The use of sinking and dispersing chemical agents for removal of surface oil is().
One disadvantage of using regular dry chemical (sodium bicarbonate) in firefighting is that().
On a bulk chemical carrier,water should NOT be used as an extinguishing agent to fight a fire if the water may come into contact with the chemical called().
If a leak occurred while loading diethylenetriamine,the chemical data guide indicates you would smell an odor similar to().
Despite the basic biological, chemical, and physical similarities found in all living things, a diversity of life exists not only among and between species but also within every natural population. The phenomenon of diversity has had a long history of study because so many of the variations that exist in nature are visible to the eye.
1) It has been suggested that sexual reproduction became the dominant type of reproduction among organisms because of its inherent advantage of variability, which is the mechanism that enables a species to adjust to changing conditions.New variations are potentially present in genetic differences, but how preponderant a variation becomes in a gene pool depends upon the number of offspring the mutants or variants produce (differential reproduction). 2)It is possible for a genetic novelty (new variation) to spread in time to all members of a population, especially if the novelty enhances the population’s chances for survival in the environment in which it exists.Thus, when a species is introduced into a new habitat, it either adapts to the change by natural selection or by some other evolutionary mechanism or else it eventually dies off. Because each new habitat means new adaptations, habitat changes have been responsible for the millions of different kinds of species and for the heterogeneity within each species.
The total number of animal and plant species is estimated at between 2,000,000 and 4,500,000; authoritative estimates of the number of extinct species range from 15,000,000 up to 16,000,000,000. 3)Although the use of classification as a means of producing some kind of order out of this staggering number of different types of organisms appears as early as the book of Genesis—with references to cattle, beasts, fowl, creeping things, trees, etc.—the first scientific attempt at classification is attributed to the Greek philosopher Aristotle, who tried to establish a system that would indicate the relationship of all things to each other.He arranged everything along a scale, or “ladder of nature”, with nonliving things at the bottom; plants were placed below animals, and man was at the top. 4)Other schemes that have been used for grouping species include large anatomical similarities, such as wings or fins, which indicate a natural relationship, and also similarities in reproductive structures.
5)At the present time taxonomy is based on two major assumptions: one is that similar body construction can be used as a criterion for a classification grouping; the other is that, in addition to structural similarities, evolutionary and molecular relationships between organisms can be used as a means for determining classification.
An advantage of a dry chemical over a carbon dioxide fire extinguisher is its().
You are on a multiple-product chemical tanker and will carry cargoes of allyl alcohol,benzene,and propanolamine. Which of the following is true? ()
When fighting a fire with a portable dry chemical fire extinguisher,the stream should be directed().
The process that occurs when heat is generated by a chemical reaction within a substance and continues to a point of ignition is known as ().
Dry chemical extinguishers extinguish class B fires to the greatest extent by().