BIO 251 Exam study question and answers rated A+

The smallest living units capable of carrying out the basic life functions are: - Answer- Cells The tissue type that can contract to generate mechanical force and movement: - Answer- Muscle What organelle synthesizes most of the ATP used by cells? - Answer- Mitochondria In direct cellular communications, ions and small molecules originating within one cell can diffuse directly into a neighboring cell through: - Answer- Gap Junctions Which of the following compartments contain most of the water found in the human body? - Answer- Intracellular fluid What is the name of the chemical that binds to a receptor and activates the receptor to produce a biological response (it creates an action) - Answer- Agonist What is the name of the chemical that blocks the action of an agonist? - Answer- Antagonist Referring to a membrane as "selectively permeable" describes its ability to: - Answer- Allow the movement of particular molecules across a membrane but restrict the movement of other molecules Which type of chemical messenger, when released, binds to receptors on the same cell that released the chemical messenger? - Answer- Autocrine Autocrine messengers create a: - Answer- self signal Paracrine messengers create a: - Answer- neighbor signal Endocrine messengers create a: - Answer- distant signal The affinity of a receptor for its messenger is a measure of the: - Answer- Number of binding sites available for the ligand In homeostasis mechanisms, a _________ detects a change in a regulated variable and sends that information to a(n) __________ which relays signals to a(n) ___________, usually a muscle or a gland - Answer- Sensor, integrating center, effector First messengers are: - Answer- extracellular factors, often hormones or neurotransmitters, such as epinephrine, growth hormone, and serotonin. Function of the secondary messenger system is to: - Answer- amplify the response of the first messenger Parasympathetic preganglionic neurons release the neurotransmitter: - Answer- Acetylcholine Sympathetic preganglionic neurons release the neurotransmitter: - Answer- Acetylcholine The electrochemical gradient for sodium across the membrane is such that the nex flux for sodium movement is directed (blank), thereby causing the cell's membrane potential to become more (blank). - Answer- inward : positive