The presence of the minute growth near the disc signifies that the bacterial innoculum contains mutant microorganisms that are able to grow in the presence of toxic substances.
<h3>What are zones of inhibition?</h3>
The sensitivity testing in a microbiology laboratory is done to determine the effect of antibiotics on various bacteria organisms
The zone of inhibition when a disk method is used signifies the area of media where bacteria are unable to grow, due to presence of a drug that impedes their growth.
If there are presence of minute growth near the disc, it means that the bacterial innoculum contains mutant microorganisms that are able to grow in the presence of toxic substances such as disinfectants.
If these mutant bacteria organisms are not cleared by the disk method, it means that they cannot be killed by the disinfectant/antiseptics that is being tested.
Learn more about antiseptics here:
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The major function of the contractile vacuole of amoeba is osmoregulation. The solute concentration found in the cell of amoeba's cytoplasm is more than the solute concentration in the freshwater that surround the external part of the organism, thus, water enter the cell through osmosis. The contractile vacuole collect the excess water and expel it through an opening in the cell membrane. By doing this, the contractile vacuole maintains the water balance in amoeba. This how the contractile vacuole normally operate.
In a situation where amoeba is placed in seawater, then water from the cell cytoplasm will rush out of amoeba cell, because of the higher salt content of the surrounding medium. The contractile vacuole will respond to the situation by increasing its contraction and pumping water out the cell in an accelerated manner, this will lead to the shrinking of the cell.
Answer: B) It controls the autonomic nervous system and regulates hunger and thirst sensations.
The answer is d. pheromones.
