Ready to give it a shot? Dive into the 10 question quiz below to get a feel for how prepared you are! Once you’ve written down your answers, hover over (or tap on a phone) the question to see the answers and explanations.
WarningPlease do keep in mind that we can’t guarantee the accuracy of this quiz, so we do recommend you also run through a full-length practice exam. The CollegeBoard offers a good one that we’ll share in the resources section below.
1: Why is a single nucleotide substitution of uracil for thymine in the coding region of a DNA strand likely to have little effect on the organism?
I. Both uracil and thymine nucleotides will pair with adenosine
II. The genetic code is redundant
III. Single nucleotide substitutions rarely have much effect
IV. The substitution is likely to be detected and repaired because DNA does not ordinarily contain uracil.
a) I only
b) III only
c) I and IV
d) II and IV
DNA contains four different nucleotide bases: adenine, thymine, guanine, and cytosine, or A, T, G, C. Adenine pairs with thymine, and guanine pairs with cytosine. Uracil is a nucleotide ordinarily found only in RNA, where it takes the place of thymine and, like thymine, pairs with adenosine. So, “I” is correct: both the original and the mutated DNA will function to produce the same messenger RNA—but is it the best answer? The genetic code IS redundant (II), meaning that there is more than one way to code for many of the amino acids in the proteins that will be constructed according to the DNA’s code, but this has nothing to do with this particular mutation. Single nucleotide substitutions CAN have quite a large effect, so “III” is incorrect. (Try having sickle cell anemia, for example!) But what about “IV,” the substitution will be repaired? It probably will be fixed, because as mentioned earlier, DNA doesn’t have uracil, and there are mechanisms in place to remove and replace uracil when detected. So the best answer is “c,” I and IV. Probably the substitution will be repaired, but if it isn’t, it’s not going to change the messenger RNA that the DNA produces.
2: When glucose molecules are metabolized in an aerobic cell, the energy is used to produce ATP in a series of biochemical steps. Place these events in the correct sequence:
I. Pyruvate is converted to Acetyl Coenzyme A
II. In the mitochondrion, electron carriers donate electrons to the electron transport chain to produce a proton gradient.
III. A molecule enters the citric acid cycle, or Krebs cycle, leading to the production of 3 NADH, 1 FADH2, and 1 ATP
IV. During glycolysis, a molecule is cleaved into two parts, producing 2 NADH and 2 ATP molecules
V. ATP synthase admits protons into the interior matrix of the mitochondrion, producing up to 34 ATP.
a) IV, I, III, II, V
b) II, I, III, IV, V
c) IV, III, I, II, V
d) II, III, I, V, IV
During glycolysis, a glucose molecule is split in two (IV), producing two molecules of pyruvate. The pyruvate is converted to Acetyl Coenzyme A (I), which enters the citric acid cycle in the mitochondrion, where electron carriers NADH and FADH2 are produced (III). These electron carriers donate their electrons to the electron transport chain to produce a proton, or H+, gradient across the inner membrane of the mitochondrion (II). ATP synthase lets these protons back into the inner chamber of the mitochondrion, producing ATP (V). This is glycolysis and cellular respiration in a nutshell. If you’ve forgotten them, you’ll need to buck up and study, but try to keep track of this “nutshell” view as a framework, so you don’t get lost. (And if you haven’t forgotten them, we’re really impressed!)
3: Which cellular organelles are likely to be more prevalent in a cell that produces steroid hormones?
c) Rough endoplasmic reticulum
d) Smooth endoplasmic reticulum
Smooth ER produces cellular products such as lipids and steroids. Rough ER makes proteins. Mitochondria produce ATP for energy, and lysosomes break down and recycle waste materials.
4: How is the endosperm of a flowering plant’s seeds produced?
a) The zygote splits in two. One of these cells produces the embryo, and the other makes the endosperm.
b) Two sperm travel down the pollen tube to the embryo sac. One fertilizes the egg, and the other fertilizes the two polar nuclei to produce triploid endosperm.
c) Two sperm travel down the pollen tube to the embryo sac. One fertilizes the egg, and the other fertilizes a polar nucleus to produce diploid endosperm.
d) The endosperm is produced entirely by the maternal cells, without the need for fertilization.
This kind of “double fertilization” is a defining characteristic of flowering plants.
5: Which is the product of anaerobic respiration in humans?
a) Carbon dioxide only
b) Carbon dioxide and ethanol
c) Lactic acid
d) Humans can’t perform anaerobic respiration.
When humans perform vigorous exercise, such as sprinting, the muscles may require more oxygen than the lungs and circulatory system can immediately supply. Usually, glucose is broken down into carbon dioxide and water, but this process of aerobic respiration requires oxygen. If the oxygen is lacking, the glucose will be converted into lactic acid temporarily. Oxygen will still be needed later to break down the lactic acid. That’s why a sprinter may be gasping for air for a while after reaching the finish line. They’re making up their “oxygen debt.” If only student loans were that easy to pay off!
6: In the above graph, the Y axis represents enzyme activity. Based on the graph, which is the optimum temperature for the peroxidase enzyme?
a) 25 °C
b) 32 °C
c) 40 °C
d) 100 °C
7: To produce the above graph, students recorded the enzyme activity at several pre-determined temperatures. In the laboratory exercise, which was the role of temperature?
a) The control
b) An independent variable
c) A dependent variable
d) An uncontrolled variable
Independent variables are controlled or determined by the experimenter, in order to figure out what their effects on the dependent variable might be. The dependent variable is what’s being affected by the experimental treatments. It’s recorded during the course of the experiment. Enzyme activity was the dependent variable in this experiment. The control is an experimental treatment used for comparison. A test tube without any enzyme in it might serve as the control. You really don’t want to have any uncontrolled variables in your experiment, because they’ll cause experimental error. If a student accidentally put more enzyme in one test tube than in another, that would make “enzyme concentration” an uncontrolled variable and mess up the results.
8: Runoff from a farm washes fertilizer into a pond, resulting in increased algal growth, reduced oxygen, and eventually death of the fish. This sequence of events is best described as which process?
b) Primary succession
Eutrophication can happen naturally but is often accelerated and more severe due to human activities. Eutrophic lakes can sometimes disappear entirely, becoming filled in by the sediments from dead organisms and bacteria.
9: Bats, whales, dogs, and humans all have a long bone in their front limbs attached to two parallel bones at a joint. Anatomical structures such as these are said to be:
a) Fulfilling the same function
Homologous structures are thought to be evidence of evolution because the same basic body plan appears to have been adapted over time to perform different functions. Vestigial structures are homologous structures that have lost their use, such as the tiny vestigial tailbone in humans. Analogous structures perform the same functions, but aren’t actually related. The wing of a butterfly and the wing of the bird are examples of analogous structures.
10: Human babies with a low birth weight and those with a high birth weight are less likely to survive than those with an average birth weight. This is an example which process?
Stabilizing selection favors intermediate traits and tends to cause traits to cluster more tightly around an optimum value. Directional selection causes traits to become more extreme in a favored direction. For example, if the fastest cheetah gets more prey and so is more likely to survive, then there is selective pressure for cheetahs to get faster and faster. Disruptive, or diversifying, selection favors a lot of variation. The human immune system is under disruptive selection, because the more variation we have in our receptors to recognize invading pathogens, the better.
More CLEP Study Resources
Looking for a study guide to fill a couple gaps, or just want a full length practice exam? You can find a few of my favorite resources below. Note that some of the links are affiliate – meaning I’ll make a few dollars if you purchase, but I’m only sharing resources that were genuinely helpful during my own CLEP journey.
Official CLEP Study Guide: It’s quite short on the study side of things, but this is the go-to practice test bank. I don’t think I’ve done a single CLEP test without taking the practice test in this book first.
REA CLEP Biology: I’m not huge on reading, but this book series is fantastic if you’re into that kind of thing. It also includes some nifty online practice tests, though I always found the official practice tests more reassuring.
InstantCert Academy: The website looks like it was made before the internet, but it’s legitimately the single most useful study guide I’ve found. Basically it’s a series of flashcards that help you learn about US History I in a fast paced and fun way.
Plenty of other resources exist – just do a quick internet search – but these are the three that I’ve personally found the most helpful back when I did CLEP.