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5 Written Questions

5 Matching Questions

  1. Ectoderm
  2. Second trimester
  3. Placenta
  4. External development
  5. Allantois
  1. a the fetus does a tremendous amount of growing; it begins to move around in teh amniotic fluid; its face appears human, and its toes and fingers elongate; by the end of the sixth month, the fetus is 30-36 cm long
  2. b a structure in the pregnant uterus for nourishing a vivaparous fetus with the mother's blood supply; formed from the uterine lining and the embryonic membranes
  3. c the outermost of the three primary germ layers in animal embryos; gives rise to the outer covering and, in some phyla, the nervous system, inner ear, and lense of the eye
  4. d the early development of many animals occurs outside of the mother's body, on land or in water; fish and amphibians lay eggs that are fertilized externally in the water; the embryo develops within the egg, feeding on nutrients stored in the yolk; reptiles, bird, and some mammals (like the duck-billed platypus) develop externally on land; fertillization occurs internally, and the fertilized egg is then laid; eggs provide protection for teh developing embryo; the eggs also include the following embryonic membranes: chorion, allantois, amnion, yolk sac
  5. e (membrane of eggs) this sac-like structure is involved in respiration and excretion and contains numerous blood vessels to transport O2, CO2, water, salt, and nitrogenous wastes

5 Multiple Choice Questions

  1. in vertebrates, groups of cells along the sides of the neural tube where it pinches off from the ectoderm; the cells migrate to various parts of teh embryo and form pigment cells in the skin and parts of the skull, teeth, adrenal glands, and peripheral nervous system
  2. an egg can be fertilized within 12-24 hours after ovulation; fertilization occurs in the lateral, widest portion of the oviduct when sperm traveling from the vagina encounter an egg; if more than one egg is fertilized, fraternal twins may be conceived
  3. the growing fetus receives oxygen directly from its mother through a specialized cirulatory system; this system not only supplies oxygen and nutrients to the fetus but removes carbon dioxide and metabolic wastes as well; the two components of this system are the placentaa and the umbilical cord, which both develop in teh first few weeks after fertilization
  4. The cord that connects the developing embryo or fetus with the placenta and through which run the umbilical arteries and vein. The matrix (the substance) of the umbilical cord is known as Wharton's jelly and is a rich source of stem cells. At birth the umbilical cord measures about 20 inches (50 cm) in length. The cord is clamped and cut after birth and its residual tip forms the umbilicus (bellybutton).
  5. the first complete cleavage of the zygote occurs approximately 32 hours after fertilization; the second cleavage occrus after 60 hours, and the third cleavage after approximately 72 hours, at which point the eight-celled embryo reaches the uterus; as cell division continues, a solid ball of embryonic cell, known as teh morula, is formed; blastulation begins when teh morula develops a fluid-filled cavity called the blastocoel, which by the fourth day becomes a hollow sphere of cells called the blastula; the blatula is the stage of teh embryo that implants in the uterus

5 True/False Questions

  1. Chorion(membrane of eggs) lines the inside of the shell; it is a moist membrane that permits gas exchance


  2. First trimesterthe seventh and eighth months are characterized by continued rapid growth and further brain development; during the ninth month, antibodies are transported by highly selective active transport from teh mother to the fetus for protection against foreign matter; the growth rate slows and the fetus become less active, as it has less room to move about


  3. Gestationpregnancy; the state of carrying developing young within the female reproductive tract; human pregnancy is about 9 months (266 days) and can be subdivided into three trimesters


  4. From blastula to gastrulaonce implanted in the uterus, cell migrations transform the single-cell layer of the blastula into a three-layered structure called teh gastrula; these three primary germ layers (ectoderm, endoderm, mesoderm) are responsible for the differential development of the tissues, organs, and systems of the body at later stages of growth


  5. Fetuschildbirth is accomplished by labor, a series of strong unterine contractions; labor can be divided into three distinct stages; in teh first stage, the cervix thins out and dilates, and the amniotic sac ruptures, releasing tis fluids; during this time, contractions are relatively mild; the second stage is characterized by rapid contractions, resulting in the birth of the baby, followed by the cutting of the umbilical cord; during the final stage, the uterus contracts, expelling the placenta and the umbilical cord


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