In the case of structural chromosomal abnormalities all of the following structural changes can occur except:
A. genetic material is deleted.
B. genetic material is duplicated.
C. genetic material is inverted.
D. a whole chromosome is added or deleted.
Question 2Chromosomal disorders involve abnormality in either the ______________ or __________________ of the chromosomes.
A. number; structure
B. position; duplication
C. misalignment; placement
D. deletions; additions
Question 3Which of the following is a characteristic of fraternal or dizygotic twins?
A. They develop from two sperms fertilizing one ovum.
B. They are of the same sex and have the same genotype.
C. They are the result of different eggs and different sperm, yet they share the same uterine environment.
D. They are more frequently born to young mothers.
Question 4The organs that develop first for a fetus during the embryonic period are the ____________, ____________, and _________________.
A. arms; legs; toes
B. brain; spinal cord; heart
C. brain, arms, spinal cord
D. legs, fingers, toes
Question 5The formal beginning of pregnancy is
A. at conception.
B. when the blastocyst attaches to the uterine wall.
C. when a woman misses her first period.
D. when the developing organism becomes a fetus.
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