CLEP Biology Study Guide

A ring of bark, including the layer just beneath it, is removed all the way around a young tree's trunk. The wood in the center is left intact. Over the following months, what is the most likely outcome?

• AThe roots slowly starve because sugars made in the leaves can no longer travel down through the phloem
• BThe stomata close permanently because the guard cells lose contact with the roots
• CThe tree grows taller because auxin from the stem tip is trapped above the ring
• DThe tree continues unharmed because phloem is found only in the center of the trunk
• EThe leaves wilt within hours because water can no longer travel up through the removed tissue

A lake stays much cooler than the surrounding land through a hot afternoon. Which property of water best explains this?

• AIts ability to dissolve salts, which cools the lake
• BIts density, because water is heavier than air at the same temperature
• CIts polarity, because the slightly charged ends of its molecules attract heat away from the surrounding air
• DIts cohesion, because molecules cling together at the lake surface
• EIts high specific heat, because hydrogen bonds absorb heat before molecules speed up

In a population at Hardy-Weinberg equilibrium, 16% of individuals show a recessive trait. What percentage of the population are heterozygous carriers?

• A24%
• B40%
• C32%
• D48%
• E60%

On a hot, dry, windy afternoon a plant's guard cells lose water and its stomata close. Which result follows directly?

• ATranspiration pulls water upward faster through the xylem vessels
• BWater loss rises because the leaf is no longer cooled by evaporation
• CWater loss falls, but carbon dioxide uptake also falls
• DSugar export through the phloem speeds up in the leaves at once
• EOxygen can no longer be made by the light reactions at all

In a cell, the final product of a pathway accumulates, and the first enzyme of that pathway slows down. Which mechanism is this?

• AInduced fit of the first substrate
• BFeedback inhibition
• CCompetitive inhibition by the substrate
• DDenaturation of every enzyme in the pathway
• EActivation by a coenzyme

A field's producers capture 20,000 kJ of energy. If about 10% of the energy passes to each higher trophic level, how much reaches the tertiary consumers?

• A2 kJ
• B10,000 kJ
• C20 kJ
• D2,000 kJ
• E200 kJ

A short-day plant normally flowers when the night lasts longer than about 10 hours. A grower gives a plant 14 hours of darkness but turns on a lamp for five minutes in the middle of the dark period. What is most likely?

• AThe plant flowers early because the extra light adds to total daylight length
• BThe plant makes more auxin and bends toward the lamp
• CThe plant flowers only if the lamp gives off red light at that hour
• DThe plant fails to flower, since the broken night acts as two short nights
• EThe plant flowers normally because 14 hours of darkness is still more than 10

A pancreatic cell makes a digestive enzyme that it exports. Which sequence follows the enzyme's path?

• ANucleus, then mitochondrion, then ribosome
• BRough ER, then Golgi apparatus, then secretory vesicle
• CGolgi apparatus, then ribosome, then secretory vesicle
• DLysosome, then nucleus, then cell membrane
• ESmooth ER, then lysosome, then ribosome

After a severe storm, most sparrows with medium-length wings survived, while those with very short or very long wings mostly died. Which process does this show?

• AStabilizing selection
• BDirectional selection
• CDisruptive selection
• DGene flow
• EGenetic drift

A seedling is laid on its side in the dark. Within a day, the stem tip curves upward. Which explanation fits?

• ACells on the upper side lose water by transpiration and shrink in size
• BPhototropism bends the stem toward the nearest light source in the room
• CGibberellin stops working on the lower side, so those cells stop growing completely
• DAuxin collects on the upper side, making those cells elongate more than the lower ones
• EAuxin collects on the lower side, so those cells elongate more