Children in northern regions experience months of inadequate sunlight exposure on the skin. To prevent possible abnormal bone development, what essential organic nutrient is necessary in the diet?
A) vitamin C
B) calcium
C) cholecalciferol
D) protein
E) retinol-A
C
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The ____ portal vein drains the organs of the digestive tract and then continues to the liver
a. hepatic b. renal c. urinary d. saphenous
What is the primary effect of antidiuretic hormone (ADH, or vasopressin)?
A.)blood glucose regulation B.)water retention by the kidneys C.)sodium retention by the kidneys D.)increases urine production by the kidneys
The event called "crossing over" in meiosis results in
A. irreversible mutations. B. a change in the gender (sex) of the embryo. C. greater vitality of sex cells making them more active. D. less genetic variety in sex cells. E. greater genetic variety in sex cells and thus in embryos.
A tumor of the ________ referred to as a pheochromocytoma.
A. adrenal medulla B. thyroid gland C. adrenal cortex D. pineal gland