The answer is C, because if something contagious we’re to threaten the population of the species then not having any variant means they’re all the same and it would kill them all and cause them to go extinct
Extensively drug-resistant
tuberculosis is a form of tuberculosis which is caused by bacteria that are
resistant to some of the most effective anti-TB drugs such as isoniazid and
rifampin. This form of tuberculosis occurs due to an individual’s mismanagement
of multidrug-resistant TB. Treatment for extensively resistant TB would include
medication with at least two drugs to which the TB is susceptible.
Troponin-tropomyosin molecules prevents a muscle contraction from occurring when the muscle is at rest.
<h3>What is
muscle contraction?</h3>
The activation of tension-producing regions within muscle cells results in muscular contraction. Because muscle tension can be created without changes in muscle length, such as when holding something heavy in the same position, muscle contraction does not always imply muscle shortening in physiology. Muscle relaxation, or the return of the muscular fibers to their low tension-generating state, occurs after a muscle contraction has finished.
Both length and tension can be used to characterize muscle contractions. If the muscle tension varies but the muscle length doesn't, the muscle contraction is said to be isometric. A muscle contraction is isotonic, however, if the tension in the muscle remains constant during the contraction.
To learn more about muscle contraction with the help of given link:
brainly.com/question/10115123
#SPJ4
The number of mitochondria per cell varies widely; for example, in humans, erythrocytes (red blood cells) do not contain any mitochondria, whereas liver cells and muscle cells may contain hundreds or even thousands. The only eukaryotic organism known to lack mitochondria is the oxymonad Monocercomonoides species.
Answer:
The correct answer is b. He determined that DNA contains four nitrogenous bases.
Explanation:
Levene was an American biochemist who studied the structure of DNA in the early 1900s and in 1920 he found that DNA consists of four nitrogenous bases that are Adenine, Guanine, Thymine, Cytosine.
He also found deoxyribose sugar and phosphate group and said that nucleotide is the basic unit of DNA which contains a ribose sugar with attached nitrogenous base and phosphate group.
He also concludes that an equal amount of adenine, guanine, thymine, and cytosine makes the DNA which is now known as tetranucleotide hypothesis. So the correct answer is b. He determined that DNA contains four nitrogenous bases.
