Answer:
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Through production of news cell-surface proteins with a different molecular structure by each new generation. Letter B</h2>
Explanation:
The life cycle of theses paratises extracellular alternate between the salivary glands of the insect transmitter and the blood of the mammal. During the set prior to the entry into the host, the metacylic parasites express a dense over formed by the Variant Surface of Glycoprotein, after entering to the mammal host they transform into a morphology that stays in the bloodstream.
<em>The parasites have to manipulate hosts cells in order to avoid the production of antimicrobial molecules and to benefit from growth factor production.</em>
<em>Intracellular protozoa have a remarkable adaptive capacity as they are able to resist killing by remodelling the phagosomal compartments where they reside and by interfering with the signalling pathway that leads to cellular activation. </em>
Answer:
The abiotic characteristics of an ecosystem that affects man includes: Land surface, rainfall and relative humidity.
Explanation:
In the ecosystem, man occupies the terrestrial habitat which is affected by the abiotic factors listed above.
Abiotic (non- living) factors determine the type of biotic (living) community that is found in an ecosystem. These factors include Land surface, rainfall and relative humidity, just to mention a few.
--> LAND SURFACE: This is responsible for the marked variation in the vegetation of a place. For example, a mountain in the tropics may have a rain forest vegetation at it's base and an afroalpine vegetation near its peak. The gradient of the slope affects the growth of organisms. A steep slope encourage fast run - off of water and therefore encourages erosion, which results in shallow and infertile soil. This in turn AFFECT man's farming activities as there would be little to no crop yield.
--> RAINFALL: Water is a very important abiotic factor that affects life. The main source of water to terrestrial habitat is rainfall. When rain falls, a greater percentage of it sinks into the soil while the rest run- off into water bodies. Water is absorbed by root hairs into the plant and used for photosynthesis to produce food. The absence of rainfall in the environment of man could lead to drought which AFFECTS man negatively.
--> RELATIVE HUMIDITY: This is a measure of the amount of moisture in the atmosphere. It's usually high in hot wet regions. It affects the rate at which water evaporates from the body surfaces of organisms. Low relative humidity cause more water (sweat) to evaporate from body surfaces giving the human body a cooling effect. But in high relative humidity, the sweat cannot evaporate leaving the body feeling hot and sticky. This AFFECTS man as the body tries to cool off in a harder way by increasing rate of respiration and depth of blood circulation.
The surface area to volume ratio of the cell decreases.
This decrease is due to the fact that the volume of the cell increases at a greater rate than the surface surrounding the cell, the cell membrane, increases. This change is also visible when we are blowing up a balloon.
When considering the cell division, the ratio remains roughly the same. It is advantageous for the cell to preserve its surface area to volume ratio, since a higher ratio means that substances are able to diffuse into and out of the cell at a fairly higher rate.
Answer:
The liver stores glucose to power the cells during periods of low blood sugar. Skipping meals and poor nutrition can lower blood sugar. By storing glucose, the liver makes sure that blood glucose levels remain steady between meals and during sleep. When blood glucose falls, cells in the pancreas secrete glucagon.
<h2>Have a nice day!!</h2>
The correct terms to fill in the blanks would be contracts and dilates. In stressful situations, the sympathetic nervous system contracts the arteries of the circulatory system resulting to the dilation of the pupils of the eyes. Also, during these situations, the blood sugar levels are raised since the hormones for stress kick in to combat the stress which in turn raises the blood sugar.
