AP Biology Exam Prep FREE Sample Exam — Fixed Set

A solution has [H+] = 1.0 x 10^-3 M (pH 3). A student dilutes it 100-fold with pure water, so [H+] falls 100-fold. What is the pH of the diluted solution?

pH 1, because dilution concentrates the acid

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pH 3, because dilution does not change pH

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pH 5, because [H+] is now 1.0 x 10^-5 M

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pH 13, because the solution is now basic

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A solution has pH 11. Using pH + pOH = 14 and [OH-] = 10^-pOH, what is its hydroxide ion concentration?

1.0 x 10^-11 M

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1.0 x 10^-14 M

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1.0 x 10^-3 M

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3 M

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How much does the temperature of 100 g of water rise when it absorbs 4,180 J? Use q = mc(delta T) with c = 4.18 J/g per degree C for water.

10 degrees C

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1.0 degree C

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0.10 degree C

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41.8 degrees C

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For a sphere, SA = 4 pi r^2 and V = (4/3) pi r^3, so SA/V = 3/r (formulas given). Compare a spherical cell of radius 1 micrometer with one of radius 3 micrometers. What are their SA/V ratios, and which exchanges materials more effectively per unit volume?

Both are 3 per micrometer, so they exchange equally

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Radius 1: 1 per micrometer; radius 3: 3 per micrometer; the larger cell exchanges better

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Radius 1: 3 per micrometer; radius 3: 1 per micrometer; the smaller cell exchanges better

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Radius 1: 9 per micrometer; radius 3: 3 per micrometer; the smaller cell exchanges better

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A rod-shaped cell is modeled as a cylinder of radius 1 micrometer and length 8 micrometers, ignoring the end caps. For a cylinder’s side, SA = 2 pi r h and V = pi r^2 h (formulas given). What is its approximate SA/V ratio?

8 per micrometer

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0.25 per micrometer

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4 per micrometer

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2 per micrometer

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A flattened cell is modeled as a box 10 x 10 x 1 micrometers. Its surface area is 2(10×10) + 4(10×1) = 240 square micrometers and its volume is 100 cubic micrometers (values given). A cube with the same volume of 100 cubic micrometers has a surface area of about 129 square micrometers. What does the comparison show?

Flattening raises SA/V from about 1.29 to 2.4 per micrometer, improving exchange without changing volume

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Flattening lowers SA/V, which is why flat cells exchange poorly

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Shape has no effect on SA/V at constant volume

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The cube must have the larger surface area because cubes are compact

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A solution of 0.20 M NaCl is held at 20 C (293 K). NaCl dissociates completely (i = 2). Using Psi_s = -iCRT with R = 0.0831 L bars/(mol K), the solute potential is closest to:

-4.9 bars

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-19.5 bars

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-0.97 bars

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-9.7 bars

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A cell is modeled as a long cylinder of radius 1 unit and length 10 units. Total surface area = 2 pi r (r + h) = 22 pi (about 69.1) and volume = pi r^2 h = 10 pi (about 31.4). Its SA:V ratio is closest to:

0.45 to 1

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2.2 to 1

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10 to 1

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1.0 to 1

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Cells take up substance X. Uptake rises with external concentration but levels off at high concentrations, and it falls nearly to zero when ATP synthesis is poisoned, even though the concentration gradient still favors entry. Substance X most likely enters by:

Simple diffusion through the bilayer

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Facilitated diffusion through a channel

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Osmosis through aquaporins

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Primary active transport through a carrier pump

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A Lineweaver-Burk plot (1/v versus 1/[S]) for an enzyme has a y-intercept of 0.02 min/micromol. Since the y-intercept equals 1/Vmax, the enzyme’s Vmax is:

0.02 micromol/min

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50 micromol/min

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20 micromol/min

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500 micromol/min

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A cellular process requires +13.0 kcal/mol. Each ATP hydrolysis releases 7.3 kcal/mol under the stated conditions. Coupling the process to two ATP hydrolyses gives a net delta G of:

+5.7 kcal/mol

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-14.6 kcal/mol

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-1.6 kcal/mol, so the coupled process is exergonic

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+27.6 kcal/mol

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On a pigment chromatogram, the solvent front traveled 7.0 cm from the origin and a pigment band traveled 4.2 cm. The Rf value of the pigment is:

0.60

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1.67

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0.42

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0.70

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AP Biology Exam Prep FREE Sample Exam — Fixed Set

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