Which of the following lists best illustrates the idea of increasing levels of complexity?
Organs, organelles, organ systems, cells, tissues.
Cells, tissues, organelles, organs, organ systems.
Organelles, cells, tissues, organs, organ systems.
Tissues, cells, organs, organelles, organ systems.
The Correct Answer is C

This list best illustrates the idea of increasing levels of complexity because it follows the biological hierarchy of organization from the simplest to the most complex units of matter.
Each level is composed of units from the previous level and has emergent properties that are not present in the lower levels.
Choice A is wrong because it reverses the order of organelles and cells. Organelles are subcellular structures that perform specific functions within cells.
Cells are the basic units of life that can carry out all the processes of living organisms.
Choice B is wrong because it reverses the order of tissues and organelles. Tissues are groups of similar cells that work together to perform a common function. Organelles are more basic than tissues and are found within cells.
Choice D is wrong because it reverses the order of organs and organelles.
Organs are structures composed of two or more types of tissues that perform a specific function or function.
Organelles are more basic than organs and are found within cells.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
The right atrium receives blood directly from the superior vena cava, inferior vena cava, and coronary sinus.

The superior vena cava and inferior vena cava bring deoxygenated blood from the upper and lower body, respectively.
The coronary sinus brings blood from the heart muscle.
Choice B is wrong because it excludes the coronary sinus, which also empties into the right atrium.
Choice C is wrong because it includes the pulmonary veins, which carry oxygenated blood from the lungs to the left atrium, not the right atrium.
Choice D is wrong because it only includes the pulmonary veins, which are not connected to the right atrium at all.
Correct Answer is C
Explanation

The sinoatrial (SA) node is the natural pacemaker of the heart.
It generates electrical impulses that cause the heart’s chambers to contract, setting the heart rate.
The SA node typically generates 60–100 heartbeats per minute when a person is at rest.
Choice A is wrong because Purkinje fibers are part of the electrical conduction system of the heart that carries impulses to the ventricles.
They are not the primary source of impulses.
Choice B is wrong because the AV bundle (also called bundle of His) is another part of the electrical conduction system of the heart that connects the atria and the ventricles.
It is not the natural pacemaker of the heart.
Choice D is wrong because an atrioventricular node is a relay station between the atria and the ventricles that delays the electrical impulses from the SA node.
It can act as a backup pacemaker if the SA node fails, but it is not the normal pacemaker of the heart.
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