practice_book_biology

A primarily in the dorsal cells of the embryos b

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Unformatted text preview: all of the cells of the embryos (E) In few, if any, of the cells of the embryos GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this page is illegal. 59 Questions 193-195 In muscle cells, Ca2+ is actively transported into the sarcoplasmic reticulum. The membranes of the sarcoplasmic reticulum can be isolated in the form of microsomes. Each microsome contains several hundred molecules of an enzyme that uses ATP as an energy source to drive the inward transport of calcium ions that are added externally. In one experiment, the results shown below were obtained. Experimental conditions: 1.0 5 5 0.1 0.1 ml of 0.1 M KCl containing: mM MgCl2 mM ATP mM CaCl2 mg protein (ATPase) 195. The specific activity for the ATPase enzyme is expressed in units of (A) (B) (C) (D) (E) mole ATPase sec−1 mole ATP sec−1 mg protein−1 mole ADP sec−1 mole ADP sec−1 mg protein−1 mole ADP sec−1 mole ATPase−1 193. What is the rate of ATP hydrolysis, expressed as micromoles of ATP hydrolyzed per milligram of protein per minute? (A) (B) (C) (D) (E) 2 1 0.5 0.25 0.1 194. What is the ratio of calcium pumped per ATP hydrolyzed? (A) (B) (C) (D) (E) 1:4 1:2 1:1 2:1 4:1 GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this page is illegal. 60 Questions 196-198 A species of long-day plant (LDP) and a species of short-day plant (SDP), each having a critical photoperiod of 10 hours, were placed in growth chambers that provided identical environmental conditions, except for the length of the photoperiod. Individuals from each species were treated as indicated in the following table for a period of many weeks. 24-hour Cycle Hours of Light Hours of Darkness 8 16 16 8 16 8 16 8 Treatment 1 2 3 4 Plant Species LDP LDP SDP SDP A second experiment was conducted under identical conditions, except that halfway through the dark period the lights were switched on for one minute and then switched off. 196. In the initial experiment, for which of the following treatments would the plants be expected to flower? (A) (B) (C) (D) (E) 1 and 2 1 and 3 1 and 4 2 and 3 2 and 4 198. Which of the following wavelengths of light would be the most effective in interrupting the dark period in the second experiment? (A) (B) (C) (D) (E) 460 nm (blue) 520 nm (green) 580 nm (yellow) 660 nm (red) 730 nm (far-red) 197. In the second experiment, for which of the following treatments would the plants be expected to flower? (A) (B) (C) (D) (E) 1 and 2 1 and 3 1 and 4 2 and 3 2 and 4 GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this page is illegal. 61 Questions 199-200 The mussel Mytilus edulis thrives in saline habitats, in both the highly salty seawater of tidal zones and the less salty estuaries. This results in two kinds of populations: one adapted to the higher salt concentrations of the tidal zone, and one adapted to the lower salt concentrations of the estuary. It has been found that the more salt-tolerant populations have high frequencies of an allele that produces an enzyme involved in maintaining osmotic equilib...
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