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12 Organisms can be classified based on homology, which is shared characteristics inherited from
a common ancestor. In the past, homologies were based on studies of anatomical structures
and patterns of embryonic development. In more recent years, the use of molecular biology
techniques has allowed homologies to be compared at the level of nucleotide sequences.
Nucleotide sequence comparisons are possible because all organisms share which of the
following?
F DNA bases
G Cellular organelles
H Division of the nuclear chromosomes
J Types of proteins needed for cellular functions
13 An informational pamphlet in a health clinic describes an interaction between body systems.
An ovum moves from an ovary into the
uterine tube where its migration toward
the uterus is aided by the peristaltic
contractions of the smooth tissues of the
uterine tube’s walls.
Which statement identifies the body systems that are directly involved in the interaction
described and explains how they accomplish the interaction?
A The nervous system produces hormones that stimulate the ovum, and the circulatory
system moves the ovum into the uterine tube.
B The circulatory system supplies the uterine wall with oxygenated blood, and the
immune system prevents damage to the ovum.
C The reproductive system produces the ovum, and the muscular system causes the
migration of the ovum by peristaltic contractions.
D The excretory system expels the ovum from the ovary, and the nervous system causes
the contractions of the smooth tissues of the uterine wall.