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
Positive feedback mechanisms move conditions away from the normal state.
They amplify the original action and produce more of the same effect.
For example, blood clotting and childbirth are positive feedback mechanisms.
Choice A is wrong because positive feedback mechanisms usually produce unstable conditions.
They do not resist change but rather enhance it.
Choice B is wrong because positive feedback mechanisms do not cause long-term changes.
They are ultimately stopped by negative feedback loops once the process they were used for is complete.
Choice D is wrong because positive feedback mechanisms do not bring conditions back to the normal state.
That is the role of negative feedback mechanisms, which oppose the stimulus and restore homeostasis.
Correct Answer is B
Explanation
B cells are a type of lymphocyte that originate from the bone marrow and are involved in humoral immunity.
When they encounter a foreign substance (antigen), they differentiate into plasma cells, which secrete antibodies.
Antibodies are proteins that bind to the antigen and neutralize it.
Choice A is wrong because megakaryocytes are large cells that produce platelets, not antibodies.
Choice C is wrong because antibodies are not cells, but products of plasma cells.
Choice D is wrong because T cells are another type of lymphocyte that originate from the thymus and are involved in cell-mediated immunity, not antibody production.
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