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25 Cards in this Set

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During development, the process by which unspecialized cells acquire specific identities is called what?
Differentiation
Which one of the following methods of reproduction is not used by animals?
a piece of an animal breask off and grow into a new individual
Which of the following statements about sexual reproductions in animals is true?
Both parents contribute gene to the offsprings
Which of the following statements about sexual and asexual reproduction is true?
Sexual rep. leads to offspring that differ genetically from their parents, while asexual rep. leads to offspring that are identical to their parents
Which of the following statements about animal sperm and eggs is false?
Sperm and eggs have the same amount oof genetic material per cell as the cells in their parent organisms.
Which of the following statements about hermaphrodites is true?
Hermaphrodites can mate with every individual of the same species that they encounter.
The number of chromosomes in secondary spermatocytes is fewer than in primary spermatocytes because
homologous pairs are separated during meiosis I
In human females, primary oocytes don't develop into mature eggs
until puberty
The second meiotic division in a secondary oocyte is completed
only if it is fertilized
Why is the head of a sperm covered with a sac of enzymes?
The enzymes are needed to digest a hole in the protective “shell” surrounding the egg.
Sperm are packed with mitochondira becaue mitochondria produce the
energy needed to power the movenent of the tail of the sperm
Would the separation of an egg and its polar body soon after fertilization harm the development of an embryo?
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.
In general, why does a female animal tend to choose her mate more carefully than a male does?
A female has more resources tied up in an egg than a male does in sperm
Humans complete their development in a protected environment inside their mother’s body, in the
uterus
In mammals, the trophoblast layer in a blastocyst will become part of the
placenta
In mammals, the blastocyst consists of hte trophoblast and the
inner cell mass
In humans, the exchanges of materials between the embro and its mother occure through the
umbilical cord
Why does an embro undergo the process of gastrulation?
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
The humans embro develops in a fluid-filled sac, called the
amnion
Which of the following would not be exchanged between a mother and her fwtus through the umbilical cord?
enzymes
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
have a very short interphase
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?
At this point, development switche from rapid cell growth to cell differentiation and migration
In humans, the yolk sac
all the above. not have yolk, produces blood cells, and contaisn cells that will eventually produce gametes.
Why do the chorionic villi have the shape of a tree?
The branches of the chorionic villi create a large amount of surface area for exchange of nutrients and gases between maternal and fetal blood
Stem cells
can differentiate into specific cell types