1. The microscopic units responsible for muscle contraction are called

A. Neurons
B. Myofibrils
C. Tendons
D. Sarcomeres

Correct answer: D

Rationale: The correct answer is D: Sarcomeres. Sarcomeres are the fundamental contractile units of skeletal muscle. They are composed of overlapping actin and myosin filaments that slide past each other during muscle contraction, resulting in muscle shortening. Neurons (A) are nerve cells that transmit signals to and from the brain. Myofibrils (B) are thread-like structures within muscle fibers that contain sarcomeres. Tendons (C) are fibrous connective tissues that attach muscles to bones, but they are not directly involved in muscle contraction like sarcomeres are.

2. What is the milky-white fluid transported by the lymphatic vessels called?

A. Plasma
B. Blood
C. Chyle
D. Mucus

Correct answer: C

Rationale: The milky-white fluid transported by the lymphatic vessels is called 'Chyle.' Chyle is formed in the small intestine during the absorption of fats. It primarily consists of lymph and emulsified fats. Plasma refers to the liquid component of blood, while blood carries red blood cells, white blood cells, platelets, and plasma. Mucus is a slimy substance produced by mucous membranes. Therefore, option C, 'Chyle,' is the correct answer in this context.

3. What is the scientific term for the monthly cycle in females that prepares the body for potential pregnancy?

A. Ovulation cycle
B. Menstrual cycle
C. Implantation cycle
D. Gestation cycle

Correct answer: B

Rationale: The correct answer is B: 'Menstrual cycle.' The menstrual cycle is the scientific term for the monthly process in females that prepares the body for potential pregnancy. During this cycle, the lining of the uterus thickens to prepare for a fertilized egg, and if no fertilization occurs, the uterus sheds this lining in the form of menstrual bleeding. Ovulation cycle refers specifically to the release of an egg from the ovary, implantation cycle is the process of a fertilized egg attaching to the uterine wall, and gestation cycle is the period of pregnancy from conception to birth. Therefore, the menstrual cycle is the most appropriate term for the monthly process described in the question.

4. What term describes the maximum displacement of particles from their rest position in a wave?

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

Correct answer: C

Rationale: The term that describes the maximum displacement of particles from their rest position in a wave is called the amplitude. Amplitude is a measure of the strength or intensity of a wave and is represented by the height of the wave from the rest position to the crest (or trough) of the wave. Frequency (A) refers to the number of complete wavelengths that pass a point in a given time, wavelength (B) is the distance between two consecutive crests (or troughs) of a wave, and velocity (D) is the speed of the wave.

5. Which part of the heart generates 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 correct answer is D, ventricular muscle cells. The QRS complex on an ECG represents the depolarization of the ventricles. This electrical activity is generated by the spread of impulses through the bundle branches and Purkinje fibers to the ventricular muscle cells. The SA node (option A) is responsible for initiating the electrical impulse in the heart, but it does not directly generate the QRS complex. The AV node (option B) delays the impulse to allow for proper coordination of atrial and ventricular contractions. The Bundle of His (option C) and its branches facilitate the conduction of the electrical signal from the AV node to the ventricles but do not generate the QRS complex directly.