Keratin is a ________ that is secreted by cells of the epidermis to waterproof the skin and protects against abrasion.
A. lipoprotein
B. carbohydrate
C. lipid
D. protein
Answer: D
You might also like to view...
The correct sequence of layers of a typical blood vessel, from superficial to deep, are ________
A) tunica media, tunica intima, tunica externa B) tunica media, tunica externa, tunica intima C) tunica externa, tunica media, tunica intima D) tunica externa, tunica intima, tunica media E) tunica intima, tunica media, tunica externa
In older individuals, wrinkling of the skin occurs because of
A) exposure to ultraviolet radiation. B) loss of subcutaneous fat. C) thinning of the dermis. D) All of the answers are correct. E) None of the answers are correct.
The binding of a hormone and a carrier protein is ________; a very ________ fraction of such a hormone in the blood is bound to a carrier at any one point in time.
A. temporary; small B. temporary; large C. permanent; small D. permanent; large
Fertilization occurs when the
A. sperm cells enter the vagina. B. oocyte is implanted in the uterus. C. oocyte ruptures from the ovary. D. sperm cell head enters the zygote. E. nuclei of the secondary oocyte and the sperm cell unite.