Biology Sections Ch. 27 1-4 Evolution

What percentage of couples experience infertility?

About 1 in 7 couples.

What usually causes female infertility?

Failure to ovulate.

What controls ovulation?

Hormones.

What are the two main modes of reproduction?

Asexual and sexual.

Why are asexual offspring identical?

No fusion of egg and sperm.

What is budding?

New individual splits off parents.

What is fission?

Parents split into equal individuals.

What is fragmentation?

Parent breaks into pieces that regrow.

What is regeneration?

Regrowth of lost body parts.

Why is asexual reproduction useful for sessile animals?

They don't need to find a mate.

What is sexual reproduction?

Fusion of haploid gametes.

What is the male gamete?

Sperm.

What is the female gamete?

Egg.

What does sexual reproduction produce?

Genetically variable offspring.

When do some animals switch to sexual reproduction?

When conditions become harsh.

Why is sexual reproduction difficult for solitary animals?

Hard to find a mate.

What is an example of an organism that reproduces both ways?

Sea anemone.

What is external fertilization?

Gametes released into water.

What is internal fertilization?

Sperm deposited inside female.

What does internal fertilization require?

Copulation and complex organs.

What are gonads?

Organs that produce gametes.

What do both sexes have besides gonads?

Ducts to deliver gametes.

What do ovaries produce besides eggs?

Estrogen.

How many follicles does a woman have at birth?

About 400,000.

How often does ovulation occur?

About every 28 days.

What is the corpus luteum?

Follicle tissue that makes estrogen and progesterone.

What does progesterone help maintain?

The uterine lining.

Where does fertilization usually occur?

Upper oviduct.

What moves the egg through the oviduct?

Cilia.

What does circumcision significantly reduce?

Risk of contracting spreading STDs, including AIDS.