Answer:
Explanation:
Immunity to a disease is achieved through the presence of antibodies to that disease in a person's system. Antibodies are proteins produced by the body to neutralize or destroy toxins or disease-carrying organisms. Antibodies are disease-specific. Viruses make us sick by killing cells or disrupting cell function. Our bodies often respond with fever (heat inactivates many viruses), the secretion of a chemical called interferon (which blocks viruses from reproducing), or by marshaling the immune system's antibodies and other cells to target the invader. A vaccine works by training the immune system to recognize and combat pathogens, either viruses or bacteria. To do this, certain molecules from the pathogen must be introduced into the body to trigger an immune response.
These molecules are called antigens, and they are present on all viruses and bacteria.
Answer:
at right angles or perpendicular to the direction they are moving
Genetic variation allows for a greater chance of a population surviving. For example, if a plant species acquires a disease, without genetic variation the disease would just keep getting passed on to the next identical organism and the population would decline and eventually die. But genetic variation prevents that from happening, because you have so many other species in the ecosystem, and genetic variation is a product of sexual reproduction meaning that the offspring of the diseased plant has a possibility of not inheriting the disease.
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