Answer the following question given this paragraph: Water is involved in many other biochemical reactions. As a result, just about all life processes depend on water. Clearly, life as we know it could not exist without water. Q: Nearly all life processes depend on what substance, which is involved in biochemical reactions? Choices: - food - hydrocarbons - air - water A:
water
Answer the following question given this paragraph: Passive transport occurs when a substance passes through the cell membrane without needing any energy to pass through. This happens when a substance moves from an area where it is more concentrated to an area where it is less concentrated. Concentration is the number of particles of a substance in a given volume. Let's say you dissolve a teaspoon of salt in a cup of water. Then you dissolve two teaspoons of salt in another cup of water. The second solution will have a higher concentration of salt. Q: When substances pass through the cell membrane without needing any energy what is it called? Choices: - active transport - kinetic transport - energetic transport - passive transport A:
passive transport
Q: Answer the following question given this paragraph: Thomas Quine (Flickr:quinet). Bees are important pollinators of flowering plants . CC BY 2.0. Q: What do bees do for flowering plants? Choices: - eat - create - feed - pollinate A:
A: pollinate
Question: Answer the following question given this paragraph: Once excited, an atom or molecule will usually spontaneously de-excite quickly. (The electrons raised to higher levels are attracted to lower ones by the positive charge of the nucleus. ) Spontaneous de-excitation has a very short mean lifetime of 8 typically about 10 s . However, some levels have significantly longer lifetimes, ranging up to milliseconds to minutes or even hours. These energy levels are inhibited and are slow in de-exciting because their quantum numbers differ greatly from those of available lower levels. Although these level lifetimes are short in human terms, they are many orders of magnitude longer than is typical and, thus, are said to be metastable, meaning relatively stable. Phosphorescence is the de-excitation of a metastable state. Glow-in-the-dark materials, such as luminous dials on some watches and clocks and on children's toys and pajamas, are made of phosphorescent substances. Visible light excites the atoms or molecules to metastable states that decay slowly, releasing the stored excitation energy partially as visible light. In some ceramics, atomic excitation energy can be frozen in after the ceramic has cooled from its firing. It is very slowly released, but the ceramic can be induced to phosphoresce by heatinga process called "thermoluminescence. " Since the release is slow, thermoluminescence can be used to date antiquities. The less light emitted, the older the ceramic. (See Figure 30.35. Q: What makes luminous dials glow in the dark? Choices: - polymer substances - devil substances - eerie substances - phosphorescent substances A:
Answer: phosphorescent substances
*Question*
Answer the following question given this paragraph: It is necessary to distinguish between the two types of covalent bonds in a C 2 H 4 molecule. A sigma bond ( bond) is a bond formed by the overlap of orbitals in an end-to-end fashion, with the electron density concentrated between the nuclei of the bonding atoms. A pi bond ( bond) is a bond formed by the overlap of orbitals in a side-by-side fashion, with the electron density concentrated above and below the plane of the nuclei of the bonding atoms. Figure below shows the two types of bonding in C 2 H 4 . The sp 2 hybrid orbitals are orange and the p z orbital is green. Three sigma bonds are formed by each carbon atom with its hybrid orbitals. The pi bond is the "second" bond of the double bond between the carbon atoms and is shown as an elongated blue lobe that extends both above and below the plane of the molecule, which contains the six atoms and all of the sigma bonds. Q: What term is used to describe a bond formed by the overlap of orbitals in an end-to-end fashion, with the electron density concentrated between the nuclei of the bonding atoms? Choices: - beta bond - lattice bond - rna bond - sigma bond A:
**Answer**
sigma bond
(Question)
Answer the following question given this paragraph: All chemical reactions, even exothermic reactions, need activation energy to get started. Activation energy is needed to bring reactants together so they can react. Q: What do all chemical reactions need to get started? Choices: - expression energy - kinetic energy - potential energy - activation energy A:
(Answer)
activation energy