Reproductive system

What is budding and where is it seen?

Budding is asexual reproduction via mitosis (seen in corals); creates a smaller offspring from the parent.

What is fission and which organisms do it?

Fission is asexual reproduction via mitosis where an organism splits into two (common in invertebrates).

What is parthenogenesis?

A form of asexual reproduction where offspring are produced from unfertilized eggs (seen in some invertebrates and vertebrates).

How are drones and workers produced in honeybees?

Drones develop from unfertilized eggs via parthenogenesis; workers come from fertilized diploid eggs.

What environments favor asexual reproduction?

Homogeneous, stable environments with consistent resources and conditions.

What is the oogonium?

Parent cell in ovaries that divides mitotically to form primary oocytes.

When is the primary oocyte arrested?

During fetal development in prophase I of meiosis.

When does the oocyte resume meiosis?

After puberty, during monthly cycles, forming a secondary oocyte arrested in metaphase II.

When is meiosis II completed in oocytes?

Only upon fertilization by a sperm cell.

What hormone stimulates Leydig cells?

LH (Luteinizing Hormone).

What do Leydig cells produce?

Testosterone, which supports spermatogenesis.

Where are Sertoli cells located?

Inside seminiferous tubules; they support spermatogenesis and secrete inhibin.

Which hormones stimulate spermatogenesis?

FSH and LH from the anterior pituitary.

What does high estradiol do to the hypothalamus?

Stimulates the hypothalamus to trigger an LH surge and ovulation.

What does low estradiol do to the anterior pituitary?

Inhibits FSH and LH secretion.

Where is sperm produced and matured?

Produced in testes, matures in epididymis.

What structure delivers sperm to the vagina?

Urethra (through the penis during erection).

What is the oviduct also called?

Fallopian tube; location of fertilization.

Homologous structures

testes, penis, bulbourethral gland?

What happens in the follicular phase?

FSH stimulates follicle growth; estrogen rebuilds uterine lining.

What triggers ovulation?

High estrogen → LH surge → release of egg.

What forms after ovulation?

Corpus luteum; produces progesterone to maintain uterine lining.

What maintains the uterine lining post-ovulation?

Progesterone from the corpus luteum.

What triggers menstruation?

Drop in progesterone (and estrogen) when no fertilization occurs.

Where does fertilization occur?

In the ampulla of the fallopian tube.

What is the cortical reaction?

Mechanism that blocks entry of additional sperm after one fertilizes the egg.

What is the sequence of early development?

Zygote → Morula → Blastocyst.

What is implantation?

Blastocyst embeds in the uterine lining 6–7 days after fertilization.

How do birth control pills prevent ovulation?

Combination of estradiol and progesterone inhibits GnRH → suppresses LH/FSH → no ovulation.

What mating system leads to simpler genitalia?

Monogamy and polygyny (low sperm competition).

What trait is common in polygynous males?

Bright, colorful plumage for mate attraction.

What do polyandrous females often have?

Multiple spermathecae (sperm storage organs).

What is cryptic female choice (CFC)?

Post-copulatory selection where females influence which sperm fertilize the egg.

Mechanisms of CFC?

Copulation duration, sperm ejection, sperm storage, selective fertilization.

What are simultaneous hermaphrodites?

Organisms that produce both sperm and eggs at the same time (e.g., sea slugs).

What is a sequential hermaphrodite?

Organism that switches sex depending on group composition (e.g., egg producer becomes sperm producer).