<h2>
Meselson and Stahl conducted an experiment to determine the correct proposed methods of DNA replication was semi-conservative
. the three proposed models for DNA replication are semi-conservative, conservative, and dispersive.</h2>
Explanation:
In Semi-conservative replication model, the two strands of DNA uncoil from each other. It perform with the original strand and a new strand.
In Conservative replication model, DNA replication didn't open at all, but the parent strands remains undamaged by creating a new and separate molecule that consists of two new strands.
In Dispersive replication model, DNA replication results in two DNA molecules that consists of both parental and daughter DNA.
He demonstrated that semi-conservative DNA replication is an universal mechanism allocated by all organisms on Earth.
Answer:
Legionella tends to form biofilms and infect other microbial cells as intracellular pathogens.
Explanation:
The Legionella genus of the bacteria is a group of gram-negative bacteria that can cause legionnaires disease.
The<em> Legionella pneumophila</em> is a species of this genus which can cause legion pneumonia. The bacteria lives in the freshwater and is resistant to chemical treatment like chlorine and the biocide treatment.
The reason for this resistance is since this species form a polysaccharide layer around the colony of the bacteria which is resistant to these treatments and also the bacteria prove parasitic to the protozoans which feed on these bacteria.
Thus, the selected option is the correct answer.
Answer:
Darwin's greatest contribution to science is that he completed the Copernican Revolution by drawing out for biology the notion of nature as a system of matter in motion governed by natural laws. With Darwin's discovery of natural selection, the origin and adaptations of organisms were brought into the realm of science
B: Antigens
Explanation: Antigens itself are the invaders that causes an infection or a disease in living organism. They do not protect against invaders in non-specific response as they themselves are the ones who are invading the body.
Digestive enzymes are the enzymes that act on a particular substrate for its action at a particular PH.
Stomach acid is the hydrochloric acid that keeps the PH of the stomach low and prevents the growth of unwanted pathogens.
Lysosomes have digestive enzymes in it. It performs the process of phagocytosis.
Answer:
The correct answer is- secondary treatment
Explanation:
Wastewater treatment is divided into three main stages which are primary, secondary and tertiary stages. In the primary treatment, the wastewater is held in the settling tank for some time and the solid waste settles with time and the remaining liquid is passed for secondary treatment.
In the secondary treatment, the organic compound present in the liquid is degraded with the help of aerobic bacteria. Aeration tank is there for providing the oxygen to bacteria and wastewater is stirred so that oxygen can be distributed evenly and bacteria can do their work properly.
