BIO 235 - EXAM 1 | Questions with 100% Verified Answers
| Latest Update 2026/2027
Question: Physiology
Answer: the study of how the body and its parts work or function
Question: Homeostasis
Answer: process by which organisms maintain a relatively stable internal environment
Question: Variables maintained by homeostasis (8)
Answer: 1) Temperature
2) pH
3) oxygen concentration
4) glucose concentration
5) blood volume
6) blood pressure
7) ion concentration (Na+, K+, Ca+...)
8) volume of water in body
Question: Why is homeostasis important?
Answer: Homeostasis is important because it is essential for the survival of cells. If our
temperature, blood sugar, or other conditions change, it could be life threatening.
Question: How homeostasis is controlled (3)
Answer: 1) Receptor/sensor
2) Control center
3) Effector
Question: Receptor/Sensor
Answer: Sensory organs detect a stimulus. Sends input to control center (the brain) via
afferent
pathway.
Ex: Nerve cells with endings in skin and brain
Question: Control center
Answer: Receives input from the receptor and generates output command when needed via
efferent pathway to effector.
Ex: The brain
, Question: Effector
Answer: Receives output from the control center and produces a response or effect that
changes
controlled condition.
Ex: sweat glands
Question: Feedback systems that maintain homeostasis (2)
Answer: 1) Negative feedback
2) Positive feedback
Question: Negative feedback
Answer: A type of regulation that responds to a change in conditions by initiating responses
that
will counteract the change. Maintains a steady state (homeostasis).
Ex: Body temperature rises so we sweat to cool down
Question: Positive feedback
Answer: A type of regulation that responds to a change in conditions by initiating responses
that
will amplify the change. Takes organism away from a steady state (moves away from
homeostasis). Stimulus further amplifies until a catastrophic event happens (like
giving
birth).
Ex: Giving birth, puberty
Question: What happens if most of your physiological regulatory mechanisms operate by
positive feedback than negative?
Answer: Your body would be out of homeostasis more often than in which means more
disease.
Question: Phospholipid bilayer
Answer: Plasma membrane layers composed of phospholipid molecules arranged with polar
heads (hydrophilic) facing the outside and non-polar tails (hydrophobic) facing the
inside.
-Flexible, yet sturdy barrier that surrounds and contains the cytoplasm of the cell
-Selectively permeable
Question: Simple Diffusion (passive transport)
Answer: Substances move freely through the lipid bilayer of plasma membranes DOWN (high
to
low concentration) their concentration gradient
-Non-polar/hydrophobic molecules move across membranes by simple diffusion (e.g.
fatty acids, steroids, O2, CO2)
-Small polar molecules (like water and urea) can move across via simple diffusion
| Latest Update 2026/2027
Question: Physiology
Answer: the study of how the body and its parts work or function
Question: Homeostasis
Answer: process by which organisms maintain a relatively stable internal environment
Question: Variables maintained by homeostasis (8)
Answer: 1) Temperature
2) pH
3) oxygen concentration
4) glucose concentration
5) blood volume
6) blood pressure
7) ion concentration (Na+, K+, Ca+...)
8) volume of water in body
Question: Why is homeostasis important?
Answer: Homeostasis is important because it is essential for the survival of cells. If our
temperature, blood sugar, or other conditions change, it could be life threatening.
Question: How homeostasis is controlled (3)
Answer: 1) Receptor/sensor
2) Control center
3) Effector
Question: Receptor/Sensor
Answer: Sensory organs detect a stimulus. Sends input to control center (the brain) via
afferent
pathway.
Ex: Nerve cells with endings in skin and brain
Question: Control center
Answer: Receives input from the receptor and generates output command when needed via
efferent pathway to effector.
Ex: The brain
, Question: Effector
Answer: Receives output from the control center and produces a response or effect that
changes
controlled condition.
Ex: sweat glands
Question: Feedback systems that maintain homeostasis (2)
Answer: 1) Negative feedback
2) Positive feedback
Question: Negative feedback
Answer: A type of regulation that responds to a change in conditions by initiating responses
that
will counteract the change. Maintains a steady state (homeostasis).
Ex: Body temperature rises so we sweat to cool down
Question: Positive feedback
Answer: A type of regulation that responds to a change in conditions by initiating responses
that
will amplify the change. Takes organism away from a steady state (moves away from
homeostasis). Stimulus further amplifies until a catastrophic event happens (like
giving
birth).
Ex: Giving birth, puberty
Question: What happens if most of your physiological regulatory mechanisms operate by
positive feedback than negative?
Answer: Your body would be out of homeostasis more often than in which means more
disease.
Question: Phospholipid bilayer
Answer: Plasma membrane layers composed of phospholipid molecules arranged with polar
heads (hydrophilic) facing the outside and non-polar tails (hydrophobic) facing the
inside.
-Flexible, yet sturdy barrier that surrounds and contains the cytoplasm of the cell
-Selectively permeable
Question: Simple Diffusion (passive transport)
Answer: Substances move freely through the lipid bilayer of plasma membranes DOWN (high
to
low concentration) their concentration gradient
-Non-polar/hydrophobic molecules move across membranes by simple diffusion (e.g.
fatty acids, steroids, O2, CO2)
-Small polar molecules (like water and urea) can move across via simple diffusion
