5 Written questions
5 Matching questions
- External development
- First trimester
- a the 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
- b 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
- c 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
- d 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
- e the fluid-filled cavity that forms in the center of a blastula
5 Multiple choice questions
- 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).
- 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.
- 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
- (membrane of eggs) lines the inside of the shell; it is a moist membrane that permits gas exchance
- bleeding or the abnormal flow of blood
5 True/False questions
Indeterminate cleavage → 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.
Birth → childbirth is accomplished by labor, a series of strong unterine contractions; labor can be divided into three distinct stages; in teh first stage, the cervix thins out and dilates, and the amniotic sac ruptures, releasing tis fluids; during this time, contractions are relatively mild; the second stage is characterized by rapid contractions, resulting in the birth of the baby, followed by the cutting of the umbilical cord; during the final stage, the uterus contracts, expelling the placenta and the umbilical cord
Neurulation → 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
Gastrula → an embryonic stage in animal development encompassing the formation of three layers: ectoderm, mesoderm, and endoderm
Ectopic pregnancy → 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