Human height is one of the traits that belong to traits that cannot easily be placed in discrete phenotypic classes (there is not only tall and short people, there is continuous variation of height between them). Such traits are usually controlled by more than one gene (polygenic traits).
On the other hand, a Mendelian trait is controlled by a single locus.
Answer:
A) A decrease in Na+ permeability, and an increase in K+ permeability.
Explanation:
When the potential action reaches a peak of about +40 mv Na+ channels are open and a high number of Na+ ions are entering the inside of the cell. Shortly after this happens the K+ channels will start to open their gates increasing the cell K+ permeability while the Na+ channels will start to close their gates, so the Na+ permeability will decrease. This happens in order to valance the positive charge on the inside of the cell. Normally the inside has a negative charge while the outside has a positive one, as the inside is more positive due to the increase in Na+ permeability at the beginning of the potential action, K+ cations (which are in abundance in the cell) will have to go out through the K+ channels so as to restore the charge valance, that means that there is an increase in K+ permeability.
Let's call the colour alleles C for dominant purple, and c for recessive white.
We have crossed Cc with Cc. So if we put that in a Punnett square, we'd have a CC, two Cc and a cc. That would give us a 3:1 ratio of purple to white, so you'd expect 15 purple and 5 white flowers. :)
The correct answers are a, c, d.
There are three types of capillaries: continuous, sinusoidal (or discontinuous) and fenestrated. Continuous capillaries are the most common type and they form tight junctions. Sinusoidal capillaries form an incomplete lining with several gaps, which allow red and white blood cells and some serum proteins to pass. These capillaries are mainly found in the bone marrow, lymph nodes and adrenal glands. Finally, fenestrated capillaries facilitate the movement of smaller molecules and plasma proteins and are mainly found in the small intestine. The majority of the fluid transport happens through the fenestrated capillaries.
Four chambered heart keeps oxygenated and deoxygenated blood separate and has double circulation while three chambered heart has a single circulation. Two chambered heart only has single atrium and single ventricle
