A scanning electron microscope is used to study ________, whereas a transmission electron microscope is used to study ________
A) live cells; dead cells
B) cell surfaces; internal cell structures
C) dead cells; live cells
D) internal cell structures; cell surfaces
Answer: B
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Which phylum features segmented bodies and jointed appendages?
a. Arthropoda b. Nematoda c. Platyhelminthes d. Annelida
In the process of diffusion, molecules move from areas where
A. their concentration is higher to areas where their concentration is lower using energy from ATP. B. their concentration is lower to areas where their concentration is higher through specific protein channels or carriers. C. their concentration is lower to areas where their concentration is higher until an equilibrium is reached. D. their concentration is higher to areas where their concentration is lower until an equilibrium is reached.
Chemical equilibrium is relatively rare in living cells. An example of a reaction at chemical equilibrium in a cell would be _____
A) one in which the free energy at equilibrium is higher than the energy content at any point away from equilibrium B) one in which the entropy change in the reaction is just balanced by an opposite entropy change in the cell's surroundings C) an endergonic reaction in an active metabolic pathway where the energy for that reaction is supplied only by heat from the environment D) a chemical reaction in which both the reactants and products are not being produced or used in any active metabolic pathway at that time in the cell
For the lac operon in E. coli, under conditions in which glucose is absent and lactose is present, which of the following is true?
a. CRP and cAMP together are bound to the DNA, and LacI is bound to the operator site. b. The lac operon is not transcribed because lactose is present. c. CRP and cAMP together are bound to the DNA, and allolactose is bound to LacI. d. The lac operon is not transcribed due to catabolite repression because glucose is absent.