Describe the mechanisms of action of antibodies.
What will be an ideal response?
Antibodies act against foreign antigens in many ways. In agglutination, several immunoglobulin (antibody) molecules bind two or more microbial cells together, causing them to clump. This process hinders the activity of pathogenic organisms and increases the chances that they will be phagocytized. Antibodies may neutralize toxins produced by pathogens by binding to critical portions of the toxins and preventing them from functioning against the body. Antibodies may bind to virus ligands or bacterial adhesions and prevent the pathogen from attaching to cells of the body. Antibodies also act as opsonins, which are molecules that stimulate phagocytosis. Binding of the antibody to foreign antigens on the surface of cells facilitates the action of natural killer lymphocytes. IgG antibody bound to antigen can become enzymatically active and produce hydrogen peroxide to damage and kill the microbe to which it is bound. IgG and IgM antibodies that have bound antigen can trigger the complement cascade. IgE antibodies trigger the release of chemicals which damage cells and inflammatory chemicals from eosinophils and basophils.
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Newborn infants can be infected with Group ________ streptococcus during birth.
Fill in the blank(s) with the appropriate word(s).
Genetic variability in meiosis results from ____
a. recombination of homologous chromosomes only b. independent assortment of chromosomes only c. random joining of male and female gametes only d. recombination between sister chromatids and homologous chromosomes e. recombination of homologous chromosomes, independent assortment of chromosomes, and random joining of male and female gametes
Which statement best describes a DNA mutation?
a. DNA polymerase adds an incorrect base during replication. b. DNA is damaged by UV irradiation. c. A mistake in DNA sequence is repaired during replication. d. A permanent change occurs in the nucleotide sequence of DNA. e. Proofreading during replication replaces a mismatched nucleotide.
If one nephron in the right kidney becomes blocked and unable to function,
A. the kidney would become non-functional. B. the person would die. C. urine formation would not be greatly affected because there are 1.3 million nephrons in each kidney. D. the kidney would no longer be able to create urine. E. the filtration and urination rates would decrease significantly.