Answer the following question given this paragraph: Potassium Concentration Glial cells, especially astrocytes, are responsible for maintaining the chemical environment of the CNS tissue. The concentrations of ions in the extracellular fluid are the basis for how the membrane potential is established and changes in electrochemical signaling. If the balance of ions is upset, drastic outcomes are possible. Normally the concentration of K+ is higher inside the neuron than outside. After the repolarizing phase of the action potential, K+ leakage channels and the Na+/K+ pump ensure that the ions return to their original locations. Following a stroke or other ischemic event, extracellular K+ levels are elevated. The astrocytes in the area are equipped to clear excess K+ to aid the pump. But when the level is far out of balance, the effects can be irreversible. Astrocytes can become reactive in cases such as these, which impairs their ability to maintain the local chemical environment. The glial cells enlarge and their processes swell. They lose their K+ buffering ability and the function of the pump is affected, or even reversed. One of the early signs of cell disease is this "leaking" of sodium ions into the body cells. This sodium/potassium imbalance negatively affects the internal chemistry of cells, preventing them from functioning normally. Q: One of the early signs of cell disease is this "leaking" of what into the body cells? Choices: - proteins - potassium ions - glucose - sodium ions A:
sodium ions
Answer the following question given this paragraph: Reptiles are a class of ectothermic, tetrapod vertebrates. They have several adaptations for living on dry land, such as tough keratin scales and efficient lungs for breathing air. They also have a three-chambered heart and relatively well-developed brain. Q: How many chambers are in a reptiles heart? Choices: - ten - two - five - three A:
three
Q: Answer the following question given this paragraph: Mammals have the ability to regulate body temperature. This is an advantage, as Earth's climate went through sudden and dramatic changes. Mastodons, saber tooth tigers, hoofed mammals, whales, primates and eventually humans all lived during the Cenozoic Era ( Figure below ). Q: The ability to regulate what, which is possessed by mammals, was an advantage as earth's climate went through sudden and dramatic changes? Choices: - mutations - reflex behaviors - hair growth - body temperature A:
A: body temperature
Question: Answer the following question given this paragraph: is the phase (or state) of matter. The three fundamental phases of matter are solid, liquid, and gas (see Figure 1.1 "The Phases of Matter"). Chemical properties are characteristics of matter that describe how matter changes form in the presence of other matter. Does a sample of matter burn? Burning is a chemical property. Does it behave violently when put in water? This reaction is a chemical property as well (Figure 1.2 "Chemical Properties"). In the following chapters, we will see how descriptions of physical and chemical properties are important aspects of chemistry. If matter always stayed the same, chemistry would be rather boring. Fortunately, a major part of chemistry involves change. A physical change occurs when a sample of matter changes one or more of its physical properties. For example, a solid may melt (Figure 1.3 "Physical Changes"), or alcohol in a thermometer may change volume as the temperature changes. A physical change does not affect the chemical composition of matter. A chemical change is the process of demonstrating a chemical property, such as the burning match in Figure 1.2 "Chemical Properties". As the matter in the match burns, its chemical composition changes, and new forms of matter with new physical properties are created. Note that chemical changes are frequently accompanied by physical changes, as the new matter will likely have different physical properties from the original matter. Q: What are the three fundamental phases of matter? Choices: - fast, slow, normal - big, small. and medium - air, water, and land - solid, liquid, and gas A:
Answer: solid, liquid, and gas
*Question*
Answer the following question given this paragraph: Figure 21.13 Extinction intensity as reflected in the fossil record has fluctuated throughout Earth's history. Sudden and dramatic losses of biodiversity, called mass extinctions, have occurred five times. Q: What are sudden and dramatic losses of biodiversity called? Choices: - explosive extinction - life extinction - normal extinction - mass extinction A:
**Answer**
mass extinction
(Question)
Answer the following question given this paragraph: Oxygen is needed to make ozone. Ozone is a molecule made of three oxygen ions. Ozone in the upper atmosphere blocks harmful solar radiation from reaching the surface. Without oxygen, life on Earth would have been very simple. Q: How many oxygen ions make up an ozone molecule? Choices: - eight - one - five - three A:
(Answer)
three