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5 Written questions

5 Matching questions

  1. Chorion
  2. Determinate cleavage
  3. Gastrula
  4. Notochord
  5. Indeterminate cleavage
  1. a 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
  2. b 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.
  3. c 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)
  4. d (membrane of eggs) lines the inside of the shell; it is a moist membrane that permits gas exchance
  5. e an embryonic stage in animal development encompassing the formation of three layers: ectoderm, mesoderm, and endoderm

5 Multiple choice questions

  1. a developing human from the 9th week of gestation until birth; has all the major structures of an adult
  2. 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).
  3. the embryo implants outside the uterus; for example, in the fallopian tube; an embryo cannot be maintained for long outside of teh uterus; it will abort spntaneously, and hemorrhaging will follow
  4. 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
  5. the fluid-filled cavity that forms in the center of a blastula

5 True/False questions

  1. External developmentfollows the neurulation process; includes organogenesis, growth, and gametogenesis


  2. Placentaa hollow ball of cells that marks the end of the cleavage stage during early embryonic development in animals


  3. From cleavage to blastulathe 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. 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


  5. Allantois(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