Which of the following organic molecules contain both an amine and carboxyl group?
Lipids.
Chitin.
Cellulose.
Proteins
The Correct Answer is D
Proteins are made up of amino acids which are organic molecules that contain both an amine functional group (–NH2) and a carboxylic acid functional group (– COOH)1.
Choice A, Lipids, is not the correct answer because lipids are a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins, monoglycerides, diglycerides, triglycerides, phospholipids, and others.
They do not contain both an amine and carboxyl group.
Choice B, Chitin, is not the correct answer because chitin is a long-chain polymer of N-acetylglucosamine, a derivative of glucose.
It does not contain both an amine and carboxyl group.
Choice C, Cellulose, is not the correct answer because cellulose is an organic compound with the formula (C6H10O5)n, a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units.
It does not contain both an amine and carboxyl group.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Calcium ions play a crucial role in initiating muscle contraction.
When a muscle cell is stimulated to contract by an action potential, calcium channels open in the sarcoplasmic membrane and release calcium into the sarcoplasm.
Some of this calcium attaches to troponin, which causes it to change shape. This shape change exposes binding sites for myosin on the actin filaments.
Myosin’s binding to actin causes cross-bridge formation, and muscle contraction begins.
The other ions mentioned in the question do not have this specific role in muscle contraction.
Potassium ions are important for maintaining the resting membrane potential of cells, but they do not bind to the troponin complex.
Phosphorus ions are important for energy metabolism but do not bind to the troponin complex.
Sodium ions are important for generating action potentials but do not bind to the troponin complex.
Correct Answer is C
Explanation
Osmosis is the movement of water molecules across a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration.
In a hypertonic solution, the concentration of solutes outside the cell is higher than inside the cell, so water flows out of the cell through aquaporins embedded in the plasma membrane to balance the concentration gradient.
Choice A. Facilitated diffusion is not correct because it is a type of passive transport that involves the movement of molecules across a membrane through specific transport proteins, but it does not specifically refer to the movement of water molecules.
Choice B. Active transport is not correct because it is a type of transport that involves the movement of molecules against their concentration gradient and requires energy in the form of ATP, but osmosis is a passive process that does not require energy.
Choice D. Diffusion is not correct because it refers to the movement of molecules from an area of higher concentration to an area of lower concentration, but it does not specifically refer to the movement of water molecules.
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