layer. Once the secondary oocyte is ovulated, it will develop an
atrium, and a thicker tertiary follicle. If not fertilized, it dies and bleeds into the atrium of the
follicle and is washed out with menstruation, and its corpus luteum degenerates.If fertilized, it
will produce another polar body, which dies, and will undergo meiosis with the sperm and
produce a zygote that will turn into an embryo. Its corpus luteum left behind will grow and
secrete HCG in preparation for embryo
Imagine yourself as part of the pituitary gland. When during life and specifically during the
ovarian cycle are you going to secrete LH and FSH and when are you not? - Answer -At
puberty, GnRH is released ; FSH and LH are released by the pituitary, which act on the ovaries
-Low estrogen levels inhibit secretion of LH from the pituitary gland
- Just before the 14th day, estrogen levels rise dramatically
-High estrogen levels stimulate secretion of LH
Estrogen levels increase and high estrogen levels have a + feedback on pituitary, causing a
sudden surge of LH
-LH spike- stimulates primary oocyte to complete meiosis 1, triggers ovulation, and transforms
the ruptured follicle into a corpus luteum, which produces inhibin, progesterone, and estrogen
