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5 Written questions

5 Matching questions

  1. Yolk sac
  2. Placenta
  3. From cleavage to blastula
  4. Gastrulation
  5. Notochord
  1. a 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
  2. b 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
  3. c (membrane of eggs) encloses the yolk; blood vessels in the yolk sac transfer food to the developing embryo
  4. d 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
  5. e 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 Multiple choice questions

  1. bleeding or the abnormal flow of blood
  2. 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
  3. during 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. member of the phylum chordata, aimals that at some point during their development have a notochord; a dorsal, hollow nerve cord; pharyngeal slits or clefts; and a muscular, post-anal tail
  5. the 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

5 True/False questions

  1. Nonplacental internal developmentthe 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

          

  2. Neural tubea tube of infolded ectodermal cells that runs along the anterior-posterior axis of a vertebrate, just dorsal to the notochord; it will give rise to teh nervous system

          

  3. From blastula to gastrulathe 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

          

  4. Determinate cleavagefter the initial cell division the fate of the resulting daughter cells is not determined -- each has the potent ial to develop into an entire organism. Sometimes this occurs; resulting individuals are genetically identical (in humans, they are called identical twins)

          

  5. Cleavageeach embryonic development is characterized by a series of rapid mitotic divisions knows as cleavage; these divisions lead to an increase in cell number without a corresponding growth in cell protoplasm (i.e., the total volume of cytoplasm remains constant); thus, cleavage results in progressively smaller cells, with an increasing ratio of nuclear-to-cytoplasmic material; cleavage also increases the surface-to-volum ration of each cell, thereby improving gas and nutrient exchange; this early developmental process consists of a series of very rapid, synchronous mitotic divisions that converts the zygote's single large cell into a solid ball of cells, known as teh morula, then into the blastula