The infinite variety of antibodies that can be generated by B cells is due to
1.the infinite variety of genes in these cells.
2.the shuffling of genes to produce an infinite variety of proteins.
3.the recombination of genes due to crossing over.
4.the infinite variety of genes in these cells and the recombination of genes due to crossing over.
5.the infinite variety of genes in these cells, the recombination of genes due to crossing over, and the shuffling of genes to produce an infinite variety of proteins.
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Most of the bacteria involved in periodontal disease are obligate (strict) anaerobes. Explain why this is the case.
A. Mouthwashes and toothpaste destroy most of the strict aerobes that are found on teeth. B. Sugar and other carbohydrates used by the oral bacteria can be more easily consumed anaerobically. C. The oral cavity is a low oxygen environment. D. The crevice between the gingiva and the tooth is low in oxygen.
How is sexual reproduction different from asexual reproduction?
A. Sexual reproduction occurs with only a single parent. B. Asexual reproduction requires testes and ovaries. C. Sexual reproduction requires fertilization of an egg by a sperm. D. Asexual reproduction requires two kinds of cell division.
Lipids have : hydrophilic head and hydrophobic tails
Answer the following statement(s) true (T) or false (F)
Water and small solutes are filtered under pressure out of the blood plasma into nephrons through the porous walls of ________, tufts of capillaries in the renal cortex.
A. juxtaglomerular apparati B. Loops of Henle C. collecting ducts D. vasa rectae E. glomeruli