human reproduction

Question 1

: What is sexual reproduction?

Answer 1

Creation of offspring by fusion of male gamete (sperm) & female gamete (egg) to form a zygote.

Question 2

What is asexual reproduction?

Answer 2

Creation of offspring without fusion of egg & sperm.

Question 3

Differences between Asexual and Sexual Reproduction?

Answer 3

• Asexual: One parent, no gametes, genetically identical offspring.
• Sexual: Two parents, gametes required, genetically varied offspring

Question 4

Why is sexual reproduction considered an evolutionary enigma?

Answer 4

• Sexual females have half as many daughters (“twofold cost”).
• Despite the cost, almost all eukaryotes reproduce sexually.

Question 5

Mechanisms of Asexual Reproduction?

Answer 5

• Budding: New individuals from outgrowths (e.g., Hydra).
• Binary Fission: Parent splits into two (invertebrates).
• Fragmentation: Body parts develop into individuals.

Question 6

What is hermaphroditism?

Answer 6

Each individual has both male & female reproductive systems (e.g., snails, worms).

Question 7

What is sex reversal?

Answer 7

Some species can switch sexes:
* Male → Female (e.g., oysters)
* Female → Male (e.g., coral reef fish)

Question 8

What is external fertilization?

Answer 8

Eggs are fertilized outside the female’s body in a moist environment

Question 9

What is spawning?

Answer 9

Individuals release eggs and sperm into water at the same time, often triggered by chemical/environmental cues.

Question 10

What is internal fertilization?

Answer 10

Sperm deposited inside/near female tract; fewer gametes produced, higher zygote survival, often with parental care.

Question 11

Basic pattern of human reproductive anatomy?

Answer 11

• Gonads (produce gametes)
• Ducts (store/deliver gametes)
• Mating structures

Question 12

Why are testes located outside the body in mammals?

Answer 12

Lower temperature needed for normal sperm production

Question 13

Penis structure and function?

Answer 13

• Three cylinders of spongy erectile tissue.
• Erection caused by blood flow.
• Glans (head) has sensitive thin skin, covered by foreskin (prepuce).

Question 14

Path of sperm from testes to exit?

Answer 14

Seminiferous tubules → Epididymis → Vas deferens → Ampulla → Seminal vesicle → Ejaculatory duct → Urethra

Question 14

Testes structure?

Answer 14

• Seminiferous tubules: site of sperm formation.
• Leydig cells: produce testosterone.
• Sertoli cells: nourish sperm (“nurse cells”).

Question 15

Composition of semen?

Answer 15

Sperm + secretions from:
* Ampullae (fructose, nutrients)
* Seminal vesicles (60% semen, fructose, prostaglandins)
* Prostate (pH buffer)
* Bulbourethral glands (mucus to neutralize acid)

Question 15

Female external reproductive structures?

Answer 15

Clitoris and 2 sets of labia

Question 16

Female internal reproductive organs?

Answer 16

Gonads (ovaries), ducts (oviducts, uterus, vagina).

Question 17

What is the endometrium?

Answer 17

Lining of the uterus rich in blood vessels.

Question 17

Function of ovaries?

Answer 17

• Contain follicles with oocytes.
• Support cells surround developing eggs

Question 18

How does the egg reach the uterus?

Answer 18

• Through the oviduct (fallopian tube), moved by cilia.

Question 19

What is the clitoris?

Answer 19

A highly sensitive structure with a glans covered by a prepuce.

Question 19

What is the vulva composed of?

Answer 19

: Labia majora, labia minora, hymen, clitoris.

Question 20

Function of mammary glands?

Answer 20

• Secrete milk via small sacs of epithelial tissue.
• Not reproductive organs but vital for reproduction.

Question 21

What is gametogenesis?

Answer 21

Production of gametes via meiosis (spermatogenesis & oogenesis).

Question 22

Spermatogenesis vs. Oogenesis?

Answer 22

* Spermatogenesis: Continuous, prolific, ~7-10 weeks maturation (~74 days cycle). * Oogenesis: Starts in embryo, matures years/decades later.

Question 23

Hormones regulating human reproduction?

Answer 23

* Hypothalamus → GnRH → Anterior pituitary → FSH & LH → Gonads * Gonads produce testosterone, estrogen (estradiol, progesterone).

Question 23

Hormonal control in males?

Answer 23

* FSH → stimulates Sertoli cells (nourish sperm). * LH → stimulates Leydig cells (produce testosterone). * Testosterone & inhibin use negative feedback to regulate hormone levels.

Question 24

Hormonal control of female reproductive cycles?

Answer 24

* Cyclic hormone secretion. * Menstruation occurs if no embryo implants. * Uterine cycle (E + P) coordinates with ovarian cycle (FSH + LH).

Question 25

Phases of the ovarian cycle?

Answer 25

* Follicular phase: Follicle growth, estradiol rise → ends with ovulation. * Luteal phase: Corpus luteum forms, secretes progesterone & estradiol.

Question 26

Phases of the uterine cycle?

Answer 26

* Proliferative phase (endometrium thickens) → Follicular phase * Secretory phase (nutrient secretion) → Luteal phase * Menstrual flow phase (shedding) → new cycle begins

Question 27

What is endometriosis?

Answer 27

Endometrial cells migrate outside uterus, causing swelling and pain

Question 28

What is menopause?

Answer 28

* Cessation of ovulation & menstruation (~500 cycles; ~40 years). * Due to decline in estrogen, LH, FSH. * May have evolved for better maternal/grandmaternal care. Use Umbilical cord or placental blood cells – store at birth

Question 28

What are fibroids?

Answer 28

Non-cancerous uterine growths linked to obesity and early puberty onset.

Question 29

what is GnRH

Answer 29

secreted by the hypothalamus & directs the release of FSH (follicle-stimulating hormone) & LH (luteinizing hormone) from the anterior pituitary

Question 30

what is the uterine cycle?

Answer 30

Changes in the uterus define the menstrual cycle

Question 31

what is the ovarian cycle?

Answer 31

Changes in the ovaries (FSH + LH) Follicle growth & an increase in the hormone estradiol characterize the follicular phase * The follicular phase ends at ovulation & the secondary oocyte is released `

Question 32

what does the corpus luteum do?

Answer 32

secretes progesterone & estradiol, which exert negative feedback on the hypothalamus & pituitary

Question 32

what happens in the luteal phase?

Answer 32

following ovulation, the follicular tissue left behind is stimulated to transform into a corpus luteum

Question 33

what happens during oogenesis?

Answer 33

starts in meiosis and stops in prophase 1, becomes primary oocyte, then secondary oocyte, secondary oocyte is ovulated and can be fertilized, if fertilized meiosis 2 completes it and forms a mature ovum

Question 34

order of follicle growth during oogenesis?

Answer 34

primary oocyte within follicle, growth follicle, mature follicle ruptured follicle, and corpus luteum

Question 35

difference between primary spermatocyte and secondary spermatocyte?

Answer 35

primary happens in meiosis 1 and divides into two secondary spermatocytes, while secondary happens in meiosis 2 and forms 2 spermatids