Q: Answer the following question given this paragraph: 2.2 Water Water has many properties that are critical to maintaining life. It is polar, allowing for the formation of hydrogen bonds, which allow ions and other polar molecules to dissolve in water. Therefore, water is an excellent solvent. The hydrogen bonds between water molecules give water the ability to hold heat better than many other substances. As the temperature rises, the hydrogen bonds between water continually break and reform, allowing for the overall temperature to remain stable, although increased energy is added to the system. Water's cohesive forces allow for the property of surface tension. All of these unique properties of water are important in the chemistry of living organisms. The pH of a solution is a measure of the concentration of hydrogen ions in the solution. A solution with a high number of hydrogen ions is acidic and has a low pH value. A solution with a high number of hydroxide ions is basic and has a high pH value. The pH scale ranges from 0 to 14, with a pH of 7 being neutral. Buffers are solutions that moderate pH changes when an acid or base is added to the buffer system. Buffers are important in biological systems because of their ability to maintain constant pH conditions. Q: An excellent solvent that holds heat well and allows hydrogen bonds, what substance has many properties critical to life? A: | OPTIONS:
- liquid
- blood
- plasma
- water
A: water

Q: Answer the following question given this paragraph: Figure 3.19 A phospholipid is a molecule with two fatty acids and a modified phosphate group attached to a glycerol backbone. The phosphate may be modified by the addition of charged or polar chemical groups. Two chemical groups that may modify the phosphate, choline and serine, are shown here. Both choline and serine attach to the phosphate group at the position labeled R via the hydroxyl group indicated in green. Q: What is a molecule with two fatty acids and a modified phosphate group attached to a glycerol backbone? A: | OPTIONS:
- carbohydrate
- polymer
- amino acid
- phospholipid
A: phospholipid

Q: Answer the following question given this paragraph: Sexual reproduction occurs when spores from two parents fuse and form a zygospore. Q: What forms when the spores from two parents fuse during sexual reproduction? A: | OPTIONS:
- xerophyte
- spirogyra
- monospore
- zygospore
A: zygospore

Q: Answer the following question given this paragraph: Echinoderms generally reproduce by external fertilization; regeneration is fairly common among echinoderms. Q: What is the method of reproduction for echinoderms? A: | OPTIONS:
- pollination
- internal fertilization
- fragmentation
- external fertilization
A: external fertilization