2025 BIO 251 Exam 1 New Latest Version Best Studying
Material with All Questions from Actual Past Exam and
100% Correct Answers
Which type of chemical messenger is released into the bloodstream by an endocrine gland where
it can affect target cells throughout the body?
A) paracrine
B) autocrine
C) cytokine
D) neurotransmitter
E) hormone ----------- Correct Answer ------------ E) hormone
In most 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.
A) sensor: integrating center : effector
B) sensor: effector : integrating center
C) stimulus : receptor : organ system
D) receptor : stimulus : regulated variable E) receptor : integrating center : positive feedback
control ----------- Correct Answer ------------ A) sensor: integrating center : effector
Direct communication between cells in contact with one another is accomplished
through
A) ligands
B) receptors
C) gap junctions
D) paracrine chemical messengers
E) endocrine hormones ----------- Correct Answer ------------ C) gap junctions
What is the integral membrane protein? ------------ Correct Answer ------------ Amphipathic (both
hydrophilic and hydrophobic regions) used for active transport
What is peripheral membrane proteins? ------------ Correct Answer ------------ Attached to the
outside of the membrane. For the bigger molecules to go through
What does cholesterol do for the plasma membrane? ------------ Correct Answer ------------
Stabilizes/adds fluidity to membrane. Tucker amongst the fatty acids
As the number of receptors for a messenger on a cell decreases, the magnitude of the response of
that cell to that messenger will
A) increase
B) decrease
C) remain the same due to saturation
D) oscillate with the concentration of the chemical messenger
,E) increase its affinity ----------- Correct Answer ------------ B) decrease
What is a molecule that is similar in structure to a messenger and binds with that messenger's
receptor to stimulate a similar response from the target cell?
A) blocker
B) synergist
C) antagonist
D) agonist
E) protagonist ----------- Correct Answer ------------ D) agonist
Heroin overdose is usually treated with an opioid _______ , such as naloxone (Narcan) which
prevents heroin from binding to opiate receptors and reverses the effects of heroin on the body.
A) agonist
B) antagonist
C) ligand
D) antihistamine
E) second messenger ----------- Correct Answer ------------ B) antagonist
Ion channels are examples of what type of membrane protein?
A) peripheral membrane protein
B) transmembrane protein
C) paramembrane protein
D) glycolipid
E) intracellular receptor ----------- Correct Answer ------------ B) transmembrane protein
Which of the following is NOT a type of integral membrane protein?
A) carrier proteins for faciliated diffusion transport
B) connexons of gap junctions
C) channels for ion diffusion across membranes
D) ion "pumps" such as the Na+/K+ ATPase
E) an intracelluar receptor for a messenger ----------- Correct Answer ------------ E) an
intracelluar receptor for a messenger
When molecules are passively transported across a membrane, the direction of their
movement is dictated by the molecule's tendency to move
A) from higher concentration to lower lower concentration
B) from lower concentration to higher concentration
C) always out of a cell
D) always into a cell
E) in both directions simultaneously ----------- Correct Answer ------------ A) from higher
concentration to lower lower concentration
Based solely upon its negative electrical charge, the inside of a typical cell will tend to attract
extracellular ______ to move inward.
A) negatively charged proteins
B) anions
, C) uncharged ions
D) cations
E) ions whose concentration gradient allows them ----------- Correct Answer ------------ D)
cations
Transporting a substance against its concentration gradient requires
A) a type of passive transporter
B) a transporter that uses metabolic energy
C) a facilitated diffusion transporter
D) that the molecule be able to freely move across the membrane by simple diffusion
E) an ion channel ----------- Correct Answer ------------ B) a transporter that uses metabolic
energy
Most cells have a resting membrane potential of
A)-5 mV.
B)-55 mV.
C) -70 mV.
D) +30 mV.
E) +100 mV. ----------- Correct Answer ------------ C) -70 mV.
What type of ion channels in the membranes of all cells allows ions to constantly move across
the membrane at rest and thereby contribute to the resting membrane potential?
A) voltage-gated channels
B) leak channels
C) resting channels
D) potential-gated channels
E) ligand-gated channels ----------- Correct Answer ------------ B) leak channels
Which of the following best describes the electrochemical forces acting on sodium and
potassium ions across the cell membrane?
A) Forces on both sodium and potassium ions are to move into the cell.
B) Forces on both sodium and potassium ions are to move out of the cell.
C) The force on sodium ions is to move out of the cell, and the force on potassium ions is to
move into the cell.
D) The force on sodium ions is to move into the cell, and the force on potassium ions is to move
out of the cell.
E) There is no force on either ion to move. ----------- Correct Answer ------------ D) The force on
sodium ions is to move into the cell, and the force on potassium ions is to move out of the cell.
The electrochemical gradient for sodium across the membrane is such that the net flux for
sodium movement is directed _____ , thereby causing the cell's membrane potential to become
more _______ .
A) inward : positive
B) inward : negative
C) outward : positive
D) outward : negative
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller qualityexamshut. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $27.99. You're not tied to anything after your purchase.
