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Proteins exhibit more and more abnormalities in amino acid sequence with age

false - mostly folding

Older people have more trouble with thermoregulation because they have more subcutaneous fat and cannot dissipate body heat efficiently

false - they have less subcutaneous fat

During implantation and about six days after ovulation, the trophoblast forms a deep layer that retains individual cells called the ____ and a superficial layer composed of a multinucleate mass of cells whose plasma membranes broke down called the _____.

cytropholast; syncytiotrophoblast

As it implants, the conceptus is nourished by means of

trophoblastic nutrition

the chorion forms the fetal part of the placenta


In order for an egg to survive, it must be fertilized within _____ hours of ovulation

12 to 24

which of these lists the stages of prenatal development in correct order?

zygote, cleavage, morula, trophoblast, embryo, fetus

the epidermis, nervous system, pituitary, internal and external ear are derived from


The skin and hair become drier in old age because of

senescence of the sebaceous glands

an individual becomes a fetus at the end of _____ of gestation.

8 weeks

Which of these organ systems shows the greatest structural change in the transitional period after birth?


The capacitation of sperm involves

the removal of cholesterol from the plasma membrane

These are derivatives of ectoderm except

the dermis

At 5 months gestation, a fetus is covered with a cheesy sebaceous secretion called

vernix caseosa

Evolutionary theorists no longer believe that a function of death is to eliminate old and frail individuals for the good of the species


The first 6 weeks of postpartum life constitute

the neonatal period

Senescence of the immune system makes older people more subject to cancer and infectious disease because of a decline in

antigen-presenting cells and helper T cells

The fine hair on the body of a 5-month-old fetus is


By the time the conceptus arrives in the uterus

it consists of 16 or more cells

Most fetal blood bypasses the liver by way of a shunt called

the ductus venosus

Teratogens usually do not cause congenital anomalies


The observation that there is a limit to how many times a cell can divide is the basis for the

replicative senescence theory

The __________ encloses all the rest of the membranes and the embryo


The optimal "window of opportunity" to conceive a child is

a few days before ovulation to less than a day after

The neonatal period of life is considered to extend to an age of

6 weeks

During implantation, the embryoblast undergoes gastrulation


If the blastocyst implants in the uterine tube instead of the uterus, the pregnancy is called


This figure shows the placenta and embryonic membranes. What does "1" represent?

the placenta

Down syndrome (trisomy-21) results from


Prior to ejaculation, __________ in the sperm plasma membrane prevents premature release of ____________

Cholesterol; acrosomal enzymes

Which of these is not part of the pre embryonic stage of development

differentiation of organs

The cytotrophoblast is composed of cells that later become the embryo


Muscular weakness tends to develop in old age for all of the following reasons except

Reduced perfusion of the muscles ?????
slower conduction??????

In the blastocyst, the trophoblast will become _____, and the embryoblast will become _______.

part of the placenta; the embryo

In the fast block polyspermy, binding of sperm opens up _________ channels, which depolarizes the egg membrane and __________

Na+; prevents the entrance of any more sperm

During implantation, the trophoblast divides into a deep layer, the _____________, composed of individual cells, and a superficial layer, the _________, composed of a multinucleate mass of cytoplasm

cytotrophoblast; syncytiotrophoblast

The digital rays of a fetus give rise to

fingers and toes

The embryonic membranes include all of the following except the


These are have potentially teratogenic effects except


a teratogen is most likely to cause

a deformity of the limbs

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