Chapter 43
48) Most fetuses can survive outside the womb after a minimum of ________ weeks. A) 32 B) 45 C) 15 D) 38 E) 20
A) 32
38) At what stage does a human embryo implant in the uterus? A) Blastocyst B) Embryonic disk C) Morula D) Gastrula E) Fetal
A) Blastocyst
44) Which of the following occurs in the placenta? A) Eroding blood vessels in the endometrium bathe chorionic villi in pools of maternal blood. B) Fetal blood and maternal blood mix. C) The amnion and the chorion grow into the endometrium. D) Hormones are absorbed to prevent them from influencing the developing fetus. E) All substances in maternal blood that may be harmful to the fetus are prevented from moving across the walls of the villi.
A) Eroding blood vessels in the endometrium bathe chorionic villi in pools of maternal blood.
14) ________ is the developmental event that results in the formation of a primitive gut and the three tissue layers. A) Gastrulation B) Cleavage C) Blastulation D) Induction E) Metamorphosis
A) Gastrulation
33) What will occur if a morula divides into three masses of cells? A) Normal identical triplets will be born. B) The resulting embryos will develop severe birth defects due to missing genes. C) Three distinctly different embryos will develop, depending on which homeoboxes went with which mass of cells. D) The resulting embryos will develop, but they may be missing some organs based on which germ layers were transferred with each section. E) The resulting embryos will die.
A) Normal identical triplets will be born.
53) Which of these hormones stimulates the production of milk? A) Prolactin B) Progesterone C) Oxytocin D) Estrogen E) Colostrum
A) Prolactin
20) If the formation of the endoderm does not take place in an embryo, yet the embryo, for whatever reason, continues to develop, which of the following structures will NOT develop? A) Stomach B) Skin C) Heart D) Nervous system E) Kidneys
A) Stomach
19) In a bird egg, the ________ provides the watery environment in which the embryo develops. A) amnion B) allantois C) blastocyst D) chorion E) yolk sac
A) amnion
37) The structure produced by cleavage of a human zygote is called a(n) A) blastocyst. B) chorion. C) gastrula. D) blastopore. E) embryonic disk.
A) blastocyst.
3) Early animal embryos are composed of stem cells, unspecialized cells that are capable of dividing and renewing themselves for long periods. If a stem cell divides by mitosis so that one cell eventually becomes part of the brain and the other cell becomes part of a salivary gland, the cells have A) differentiated. B) increased their genetic variability. C) diffused. D) taken up genes from surrounding cells. E) lost genes.
A) differentiated.
1) One characteristic of animal development is the specialization in both structure and function that cells undergo. This is called A) differentiation. B) direct development. C) indirect development. D) placental development. E) internal development.
A) differentiation.
6) Birds hatch out of their eggs looking like small versions of the adult. This is an example of A) direct development. B) indirect development. C) external development. D) internal development. E) genetic dwarfism.
A) direct development.
49) The last 7 months of pregnancy are devoted to A) growth. B) formation of tissue layers. C) formation of major organs. D) organization of organs into organ systems. E) formation of the brain.
A) growth.
28) Cells differentiate during development because A) in each cell only some of the genes are expressed. B) each cell contains only a portion of the genes. C) chemicals in the sperm cytoplasm determine which cells develop. D) genes respond only to influences outside the mother's body.
A) in each cell only some of the genes are expressed.
30) Based on experiments with amphibian embryos, Spemann and Mangold found that A) in most cases, transplanted donor cells assumed the developmental fate of the area to which they were transplanted in the host. B) donor cells maintained their original differentiation no matter where in the host they were transplanted. C) transplanted cells always formed a whole new embryo. D) transplanted cells completely undifferentiated into random masses of tissue. E) transplanted cells always died.
A) in most cases, transplanted donor cells assumed the developmental fate of the area to which they were transplanted in the host.
26) Transplanting embryonic eye tissue into the back of a developing tadpole will cause a lens to grow on the back of the tadpole. This is an example of A) induction. B) gastrulation. C) cleavage. D) programmed cell death. E) metamorphosis.
A) induction.
22) Your biceps muscle is derived from the A) mesoderm. B) blastopore. C) ectoderm. D) amnion. E) endoderm.
A) mesoderm.
29) The proteins that bind to the DNA near regions where gene transcription begins are called A) transcription factors. B) homeobox genes. C) the gray crescent. D) promoter genes. E) mRNA.
A) transcription factors.
31) A human embryo is known as a fetus after ________ weeks. A) 12 B) 8 C) 4 D) 2 E) 16
B) 8
40) At which stage is the human embryo most susceptible to toxic substances? A) During the last trimester B) During organogenesis C) During the fourth and fifth months D) During cleavage E) Just before birth
B) During organogenesis
51) Most microbes cannot gain access to the fetus. However, ________, which causes syphilis in adults, can cross the placenta and attack the fetus, causing stillbirths and mental retardation. A) Staphylococcus B) Treponema pallidum C) Listeria D) rubella E) HIV
B) Treponema pallidum
45) ________ diffuse(s) from fetal blood to maternal blood in the placenta. A) Nutrients B) Wastes C) Infectious organisms D) Oxygen E) Alcohol
B) Wastes
42) A human embryologist examines a 3-week-old embryo and notices that it has not developed a notochord. If the embryo survives, it will lack A) skin and blood vessels. B) a brain and a spinal cord. C) a heart and lungs. D) a stomach and a pancreas.
B) a brain and a spinal cord.
27) Induction refers to A) the migration of cells to form the gastrula. B) chemical messengers from one embryonic cell influencing the development of other cells. C) the formation of the nervous system. D) hormones from the mother's blood altering the development of the embryo. E) the formation of the mesoderm layer in a gastrula.
B) chemical messengers from one embryonic cell influencing the
11) The nervous system forms from the A) endoderm. B) ectoderm. C) chorion. D) yolk. E) mesoderm.
B) ectoderm.
24) In the 1920s, two German embryologists, Hans Spemann and Hilde Mangold, demonstrated that a small patch of cells, called the dorsal lip of the blastopore, would A) lack the genes necessary to develop the embryo. B) induce the surrounding cells to differentiate. C) become the digestive tract. D) become the neural tube. E) form the chorion.
B) induce the surrounding cells to differentiate.
50) Stem cells developed by inserting genes that regulate the transcription of specific genes into cells from an adult are ________ cells. A) chorionic villi B) induced pluripotent stem C) embryonic stem D) gastrula E) embryonic disk
B) induced pluripotent stem
32) A developing human is considered an embryo after ________ weeks. A) 12 B) 4 C) 2 D) 16 E) 8
C) 2
16) Which extraembryonic membrane lies immediately beneath the shell of a reptile embryo? A) Yolk sac B) Amnion C) Chorion D) Placenta E) Allantois
C) Chorion
15) Which germ layer forms the pancreas? A) Endodermis B) Epidermis C) Endoderm D) Mesoderm E) Ectoderm
C) Endoderm
41) Suppose a pregnant woman took a drug that causes incomplete brain formation during fetal development. When must the woman have taken the drug for this effect to occur? A) Between the fifth and sixth months of development B) During labor C) In the first month of development D) Between the seventh and eighth months of development E) Between the second and third months of development
C) In the first month of development
2) What is differentiation? A) The process in which different tissues specialize into specific organs B) The process in which different organs specialize in function C) The process in which different cells develop into different cell types D) The process in which different organ systems become specialized
C) The process in which different cells develop into different cell types
10) As a morula, the embryo consists of A) cells that have different DNA content. B) a solid mass of cells, each the size of the zygote. C) a cluster of cells that are much larger than normal cells. D) three differentiated layers of cells. E) a hollow ball of cells.
C) a cluster of cells that are much larger than normal cells.
43) The outer cell layer of the blastocyst becomes the ________, which forms the embryonic portion of the placenta. A) primitive streak B) yolk sac C) chorion D) inner cell mass E) embryonic disk
C) chorion
4) When a researcher transplanted the nucleus of an intestinal cell from a tadpole into an egg cell whose nucleus had been destroyed, the egg developed into a normal frog. This illustrates that A) a nucleus that is removed from its normal location is influenced by adjoining cells. B) the homeobox genes in a transplanted nucleus undergo mutation. C) each cell of an organism has all the genes needed for development. D) genes are gained during the process of differentiation. E) scientists can clone a human by putting one of his or her nuclei into an egg cell.
C) each cell of an organism has all the genes needed for development.
81) A mad scientist decides to start combining embryos and see what develops. He takes cells from the blastula of a frog with blue skin and transplants them into the blastula of a yellow-skinned frog. The embryo receiving the cells develops blue cells in its brain and spinal cord. The scientist must have transplanted the cells into the ________ of the recipient embryo. A) allantois B) mesoderm C) ectoderm D) endoderm E) yolk sac
C) ectoderm
25) After induction occurs, the A) cells have different genes. B) DNA of the mitochondria differentiates into new genes. C) fate of each cell is permanently fixed. D) transcription of all genes stops.
C) fate of each cell is permanently fixed.
5) The metamorphosis of a caterpillar into a butterfly is an example of A) direct development. B) internal development. C) indirect development. D) placental development. E) external development.
C) indirect development
54) Prior to birth, stretching of the cervix by the baby's head stimulates the release of A) prolactin. B) colostrum. C) oxytocin. D) estrogen. E) progesterone.
C) oxytocin.
8) The embryo of a ________ undergoes direct development. A) frog B) lobster C) snake D) dragonfly E) butterfly
C) snake
34) In humans, fertilization occurs in the A) ovary. B) vagina. C) uterine tube. D) uterus. E) testes.
C) uterine tube.
17) In a reptile egg, which membrane is analogous to a lung? A) Allantois B) Blastocyst C) Amnion D) Chorion E) Yolk sac
D) Chorion
52) ________ is the medication given to combat morning sickness that caused deformed and missing limbs in infants in the late 1950s and early 1960s. A) Nicotine B) Rubella C) Accutane® D) Thalidomide E) Alcohol
D) Thalidomide
39) The umbilical cord of a mammal connects the A) maternal and fetal bloodstreams. B) embryo and the amnion. C) yolk sac and the allantois. D) fetus and the placenta. E) amnion and the chorion.
D) fetus and the placenta.
7) Human embryos differ from bird embryos in that A) bird embryos have an extra membrane, the allantois, that is not found in human embryos. B) bird embryos undergo metamorphosis to become sexually mature adults. C) human embryos do not undergo cleavage. D) human embryos have a yolk sac, but it contains very little yolk. E) human embryos have no yolk sac.
D) human embryos have a yolk sac, but it contains very little yolk.
21) During mammalian development, a A) zygote becomes a blastula. B) gastrula becomes a morula. C) morula becomes gastrula. D) morula becomes a blastula. E) blastula becomes a zygote.
D) morula becomes a blastula.
36) The birth defect spina bifida results in part of the spinal cord lying outside of the body. This defect is due to abnormal development of the A) placenta. B) gill grooves. C) allantois. D) neural tube. E) embryonic disk.
D) neural tube.
47) As early as the ________ month, as the brain and spinal cord grow, the fetus can demonstrate movement and respond to stimuli. A) fourth B) fifth C) second D) third E) sixth
D) third
13) Which of the following is the result of gastrulation? A) A hollow ball of cells B) The formation of organs C) A zygote D) A blastula E) A three-layered embryo
E) A three-layered embryo
23) What makes the cells of a developing embryo differentiate into various types of cells? A) The DNA of their mitochondria is different. B) Special genes in the cytoplasm cause this differentiation. C) Once certain genes of a cell have caused it to differentiate, the other genes are lost. D) They have different genes. E) Different genes are activated.
E) Different genes are activated.
46) The placental blood vessels A) draw oxygen from the fetal blood and pass it to the mother. B) manufacture hormones that slow the growth of the embryo, preventing it from outgrowing the uterus. C) mix maternal blood and fetal blood. D) prevent all microbes and toxins from crossing from mother to child. E) allow for the exchange of wastes and nutrients but keep the maternal and fetal circulations separate.
E) allow for the exchange of wastes and nutrients but keep the maternal and fetal circulations separate.
9) During the embryonic stage, a hollow ball of cells is known as a A) chorion. B) morula. C) gastrula. D) larva. E) blastula.
E) blastula.
18) In placental organisms, the ________ of the embryo merges with the endometrial lining of the uterus to form the placenta. A) allantois B) yolk sac C) amnion D) blastopore E) chorion
E) chorion
55) The cells of an aging animal function less efficiently because A) cell metabolism is slower. B) organelles and cellular components decline. C) protein synthesis ceases. D) cells can no longer mitotically divide. E) damaged DNA cannot be repaired.
E) damaged DNA cannot be repaired.
12) The cells that line the inside of the blastopore become the A) nervous system. B) skeleton. C) muscles. D) skin. E) digestive tract.
E) digestive tract.
35) In humans, implantation occurs A) immediately after fertilization. B) after the formation of the neural tube. C) when the embryo is a gastrula. D) just prior to fertilization. E) when the zygote is a blastocyst.
E) when the zygote is a blastocyst.
57) In animals that undergo indirect development, the newborn has a similar body structure to that of the adult.
FALSE
59) The process through which a human embryo develops into an adult is called metamorphosis.
FALSE
61) The small, hollow ball of cells in early development is the zygote.
FALSE
65) The nervous system develops from the endoderm.
FALSE
69) Yolk sacs are found only in animals with shelled eggs.
FALSE
73) The developing fetus secretes chorionic gonadotropin only during the first 2 weeks of pregnancy.
FALSE
75) At 10 weeks, the blastocyst becomes an embryo.
FALSE
78) Maternal blood and fetal blood are mixed in the placenta.
FALSE
79) The placenta prevents pathogenic microbes such as HIV and chemicals such as alcohol from reaching the baby's bloodstream.
FALSE
56) All cells in an animal, with the exception of gametes, are genetically identical.
TRUE
58) In indirect development, the embryo hatches into a sexually immature stage called a larva.
TRUE
60) In species with direct development, fewer offspring are produced, but a higher proportion survives to adulthood.
TRUE
62) Mitotic cell divisions of the zygote are collectively called cleavage.
TRUE
63) A morula is a solid ball of undifferentiated cells.
TRUE
64) The blastopore forms during gastrulation.
TRUE
66) The mesoderm develops into the dermis of the skin and the skeleton.
TRUE
67) The amnion forms the watery environment that encloses the embryo.
TRUE
68) Amphibians, reptiles, and mammals pass through embryonic stages in which they have tails and webbed fingers and toes.
TRUE
70) Homeobox genes determine the overall shape of the body and the location of its parts.
TRUE
71) Cellular differentiation depends on which genes are turned on or expressed in the cell.
TRUE
72) In blastulas, if cells from an area that would normally become skin are transplanted into an area that would become the nervous system, the transplanted cells will form structures of the nervous system.
TRUE
74) The blastocyst implants in the endometrium about 7 days after fertilization.
TRUE
76) The most rapid differentiation in an embryo occurs during the first 2 months of pregnancy.
TRUE
77) The extraembryonic membrane that sends blood vessels into the endometrium is the chorion.
TRUE
80) Longevity in animals appears to be most related to their cells' ability to repair damage to their own
TRUE