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25 Cards in this Set
- Front
- Back
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During development, the process by which unspecialized cells acquire specific identities is called what?
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Differentiation
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Which one of the following methods of reproduction is not used by animals?
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a piece of an animal breask off and grow into a new individual
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Which of the following statements about sexual reproductions in animals is true?
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Both parents contribute gene to the offsprings
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Which of the following statements about sexual and asexual reproduction is true?
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Sexual rep. leads to offspring that differ genetically from their parents, while asexual rep. leads to offspring that are identical to their parents
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Which of the following statements about animal sperm and eggs is false?
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Sperm and eggs have the same amount oof genetic material per cell as the cells in their parent organisms.
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Which of the following statements about hermaphrodites is true?
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Hermaphrodites can mate with every individual of the same species that they encounter.
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The number of chromosomes in secondary spermatocytes is fewer than in primary spermatocytes because
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homologous pairs are separated during meiosis I
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In human females, primary oocytes don't develop into mature eggs
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until puberty
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The second meiotic division in a secondary oocyte is completed
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only if it is fertilized
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Why is the head of a sperm covered with a sac of enzymes?
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The enzymes are needed to digest a hole in the protective “shell” surrounding the egg.
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Sperm are packed with mitochondira becaue mitochondria produce the
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energy needed to power the movenent of the tail of the sperm
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Would the separation of an egg and its polar body soon after fertilization harm the development of an embryo?
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No; the polar body is essentially a trash can. Excess DNA is placed there, but since it contains little cytoplasm it cannot develop into an embryo.
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In general, why does a female animal tend to choose her mate more carefully than a male does?
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A female has more resources tied up in an egg than a male does in sperm
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Humans complete their development in a protected environment inside their mother’s body, in the
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uterus
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In mammals, the trophoblast layer in a blastocyst will become part of the
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placenta
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In mammals, the blastocyst consists of hte trophoblast and the
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inner cell mass
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In humans, the exchanges of materials between the embro and its mother occure through the
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umbilical cord
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Why does an embro undergo the process of gastrulation?
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Cells in the blastocyst differentiate to form embryonic tissues, but are not originally located in the right place. Gastrulation moves these cells to the proper position in the embryo
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The humans embro develops in a fluid-filled sac, called the
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amnion
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Which of the following would not be exchanged between a mother and her fwtus through the umbilical cord?
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enzymes
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During the rapid cell division that occures after fertilization, cells increase rapidly in #, but the embryo stays the same size. The cells of this very early embryo must
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have a very short interphase
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The graph shows the rate of cell division in a developing frog embryo. Why does the rate of growth decrease dramatically after the pint indicated by the arrow?
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At this point, development switche from rapid cell growth to cell differentiation and migration
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In humans, the yolk sac
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all the above. not have yolk, produces blood cells, and contaisn cells that will eventually produce gametes.
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Why do the chorionic villi have the shape of a tree?
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The branches of the chorionic villi create a large amount of surface area for exchange of nutrients and gases between maternal and fetal blood
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Stem cells
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can differentiate into specific cell types
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