during a healthy heartbeat the p wave on an ecg represents

ATI TEAS 7

TEAS 7 practice test science

1. During a healthy heartbeat, the P wave on an ECG represents

A. The repolarization of the ventricles.
B. The electrical conduction through the AV node.
C. The contraction phase of the ventricles (systole).
D. The depolarization of the atria.

Correct answer: D

Rationale: The P wave on an ECG represents the depolarization of the atria. This electrical activity initiates the contraction of the atria, allowing blood to be pumped into the ventricles. The P wave is the first positive deflection seen on the ECG and signifies the beginning of atrial depolarization, which is a critical step in the cardiac cycle. Choices A, B, and C are incorrect. Option A (The repolarization of the ventricles) is represented by the T wave on the ECG. Option B (The electrical conduction through the AV node) is not represented by the P wave but rather by the PR interval on the ECG. Option C (The contraction phase of the ventricles (systole)) is more related to the QRS complex on the ECG, which represents ventricular depolarization and contraction.

2. Which of the following correctly describes a strong acid?

A. A strong acid completely ionizes in water.
B. A strong acid donates more than one proton.
C. A strong acid contains at least one metal atom.
D. A strong acid will not decompose.

Correct answer: A

Rationale: The correct answer is A. A strong acid is defined as an acid that completely ionizes in water, meaning it dissociates fully into its constituent ions in solution. This characteristic differentiates strong acids from weak acids, which do not fully dissociate in water. Choice B is incorrect because the number of protons donated does not solely define the strength of an acid. Choice C is incorrect as strong acids are not defined by the presence of metal atoms, and Choice D is incorrect because all acids can decompose, but the strength of the acid is based on its ability to ionize in water.

3. Which of the following situations represents work being done on an object?

A. Pushing against a wall without moving it
B. Carrying a heavy object without lifting it
C. Lifting a box to place it on a shelf
D. Holding a book stationary in your hand

Correct answer: C

Rationale: Work is defined as the product of the force applied to an object and the distance over which the force is applied. In the situation of lifting a box to place it on a shelf, work is being done on the object. This is because lifting the box involves applying a force over a distance (the height of the shelf). The force applied to lift the box results in work being done on the object by raising it against the force of gravity. Choices A, B, and D do not involve work being done on the object as they either do not involve movement against a force (A, D) or do not cover distance against a force (B).

4. What breaks down into glucose to provide energy?

A. Lipids
B. Proteins
C. Carbohydrates
D. Nucleic acids

Correct answer: C

Rationale: Carbohydrates are broken down into glucose during digestion, providing energy for cellular processes through glycolysis and cellular respiration. Glucose is a primary source of energy for cells, and its breakdown is essential for powering various cellular activities. Lipids are broken down into fatty acids and glycerol, not glucose. Proteins are broken down into amino acids and are not a direct source of glucose. Nucleic acids are not broken down into glucose for energy production.

5. Which of the following substances can donate a hydroxide ion (OH-) in solution?

A. Salt
B. Base
C. Neutral compound
D. Dehydrating agent

Correct answer: B

Rationale: The correct answer is B: Base. A base is a substance that can donate hydroxide ions (OH-) in solution. Bases increase the concentration of hydroxide ions by either accepting protons (H+) or donating hydroxide ions. Salts are ionic compounds made of cations and anions, which do not directly donate hydroxide ions. Neutral compounds do not significantly affect the concentration of hydroxide ions. Dehydrating agents are substances that remove water molecules from other compounds, unrelated to donating hydroxide ions.