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5 Written questions

5 Matching questions

  1. Gametogenesis
  2. Gastrulation
  3. Neural tube
  4. Ectoderm
  5. Notochord
  1. a 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
  2. b eggs develop in women and sperm develop in men, which results in the possibility of reproduction occuring
  3. c 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. d a 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
  5. e 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

5 Multiple choice questions

  1. the fluid-filled cavity that forms in the center of a blastula
  2. 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
  3. 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
  4. follows the neurulation process; includes organogenesis, growth, and gametogenesis
  5. 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 True/False questions

  1. Placenta and Umbilical cord formationthe 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


  2. Maturationthe 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


  3. Neurulationby 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


  4. Endodermthe 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


  5. External developmentthe 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