In all organisms, the basic unit of structure and function is:
The cell.
The molecule.
The atom.
The macromolecule.
The Correct Answer is A
The cell is the basic unit of structure and function of all known living organisms.
The cell theory states that all living things are composed of cells and that new cells are made from preexisting cells.
Cells are organized from atoms, molecules, and macromolecules, and contain organelles that perform specialized functions.
Choice B is wrong because a molecule is a group of atoms bonded together, not a living unit.
Choice C is wrong because an atom is the smallest unit of matter, not a living unit.
Choice D is wrong because a macromolecule is a large molecule composed of smaller molecules, not a living unit.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
This sequence ensures that the atria contract before the ventricles and that the ventricles contract from the bottom up.
Choice A is wrong because it reverses the order of the SA node and the AV node. The SA node is the pacemaker of the heart and initiates the cardiac impulses.
Choice B is wrong because it places the Purkinje fibers before the AV node.
The Purkinje fibers are the last part of the conduction system and stimulate the ventricular muscle fibers.
Choice D is wrong because it reverses the order of the entire sequence.
The AV node is not the pacemaker of the heart and does not initiate cardiac impulses.
Correct Answer is C
Explanation
The endocrine system may have a longer-lasting effect than the nervous system because the hormones it produces can circulate in the bloodstream for a long time and affect many organs and tissues.
The nervous system, on the other hand, uses nerve impulses and neurotransmitters for communication, which are faster but more short-lived.
Choice A is wrong because the endocrine system is essential to life.
It regulates many vital functions such as metabolism, growth, reproduction, mood, sleep, and blood pressure.
Choice B is wrong because the endocrine system takes longer than the nervous system to deliver its messages.
The hormones have to travel through the bloodstream to reach their target cells, while the nerve impulses can travel along the nerve fibers at high speeds.
Choice D is wrong because the endocrine system does use receptors.
The hormones bind to specific receptors on the target cells to trigger a response.
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