Q: What structures formed of twisted actin chains are found in almost every cell, and are numerous in muscle cells and cells that move by changing shape? Read this paragraph and choose the correct option from the provided answers: Microfilaments , shown in Figure below (b) , are made of two thin actin chains that are twisted around one another. Microfilaments are mostly concentrated just beneath the cell membrane, where they support the cell and help the cell keep its shape. Microfilaments form cytoplasmatic extensions, such as pseudopodia and microvilli, which allow certain cells to move. The actin of the microfilaments interacts with the protein myosin to cause contraction in muscle cells. Microfilaments are found in almost every cell, and are numerous in muscle cells and in cells that move by changing shape, such as phagocytes (white blood cells that search the body for bacteria and other invaders). Choices: - RNA - DNA - vesicles - microfilaments A:
microfilaments
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Q: As temperature increases, the solubility of the majority of solid substances does what? Read this paragraph and choose the correct option from the provided answers: The solubility of the majority of solid substances increases as the temperature increases. However, the effect is difficult to predict and varies widely from one solute to another. The temperature dependence of solubility can be visualized with the help of a solubility curve , a graph of the solubility vs. temperature (see Figure below ). Choices: - stays the same - reduces - mutates - increases A:
increases
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Q: Some microorganisms can digest cellulose, breaking it down into what? Read this paragraph and choose the correct option from the provided answers: Choices: - gluclose polymers - fructose polymers - fructose monomers - glucose monomers A:
glucose monomers
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Q: A reptile's what doesn't generate enough energy to keep their body temperature stable? Read this paragraph and choose the correct option from the provided answers: Like amphibians, reptiles are ectotherms with a slow metabolic rate. Their metabolism doesn't generate enough energy to keep their body temperature stable. Instead, reptiles regulate their body temperature through their behavior. For example, the crocodile in Figure below is soaking up heat from the environment by basking in the sun. Because of their ectothermy, reptiles can get by with as little as one tenth the food needed by endotherms such as mammals. Some species of reptiles can go several weeks between meals. Choices: - respiration - tissue - skin - metabolism A:
metabolism
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