Daily Practice Questions

6 questions across multiple subjects, with detailed explanations and study tips.

📝 Questions

🧬 AP Biology Easy
A repressible operon in bacteria codes for the genes required to produce the amino acid serine. Serine functions as a corepressor for the operon. If serine is present in the bacteria’s environment, which of the following is most likely?
  1. A. increased digestion of serine
  2. B. increase in the levels of serine
  3. C. increased production of the repressor protein
  4. D. increased binding of the repressor protein to the operator ✓
Explanation: In a repressible operon, the end product of the pathway (serine) acts as a corepressor that binds to an inactive repressor protein, activating it so it can attach to the operator and block transcription. Therefore, when serine levels are high, more active repressor-corepressor complexes form, leading to increased binding to the operator and shutting down further synthesis. This negative feedback loop prevents the bacteria from wasting energy producing amino acids they already have in abundance.
🧪 AP Chemistry Medium
All the bases in the diagram behave as Brønsted–Lowry bases in the same way; in each case, they accept a hydrogen ion to the same atom. How is this acceptance of a hydrogen ion accomplished?
  1. A. A hydrogen ion attaches to the lone pair on the nitrogen atom. ✓
  2. B. The hydroxide ion reacts with the hydrogen ion to form water.
  3. C. The hydrogen ion forms a hydrogen bond to the base.
  4. D. The hydrogen ion combines with a hydrogen atom from the base to form H _{2} gas.
Explanation: A —As in ammonia, all these compounds behave as Brønsted–Lowry bases by accepting a hydrogen ion. The reaction involves the hydrogen ion attaching to the lone pair on the nitrogen atoms. The stem says “they accept a hydrogen ion to the same atom,” and only hydroxylamine contains oxygen; therefore, any answer focusing on O cannot be correct.
📝 ACT Prep Hard
Which of the following best represents a general trend associated with mammalian evolution?
  1. A. Enhancement of bodily movement from right to left and left to right
  2. B. Minimization of muscle groups oriented lateral to the vertebral column ✓
  3. C. The development of propulsive fins from paired limbs
  4. D. Secondary return to the sea
Explanation: The correct answer is (B) because mammalian evolution involved a shift toward efficient terrestrial locomotion, which favored minimizing lateral muscle mass in favor of muscles oriented along the long axis of the vertebral column to facilitate forward propulsion. This anatomical trend distinguishes mammals from many other vertebrates that rely more heavily on lateral undulation for movement. Choice (A) describes lateral undulation typical of aquatic animals, while choice (C) refers to a transition seen in fish-to-tetrapod evolution rather than the specific trend within mammals, and choice (D) is not a general trend but a specific evolutionary event like that of cetaceans.
📖 SAT Reading & Writing Medium
Which finding, if true, would most directly support the physicians’ claim? “On the Firing Line of Education” is a 1919 paper by A.J. Ladd, a professor of education at the State University of North Dakota. In the paper, Professor Ladd discusses the future of vocational education in American high schools. He asserts that schools should help guide students into their most appropriate vocational paths.
  1. A. Researchers find that they can successfully differentiate between broken-heart syndrome and a heart attack by determining whether plaque is blocking the arteries. ✓
  2. B. Sociologists report that increasing numbers of people are experiencing a decrease in their mental health due to prolonged stress.
  3. C. Psychiatrists find that there is a roughly equivalent likelihood of dying of broken-heart syndrome as there is from dying of a heart attack.
  4. D. A randomly controlled survey of adults between 50 and 70 years of age finds that heart attacks are a greater source of worry than broken-heart syndrome.
Explanation: If we examine the first sentence of the text, we see that broken-heart syndrome often looks like a heart attack with one key difference—there is no arterial blockage. That would mean that if we wished to tell the difference between the two, we could simply look for arterial blockage. If it were absent, we could conclude that the patient is suffering from broken-heart syndrome, not a heart attack. This makes choice (A) the best answer. The other choices do not directly relate to the claim as stated in the first sentence of the text.
⚛️ AP Physics C Medium
Given only the constant net force on an object and the object’s net displacement, which of the following quantities can be calculated?
  1. A. the net change in the object’s velocity
  2. B. the net change in the object’s mechanical energy
  3. C. the average acceleration
  4. D. the net change in the object’s kinetic energy ✓
  5. E. the net change in the object’s potential energy
Explanation: Because the force is constant, the work done by the force can be calculated according to the equation W = F · Δ r . The work done by the net force is always equal to the change in an object’s kinetic energy (according to the work-energy theorem). The change in velocity and the average acceleration depend on the object’s mass. The change in the object’s mechanical energy cannot be calculated without knowledge of whether the forces acting on the object are conservative or nonconservative.
📊 SAT Math Hard
18. Which age group’s ratio of action to romance is closest to the total’s ratio of action to romance?
  1. A. 15–24
  2. B. 25–34
  3. C. 35–44
  4. D. 45–54 ✓
Explanation: Getting to the Answer: The ratio of action to romance for the total sample is \frac{169}{79}, which is a bit greater than 2:1. The ratio for ages 15–24 is 65:20. For ages 25–34, the ratio is 49:27. The applicable ratio for ages 35–44 is 40:25. Finally, the ratio for ages 45–54 is 15:7. Eliminate (B) and (C) because they are much less than 2:1. (A) is greater than 3:1, and ( D ) is, like the overall ratio, just a bit more than 2:1, so that is the correct choice.

💡 Study Tips

📖 Take handwritten notes

Writing notes by hand (rather than typing) forces you to process and summarize information in your own words. This can help you build deeper conceptual understanding compared to passively copying text.

📖 Test yourself before you feel ready

Retrieval practice — actively trying to recall information without looking at your notes — is one of the most effective study techniques. Even getting answers wrong strengthens your memory more than re-reading.

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