chapter 21 study human bio

Embryonic germ layer (innermost layer) that forms the lining of the digestive tube and its associated structures

Endoderm *it gives rise to the liver and pancreas, the alveoli of the lungs, the lining of the urinary bladder, urethra and vagina, and several glands

How do the skulls of adult chimpanzees and humans differ? a. Adult chimpanzees have heavier brow ridges. b. Adult chimpanzees have less massive jaws. c. Adult chimpanzees have a less angled skull. d. Adult chimpanzees have more rounded faces.

a

Which of the following events is correctly matched with the month of prenatal development? a. kidneys produce urine: month 3 b. heart pumps to circulate blood: month 4 c. gender development is completed: month 5 d. bone marrow takes over blood cell production: month 7

a

Which process is best described as individual cells taking on specialized forms and functions? a. differentiation b. morphogenesis c. cleavage d. growth

a *Differentiation is the process by which a less specialized cell changes to take on a specific form and function.

Mice with two X chromosomes who are also genetically engineered to express the SRY (Sex-determining Region Y) gene develop male genitalia. This demonstrates which of the following? a. Gender is determined by the presence or absence of the SRY gene. b. Sperm do not normally play a role in gender determination. c. The "default" condition is the male gender. d. Gender is determined by whether the embryo has one or two X chromosomes.

a *The SRY gene, normally only present on the Y chromosome, codes for a protein that triggers male development.

The ultimate human stem cell that divides mitotically to give rise to all adult tissues and organs is called the __________. a. zygote b. blastocyst c. oocyte d. embryo

a *The zygote is the one-cell fertilized egg that will divide to form all the cells of a human body

Which of the following statements about the germ layers is NOT correct? a. The endoderm gives rise to the nervous system. b. The germ layers (ectoderm, mesoderm, and endoderm) arise from the embryonic disk. c. The ectoderm gives rise to the nervous system. d. The mesoderm gives rise to the connective tissue.

a *This is the statement that is false. The endoderm develops into the lining of the digestive, urinary, and respiratory tracts, and problems with its formation could result in an unformed bladder.

Which of the following is a critical organ system whose failure will lead to death in a matter of minutes? a. cardiovascular b. urinary c. digestive d. immune

a *Without oxygen and nutrient delivery to all cells, life will end very quickly.

Which of the following occurs during days 1-14 of development? a. Implantation occurs in the endometrium (inner lining) of the uterus. b. The mesoderm forms. c. Embryonic development occurs. d. The heart of the embryo forms and begins beating.

a *During the first 14 days of development, the pre-embryo divides many times while traveling down the oviduct, then implants within the endometrium of the uterus.

identical twins arise when

a zygote divides in two during development

the tip of the sperm head is called

acrosome

A fluid similar to interstitial fluid that surrounds and protects the fetus during pregnancy.

amniotic fluid

From about the beginning of week three until the end of week eight, the developing human is called

an embryo

All of the following are theories regarding causes of aging, EXCEPT that __________. a. a decline in one critical body system induces parallel declines in others b. cortisol production increases, and the stress response contributes to aging c. cells run out of telomeres and stop dividing d. cells can no longer repair themselves properly, and damage accumulates

b

Which fetal hormone plays a role in initiating labor? a. oxytocin b. ACTH c. estrogen d. progesterone

b

Which of the following lists the correct order of structures through which a sperm must pass to accomplish fertilization? a. ovum plasma membrane, corona radiata, zona pellucida b. corona radiata, zona pellucida, secondary oocyte plasma membrane c. zona pellucida, secondary ooctye plasma membrane, corona radiata d. zona pellucida, corona radiata, secondary oocyte plasma membrane

b

Which of the following will result in fraternal twins? a. the division of a fertilized egg into two masses after differentiation has begun b. the fertilization of two eggs by two different sperm c. the fertilization of one egg by two different sperm d. the division of a fertilized egg into two masses before differentiation has begun

b

Which of these is a difference between the skull of an adult chimpanzee and the skull of an adult human? a. The chimpanzee skull is sharper and more angular. b. All of these are differences between adult chimpanzee and adult human skulls. c. The chimpanzee skull has heavier brow ridges. d. The chimpanzee skull has more massive joints. e. They result from different patterns of allometric growth.

b

__________ stimulates the production of milk, whereas __________ causes ejection of milk from the breast. a. Estrogen; oxytocin b. Prolactin; oxytocin c. Estrogen; prolactin d. Oxytocin; prolactin

b

What accounts for human infants having large heads on small bodies? a. formation of the head before the rest of the body during fetal development b. allometric growth c. at birth the human head is NOT relatively large compared to the rest of the body d. the need to get the infant out through the birth canal

b *"Allometric Growth" refers to variations in the rates of growth seen in different parts of the body.

When discussing neurulation, we can say that ________. a. the neural plate folds outward, forming a ridge that then recedes and is covered by an expanding layer of ectoderm b. the neural plate folds inward, forming the neural groove. The edges of the groove fuse to form the neural tube, which in turn gives rise to the brain and spinal cord c. the neural tube, which forms during gastrulation, gives rise to the neural plate, which gives rise to the neural groove from which the brain and spinal cord develop d. neurulation involves three separate structures: the neural plate, the neural groove, and the neural tube. These structures develop simultaneously in separate parts of the embryo in order to form the brain and the spinal cord.

b *The neural plate folds inward, forming the neural groove. The edges of the groove fuse to form the neural tube, which in turn gives rise to the brain and spinal cord.

Which of the following statements about the notochord is NOT correct? a. The notochord prompts overlying ectoderm to thicken and form the neural plate. b. The notochord gives rise to the spinal cord. c. The notochord is located where the future vertebral column will be found. d. The notochord is mesodermal in origin.

b *This statement is false. The notochord is not composed of nervous tissue.

At __________, the circulatory, respiratory, and digestive systems function independently for the first time. a. morula stage b. birth c. three weeks d. six weeks

b *Upon birth, the organ systems of the neonate must function independently of the mother.

stage of early embryonic development. The product of cleavage.

blastocyst

the _____ is the hallow ball that implants in the lining of the uterus

blastocyst

Brain growth is nearly complete (95% of its final size) by the end of __________. a. the neonatal period b. adolescence c. childhood d. infancy

c

Possible activities of telomerase could be __________. a. blocking cancer by restoring telomeres after cell divisions b. stopping the aging process by rebuilding the telomeres c. both stopping the aging process by rebuilding the telomeres and contributing to cancer by allowing tumor cells to continue dividing indefinitely d. contributing to cancer by allowing tumor cells to continue dividing indefinitely

c

Which is the correct order of events in embryonic development? a. cleavage stage, blastocyst formation, morula formation, gastrulation, neurulation b. cleavage stage, gastrulation, morula formation, blastocyst formation, neurulation c. cleavage stage, morula formation, blastocyst formation, gastrulation, neurulation d. cleavage stage, morula formation, blastocyst formation, neurulation, gastrulation

c

Which of the following processes is the first to occur as a fertilized egg begins its journey down a uterine tube toward the uterus? a. growth b. differentiation c. cleavage d. all of these choices

c

Variations in allometric growth patterns demonstrate how _____. a. differences in the fetal skulls of chimpanzees and humans lead to very similar adult skulls b. adult chimpanzees are basically juvenile humans that have gained the ability to reproduce c. relatively small genetic changes can have a major impact on phenotype d. relatively large genetic changes can have a minor impact on phenotype

c *Relatively small changes that affect the timing of developmental events can have a major impact on growth patterns.

Which of the following is the event that begins the process of labor? a. Maternal estrogen stimulates the production of prostaglandins. b. Steroid hormones from the fetal adrenal gland cause the placenta to increase estrogen production and decrease progesterone production. c. ACTH is released by the mature fetal pituitary gland. d. Stretching of the cervix causes release of oxytocin.

c *The mature fetal pituitary gland of the fetus begins the process of labor by releasing ACTH, which causes a cascade of hormone events culminating in birth of the neonate.

placenta previa a. is not connected to the umbilical cord. b. effectively protects the embryo from alcohol c. allows for the exchange of nutrients, gases, and antibodies between maternal and embryonic circulations d. permits direct mixing of maternal and fetal blood

c *The placenta is a filter that allows the entry of nutrients and the removal of wastes.

Which of the following events occurs in the third trimester of development? a. In the female, follicles start forming in the ovaries. b. Gender is determined. c. In the male, the testes descend into the scrotal sac. d. The fetus begins eliminating urine into the amniotic fluid

c *The testes develop internally early in pregnancy, but descend into the scrotal sac during the third trimester before birth

A blastocyst is a large cluster of cells with a fluid-filled cavity. It consists of two parts: one that develops into the embryo and one that gives rise to part of the placenta. Name these two parts, and identify which part is which. a. The morula develops into the embryo proper, and the trophoblast develops into the placenta. b. The inner cell mass develops into the embryo proper, and the morula develops into the placenta. c. The inner cell mass develops into the embryo proper; the trophoblast develops into the placenta. d. The inner cell mass develops into the placenta, and the trophoblast develops into the embryo proper.

c *The two parts of the blastocyst are the inner cell mass, which develops into the embryo, and the trophoblast, which is a thin layer of cells that develops into part of the placenta.

Outermost fetal membrane. Helps form the placenta

chorion

An early phase of embryonic development consisting of rapid mitotic cell divisions without cell growth

cleavage

a series of cell divisions without cell growth or differentiation during the first four days following fertilization.

cleavage

Fertilization is most likely to occur if intercourse occurs during a time period __________. a. from 1 day before ovulation to 3 days after ovulation b. from 5 days before ovulation to 2 days after ovulation c. from 1 day before ovulation to 2 days after ovulation d. from 2 days before ovulation to 1 day after ovulation

d

Which of the following are MISMATCHED? a. neural groove: spinal cord b. urogenital groove: urethra c. placenta: chorion and endometrium d. mesoderm: gastrointestinal tract lining

d

By week eight of development, __________. a. growth, differentiation, and morphogenesis slow down temporarily b. amniocentesis is performed if there is a family history of a genetic disease c. most organ systems are fully functional d. the heart and circulatory systems complete their development

d *By week eight of embryonic development, blood is circulating throughout the fetus in a functional circulatory system.

process by which a cell changes in form or function

differentiation

epidermis of skin, including hair, nails, and glands mammary glands the nervous system, including the brain, spinal cord, and all nerves cornea, retina, and lens of eye enamel of teeth posterior pituitary gland adrenal medulla epithelial lining of nose, mouth, and anus derived from what primary germ layer?

ectoderm

the outermost layer, the one exposed to the amniotic cavity.

ectoderm

Embryonic germ layer (outermost layer) that forms the epidermis of the skin and its derivatives, and nerve tissues

ectoderm *tissues derived from the ectoderm become the epidermis of the skin, the nervous system, hair, nails, enamel of teeth, parts of the eye, and several other organs and tissues

embryonic disk differentiates into two cell types called

ectoderm and endoderm

A pregnancy that results from implantation outside the uterus

ectopic pregnancy

refers to the developing human from about the beginning of week three until the end of week eight.

embryo

the embryonic disk will develop into the

embryo

A flattened disk of cells that develops in the blastocyst shortly after implantation.

embryonic disk

embryonic germ layer, gives rise to the liver and pancreas, the alveoli of the lungs, the linings of the urinary bladder, urethra and vagina, and several glands.

endoderm

epithelial tissues lining the digestive tract (except mouth and anus), vagina, bladder, and urethra alveoli of lungs liver and pancreas thyroid, parathyroid, and thymus glands anterior pituitary gland tonsils portions of the inner ear

endoderm

ectoderm forms the

epidermis of the skin and its derivatives, and nerve tissue

fusion of the nuclei of sperm and egg, there by creating a zygote

fertilization

identical twins are always of the same

gender and are usually closely alike in phenotypic appearance

The process by which the blastocyst becomes buried within the endometrium is called

implantation

dermis of skin all connective tissue, cartilage, and bone all muscle tissue (heart, skeletal, smooth) bone marrow (blood cells) kidneys and ureters testes, ovaries, and reproductive ducts lining of blood vessels lymphatic vessels adrenal cortex derived from what primary germ layer

mesoderm

primary germ layer that forms the skeleton and muscles of the body

mesoderm

Primary germ layer that forms the skeleton and muscles of the body (middle layer)

mesoderm *the middle layer or mesoderm, becomes muscle, connective tissue and bone, kidneys and uterus, bone marrow, testes or ovaries, the lining of the blood vessels, and other organs and tissues

process involving dramatic changes in shape and form that an organism goes through during development

morphogenesis

the _____ is the female gamete

oocyte

female gamete, also called an egg

ovum

An organism during the first two weeks after fertilization.

pre-embryo

fraternal twins arise from

the ovulation of more than one oocyte in a particular cycle

The diploid cell formed by the union of the ovum and a sperm. The zygote is the product of fertilization

zygote