Q: What can happen spontaneously or as a result of mutagens in the environment? Read this paragraph and choose the correct option from the provided answers: Many mutations are not caused by errors in replication. Mutations can happen spontaneously, and they can be caused by mutagens in the environment. Some chemicals, such as those found in tobacco smoke, can be mutagens. Sometimes mutagens can also cause cancer. Tobacco smoke, for example, is often linked to lung cancer. Choices: - lesions - combustion - traits - mutations A:
mutations

Q: How many chromosomes do mature gametes contain? Read this paragraph and choose the correct option from the provided answers: Spermatogenesis As just noted, spermatogenesis occurs in the seminiferous tubules that form the bulk of each testis (see Figure 27.4). The process begins at puberty, after which time sperm are produced constantly throughout a man's life. One production cycle, from spermatogonia through formed sperm, takes approximately 64 days. A new cycle starts approximately every 16 days, although this timing is not synchronous across the seminiferous tubules. Sperm countsthe total number of sperm a man producesslowly decline after age 35, and some studies suggest that smoking can lower sperm counts irrespective of age. The process of spermatogenesis begins with mitosis of the diploid spermatogonia (Figure 27.5). Because these cells are diploid (2n), they each have a complete copy of the father's genetic material, or 46 chromosomes. However, mature gametes are haploid (1n), containing 23 chromosomesmeaning that daughter cells of spermatogonia must undergo a second cellular division through the process of meiosis. Choices: - 19 - 13 - 17 - 23 A:
23

Q: Hfcs are used as a replacement for what? Read this paragraph and choose the correct option from the provided answers: HFCs are used as a replacement for CFCs. The molecular structure of HFC134a is shown in this ball-and-stick model. Choices: - nitrofluorocarbons - pollutants - gases - cfcs A:
cfcs

Q: The plasma membrane pulls away from the cell wall as it shrivels. what is this process called? Read this paragraph and choose the correct option from the provided answers: A cell that does not have a rigid cell wall (such as a red blood cell), will swell and lyse (burst) when placed in a hypotonic solution. Cells with a cell wall will swell when placed in a hypotonic solution, but once the cell is turgid (firm), the tough cell wall prevents any more water from entering the cell. When placed in a hypertonic solution, a cell without a cell wall will lose water to the environment, shrivel, and probably die. In a hypertonic solution, a cell with a cell wall will lose water too. The plasma membrane pulls away from the cell wall as it shrivels, a process called plasmolysis. Animal cells tend to do best in an isotonic environment, plant cells tend to do best in a hypotonic environment. This is demonstrated in Figure below . Choices: - sporozoans - fluctuations - osmosis - plasmolysis A:
plasmolysis