Answer the following question given this paragraph: The burner on a gas stove burns with a pretty blue flame like the one pictured in the opening image. The fuel burned by most gas stoves is natural gas, which consists mainly of methane. Methane is a compound that contains only carbon and hydrogen. Like many other compounds that consist of just these two elements, methane is used for fuel because it burns very easily. Methane is an example of a covalent compound. Q: Natural gas, such as those burned by gas stoves, is composed mostly of this? Choices: - sulfur - carbon monoxide - oxygen - methane A:
methane
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Answer the following question given this paragraph: There is a second distinction between the types of cleavage in protostomes and deuterostomes. In addition to spiral cleavage, protostomes also undergo determinate cleavage. This means that even at this early stage, the developmental fate of each embryonic cell is already determined. A cell does not have the ability to develop into any cell type. In contrast, deuterostomes undergo indeterminate cleavage, in which cells are not yet pre-determined at this early stage to develop into specific cell types. These cells are referred to as undifferentiated cells. This characteristic of deuterostomes is reflected in the existence of familiar embryonic stem cells, which have the ability to develop into any cell type until their fate is programmed at a later developmental stage. Q: In addition to spiral cleavage, protostomes also undergo which other form of cleavage? Choices: - straight - diagonal - dispersive - determinate A:
determinate
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Answer the following question given this paragraph: Almost all surfaces reflect some of the light that strikes them. The still water of the lake in Figure above reflects almost all of the light that strikes it. The reflected light forms an image of nearby objects. An image is a copy of an object that is formed by reflected or refracted light. Q: A visual "copy" of an object that is formed by reflected or refracted light is called what? Choices: - mirror - instance - photo - image A:
image
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Answer the following question given this paragraph: Each separate substance in a medium, such as the extracellular fluid, has its own concentration gradient, independent of the concentration gradients of other materials. Additionally, each substance will diffuse according to that gradient. Several factors affect the rate of diffusion. Extent of the concentration gradient: The greater the difference in concentration, the more rapid the diffusion. The closer the distribution of the material gets to equilibrium, the slower the rate of diffusion becomes. Mass of the molecules diffusing: More massive molecules move more slowly, because it is more difficult for them to move between the molecules of the substance they are moving through; therefore, they diffuse more slowly. Temperature: Higher temperatures increase the energy and therefore the movement of the molecules, increasing the rate of diffusion. Solvent density: As the density of the solvent increases, the rate of diffusion decreases. The molecules slow down because they have a more difficult time getting through the denser medium. Q: In a medium, the closer the distribution of the material gets to what state, the slower the rate of diffusion becomes? Choices: - erosion - gas - elastic - equilibrium A:
equilibrium
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