Exposure to a light source
a. decreases melatonin levels.
b. increase melatonin levels.
c. decrease testosterone levels.
d. is used to treat SAD and jet lag.
e. does more than one of these
E
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Unique features of skates and rays are their
a. gill slits. b. adipose tissues. c. flat bodies. d. spiracles. e. countershaded bodies.
Which of the following hormones does not promote growth?
a. antidiuretic hormone b. growth hormone c. insulin-like growth factors d. thyroid hormones e. testosterone
An individual receives a flu vaccine and is well protected for the current flu season. The following flu season, the individual fails to get another flu vaccine and comes down with the flu
What is the most likely explanation for vaccine ineffectiveness in the subsequent flu season? A) Antibiotic-resistant bacteria were able to overcome the effects of the vaccine. B) The immune system becomes weaker when continually exposed to the same virus contained in the vaccine. C) The flu virus mutated, leading to a new strain of virus that could escape detection by the immune system. D) Most vaccines have a limited lifetime and eventually break down and become ineffective.
Which event occurs first during embryonic development?
A) gastrulation B) neurulation C) cleavage D) organ formation