The cells within the thymus gland probably originated from the _____.
A) spleen
B) liver
C) bone marrow
D) Peyer's patches
Ans: C) bone marrow
In development, leukocytes and erythrocytes begin as stem cells in the yolk sac which then enter the fetus and migrate to blood islands in the bone marrow; some of these cells migrate to and remain in the thymus.
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Of the different sources of genetic variability which one produces the variation in the combinations of alleles on a single chromosome?
A) independent assortment B) crossing over C) random fertilization D) mutation
Which of the following is not a component of the vulva?
A. Vaginal orifice B. Mons pubis C. Clitoris D. Cervix E. Labia minora
100 ml of a solution at pH 7.45 contains 10 times more H+ ions per liter than 10 ml of a solution at pH 7.45
Indicate whether the statement is true or false
Taste buds
A. can perceive seven basic tastes. B. have axons and generate their own action potentials. C. can be found covering both the superior and inferior surfaces of the tongue. D. can only perceive taste if the molecules are in solution. E. are replaced approximately every 30 days.