Answer:
b.
Explanation:
They used Franklin's photo to determine that DNA was a double helix.
Distention from accumulating gas and fluid impede venous return, leading to bowel wall ischemia.
<u>Explanation:</u>
When the bowel lumen is obstructed, the gases and fuids starts accumulating as a repose to the obstruction. The accumulated fluid and gases results in the swelling or enlargement. This will result in the production of electrolytes and water inside the mumen that is in obstruction. The wall of the bowle will also enlarge and becomes swollen.
As more and more fluid and gas gets accumulated in the bowel, the bowel wall will be enlarged and as there is an increase in the pressure due to this accumulation, the fluid starts to leak from the wall. This will enter peritoneum and necrosis. This will result in an acute emergency when it becomes serious.
Discovery In 1928 it was discovered by Frederick Griffith in an experiment generally known as transformation.
Experiment
In his experiment he considered two strains of <em>streptococus pneumonia,</em> one was R-type which was non-virulent and cause no disease in mice, other was virulent and S-type which cause disease and at last death of mice.
This experiment was comprised of four steps which are as follow:
Step 1: First he injected living strain of S into mice, after sometime mouce died.
Step 2: He injected living strain of R into mice, the mice alive as he did not got any disease.
Step 3: He injected heat killed strain of S into mice and mice remain alive.
Step 4: He mixed living R strain with heat killed S strain and then inject into mice. As a result the mice died.
Conclusion: It was found that genetic material from heat killed S stain were transferred to living R (non-virulent) strain, as a result R become virulent and cause the death of mice.
The DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones
I guess because of concentration.....it stops !