Answer the following question given this paragraph: Third, there are some exceptions to the previous point. A few elements, all metals, can form more than one possible charge. For example, iron atoms can form 2+ cations or 3+ cations. Cobalt is another element that can form more than one possible charged ion (2+ and 3+), while lead can form 2+ or 4+ cations. Unfortunately, there is little understanding which two charges a metal atom may take, so it is best to just memorize the possible charges a particular element can have. Note the convention for indicating an ion. The magnitude of the charge is listed as a right superscript next to the symbol of the element. If the charge is a single positive or negative one, the number 1 is not written; if the magnitude of the charge is greater than 1, then the number is written before the + or sign. An element symbol without a charge written next to it is assumed to be the uncharged atom. Naming an ion is straightforward. For a cation, simply use the name of the element and add the word ion (or if you want to be more specific, add cation) after the element's name. So Na+ is the sodium ion; Ca2+ is the calcium ion. If the element has more than one possible charge, the value Saylor URL: http://www. saylor. org/books. Q: An element symbol without a charge written next to it is assumed to be what? A:

OPTIONS:
- dead atom
- corroborate atom
- surfactants atom
- uncharged atom

Answer: uncharged atom

Problem: OPTIONS:
- algae
- pollen
- viruses
- bacteria
Q: Answer the following question given this paragraph: The Nitrogen Cycle Getting nitrogen into the living world is difficult. Plants and phytoplankton are not equipped to incorporate nitrogen from the atmosphere (which exists as tightly bonded, triple covalent N2) even though this molecule comprises approximately 78 percent of the atmosphere. Nitrogen enters the living world via free-living and symbiotic bacteria, which incorporate nitrogen into their macromolecules through nitrogen fixation (conversion of N2). Cyanobacteria live in most aquatic ecosystems where sunlight is present; they play a key role in nitrogen fixation. Cyanobacteria are able to use inorganic sources of nitrogen to "fix" nitrogen. Rhizobium bacteria live symbiotically in the root nodules of legumes (such as peas, beans, and peanuts) and provide them with the organic nitrogen they need. Free-living bacteria, such as Azotobacter, are also important nitrogen fixers. Organic nitrogen is especially important to the study of ecosystem dynamics since many ecosystem processes, such as primary production and decomposition, are limited by the available supply of nitrogen. As shown in Figure 46.17, the nitrogen that enters living systems by nitrogen fixation is successively converted from organic nitrogen back into nitrogen gas by bacteria. This process occurs in three steps in terrestrial systems: ammonification, nitrification, and denitrification. First, the ammonification process converts nitrogenous waste from living animals or from the remains of dead animals. Q: The nitrogen that enters living systems by nitrogen fixation is successively converted from organic nitrogen back into nitrogen gas by what? A:
Answer: bacteria

Problem:OPTIONS:
- vibrate
- pull
- expand
- contract

Answer the following question given this paragraph: Muscles can only contract. They can't actively lengthen. Therefore, to move bones back and forth at a joint, skeletal muscles must work in pairs. For example, the bicep and triceps muscles of the upper arm work as a pair. You can see how this pair of muscles works in Figure below . When the bicep muscle contracts, it bends the arm at the elbow. When the triceps muscle contracts, it straightens the arm. Q: Skeletal muscles must work in pairs to move bones back and forth at a joint because they can only do what? A:
****
A: contract

Answer the following question given this paragraph: When fuel is burned, most of the energy is released as heat. Some of this heat can be used to do work. Heat cooks food or warms your house. Sometimes the heat is just waste heat. It still heats the environment, though. Q: When fuel is burned, most of the energy is released in what form? A:
OPTIONS:
- precipitation
- carbon dioxide
- humidity
- heat
heat

Answer the following question given this paragraph: Upwelling takes place at some coastlines or along the Equator. Upwelling brings cool, nutrient-rich water to the surface. Q: What takes place at some coastlines or along the equator and brings cool, nutrient-rich water to the surface? A:
OPTIONS:
- high tide
- red tide
- flooding
- upwelling

Answer: upwelling

input with options: Answer the following question given this paragraph: Q: Insulin is made up of how many polypeptide chains? A:
OPTIONS:
- three
- four
- twelve
- two
output:
two