Q: The outer layer of what anatomical structure is so tough that it keeps out most pathogens? Read this paragraph and choose the correct option from the provided answers: This drawing shows that the skin has many layers. The outer layer is so tough that it keeps out most pathogens. Choices: - liver - steel - bark - skin A:
skin

Q: What property of warm air causes it to rise above cold air? Read this paragraph and choose the correct option from the provided answers: The warm-air vent is placed near the floor of the room. Warm air is less dense than cold air so it rises. If the warm-air vent were placed near the ceiling instead, how would this affect the transfer of thermal energy throughout the room?. Choices: - greater pressure - greater density - higher temperature - lower density A:
lower density

Q: Rubber is an example of what type of substances that do not allow electrons to move through them? Read this paragraph and choose the correct option from the provided answers: A common method of producing charge in the lab is to rub cat or rabbit fur against stiff rubber, producing a negative charge on the rubber rod. If you hold a rubber rod on one end and rub only the tip of the other end with a fur, you will find that only the tip becomes charged. The electrons you add to the tip of the rod remain where you put them instead of moving around on the rod. Rubber is an insulator. Insulators are substances that do not allow electrons to move through them. Glass, dry wood, most plastics, cloth, and dry air are common insulators. Materials that allow electrons to flow freely are called conductors. Metals have at least one electron that can move around freely, and all metals are conductors. Choices: - conductor - semi-conductor - solids - insulators A:
insulators

Q: What do marine autotrophs acquire in carbonic acid, its dissolved form? Read this paragraph and choose the correct option from the provided answers: The Biological Carbon Cycle Living organisms are connected in many ways, even between ecosystems. A good example of this connection is the exchange of carbon between heterotrophs and autotrophs within and between ecosystems by way of atmospheric carbon dioxide. Carbon dioxide is the basic building block that autotrophs use to build multi-carbon, high-energy compounds, such as glucose. The energy harnessed from the Sun is used by these organisms to form the covalent bonds that link carbon atoms together. These chemical bonds store this energy for later use in the process of respiration. Most terrestrial autotrophs obtain their carbon dioxide directly from the atmosphere, while marine autotrophs acquire it in the dissolved form (carbonic acid, HCO3). However the carbon dioxide is acquired, a byproduct of fixing carbon in organic compounds is oxygen. Photosynthetic organisms are responsible for maintaining approximately 21 percent of the oxygen content of the atmosphere that we observe today. The partners in biological carbon exchange are the heterotrophs (especially the primary consumers, largely herbivores). Heterotrophs acquire the high-energy carbon compounds from the autotrophs by consuming them and breaking them down by respiration to obtain cellular energy, such as ATP. The most efficient type of respiration, aerobic respiration, requires oxygen obtained from the atmosphere or dissolved in water. Thus, there is a constant exchange of oxygen and carbon dioxide between the autotrophs (which need the carbon) and the heterotrophs (which need the oxygen). Autotrophs also respire and consume the organic molecules they form: using oxygen and releasing carbon dioxide. They release more oxygen gas as a waste product of photosynthesis than they use for their own respiration; therefore, there is excess available for the respiration of other aerobic organisms. Gas exchange through the atmosphere and water is one way that the carbon cycle connects all living organisms on Earth. The Biogeochemical Carbon Cycle The... Choices: - silicon dioxide - chlorine dioxide - carbon monoxide - carbon dioxide A:
carbon dioxide