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Questions in biology

[Answered] 92. If a given enzyme works only at temperature range of 20 and 45 °C and the potential of hydrogen ions that ranges from 4 to 9. Which one of the following works best during the optimization of these two factors for the enzyme activity? A. The optimum pH under which this enzyme is most active is found below 4. B. Adjusting the temperature between 20°C and 45°C results little denaturation and increased number of collisions. C. Adjusting the pH above 9 can increase the probability of collisions between the enzyme and the substrate. D. Adjusting the temperature below 20°C makes the enzyme more active, hence the temperature at this value is optimal. 93. All of the following features define a chromosome EXCEPT A. functional unit of inheritance. B. made up of DNA and protein. C. exists in pairs in diploid organisms. D. contains hundreds to thousands of genes. 94. Which structural and functional difference is observed between DNA and RNA? A. DNA is very stable molecule while RNA is degraded quickly. B. RNA stores the genetic material while DNA involves in protein synthesis. C. RNA produces DNA through the process of transcription. D. Both DNA and RNA have the same nitrogenous bases but differ in pentose sugar. 95. All of the following events occur during telophase I of meiosis I cell division EXCEPT A. nuclear envelope reforms. B. set of chromosomes come together. C. each of the spindle fibers disappears. D. crossing over takes place.

[Answered] Which of the following is a statement about weather? A. The weather in Seattle tends to be rainy. B. The tropical rain forest has high annual precipitation. C. The forecast says the temperature will be 80°F tomorrow. D. The sky is overcast with clouds on average 200 days per year.

[Answered] Which of the following best explains why the diversity of organisms decreases as you move from shallow seas to deep oceans? A. The levels of oxygen in the deep ocean are too high for many organisms to thrive. B. The low temperatures of the deep ocean would freeze most organisms. C. The salinity of the deep ocean is too high for most organisms to live. D. The lack of sunlight in the deep ocean limits the types of organisms that can survive.

[Answered] A DNA molecule can be described as a twisted ladder. The ________ form the sides, and the ________ form the rungs. Select one: A. sugar-phosphate chains; base pairs B. base pairs; sugar-phosphate chains C. sugars; phosphates D. sugars; base pairs

[Answered] Organic macromolecules called _______ are insoluble in water, are often found in biological membranes and other waterproof coverings, and have the ability to store energy for extended periods of time. A. proteins B. lipids C. nucleic acids D. carbohydrates

[Answered] The walking catfish, or Clarias batrachus, is an invasive species that can migrate over land. Which of the following describes the most likely long-term consequence of the introduction of the walking catfish? A. The walking catfish will become unable to survive in its native territory as it continues to migrate. B. Dissolved oxygen levels will increase as more fish are able to breathe and survive above water. C. Native fish populations will decline and possibly become extinct as they compete for food and space. D. Larger fish will overpopulate due to the presence of an additional food source.

[Answered] In pea plants, the allele for tall plants is dominant to the allele for short plants. If a homozygous tall plant is crossed with a homozygous short plant, what percent of offspring would you expect to be short? A. 0 percent B. 25 percent C. 50 percent D. 100 percent

[Answered] Fossils in Precambrian rocks are rare, while there are many fossils in rocks from the Phanerozoic eon. What does this evidence suggest? A. There was a major change in the diversity of life in the Phanerozoic eon, probably due to mass extinction. B. There was no life in the Precambrian eon. C. The rocks from the Phanerozoic eon are much harder than those from the Precambrian eon. D. There was no change in the diversity of life in the Phanerozoic eon.

[Answered] Which of the following statements about the two strands of a DNA molecule is true? Select one: A. The strands are a pair of sister chromatids. B. The strands are connected to each other by sugar-phosphate bonds. C. A T base on one strand always pairs with an A base on the other strand. D. An A base on one strand always pairs with a G base on the other strand. E. The strands have identical base sequences.

[Answered] 1. What element has 81 protons in the nuclei of its atoms? A. Platinum B. Lead C. Thallium D. Uranium