Biology 30: Menstrual Cycle, Fertilization & Development, Birth

What are the 2 functions of LH in the menstrual cycle?

Triggers ovulation and stimulates the corpus luteum to form.

On what day does LH usually spike?

Around day 14 of a 28-day menstrual cycle.

How does estrogen control endometrial development?

Stimulates the endometrium to thicken and rebuild.

How does progesterone control endometrial development?

Maintains the thick endometrium for possible implantation.

What happens when estrogen and progesterone levels decrease?

The endometrium breaks down and menstruation begins.

What hormones does the follicle release?

Estrogen.

What hormones does the corpus luteum release?

Progesterone and estrogen.

What hormone does the chorion layer release?

Human chorionic gonadotropin (hCG).

What does FSH do during the menstrual cycle?

Stimulates follicle development and estrogen production.

What does estrogen do during the menstrual cycle?

Thickens the endometrium and helps trigger the LH surge.

What does LH do during the menstrual cycle?

Triggers ovulation and corpus luteum formation.

What does progesterone do during the menstrual cycle?

Maintains the endometrium after ovulation.

How are identical twins formed?

One fertilized egg splits into two separate embryos.

How are fraternal twins formed?

Two separate eggs are fertilized by two different sperm.

How many cells result from 1 round of mitosis?

2 cells.

How many cells result from 2 rounds of mitosis?

4 cells.

How many cells result from 3 rounds of mitosis?

8 cells.

How many cells result from 4 rounds of mitosis?

16 cells.

When is mitosis used?

For growth, repair, and replacing cells.

When is meiosis used?

To produce haploid sex cells (gametes).

What are the stages of mitosis in order?

Prophase, metaphase, anaphase, telophase, and cytokinesis.

What happens during prophase?

Chromosomes condense, the nuclear membrane breaks down, and spindle fibres form.

What happens during metaphase?

Chromosomes line up at the middle of the cell.

What happens during anaphase?

Sister chromatids separate and move to opposite poles.

What happens during telophase?

New nuclear membranes form around each set of chromosomes.

What happens during cytokinesis?

The cytoplasm divides, forming two daughter cells.

What is the correct order of early fetal development?

Zygote, blastocyst, implantation, gastrulation.

When does implantation occur?

When the blastocyst attaches to the uterine lining.

What is gastrulation?

The process that forms the three primary germ layers.

What is the correct order of major fetal development events?

Zygote

Blastocyst

Implantation

Gastrulation

Nervous system forms

Heart begins beating

Arms and legs form

Sex differentiation

Respiratory system matures

Birth

What develops from the ectoderm?

Nervous system, brain, spinal cord, and outer skin.

What develops from the mesoderm?

Muscles, bones, circulatory system, and reproductive system.

What develops from the endoderm?

Digestive tract lining, respiratory tract lining, and organs such as the liver.

What is the function of the placenta?

Exchanges oxygen, nutrients, and wastes between maternal and fetal blood.

How does oxygen reach the fetus?

Oxygen passes from maternal blood through the placenta into fetal blood and travels through the umbilical vein.

How do nutrients reach the fetus?

Nutrients pass from maternal blood through the placenta into fetal blood.

How does carbon dioxide leave the fetus?

Carbon dioxide travels through fetal blood to the placenta and enters maternal blood.