1. Which list contains only biotic factors?
A. winds, sunlight, fern, frog
B. soil, sunlight, frog, tree
C. frog, butterfly, fern, tree Correct
D. Soil, frog, butterfly, fern
Explanation
Biotic factors refer to the living components of an ecosystem, such as plants and animals. Choice C includes only living organisms: frog (animal), butterfly (animal), fern (plant), and tree (plant). The other choices include abiotic factors like winds, sunlight, and soil, which are non-living.
2. Scientists have been examining increased levels of carbon dioxide in the atmosphere and its effect on the growth of marine viruses, the growth of their bacterial hosts, the ocean's temperatures, and the circulation of ocean waters. Which factor being studied by the scientists is biotic?
A. Ocean temperature
B. Bacteria Correct
C. Ocean circulation
D. Carbon dioxide
Explanation
Biotic factors refer to living or once-living components of an ecosystem, such as organisms like bacteria and viruses. In contrast, ocean temperature, ocean circulation, and carbon dioxide are abiotic factors, as they are non-living physical or chemical elements influencing the environment.
3. A population of Pseudomonas aeruginosa is exposed to successive, short rounds of ampicillin and chloramphenicol. What will happen to the population?
A. The population will become resistant to chloramphenicol. Correct
B. The population will die.
C. The population will become resistant to ampicillin and chloramphenicol.
D. The population will become resistant to ampicillin.
Explanation
Assuming the population is exposed to chloramphenicol, natural selection will favor individuals with resistance to chloramphenicol, leading to a population resistant to it over time. Without context of ampicillin exposure, resistance to it isn't implied.
4. Climate change is affecting the chemistry of the world's oceans. In particular, the ocean water is becoming more acidic. For purple sea urchins, this poses problems as their calcium-based exoskeletons may dissolve in acidic conditions. In a certain population of purple sea urchins, some individuals possess a trait that makes their exterior more resistant to acid. If global climate change continues (as predicted) to make ocean water more acidic, how might this population of purple sea urchins evolve in response to this increased acidification?
A. Purple sea urchins with a trait that make their exoskeletons less resistant to dissolving in acidic water would become more common.
B. Purple sea urchins with a trait that make their exoskeletons resistant to dissolving in acidic water would become more common. Correct
C. Purple sea urchins with a trait of having longer, more rigid spines would become more common.
D. Purple sea urchins with a trait of having shorter, more flexible spines would become more common.
Explanation
Through natural selection, traits that improve survival in acidic waters, such as exoskeletons resistant to dissolution, will become more prevalent in the population as less resistant individuals are less likely to survive and reproduce.
5. What evolutionary mechanism would explain the increased frequency of male birds with narrow, elongated tail feathers within this population?
A. Gene flow
B. Sexual selection Correct
C. Genetic drift
D. Artificial selection
Explanation
Sexual selection occurs when certain traits increase an individual's chances of mating. Narrow, elongated tail feathers likely attract mates, leading to higher reproductive success and increased frequency of the trait.