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5 Written Questions

5 Matching Questions

  1. Nonplacental internal development
  2. Placenta and Umbilical cord formation
  3. Neurulation
  4. Determinate cleavage
  5. Yolk sac
  1. a by the end of gastrulation, regions of the germ layers begin to develop into a rudimentary nervous system; this process is known as neurulation; a rod of mesodermal cells, called teh notochord, develops along the longitudinal axis just under the dorsal layer of the ectoderm; the notochord has an inductive effect on the overlying ectoderm, causing it to bend inward and form a groove along the dorsal surface of teh embryo; the dorsal ectoderm folds on either side of the groove; these neural folds grow upwards and finally fuse, forming a closed tube; this is the neural tube, which give rise to the brain and spinal cord (central nervous system); once the neural tube is formed, it detaches from teh seurface ectoderm; the cells at the tip of each neural fold are called neural crest cells; these cells migrate laterally and give rise to many components of the peripheral nervous system, including the sensory ganglia, autonomic ganglia, adrenal medulla, and schwann cells
  2. b the placenta and the umbilical cord are outgrowths of the four extra-embryonic membranes formed during development: the amnion, chorion, allantois, and yolk sac; the amnion is a thin, tough membrane containing a watery fluid called amniotic fluid; amniotic fluid acts as a shock absorber of external pressure and localized pressure from the uterine contraction during labor; placenta formation begins with the chorion, a membrane that completely surrounds the amnion; a third membrane, the allantois, develops as an outpocketing of the gut; the blood vessels of the allantoid wall enlarge and become the umbilical vessels, which will connect teh fetus to teh developing placenta; the yolk sac, the site of early developmental blood vessels, becomes associated with the umbilical vessels
  3. c early 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
  4. d (membrane of eggs) encloses the yolk; blood vessels in the yolk sac transfer food to the developing embryo
  5. e after the intitial cell division the fate of the resulting daughter cells is determined -- they can only develop into specific tissues, not the whole organisms.

5 Multiple Choice Questions

  1. the embryo develops into the adult through the process of maturation, which involves cell division, growth, and differentiation; in some animals, maturation is suspended in a temporary state; for example, arthropods have a pupal stage; mammals develop uninterrupted; differentiation of cells is complete when all organs reach adult form
  2. the fluid-filled cavity that forms in the center of a blastula
  3. (membrane of eggs) this membrane encloses the amniotic fluid; amniotic fluid provides an aqueous environment that protects the developing embryo from shock
  4. 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. fter 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 True/False Questions

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

          

  2. Neural crest cellsin 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

          

  3. Hemorrhagemember 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

          

  4. Notochorda 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. Gestationin animal development, a series of cell and tissue movements in which the blastula-stage embryo folds inwards, producing a three-layered embryo, the gastrula

          

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