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Answer:
<u>3) Uncontrolled cell division occurred as a result of gene mutations</u>
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Explanation:
Spontaneous modifications within the genome may occur during the process of cell division. When copies of the DNA inside the cell are made, these mutations cause errors; and can include small single nucleotide polymorphisms, and large scale additions or deletions across multiple genes.
Some, like somatic mutations, exist only inside vegetative (body) cells, that cannot be passed onto offspring. This is caused by several factors like
- UV radiation,
- chemical mutagens,
- infective agents
UV radiation damages strands of DNA, by causing dimers to form; here, consecutive nucleotide bases covalently bond instead of those on the complementary strand. This conformational change causes errors in DNA proofreading and repair mechanisms where bases are not well-incorporated into the strand- tumors (clumps of uncontrolled cell growth) may form, resulting in melanoma, a type of skin cancer.
Answer:
B. MacConkey is both a differential and a selective medium.
Explanation:
Selective media contain the ingredients that allows for the growing of specific microbes while inhibiting the others.
For example MacConkey media facilitate the growth of gram negative bacteria and inhibit the growth of gram positive bacteria. That why E. coli and P. mirabilis grew on the media because these are gram negative and S. saprophyticus does not grew being gram positive.
Differential media allow to differentiate between selected microbes by visual observation.
For Example MacConkey media differentiate between organisms that can ferment lactose to the organisms that can't ferment it. That why E. coli appeared pink on the media because it can ferment lactose while P. mirabilis appears colorless because it usually cannot ferment lactose.