Freshwater fish lose water by osmosis
a. true
b. false
b. false
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The unique feature of HeLa cells that make them important for research is that they are
a. identical to all other human cells. b. immortal cells and will grow in culture. c. limited in growth cycles. d. identical to stem cells. e. cannot propagate.
What are homologous chromosomes?
A) chromosome that almost always contain identical alleles B) chromosomes that generally contain the same genes C) chromosomes that are inherited together because they don't separate during meiosis D) chromosomes that are fewer in body cells than in gametes
Which of the following is generally accepted as the origin of living organisms?
a. Life was seeded on Earth from some distant place by meteorites and comets crashing into Earth. b. Spontaneous generation c. Life originated from an oxygen-rich atmosphere on Earth. d. Life can originate from nonliving matter. e. Prebiotic chemical evolution gave rise to progressively more complex molecules and eventually to living organisms
Consider the reaction X->Y in a cell at 37°C. At equilibrium, the concentrations of X and Y are 50 ?M and 5 ?M, respectively. Use this information and the equations below to answer questions A–E
?G° = –0.616 ln Keq ?G = ?G° + 0. 616 ln [Y]/[X] Recall that the natural log of a number z will have a negative value when z< 1, positive when z> 1, and 0 when z = 1. A. What is the value of Keq for this reaction? B. Is the standard free-energy change of this reaction positive or negative? Is the reaction X->Y an energetically favorable or unfavorable reaction under standard conditions? C. What is the value of the standard free energy? Refer to Table 3–1 in the textbook or use a calculator. D. Imagine circumstances in which the concentration of X is 1000 ?M and that of Y is 1 ?M. Is conversion of X to Y favorable? Will it happen quickly? E. Imagine starting conditions in which the reaction X->Y is unfavorable, yet the cell needs to produce more Y. Describe two ways in which this may be accomplished.