C. How long does it take a paper bag to break down?
The question is incomplete. The complete question is:
Question: Impulses originating in the part of the brain called the medulla would most directly affect which body structure?
a. A leg muscle
b. A ligament
c. An arm bone
d. The heart
Answer:
d. The heart
Explanation:
The medulla oblongata contains a number of reflex centers for regulating vital body functions such as heartbeat, breathing, and vasoconstriction. The medulla contains several nuclei, a collection of neuronal cell bodies.
For example, impulses originated in the cardiovascular center regulates the rate and force of the heartbeat and the diameter of blood vessels. Impulses from the cardiovascular center flow along sympathetic and parasympathetic neurons. An increase in sympathetic stimulation from the cardiovascular center of medulla increases heart rate and contractility while a decrease in sympathetic stimulation decreases heart rate and contractility.
Answer: crossing over
during the process of fertilization, a sperm and egg join together to create a zygote. since a sperm had half the number of chromosomes and an egg has half the number of chromosomes, when they join together the zygote had a complete diploid set of chromosomes. the assortment of chromosomes and crossing over promotes genetic variation during the process of reproduction
