Q: How thick is the earth's continental crust, on average? Read this paragraph and choose the correct option from the provided answers: Continental crust is much thicker than oceanic crust. It is 35 kilometers (22 miles) thick on average, but it varies a lot. Continental crust is made up of many different rocks. All three major rock types igneous, metamorphic, and sedimentary are found in the crust. On average, continental crust is much less dense (2.7 g/cm3) than oceanic crust. Since it is less dense, it rises higher above the mantle than oceanic crust. Choices: - 60 kilometers - 15 kilometers - 25 kilometers - 35 kilometers A:
35 kilometers

Q: What is the term that refers to stored chemical energy in organic matter or wastes? Read this paragraph and choose the correct option from the provided answers: The stored chemical energy in organic matter or wastes is called biomass energy. The organic matter may be trees or other plants, or it may be wastes from homes and industries. When biomass is burned, it produces thermal energy that can be used for heating homes, cooking, or generating electricity. Biomassespecially woodis an important energy source in the poorer nations where most people can't afford fossil fuels. However, burning biomass releases air pollution and contributes to global climate change. Biomass can be used to make ethanol, a fuel that is added to gasoline. Although ethanol releases less pollution than gasoline, large areas of land are needed to grow the plants needed to make it (see Figure below ). This reduces the amount of land available for food production. Choices: - nuclear energy - potential energy - starch energy - biomass energy A:
biomass energy

Q: E. coli need what kind of acids to survive? Read this paragraph and choose the correct option from the provided answers: The trp Operon: A Repressor Operon Bacteria such as E. coli need amino acids to survive. Tryptophan is one such amino acid that E. coli can ingest from the environment. coli can also synthesize tryptophan using enzymes that are encoded by five genes. These five genes are next to each other in what is called the tryptophan (trp) operon (Figure 16.3). If tryptophan is present in the environment, then E. coli does not need to synthesize it and the switch controlling the activation of the genes in the trp operon is switched off. However, when tryptophan availability is low, the switch controlling the operon is turned on, transcription is initiated, the genes are expressed, and tryptophan is synthesized. Choices: - hydrochloric - bacterial - boric - amino A:
amino