Answer the following question given this paragraph: Electrical Synapse While electrical synapses are fewer in number than chemical synapses, they are found in all nervous systems and play important and unique roles. The mode of neurotransmission in electrical synapses is quite different from that in chemical synapses. In an electrical synapse, the presynaptic and postsynaptic membranes are very close together and are actually physically connected by channel proteins forming gap junctions. Gap junctions allow current to pass directly from one cell to the next. In addition to the ions that carry this current, other molecules, such as ATP, can diffuse through the large gap junction pores. There are key differences between chemical and electrical synapses. Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is unidirectional. Signaling in electrical synapses, in contrast, is virtually instantaneous (which is important for synapses involved in key reflexes), and some electrical synapses are bidirectional. Electrical synapses are also more reliable as they are less likely to be blocked, and they are important for synchronizing the electrical activity of a group of neurons. For example, electrical synapses in the thalamus are thought to regulate slow-wave sleep, and disruption of these synapses can cause seizures. Q: Although fewer in number than chemical synapses, what type of synapses are found in all nervous systems and play important and unique roles? Choices: - duplicating synapses - beginning synapses - dual synapses - electrical synapses A:
electrical synapses
Answer the following question given this paragraph: Photosynthesis is the base of nearly all food chains on Earth. This is true of marine food chains, too. Q: What is the base of nearly all food chains on earth? Choices: - glycolysis - atherosclerosis - synthesis - photosynthesis A:
photosynthesis
Q: Answer the following question given this paragraph: Consider the simple ramp in Figure below . A ramp can be used to raise an object up off the ground. The input distance is the length of the sloped surface of the ramp. The output distance is the height of the ramp, or the vertical distance the object is raised. Therefore, the ideal mechanical advantage of the ramp is:. Q: The length of the sloped surface of a ramp is referred to as what? Choices: - accumulation distance - output distance - furlong - input distance A:
A: input distance
Question: Answer the following question given this paragraph: Because isomers are different compounds, they have different properties. Generally, branched-chain isomers have lower boiling and melting points than straight-chain isomers. For example, the boiling and melting points of iso -butane are -12 C and -160 C, respectively, compared with 0 C and -138 C for n -butane. The more branching there is, the lower the boiling and melting points are. Q: Which type of isomers generally have lower boiling and melting points than straight-chain isomers? Choices: - straight-chain isomers - branched-looping isomers - branched - solar isomers - branched-chain isomers A:
Answer: branched-chain isomers
*Question*
Answer the following question given this paragraph: The Dutch scientist Christiaan Huygens (16291695) developed a useful technique for determining in detail how and where waves propagate. Starting from some known position, Huygens's principle states that: Every point on a wavefront is a source of wavelets that spread out in the forward direction at the same speed as the wave itself. The new wavefront is a line tangent to all of the wavelets. Figure 27.5 shows how Huygens's principle is applied. A wavefront is the long edge that moves, for example, the crest or the trough. Each point on the wavefront emits a semicircular wave that moves at the propagation speed v . These are drawn at a time t later, so that they have moved a distance s = vt . The new wavefront is a line tangent to the wavelets and is where we would expect the wave to be a time t later. Huygens's principle works for all types of waves, including water waves, sound waves, and light waves. We will find it useful not only in describing how light waves propagate, but also in explaining the laws of reflection and refraction. In addition, we will see that Huygens's principle tells us how and where light rays interfere. Q: Dutch scientist christiaan huygens' principle of what states that every point on a wavefront is a source of wavelets that spread out in the forward direction at the speed of the wave itself? Choices: - electromagnetic dynamics - energy propagation - wave dynamics - wave propagation A:
**Answer**
wave propagation
(Q).
Answer the following question given this paragraph: Raising the temperature of a chemical reaction usually results in a higher rate of reaction. When the reactant particles are heated, they move faster and faster. This results in a greater frequency of collisions. A more important effect of the temperature increase is that the collisions occur with a greater force and are thus more likely to surmount the activation energy barrier and go on to form products. Increasing the temperature of a reaction increases the number of effective collisions between reacting particles, so the reaction rate increases. Q: Higher temperatures increase the rate of reaction in a lot of chemical reactions because they increase the frequency of what interaction between reactant particles? Choices: - electric - explosions - waves - collisions A:
(A).
collisions