The human life cycle begins with ___ and ends with ___ phase.

Fertilization; death

True or False: The prenatal stage of the human life cycle includes postnatal growth and development.

False; the prenatal stage does not include postnatal growth and development.

What marks the beginning of the prenatal stage in human development?

The union of a man's sperm and a woman's egg to form a zygote.

Fill in the blank: The human life cycle is characterized by biological transitions that occur during ___ and ___ phases.

Maturity; senescence

Which two main stages comprise the human life cycle?

Prenatal stage and postnatal stage.

The embryonic stage lasts from conception to ___ weeks of pregnancy.

8 weeks

True or False: The heart starts beating and is visible by ultrasound almost immediately after conception.

False. The heart starts beating around 5 weeks of pregnancy.

By 6 weeks, the embryo measures less than ___ inch long from head to rump.

¼ inch

What significant developments occur in the embryo by the end of the 6th week?

Major developments occur by week 6.

• Heart starts pumping blood.

• All four heart chambers present.

• Formation of body cavities begins.

True or False: The embryo reflexively responds to light touch on the face by 7½ weeks.

True

Fill in the blank: The embryonic stage is characterized by rapid cell division and the embryo embedding itself into the ___ of the womb.

Wall

What major structures begin to form in the embryo by 5 weeks of gestation?

The brain, spinal cord, and heart begin to develop.

At 10 weeks, the developing human is referred to as a ___ which means 'little one' or 'unborn offspring.'

Fetus

True or False: By 10 weeks, the kidneys of the embryo have begun producing and releasing urine.

True

Fill in the blank: By 12 weeks, fingerprints start forming while ___ and ___ begin to grow.

Fingernails and toenails

What significant development occurs in the fetus at 17 weeks regarding blood cell formation?

Blood cell formation moves to its permanent location inside the bone marrow.

True or False: The cochlea, the organ of hearing, reaches adult size by 18 weeks.

False; it reaches adult size by 22 weeks.

At what week do gender differences begin to emerge, particularly regarding jaw movements?

16 weeks

Fill in the blank: By 20 weeks, the skin has developed sweat glands and is covered by a greasy white substance called ___.

Vernix

What role does the vernix serve for the developing fetus?

It provides protection from the amniotic fluid.