Answer:
a. Species A survived because of its widespread range including some areas that were not as affected by mass extinction.
Explanation:
The species distribution might confer extinction resistance during massive extinction events. One of the most important reasons for a species -or any other taxonomic group- to survive massive extinction is its wide distribution area.
The broad geographical range of a group -as Species A in the example- enhances the survival chances during mass extinctions. When the event occurs, it severely affects most individuals of a certain area. If the species is restricted to that area, then the species will probably disappear, no matter the number of individuals living there.
But if the species is widely distributed, there are more survival chances. The extinction event will only affect a few regions, but not all of them, meaning that some of the individuals of the species will be able to survive.
Probably as only a few individuals of species A got to survive, they must have suffered the effects of genetic drift after the disaster, causing a reduction in genetic variability.
Answer:
One of the major goals of environmental science is to understand and to solve environmental problems. In order to accomplish this goal, scientists study two main types of interactions between humans and their environment. One area of focus is on how we use natural resources, such as water and plants.
Explanation:
Environmental science is important because it enables you to understand how these relationships work. For example, humans breathe out carbon dioxide, which plants need for photosynthesis. Plants, on the other hand, produce and release oxygen to the atmosphere, which humans need for respiration.
This occurs when a function of the output of a system or process is fed back, reducing the changes in the output.
The cardiovascular condition with no overt symptoms and known as the "silent killer" is the hypertension.
Blood pressure is recorded in two numbers. The upper limit is the systolic pressure and the lower limit is diastolic pressure. Systolic pressure is the maximum pressure at which the heart pumps the blood to the different parts of the body and it is 120 mm/Hg. Diastolic pressure is the minimum pressure in the arteries during the relaxation of the heart and it is 80 mm/Hg. The normal blood pressure is given by 120/80 mmHg.
Hypertension, also known as the high blood pressure is a condition in which the blood pressure in the arteries is constantly high or elevated. Blood pressure with a value higher than 140/90 mm/Hg is considered to be hypertension. It is a silent killer because it normally does not exhibit any distinctive symptoms. The most common symptoms of hypertension are head ache, problems with vision, fatigue which are often ignored and remain untreated. This untreated, long-term hypertension is one of the important causes of cardiac diseases, renal failure, stroke and other fatal conditions.
Thus, no overt symptoms and the impact of hypertension associated with many life-threatening diseases makes it a "silent killer".
