Answer the following question given this paragraph: Biotic factors are all of the living or once-living aspects of the environment. They include all the organisms that live there as well as the remains of dead organisms. Q: What are all of the living or once-living aspects of the environment called? A:

OPTIONS:
- abiotic factors
- photic factors
- fossils
- biotic factors

Answer: biotic factors

Answer the following question given this paragraph: Myopia is also called nearsightedness. It affects about one third of people. People with myopia can see nearby objects clearly, but distant objects appear blurry. The picture below shows how a person with myopia might see two boys that are a few meters away ( Figure below ). Q: What is another name for nearsightedness? A:

OPTIONS:
- hyperopia
- astigmatism
- presbyopia
- myopia

Answer: myopia

Answer the following question given this paragraph: The process in which an atom becomes an ion is called ionization. It may occur when atoms are exposed to high levels of radiation or when atoms transfer electrons to or from other atoms. Q: What process can occur when atoms are exposed to high levels of radiation or when atoms transfer electrons to or from other atoms? A:

OPTIONS:
- fusion
- diffusion
- oxidation
- ionization

Answer: ionization

Answer the following question given this paragraph: The deadly nerve gas Sarin irreversibly inhibits acetycholinesterase. What effect would Sarin have on muscle contraction? After depolarization, the membrane returns to its resting state. This is called repolarization, during which voltagegated sodium channels close. Potassium channels continue at 90% conductance. Because the plasma membrane sodiumpotassium ATPase always transports ions, the resting state (negatively charged inside relative to the outside) is restored. The period immediately following the transmission of an impulse in a nerve or muscle, in which a neuron or muscle cell regains its ability to transmit another impulse, is called the refractory period. During the refractory period, the membrane cannot generate another action potential. The refractory period allows the voltage-sensitive ion channels to return to their resting configurations. The sodium potassium ATPase continually moves Na+ back out of the cell and K+ back into the cell, and the K+ leaks out leaving negative charge behind. Very quickly, the membrane repolarizes, so that it can again be depolarized. Q: The period immediately following the transmission of an impulse in a nerve or muscle, in which a neuron or muscle cell regains its ability to transmit another impulse, is called the ______ period. A:

OPTIONS:
- activation
- extraction
- interstitial
- refractory

Answer:
refractory