prokaryotic cells do not have a nucleus.
<span>Microevolution refers to changes in the genetic pool
of a species population. The changes in the genes (probably gene and allele frequencies)
are observed over short time periods hence are small changes. This is in comparison
to macroevolution that observes huge changes over longer time periods in the population that warrant that the new populations
is considered to be a new species</span>
Answer: possibly A
Explanation: B an C are not it because they are more like mutations. D humans don’t always become immune.
The best answer is b. 4
The human heart has four chambers - two atria and two ventricles.
1. Right atrium - receives oxygen-poor blood from the body and pumps it to the right ventricle.
2. Right ventricle - pumps oxygen-poor blood to the heart.
3. Left atrium - receive oxygen - rich blood from the lungs.
4. Left ventricle - pumps oxygen rich blood to the body.
The heart is a muscular organ. It is about the size of a closed fist. It is located in the thoracic cavity. It is protected by the rib cage and is the major organ of the circulatory system.