PHGY 215 – MIDTERM 2026 ACTUAL EXAM
PAPER QUESTIONS WITH SOLUTIONS GRADED
A+
◉ Homeostasis.
Answer: The ability of a cell or organism to regulate and maintain its
internal environment regardless of the influences of the external
environment
◉ Set Point.
Answer: The range or point at which a variable physiological state
tends to stabilize
◉ 3 components of a homeostatic control system.
Answer: Sensor, Integrator, Effector
◉ Sensor.
Answer: The sensor is responsible for detecting an environmental
change
◉ Integrator.
,Answer: The integrator compares the variable being detected to its
set point
◉ Effector.
Answer: The effector is responsible for initiating the changes to
restore the variable back to the set point
◉ Intrinsic Control.
Answer: The sensor, integrator, and effector are all located in a tissue
so that the tissue can regulate its own internal environment
◉ Extrinsic Control.
Answer: The regulatory mechanisms are outside of the tissue or
organ
◉ Positive Feedback.
Answer: When the effector causes changes that amplify the initial
signal - not homeostatic
◉ Negative Feedback.
Answer: A change in an environmental parameter causing the
effector to initiate a response in the opposite direction, restoring the
parameter to the set point - system stops signalling once set point is
achieved
,◉ Plasma Membrane.
Answer: The barrier that separates the cell's internal and external
environments that serves as protection and allows cells to maintain
an internal fluid composition different than the external fluid
composition
◉ Roles of the Plasma Membrane.
Answer: - Plays an active role in regulating the internal fluid
composition as it controls which molecules flow in and out
- Allows nutrients to enter cells and waste products to leave
Permits chemical signals released from other cells in the body to
influence a cell allowing cell to cell communication
- Participates in joining cells together to form tissues and organs
◉ Three primary functions of the plasma membrane.
Answer: - ensure the cell's survival
- maintain homeostasis
function cooperatively and in coordination with surrounding cells
◉ Phospholipids in the Plasma Membrane.
Answer: - The lipid bilayer is comprised of phospholipids
, - A phospholipid has a polar head with a negatively charged
phosphate group and two non-polar fatty acid tails
- the head is hydrophilic and the tail is hydrophobic
◉ Cholesterol in the Plasma membrane.
Answer: - Found tucked in between the phospholipids
- Prevent the fatty acid chains from packing too tightly together and
forming rigid structures
- keeps the membrane fluid
◉ Membrane Proteins.
Answer: - Inserted into the phospholipid membrane
- associated with inner or outer sides or pass all the way through the
membrane
- Functions to maintain structure, regulate cell function, allow
transport across the membrane, and facilitate signalling
◉ Ion Channels.
Answer: Specialized membrane proteins that span the entire lipid
membrane and permit the entry and exit of ions
◉ Carbohydrate Chains in the Plasma Membrane.
PAPER QUESTIONS WITH SOLUTIONS GRADED
A+
◉ Homeostasis.
Answer: The ability of a cell or organism to regulate and maintain its
internal environment regardless of the influences of the external
environment
◉ Set Point.
Answer: The range or point at which a variable physiological state
tends to stabilize
◉ 3 components of a homeostatic control system.
Answer: Sensor, Integrator, Effector
◉ Sensor.
Answer: The sensor is responsible for detecting an environmental
change
◉ Integrator.
,Answer: The integrator compares the variable being detected to its
set point
◉ Effector.
Answer: The effector is responsible for initiating the changes to
restore the variable back to the set point
◉ Intrinsic Control.
Answer: The sensor, integrator, and effector are all located in a tissue
so that the tissue can regulate its own internal environment
◉ Extrinsic Control.
Answer: The regulatory mechanisms are outside of the tissue or
organ
◉ Positive Feedback.
Answer: When the effector causes changes that amplify the initial
signal - not homeostatic
◉ Negative Feedback.
Answer: A change in an environmental parameter causing the
effector to initiate a response in the opposite direction, restoring the
parameter to the set point - system stops signalling once set point is
achieved
,◉ Plasma Membrane.
Answer: The barrier that separates the cell's internal and external
environments that serves as protection and allows cells to maintain
an internal fluid composition different than the external fluid
composition
◉ Roles of the Plasma Membrane.
Answer: - Plays an active role in regulating the internal fluid
composition as it controls which molecules flow in and out
- Allows nutrients to enter cells and waste products to leave
Permits chemical signals released from other cells in the body to
influence a cell allowing cell to cell communication
- Participates in joining cells together to form tissues and organs
◉ Three primary functions of the plasma membrane.
Answer: - ensure the cell's survival
- maintain homeostasis
function cooperatively and in coordination with surrounding cells
◉ Phospholipids in the Plasma Membrane.
Answer: - The lipid bilayer is comprised of phospholipids
, - A phospholipid has a polar head with a negatively charged
phosphate group and two non-polar fatty acid tails
- the head is hydrophilic and the tail is hydrophobic
◉ Cholesterol in the Plasma membrane.
Answer: - Found tucked in between the phospholipids
- Prevent the fatty acid chains from packing too tightly together and
forming rigid structures
- keeps the membrane fluid
◉ Membrane Proteins.
Answer: - Inserted into the phospholipid membrane
- associated with inner or outer sides or pass all the way through the
membrane
- Functions to maintain structure, regulate cell function, allow
transport across the membrane, and facilitate signalling
◉ Ion Channels.
Answer: Specialized membrane proteins that span the entire lipid
membrane and permit the entry and exit of ions
◉ Carbohydrate Chains in the Plasma Membrane.
