Q: The stomach mucosa's epithelial lining consists only of surface mucus cells, which secrete a protective coat of what? Read this paragraph and choose the correct option from the provided answers: The stomach mucosa's epithelial lining consists only of surface mucus cells, which secrete a protective coat of alkaline mucus. A vast number of gastric pits dot the surface of the epithelium, giving it the appearance of a well-used pincushion, and mark the entry to each gastric gland, which secretes a complex digestive fluid referred to as gastric juice. Although the walls of the gastric pits are made up primarily of mucus cells, the gastric glands are made up of different types of cells. The glands of the cardia and pylorus are composed primarily of mucus-secreting cells. Cells that make up the pyloric antrum secrete mucus and a number of hormones, including the majority of the stimulatory hormone, gastrin. The much larger glands of the fundus and body of the stomach, the site of most chemical digestion, produce most of the gastric secretions. These glands are made up of a variety of secretory cells. These include parietal cells, chief cells, mucous neck cells, and enteroendocrine cells. Parietal cellsLocated primarily in the middle region of the gastric glands are parietal cells, which are among the most highly differentiated of the body's epithelial cells. These relatively large cells produce both hydrochloric acid (HCl) and intrinsic factor. HCl is responsible for the high acidity (pH 1.5 to 3.5) of the stomach contents and is needed to activate the protein-digesting enzyme, pepsin. The acidity also kills much of the bacteria you ingest with food and helps to denature proteins, making them more available for enzymatic digestion. Intrinsic factor is a glycoprotein necessary for the absorption of vitamin B12 in the small intestine. Chief cellsLocated primarily in the basal regions of gastric glands are chief cells, which secrete pepsinogen, the inactive proenzyme form of pepsin. HCl is necessary for the conversion of pepsinogen to pepsin. Mucous neck cellsGastric glands in the upper part of the stomach contain mucous neck cells that secrete thin, acidic mucus that is much different from the mucus... Choices: - bile mucus - phosphate mucus - acidic mucus - alkaline mucus A:
alkaline mucus
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Q: Mutualism is a symbiotic relationship that has what effect on both species involved? Read this paragraph and choose the correct option from the provided answers: Mutualism is a symbiotic relationship in which both species benefit. Choices: - disadvantageous - harmful - destructive - beneficial A:
beneficial
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Q: Which theorem states that, if a population meets certain conditions, it will be in equilibrium? Read this paragraph and choose the correct option from the provided answers: The Hardy-Weinberg theorem states that, if a population meets certain conditions, it will be in equilibrium. In an equilibrium population, allele and genotype frequencies do not change over time. The conditions that must be met are no mutation, no migration, very large population size, random mating, and no natural selection. Choices: - hardy- jacksons theorem - hardy - henkel theorem - hardy - zeiss theorem - hardy-weinberg theorem A:
hardy-weinberg theorem
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Q: Nonmetal structures contain what type of bonds? Read this paragraph and choose the correct option from the provided answers: Structures of the Nonmetals The structures of the nonmetals differ dramatically from those of metals. Metals crystallize in closely packed arrays that do not contain molecules or covalent bonds. Nonmetal structures contain covalent bonds, and many nonmetals consist of individual molecules. The electrons in nonmetals are localized in covalent bonds, whereas in a metal, there is delocalization of the electrons throughout the solid. The noble gases are all monatomic, whereas the other nonmetal gaseshydrogen, nitrogen, oxygen, fluorine, and chlorinenormally exist as the diatomic molecules H2, N2, O2, F2, and Cl2. The other halogens are also diatomic; Br2 is a liquid and I2 exists as a solid under normal conditions. The changes in state as one moves down the halogen family offer excellent examples of the increasing strength of intermolecular London forces with increasing molecular mass and increasing polarizability. Oxygen has two allotropes: O2, dioxygen, and O3, ozone. Phosphorus has three common allotropes, commonly referred to by their colors: white, red, and black. Sulfur has several allotropes. There are also many carbon allotropes. Most people know of diamond, graphite, and charcoal, but fewer people know of the recent discovery of fullerenes, carbon nanotubes, and graphene. Descriptions of the physical properties of three nonmetals that are characteristic of molecular solids follow. Choices: - prevalent - polymeric - gravitational - covalent A:
covalent
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