The semilunar valves:a
prevent blood from moving from the atria back into the veins.
b. prevent blood from moving from the ventricles back into the atria.
c. prevent blood from moving from the arteries back into the ventricles.
d. prevent blood from moving backwards in the capillaries.
e. prevent blood from moving backward in the arteries.
C
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Edouard van Beneden proposed that an egg and a sperm, each containing half the complement of chromosomes found in somatic cells, fuse to produce a single cell called a(n) ______.
A. zygote B. karyotype C. embryo D. oocyte
In systemic acquired resistance, the regulatory protein NPR-1 moves from the cytoplasm to the cell
nucleus, apparently in response to a buildup of ____ in the cytoplasm.
a. ethylene b. brassinosteroids c. oligosaccharins d. jasmonates e. salicylic acid
To maximize the number of thymine dimer mutations following UV exposure, should you keep human cells in tissue culture in the dark, in the light, or does it matter at all?
A. The dark-light will activate the photorepair systems that can break thymine dimers induced by UV light. B. The light-it's important to keep on producing the thymine dimers by keeping the plate exposed to light as much as possible. C. It's best to alternate light and dark every hour to increase the chances that thymine dimers will form in the human cells, but still keep the photorepair systems from correcting them as they are formed. D. It doesn't matter-human cells don't possess the enzymes needed for photorepair of thymine dimers.
What situation relates to the reason why hot-air balloons are able to fly?
A) Precipitation falls on the leeward side of a mountain. B) Water droplets can freeze inside clouds. C) Very little rain falls at 30° north and south of the equator. D) The tops of hills are warmer than the valleys below.