Common mistakes and misconceptions
Natural selection is a mechanism, or cause, of evolution. Adaptations are physical or behavioral traits that make an organism better suited to its environment. Heritable variation comes from random mutations. Random mutations are the initial cause of new heritable traits.
Answer:
B. decreases salivation and increases blood pressure
Explanation:
The sympathetic nervous system is part of the autonomous nervous system which controls involuntary responses of the body such as salivation and blood pressure.
The sympathetic nervous system is majorly responsible for body actions that are produced when threat is perceived. It generates responses referred to as the “fight or flight” response. Examples of such responses include, increased breathing, increased high blood pressure, dilation, decreased salivation, etc.
Activation of the sympathetic nervous system would result in rise in the blood pressure as can be witnessed by someone whose body has perceived a threat or reacting to a stressful situation.
The control of salivary production by the sympathetic nervous system leads to the release of noradrenaline which acts on certain receptors that results in decrease in the production of saliva. This is evident in a person that is facing a threat also.
Answer:
All cells share four common components: (1) a plasma membrane, an outer covering that separates the cell's interior from its surrounding environment; (2) cytoplasm, consisting of a jelly-like region within the cell in which other cellular components are found; (3) DNA, the genetic material of the cell;
Explanation:
Gills. Gills greatly increase the surface area for gas exchange. ... Gills are very efficient at removing oxygen from water: there is only 1/20 the amount of oxygen present in water as in the same volume of air. Water flows over gills in one direction while blood flows in the opposite direction through gill capillaries.
