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5 Written Questions

5 Matching Questions

  1. Placenta
  2. Fertilization
  3. Chorion
  4. Embryology
  5. From blastula to gastrula
  1. a once 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
  2. b (membrane of eggs) lines the inside of the shell; it is a moist membrane that permits gas exchance
  3. c the study of the development of a unicellular zygote into a complete, multicellular organism; in the course of nine months, a unicellular human zygote undergoes cell division, cellular differentiation, and morphogenesis in preparation for life outside teh uterus; much of what is known about mammalian development stems from the study of less complex organisms such as sea urchins and frogs
  4. d 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
  5. e 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

5 Multiple Choice Questions

  1. pregnancy; 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
  2. the innermost of the three primary germ layers in animal embryos; lines the archeenteron and gives rise to the liver, pancreas, lungs, and the lining of the digestive tract in species that have these structures
  3. a longitudinal, flexible rod made of tightly packed mesodermal cells that runs along the anterior-posterior axis of a chordate (member of the phylum chordata) in the dorsal part of teh body
  4. in animal development, a series of cell and tissue movements in which the blastula-stage embryo folds inwards, producing a three-layered embryo, the gastrula
  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. Gastrulaa hollow ball of cells that marks the end of the cleavage stage during early embryonic development in animals

          

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

          

  3. First trimesterduring the first weeks, the major organs begin to develop; the heart begins to beat at approximately 22 days, and soon afterwards, the eyes, gonads, limbs, and liver start to form; by five weeks the embryo is 10mm in lenght; by six weeks the embryo has grown to 15mm; the cartilaginous skeleton begins to turn into bone by the seventh week; by the end of eight weeks, most of teh organs have formed, the brain is fairly developed, and the embryo is referred to as a fetus; at teh end of teh third month, the fetus is about 9 cm long

          

  4. Nonplacental internal developmentearly development within the body of the mother protects the young; certain animals, including marsupials and some tropical fish, develop in the mother without a placenta; without a placenta, exchange of food and oxygen between teh young and the mother is limited; the young may be born very early in development

          

  5. Ectodermthe 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

          

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