which part of the heart generates the qrs complex on an ecg

ATI TEAS 7

TEAS 7 science practice

1. Which part of the heart is responsible for generating the QRS complex on an ECG?

A. Sinoatrial node (SA node)
B. Atrioventricular node (AV node)
C. Bundle of His
D. Ventricular muscle cells

Correct answer: D

Rationale: The QRS complex on an ECG represents ventricular depolarization. This electrical activity is generated by the ventricular muscle cells. While the SA node generates the P wave, the AV node delays the impulse, and the Bundle of His and Purkinje fibers assist in rapidly conducting the impulse through the ventricles, it is the ventricular muscle cells that specifically create the QRS complex. Therefore, choice D, Ventricular muscle cells, is the correct answer. Choices A, B, and C are incorrect as they are primarily involved in initiating and coordinating the electrical impulses in the heart but do not directly generate the QRS complex on an ECG.

2. What is the process by which simple cells become highly specialized cells?

A. Cellular complication
B. Cellular specialization
C. Cellular differentiation
D. Cellular modification

Correct answer: C

Rationale: The correct answer is 'Cellular differentiation'. Cellular differentiation is the process by which simple cells become highly specialized cells. During cellular differentiation, cells acquire specific structures and functions that allow them to perform particular roles within an organism. This process involves the activation and silencing of specific genes, leading to the development of various cell types with distinct characteristics and functions. 'Cellular complication' (Choice A) is incorrect as it does not describe the specific process of cells becoming specialized. 'Cellular specialization' (Choice B) is not the most precise term for the process, as it does not capture the transformation from simple cells to specialized cells. 'Cellular modification' (Choice D) is incorrect as it is a vague term that does not specifically refer to the process of cellular specialization.

3. During which phase of the cell cycle does DNA replication occur?

A. Interphase
B. Mitosis
C. Meiosis
D. Cytokinesis

Correct answer: A

Rationale: Interphase is the phase of the cell cycle where the cell spends the majority of its time and is characterized by three subphases: G1 (Gap 1), S (Synthesis), and G2 (Gap 2). DNA replication specifically occurs during the S phase of interphase. This is a crucial step as it ensures that each daughter cell produced during cell division receives an exact copy of the genetic material. Mitosis is responsible for the equal distribution of the replicated DNA to the daughter cells during cell division. Meiosis is a specialized cell division process for gamete production in sexually reproducing organisms, involving two rounds of division to generate haploid cells. Cytokinesis is the final step of the cell cycle, where the cytoplasm divides to complete the formation of two separate daughter cells following nuclear division.

4. The chemical equation below is unbalanced. When it is properly balanced, how many molecules of carbon dioxide (CO2) are produced for each molecule of propane (C3H8) in the reaction? 3C3H8 + 5O2 → 3CO2 + 4H2O

A. One Half.
B. Two.
C. Three.
D. Five.

Correct answer: B

Rationale: The balanced chemical equation for the combustion of propane is: 3C3H8 + 5O2 → 3CO2 + 4H2O. This equation shows that for every 3 molecules of propane (C3H8) consumed, 3 molecules of carbon dioxide (CO2) are produced. Therefore, when properly balanced, 3CO2 are produced for each molecule of propane used. Thus, the correct answer is B: Two. Choices A, C, and D are incorrect because they do not reflect the correct stoichiometry as determined by the balanced equation.

5. Which property of a wave is measured in Hertz (Hz)?

A. Amplitude
B. Wavelength
C. Speed
D. Frequency

Correct answer: D

Rationale: Frequency is the property of a wave that is measured in Hertz (Hz). It represents the number of complete cycles of the wave that occur in one second. Amplitude refers to the height of the wave, wavelength is the distance between two consecutive points on a wave that are in phase, and speed is the rate at which the wave travels through a medium. Therefore, the correct answer is frequency as it directly corresponds to the unit Hertz (Hz) used to measure the number of wave cycles per second.