PSIO 201 Final Study Guide Question
and answers 100% correct 2025/2026
Define homeostasis. - correct answer ✔*Homeostasis* - Relative constancy of internal env't. The
physical & chemical parameters of living systems tend to remain constant over time.
Describe the elements that comprise a feedback loop. - correct answer ✔*Feedback Loop:* Stimulus
(heat) --> receptor (temp sensor) --> control center (brain) --> effector (sweat gland) --> response
(sweat) --> controlled condition (evap cooling)
Identify a representative example of a positive vs. a negative feedback loop, and explain why one
category is called 'positive' and the other is called 'negative.' - correct answer ✔*Positive:* Original
stimulus is intensified or strengthened in a controlled condition (childbirth).
*Negative:* REVERSES A CHANGE IN CONTROLLED CONDITION, used for common adjustments (blood
pressure).
Compare and contrast integral and peripheral membrane proteins. - correct answer ✔*Integral
proteins:* Amphipathic with hydrophobic portions hiding among phospholipid layers, extend across cell
membrane.
Peripheral membrane proteins: Attracted to inner or outer surface of cell membrane and are easily
removed from it.
Comment on why 'amphiphilicity' of phospholipid & protein structure is important in establishing stable
membrane structure. - correct answer ✔Amphiphilic structure is important because like seeks like.
Define osmosis. Predict the direction of net osmotic water flow. - correct answer ✔Net flow of water
across semipermeable membrane in response to gradient in the chemical activity of water. Flow: high
water concentration --> low water concentration
,Compare and contrast the concepts of osmolarity and tonicity. - correct answer ✔*Osmolarity:*
Movement in direction of gradient.
Tonicity: Measure of the solutions ability to change the volume of cells by altering their water content.
Compare and contrast the characteristics that distinguish passive diffusion from carrier ‐mediated
transport. - correct answer ✔*Passive:* No energy, high to low
*Carrier-mediated:* Active transport/facilitated Diffusion
Discuss two diagnostic characteristics of carrier‐mediated transport. - correct answer ✔1.
*Saturability* - Finite # of transporters & each transporter has a finite "turnover"
2. *Selectivity* - Each transport protein can "accept" a limited range of chemical structures as substrates
Compare and contrast the characteristics of facilitated diffusion and active transport. - correct answer
✔*Facilitated diffusion:* Passive transport w/ help of protein
Active transport: Sources of energy, low to high
Compare and contrast the characteristics of primary and secondary active transport. - correct answer
✔*Primary:* Immediate energy source is ATP
*Secondary:* Immediate energy source is transmembrane ion gradients
List the categories of vesicular transport and describe a representative example of each. - correct
answer ✔*Endocytosis* - bringing something into cell
*Exocytosis* - releasing something out of cell
Describe the function of the following cell structures: cytoskeleton; smooth and rough endoplasmic
reticulum; lysosomes and peroxisomes. - correct answer ✔*Cytoskeleton:*
*Microfilaments* - connect organelles to membrane, influence cell motility & shape
*Intermediate filaments* - structural stability
, *Microtubules* - cell structure & shape, motility, organelle movement
*Smooth ER:* Lipid synthesis, calcium storage, detoxification
*Rough ER:* Protein synthesis & storage
*Lysosomes & peroxisomes:* Contains digestive enzymes for turning over old cellular material;
detoxification
Compare and contrast the characteristics of ATP production by oxidative vs. anaerobic (i.e., glycolytic)
metabolism. - correct answer ✔*Oxidative phosphorylation:* Enzymatically breaking of bonds by
consuming O2, producing CO2.
*Anaerobic metabolism:* Glycolysis. glucose goes in to produce 2 pyruvate in the end
List and describe the functions of the 4 cell types found in bone. - correct answer ✔*Osteogenic cells* -
Develop into osteoblasts
*Osteoblasts* - Form bone matrix
*Osteocytes* - Maintain of bone tissue; sense bone microdamage & mechanical forces
*Osteoclasts* - Resorption & breakdown of bone matrix
Discuss modeling and remodeling of bone. - correct answer ✔*Modeling (construction):* Bone is
formed by osteoblasts w/o prior bone resorption. Happens during growth & produces change in size &
shape
*Remodeling (reconstruction):* Occurs when bone is first resorbed by osteoclasts & then formed in
same location by osteoblasts. Happens throughout life
List the components of the matrix of bone and describe how each component
contributes to the bone's strength. - correct answer ✔*Ground substance* - negatively charged, traps
water
*Collagen fibers* - Resistant to pulling forces, provides flexibility & framework for deposition of calcium
crystals
*Water* - 25% of ECM
and answers 100% correct 2025/2026
Define homeostasis. - correct answer ✔*Homeostasis* - Relative constancy of internal env't. The
physical & chemical parameters of living systems tend to remain constant over time.
Describe the elements that comprise a feedback loop. - correct answer ✔*Feedback Loop:* Stimulus
(heat) --> receptor (temp sensor) --> control center (brain) --> effector (sweat gland) --> response
(sweat) --> controlled condition (evap cooling)
Identify a representative example of a positive vs. a negative feedback loop, and explain why one
category is called 'positive' and the other is called 'negative.' - correct answer ✔*Positive:* Original
stimulus is intensified or strengthened in a controlled condition (childbirth).
*Negative:* REVERSES A CHANGE IN CONTROLLED CONDITION, used for common adjustments (blood
pressure).
Compare and contrast integral and peripheral membrane proteins. - correct answer ✔*Integral
proteins:* Amphipathic with hydrophobic portions hiding among phospholipid layers, extend across cell
membrane.
Peripheral membrane proteins: Attracted to inner or outer surface of cell membrane and are easily
removed from it.
Comment on why 'amphiphilicity' of phospholipid & protein structure is important in establishing stable
membrane structure. - correct answer ✔Amphiphilic structure is important because like seeks like.
Define osmosis. Predict the direction of net osmotic water flow. - correct answer ✔Net flow of water
across semipermeable membrane in response to gradient in the chemical activity of water. Flow: high
water concentration --> low water concentration
,Compare and contrast the concepts of osmolarity and tonicity. - correct answer ✔*Osmolarity:*
Movement in direction of gradient.
Tonicity: Measure of the solutions ability to change the volume of cells by altering their water content.
Compare and contrast the characteristics that distinguish passive diffusion from carrier ‐mediated
transport. - correct answer ✔*Passive:* No energy, high to low
*Carrier-mediated:* Active transport/facilitated Diffusion
Discuss two diagnostic characteristics of carrier‐mediated transport. - correct answer ✔1.
*Saturability* - Finite # of transporters & each transporter has a finite "turnover"
2. *Selectivity* - Each transport protein can "accept" a limited range of chemical structures as substrates
Compare and contrast the characteristics of facilitated diffusion and active transport. - correct answer
✔*Facilitated diffusion:* Passive transport w/ help of protein
Active transport: Sources of energy, low to high
Compare and contrast the characteristics of primary and secondary active transport. - correct answer
✔*Primary:* Immediate energy source is ATP
*Secondary:* Immediate energy source is transmembrane ion gradients
List the categories of vesicular transport and describe a representative example of each. - correct
answer ✔*Endocytosis* - bringing something into cell
*Exocytosis* - releasing something out of cell
Describe the function of the following cell structures: cytoskeleton; smooth and rough endoplasmic
reticulum; lysosomes and peroxisomes. - correct answer ✔*Cytoskeleton:*
*Microfilaments* - connect organelles to membrane, influence cell motility & shape
*Intermediate filaments* - structural stability
, *Microtubules* - cell structure & shape, motility, organelle movement
*Smooth ER:* Lipid synthesis, calcium storage, detoxification
*Rough ER:* Protein synthesis & storage
*Lysosomes & peroxisomes:* Contains digestive enzymes for turning over old cellular material;
detoxification
Compare and contrast the characteristics of ATP production by oxidative vs. anaerobic (i.e., glycolytic)
metabolism. - correct answer ✔*Oxidative phosphorylation:* Enzymatically breaking of bonds by
consuming O2, producing CO2.
*Anaerobic metabolism:* Glycolysis. glucose goes in to produce 2 pyruvate in the end
List and describe the functions of the 4 cell types found in bone. - correct answer ✔*Osteogenic cells* -
Develop into osteoblasts
*Osteoblasts* - Form bone matrix
*Osteocytes* - Maintain of bone tissue; sense bone microdamage & mechanical forces
*Osteoclasts* - Resorption & breakdown of bone matrix
Discuss modeling and remodeling of bone. - correct answer ✔*Modeling (construction):* Bone is
formed by osteoblasts w/o prior bone resorption. Happens during growth & produces change in size &
shape
*Remodeling (reconstruction):* Occurs when bone is first resorbed by osteoclasts & then formed in
same location by osteoblasts. Happens throughout life
List the components of the matrix of bone and describe how each component
contributes to the bone's strength. - correct answer ✔*Ground substance* - negatively charged, traps
water
*Collagen fibers* - Resistant to pulling forces, provides flexibility & framework for deposition of calcium
crystals
*Water* - 25% of ECM
