PSYB64 Final Exam with Guaranteed
Pass Solutions 2025-2026 Updated.
Is the fetus initially differentiated in regards to sex? - Answer -The fetus is initially
undifferentiated in regard to sex (without exposure to male hormones, all babies would be born
with female physical appearance and behavior)
What is Turner syndrome? - Answer -a condition in which a child receives only a single X
chromosome from the parent
- From this we have learned that a single X chromosome carries enough genetic material to
produce a person who is normal but because he/she lacks the second chromosome, the person
faces difficulties in growth, fertility, hormone production, risk of diabetes, osteoporosis, and
cardiovascular disease
o Individuals with this disease have normal female genitalia but the ovaries develop abnormally
-Unidentified regions on the X chromosome are responsible for development of ovaries but
having only 1 X chromosome interferes in this process
- In most cases, the ovaries don't produce either the ova or normal levels of female hormones
which leads to infertility but when the X chromosome is missing in some but not all cells,
women may be fertile
- Women with Turner syndrome are short and may have increased skin folds at the neck;
intelligence is normal but specific deficits in spatial relationships and memory can occur
What is Klinefelter syndrome? - Answer - it is the most common genetic abnormality related
to sex chromosomes and features an XXY genotype
o These individuals are male but experience reduced fertility and require hormone treatment at
puberty to promote the development of secondary make sex characteristics and to inhibit
female characteristics
o The process of X-inactivation is also disturbed, leading to other symptoms
o It is associated with normal intelligence along with cognitive deficits and social awkwardness
o Delayed, reduced verbal skills, left-handedness, brain lateralization is affected along with
localization of specific functions
- An XYY genotype has also been identified (1/1000 births) in which boys appear to be physically
within typical limits although they tend to be somewhat taller and leaner, suffer from acne, and
have a higher risk for minor injuries
o IQ scores are lower than average
o The men are fertile but they have a higher chance of producing sperm with sex chromosome
abnormalities
- A report has suggested that individuals with XYY genotype were overrepresented in prison
,What are the three stages of prenatal development? - Answer - 3 distinct phases of
development:
o Development of gonads
o Development of internal organs
o Development of external genitalia
- Normally, all 3 processes occur congruently to produce an unambiguous male or female but in
a rare condition called intersex, elements of both male and female development occurs in the
same fetus
What happens during the development of the gonads stage? - Answer o Up until 6 weeks of
conception, male and female fetuses have the same gonads with the capacity to either develop
into ovaries or testes
o After the 6 weeks, the sex determining region of the Y chromosome (SRY) is expressed in male
embryos
o SRY encodes the Testis-determining factor protein which causes the gonads to develop into
testes
o In female embryos, there is no SRY gene or testis-determining factor protein so alternate
genes guide the formation of the ovaries
What happens during the differentiation of the internal organs? - Answer o In about the 3rd
month of development, both males and females fetuses possess a male Wolffian system and a
female Mullerian system
o In males, the Wolffian system develops into seminal vesicles, vas deferens and the prostate
o In females, the Mullerian system develops into the uterus, upper portion of vagina and
fallopian tubes
o During the 3rd month, the male's testes begin to secrete testosterone (promotes
development of Wolffian system) and anti-Mullerian hormone (initiates degeneration of the
Mullerian system)
o In the female fetus, no additional hormones are required for development; the ovaries are not
active during fetal development; the Mullerian system will just develop in the typical female
direction but the nonfunctional remnants of the Wolffian system still remain throughout a
woman's life
What is Androgen Insensitivity Syndrome (AIS)? - Answer o Androgen insensitivity syndrome
(AIS) is a defective gene that produces abnormal androgen receptors and disrupts the normal
development of the Wolffian system in males
o In AIS, the fetus's tissues are blind to the presence of androgens
o Fetuses with AIS have an XY genotype and normal testes and the testes release androgens and
the anti-Mullerian hormone in a normal manner but the lack of functional androgen receptors
prevents the development of the Wolffian system
o The anti-Mullerian hormone still works normally, so the female Mullerian system also fails to
develop
,o Adult individuals with AIS are infertile, their external appearance is quite typically female
o Individuals with AIS are genetic males but typically have female appearance and strong female
gender identities
o AIS might be an advantage for women in sports
What happens during the devleopment of external genitalia? - Answer o Happens during the
6th week after conception
o No hormonal activity is required in order to develop female external genitalia
o 5-alpha-dihydrotestosterone must be recognized by receptor sites for the male external
genitalia to develop normally
o The absence of 5-alpha-dihydrotestosterone leads the immature genitalia to develop in the
female pattern
What is Congenital Adrenal Hyperplasia (CAH)? - Answer o If genetic females are exposed to
excess androgens prenatally, their external genitalia become masculinized (congenital adrenal
hyperplasia CAH)
o CAH is a recessive heritable condition in which the fetus's adrenal glands release high levels of
androgens
o Males with CAH don't show observable effects since they are already exposed to high levels of
androgens but for females it is obvious because the clitoris is enlarged, the labia resemble the
scrotum and sometimes there is no vaginal opening. They describe themselves as tomboys,
engage in more male-interest play and are more likely to engage in bisexual and lesbian
behavior
o However, the majority of women with CAH are heterosexual and the majority of bisexual and
lesbian women DO NOT have CAH or any similar condition
What happens in development at puberty? - Answer - At puberty, additional hormonal
events lead to maturation of the genitals and the development of secondary sex characteristics
- The average age of puberty has dropped from age 16 to 12 possibly because of increased rates
of obesity (accumulation of enough body fat to support reproduction might serve as a signal for
puberty)
- All edible tissues from animals contain a type of estrogen called estradiol which can also
trigger early puberty
- Consumption of treated meat can also increase exposure to estrogens by 40%
- At the onset of puberty, gonadotropin-releasing hormone (GnRH
- ) is released by the hypothalamus which causes the release of follicle-stimulating hormone
(FSH) and luteinizing hormone (LH)
- Both males and females release the same hormones but with different effects
- In response to FSH and LH, the testes produce more testosterone and the ovaries produce
estradiol
, - The testes also small amounts of estrogen and the ovaries produce a small amount of
testosterone
- In males, the burst of androgens stimulates muscular development, maturity of external
genitalia, facial hair and a deeper voice (enlarged larynx)
- Testosterone regulates the production of sperm and affects a male's hairline and can result in
baldness later in adulthood
- In both sexes, estradiol slows down skeletal growth
What is 5-alpha-reductase deficiency? - Answer - 5-alpha-reductase deficiency is a condition
that affects the maturation of external genitalia and affects the male's ability to produce 5-
alpha-reductase which converts testosterone into 5-alpha-dihydrotestosterone
o 5-alpha-dihydrotestosterone is responsible for the masculinization of the external genitalia in
the fetus
o Without sufficient 5-alpha-reductase, these individuals are born with ambiguous external
genitalia and are raised as females
o Development of male internal sexual structures is not affected because this process is
governed by unconverted testosterone
How do hormones affect sexual behaviour? - Answer - Sex hormones organize circuits in the
brain that differ according to sex and these circuits are activated by the sex hormones at the
onset of puberty
- Sex hormones are classified as steroids
- Males and females both produce androgens and estrogens but in different amounts
How are sex hormones regulated by the Hypothalamus and pituitary gland? - Answer -
Hypothalamus exerts control over release of sex hormones through secretion of GnRH
- Light sensed by the retina increases GnRH secretion through its action on melatonin which
normally inhibits the release of GnRH, and light in turn inhibits melatonin which is secreted at
night
- Light increases GnRH release by reducing the inhibition normally produced by melatonin
- In non-human species, the response of the hypothalamus to light provides means for
producing offspring at the right time of year (humans also show some evidence of seasonality in
birth rates)
- GnRH secreted by the hypothalamus travels to the anterior pituitary gland which in turn
releases FSH and LH
- The initial release of these hormones is associated with the onset of puberty and from puberty
on, the gonadotropins continue to play a major role in fertility
- In males, LH signals the testes to produce testosterone
- Both testosterone and FSH are required for the maturation of sperm
- In females, LH and FSH control the menstrual cycle
Pass Solutions 2025-2026 Updated.
Is the fetus initially differentiated in regards to sex? - Answer -The fetus is initially
undifferentiated in regard to sex (without exposure to male hormones, all babies would be born
with female physical appearance and behavior)
What is Turner syndrome? - Answer -a condition in which a child receives only a single X
chromosome from the parent
- From this we have learned that a single X chromosome carries enough genetic material to
produce a person who is normal but because he/she lacks the second chromosome, the person
faces difficulties in growth, fertility, hormone production, risk of diabetes, osteoporosis, and
cardiovascular disease
o Individuals with this disease have normal female genitalia but the ovaries develop abnormally
-Unidentified regions on the X chromosome are responsible for development of ovaries but
having only 1 X chromosome interferes in this process
- In most cases, the ovaries don't produce either the ova or normal levels of female hormones
which leads to infertility but when the X chromosome is missing in some but not all cells,
women may be fertile
- Women with Turner syndrome are short and may have increased skin folds at the neck;
intelligence is normal but specific deficits in spatial relationships and memory can occur
What is Klinefelter syndrome? - Answer - it is the most common genetic abnormality related
to sex chromosomes and features an XXY genotype
o These individuals are male but experience reduced fertility and require hormone treatment at
puberty to promote the development of secondary make sex characteristics and to inhibit
female characteristics
o The process of X-inactivation is also disturbed, leading to other symptoms
o It is associated with normal intelligence along with cognitive deficits and social awkwardness
o Delayed, reduced verbal skills, left-handedness, brain lateralization is affected along with
localization of specific functions
- An XYY genotype has also been identified (1/1000 births) in which boys appear to be physically
within typical limits although they tend to be somewhat taller and leaner, suffer from acne, and
have a higher risk for minor injuries
o IQ scores are lower than average
o The men are fertile but they have a higher chance of producing sperm with sex chromosome
abnormalities
- A report has suggested that individuals with XYY genotype were overrepresented in prison
,What are the three stages of prenatal development? - Answer - 3 distinct phases of
development:
o Development of gonads
o Development of internal organs
o Development of external genitalia
- Normally, all 3 processes occur congruently to produce an unambiguous male or female but in
a rare condition called intersex, elements of both male and female development occurs in the
same fetus
What happens during the development of the gonads stage? - Answer o Up until 6 weeks of
conception, male and female fetuses have the same gonads with the capacity to either develop
into ovaries or testes
o After the 6 weeks, the sex determining region of the Y chromosome (SRY) is expressed in male
embryos
o SRY encodes the Testis-determining factor protein which causes the gonads to develop into
testes
o In female embryos, there is no SRY gene or testis-determining factor protein so alternate
genes guide the formation of the ovaries
What happens during the differentiation of the internal organs? - Answer o In about the 3rd
month of development, both males and females fetuses possess a male Wolffian system and a
female Mullerian system
o In males, the Wolffian system develops into seminal vesicles, vas deferens and the prostate
o In females, the Mullerian system develops into the uterus, upper portion of vagina and
fallopian tubes
o During the 3rd month, the male's testes begin to secrete testosterone (promotes
development of Wolffian system) and anti-Mullerian hormone (initiates degeneration of the
Mullerian system)
o In the female fetus, no additional hormones are required for development; the ovaries are not
active during fetal development; the Mullerian system will just develop in the typical female
direction but the nonfunctional remnants of the Wolffian system still remain throughout a
woman's life
What is Androgen Insensitivity Syndrome (AIS)? - Answer o Androgen insensitivity syndrome
(AIS) is a defective gene that produces abnormal androgen receptors and disrupts the normal
development of the Wolffian system in males
o In AIS, the fetus's tissues are blind to the presence of androgens
o Fetuses with AIS have an XY genotype and normal testes and the testes release androgens and
the anti-Mullerian hormone in a normal manner but the lack of functional androgen receptors
prevents the development of the Wolffian system
o The anti-Mullerian hormone still works normally, so the female Mullerian system also fails to
develop
,o Adult individuals with AIS are infertile, their external appearance is quite typically female
o Individuals with AIS are genetic males but typically have female appearance and strong female
gender identities
o AIS might be an advantage for women in sports
What happens during the devleopment of external genitalia? - Answer o Happens during the
6th week after conception
o No hormonal activity is required in order to develop female external genitalia
o 5-alpha-dihydrotestosterone must be recognized by receptor sites for the male external
genitalia to develop normally
o The absence of 5-alpha-dihydrotestosterone leads the immature genitalia to develop in the
female pattern
What is Congenital Adrenal Hyperplasia (CAH)? - Answer o If genetic females are exposed to
excess androgens prenatally, their external genitalia become masculinized (congenital adrenal
hyperplasia CAH)
o CAH is a recessive heritable condition in which the fetus's adrenal glands release high levels of
androgens
o Males with CAH don't show observable effects since they are already exposed to high levels of
androgens but for females it is obvious because the clitoris is enlarged, the labia resemble the
scrotum and sometimes there is no vaginal opening. They describe themselves as tomboys,
engage in more male-interest play and are more likely to engage in bisexual and lesbian
behavior
o However, the majority of women with CAH are heterosexual and the majority of bisexual and
lesbian women DO NOT have CAH or any similar condition
What happens in development at puberty? - Answer - At puberty, additional hormonal
events lead to maturation of the genitals and the development of secondary sex characteristics
- The average age of puberty has dropped from age 16 to 12 possibly because of increased rates
of obesity (accumulation of enough body fat to support reproduction might serve as a signal for
puberty)
- All edible tissues from animals contain a type of estrogen called estradiol which can also
trigger early puberty
- Consumption of treated meat can also increase exposure to estrogens by 40%
- At the onset of puberty, gonadotropin-releasing hormone (GnRH
- ) is released by the hypothalamus which causes the release of follicle-stimulating hormone
(FSH) and luteinizing hormone (LH)
- Both males and females release the same hormones but with different effects
- In response to FSH and LH, the testes produce more testosterone and the ovaries produce
estradiol
, - The testes also small amounts of estrogen and the ovaries produce a small amount of
testosterone
- In males, the burst of androgens stimulates muscular development, maturity of external
genitalia, facial hair and a deeper voice (enlarged larynx)
- Testosterone regulates the production of sperm and affects a male's hairline and can result in
baldness later in adulthood
- In both sexes, estradiol slows down skeletal growth
What is 5-alpha-reductase deficiency? - Answer - 5-alpha-reductase deficiency is a condition
that affects the maturation of external genitalia and affects the male's ability to produce 5-
alpha-reductase which converts testosterone into 5-alpha-dihydrotestosterone
o 5-alpha-dihydrotestosterone is responsible for the masculinization of the external genitalia in
the fetus
o Without sufficient 5-alpha-reductase, these individuals are born with ambiguous external
genitalia and are raised as females
o Development of male internal sexual structures is not affected because this process is
governed by unconverted testosterone
How do hormones affect sexual behaviour? - Answer - Sex hormones organize circuits in the
brain that differ according to sex and these circuits are activated by the sex hormones at the
onset of puberty
- Sex hormones are classified as steroids
- Males and females both produce androgens and estrogens but in different amounts
How are sex hormones regulated by the Hypothalamus and pituitary gland? - Answer -
Hypothalamus exerts control over release of sex hormones through secretion of GnRH
- Light sensed by the retina increases GnRH secretion through its action on melatonin which
normally inhibits the release of GnRH, and light in turn inhibits melatonin which is secreted at
night
- Light increases GnRH release by reducing the inhibition normally produced by melatonin
- In non-human species, the response of the hypothalamus to light provides means for
producing offspring at the right time of year (humans also show some evidence of seasonality in
birth rates)
- GnRH secreted by the hypothalamus travels to the anterior pituitary gland which in turn
releases FSH and LH
- The initial release of these hormones is associated with the onset of puberty and from puberty
on, the gonadotropins continue to play a major role in fertility
- In males, LH signals the testes to produce testosterone
- Both testosterone and FSH are required for the maturation of sperm
- In females, LH and FSH control the menstrual cycle
