A patient, complaining about persistent drowsiness and difficulty conceiving children undergoes a series of tests, during which it is shown that he has a significantly diminished sperm count. Excess production of which hormone could account for these symptoms?
a. luteinizing hormone
b. testosterone
c. melatonin
d. cortisol
c. melatonin
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Pyrimidines and purines can exist in alternate forms, or tautomers, shown here. Under common cellular conditions (physiological pH) the most common form of each purine or pyrimidine is shown on the left, and the rare tautomer on the right
Tautomers differ in the placement of hydrogen atoms and double bonds. Consider cytosine and its tautomer, the rare imino form of cytosine. With which nitrogenous base will the imino form of cytosine most likely base pair in a double stranded DNA? A. adenine B. cytosine C. guanine D. thymine E. uracil
Humans have ____
a. more taste receptors than olfactory receptors b. more olfactory receptors than taste receptors c. a high degree of dependency on pheromones d. approximately six types of olfactory receptors e. an advanced vomeronasal organ
Filtrate moves from the space within the glomerular capsule to ________, the portion of the renal tubule with microvilli
Fill in the blank(s) with correct word
The H substance is needed for the proper phenotypic expression of the A, B, and AB blood types in the ABO blood typing system in humans. Individuals who are recessive for the H substance (hh) will have a type O phenotype, even if they have the A and/or B alleles. Two individuals, each with type AB blood and heterozygous at the H locus have children. What is the probability they will have a child who is phenotypically type O?
A. 3/16 B. 4/16 C. 6/16 D. 100% E. No chance