What causes lymphedema, a chronic condition, to occur?

Correct Answer: B

Rationale: Lymphedema is a chronic condition that occurs when lymph vessels become blocked, leading to swelling and fluid retention in the affected area. Inflammation of lymph nodes, spleen malfunction, or decreased bone marrow production are not directly associated with the development of lymphedema. Lymph vessels play a crucial role in carrying lymphatic fluid, and when they are blocked, it disrupts the normal flow of fluid, resulting in lymphedema. Therefore, the correct answer is that lymphedema occurs when lymph vessels become blocked.

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.

Correct Answer: A

Rationale: The stratum corneum, the outermost layer of the epidermis, is primarily composed of keratinized dead cells. These cells are flattened, fully keratinized, and lack nuclei, serving a protective function for the skin. Melanocytes are responsible for producing melanin, providing skin pigmentation. Langerhans cells are involved in the immune response within the skin. Merkel cells are associated with sensory functions in the skin, particularly in touch sensations. Therefore, the correct answer is A as it accurately reflects the main constituent of the stratum corneum, which acts as a barrier against external factors.

Correct Answer: A

Rationale: The correct answer is A: Head, neck, and trunk. The axial skeleton comprises bones located in the head, neck, and trunk region, such as the skull, vertebral column, and rib cage. These bones provide structural support and protect vital organs like the brain, spinal cord, and heart. Choices B and C are incorrect because arms, legs, hands, and feet are part of the appendicular skeleton, not the axial skeleton. The appendicular skeleton is responsible for movement, manipulation, and mobility, while the axial skeleton primarily provides central support and protection for essential organs.

Correct Answer: A

Rationale: The work done is calculated using the formula: Work = Force x Distance x cos(theta), where theta is the angle between the force and the direction of motion. In this case, the force and the direction of motion are in the same direction, so cos(theta) = 1. Therefore, Work = 20 N x 5 m x 1 = 100 Joules. Since the force and distance are given and are in the same direction, the work done can be directly calculated without needing to know the object's mass. Choice A, 100 Joules, is the correct answer as calculated. Choice B and C are incorrect as they do not correspond to the correct calculation. Choice D is incorrect because knowing the object's mass is not necessary to calculate work in this scenario, as work is dependent on force, distance, and the angle between them, not mass.