Ques: Q: What do corals secrete that builds up to become a coral reef? Read this paragraph and choose the correct option from the provided answers: Cnidarians include jellyfish and corals. They are aquatic invertebrates. They have tissues and radial symmetry. They also have tentacles with stingers. There are two cnidarian body plans: the polyp and the medusa. They differ in several ways. Many corals secrete an exoskeleton that builds up to become a coral reef. Choices: - membrane - mucous - scales - exoskeleton A:
Ans: exoskeleton

Ques: Q: Before the atmosphere became oxygenated, the planet was subjected to what harmful energy source, meaning the first organisms would have flourished where they were more protected? Read this paragraph and choose the correct option from the provided answers: Before the atmosphere became oxygenated, the planet was subjected to strong radiation; thus, the first organisms would have flourished where they were more protected, such as in ocean depths or beneath the surface of Earth. At this time, too, strong volcanic activity was common on Earth, so it is likely that these first organismsthe first prokaryoteswere adapted to very high temperatures. These are not the typical temperate environments in which most life flourishes today; thus, we can conclude that the first organisms that appeared on Earth likely were able to withstand harsh conditions. Microbial mats may represent the earliest forms of life on Earth, and there is fossil evidence of their presence, starting about 3.5 billion years ago. A microbial mat is a large biofilm, a multi-layered sheet of prokaryotes (Figure 13.3a), including mostly bacteria, but also archaea. Microbial mats are a few centimeters thick, and they typically grow on moist surfaces. Their various types of prokaryotes carry out different metabolic pathways, and for this reason, they reflect various colors. Prokaryotes in a microbial mat are held together by a gummy-like substance that they secrete. The first microbial mats likely obtained their energy from hydrothermal vents. A hydrothermal vent is a fissure in Earth's surface that releases geothermally heated water. With the evolution of photosynthesis about 3 billion years ago, some prokaryotes in microbial mats came to use a more widely available energy sourcesunlightwhereas others were still dependent on chemicals from hydrothermal vents for food. Choices: - evaporation - conduction - convection - radiation A:
Ans: radiation

Ques: Q: Iron is oxidized to fe2+(aq) at an anodic site on the surface of the iron, which is often an impurity or this? Read this paragraph and choose the correct option from the provided answers: Iron is oxidized to Fe2+(aq) at an anodic site on the surface of the iron, which is often an impurity or a lattice defect. Oxygen is reduced to water at a different site on the surface of the iron, which acts as the cathode. Electrons are transferred from the anode to the cathode through the electrically conductive metal. Water is a solvent for the Fe2+ that is produced initially and acts as a salt bridge. Rust (Fe2O3xH2O) is formed by the subsequent oxidation of Fe2+ by atmospheric oxygen. In the corrosion process, iron metal acts as the anode in a galvanic cell and is oxidized to Fe2+; oxygen is reduced to water at the cathode. The relevant reactions are as follows:. Choices: - displacement defect - spontaneous mutation - ladder complex - lattice defect A:
Ans: lattice defect

Ques: Q: Water is a polar compound, so its molecules are attracted to each other and form what kind of bonds? Read this paragraph and choose the correct option from the provided answers: Water is a polar compound, so its molecules are attracted to each other and form hydrogen bonds. Choices: - mixed - carbon - helium - hydrogen A:
Ans:
hydrogen