APEX NIH STROKE SCALE GROUP B ACTUAL
TEST PAPER 2026 QUESTIONS WITH
SOLUTIONS GRADED A+
◉ Signal transduction Answer: Cell converts extracellular signal into
an intracellular response
◉ Where are most receptors located? Answer: Embedded in the cell
membrane
◉ 3 types of membrane bound receptors Answer: -Ion channel
-G-protein coupled receptor
-Enzyme linked receptor
◉ Ion channels definition and examples Answer: Allow or inhibit
ions from moving along their concentration gradients
ex) voltage gated sodium channel in a neuron
Nicotinic N (ANS, CNS), Nicotinic M (NMJ)
◉ A G-protein coupled receptor works in one of two ways: Answer:
1.Opens or closes an ion channel
,2.Activates or inhibits an enzyme inside the cell
◉ Example of a G-protein coupled receptor that opens/closes an ion
channel Answer: Muscarinic-2 receptor in the SA node
(all muscarinic receptors??? - may not be true)
◉ Example of a G-protein coupled receptor that activates/inhibits an
enzyme inside the cell Answer: Alpha-1 receptor in vascular smooth
muscle
(All Alpha, Beta, Dopamine, Histamine, Vasopressin - this may not be
true!!)
◉ Enzyme Linked Receptors are also ________.
At rest the ELR is __________.
When does it become activated? Answer: ELRs are also enzymes.
At rest the catalytic domain is inactive.
,When the signal binds, catalytic domain becomes activated.
◉ Example of enzyme linked receptor Answer: Insulin receptor in
skeletal muscle, linked to tyrosine kinase
◉ How do intracellular receptors work? Answer: A signal diffuses
through the cell membrane and binds to a receptor located inside of
the cell
◉ Example of intracellular receptor Answer: Steroids bind to
receptors in the cytoplasm
-Thyroid hormone binds to receptors in the cell nucleus
◉ Order of how a cellular response is elicited for GPCR Answer: First
Messenger--> GPCR--> Effector --> Second messenger --> Cellular
Response
◉ What is a first messenger? Answer: A ligand that binds to the
GPCR
Could be endogenous (neurotransmitter or hormone) or exogenous
(drug)
◉ Protein structure of GPCR:
, Where is the receptor located?
Where is the G -protein located?What it is made up of? Answer: The
receptor is located is outside the cell membrane.
G-protein is located inside the cell and is made up of the alpha, beta,
gamma subunits
◉ What are the G-stimulatory proteins? What do they do? Answer: -
Gs or Gq
-They turn on an effector
◉ What is the G-inhibitory protein?
what do they do? Answer: -Gi
-Turn off the effector
◉ 3 subunits of a G protein Answer: Alpha, beta, and gamma
◉ What happens when ligand binds GPCR? (4) Answer: 1. Ligand
binding outside receptor activates G-protein
2.Ligand binding causes alpha subunit to dissociate from
beta/gamma subunit
TEST PAPER 2026 QUESTIONS WITH
SOLUTIONS GRADED A+
◉ Signal transduction Answer: Cell converts extracellular signal into
an intracellular response
◉ Where are most receptors located? Answer: Embedded in the cell
membrane
◉ 3 types of membrane bound receptors Answer: -Ion channel
-G-protein coupled receptor
-Enzyme linked receptor
◉ Ion channels definition and examples Answer: Allow or inhibit
ions from moving along their concentration gradients
ex) voltage gated sodium channel in a neuron
Nicotinic N (ANS, CNS), Nicotinic M (NMJ)
◉ A G-protein coupled receptor works in one of two ways: Answer:
1.Opens or closes an ion channel
,2.Activates or inhibits an enzyme inside the cell
◉ Example of a G-protein coupled receptor that opens/closes an ion
channel Answer: Muscarinic-2 receptor in the SA node
(all muscarinic receptors??? - may not be true)
◉ Example of a G-protein coupled receptor that activates/inhibits an
enzyme inside the cell Answer: Alpha-1 receptor in vascular smooth
muscle
(All Alpha, Beta, Dopamine, Histamine, Vasopressin - this may not be
true!!)
◉ Enzyme Linked Receptors are also ________.
At rest the ELR is __________.
When does it become activated? Answer: ELRs are also enzymes.
At rest the catalytic domain is inactive.
,When the signal binds, catalytic domain becomes activated.
◉ Example of enzyme linked receptor Answer: Insulin receptor in
skeletal muscle, linked to tyrosine kinase
◉ How do intracellular receptors work? Answer: A signal diffuses
through the cell membrane and binds to a receptor located inside of
the cell
◉ Example of intracellular receptor Answer: Steroids bind to
receptors in the cytoplasm
-Thyroid hormone binds to receptors in the cell nucleus
◉ Order of how a cellular response is elicited for GPCR Answer: First
Messenger--> GPCR--> Effector --> Second messenger --> Cellular
Response
◉ What is a first messenger? Answer: A ligand that binds to the
GPCR
Could be endogenous (neurotransmitter or hormone) or exogenous
(drug)
◉ Protein structure of GPCR:
, Where is the receptor located?
Where is the G -protein located?What it is made up of? Answer: The
receptor is located is outside the cell membrane.
G-protein is located inside the cell and is made up of the alpha, beta,
gamma subunits
◉ What are the G-stimulatory proteins? What do they do? Answer: -
Gs or Gq
-They turn on an effector
◉ What is the G-inhibitory protein?
what do they do? Answer: -Gi
-Turn off the effector
◉ 3 subunits of a G protein Answer: Alpha, beta, and gamma
◉ What happens when ligand binds GPCR? (4) Answer: 1. Ligand
binding outside receptor activates G-protein
2.Ligand binding causes alpha subunit to dissociate from
beta/gamma subunit
