Helper T cells are very important cells in the adaptive immunity. They are required for almost all adaptive immune responses and They also help activate cytotoxic T cells and macrophages to attack infected cells.
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The correct answer for the question that is being presented above is this one: "Protista." <span>In the new 6-kingdom system of classification, like the old 5-kingdom system, organisms are basically grouped by what is called Protista. Protista is the kingdom that contains anything that isn't classified as an animal, plant, fungi or bacteria.</span>
Answer:
SARS-CoV-2 is the seventh coronavirus strain known to infect humans and it causes respiratory disease in humans. These viruses infect humans and are currently causing a pandemic in the world.
A pathogen is an infectious organism that causes illness or disease to its host. There are many types of pathogens that infect the body of the host that disrupts the normal physiological process of an organism. SARS CoV2 is also a pathogen as it infects the human body and disrupts its physiology and causes disease.
Earth's crust is made of rock, and rock is made of natural substances called minerals. There are three main types of rock: sedimentary, igneous, and metamorphic rock. Each type is produced in different ways. The oldest rocks on Earth were formed about 3.8 billion years ago.
There were two approaches for the planetary paths. The idea about the planets revolving around the Earth, the planetary paths were plotted and were erratic. It was not relevant to the laws of motion and gravity. That fact was neglected by the believers in an Earth-centered Solar System.
Sun-centered Solar System was theorized by Copernicus. The paths assumed to be relatively circular (or elliptical).
