BIO 2301 Human Physiology - Exam 1
(CSCC - SU18) UPDATED Exam Questions
and CORRECT Answers
Homeostasis - CORRECT ANSWER - The body's ability to maintain internal stability,
even in the face of external change
Components of a homeostatic mechanism - CORRECT ANSWER - - Control center:
usually found in the hypothalamus of the brain, contains the "set point" for the variable, receives
info from the receptors and sends instructions to effectors
- Receptors: detect or sense the variable and send that info to the control center
- Effectors: receive instructions from the control center and carry them out to get the variable
back to normal
Examples of homeostatic mechanisms - CORRECT ANSWER - - The maintenance of
body temperature
- Blood glucose levels
- Blood sodium levels
- Blood pressure
Negative feedback - CORRECT ANSWER - - When a change in the variable occurs, the
body responds by causing a change in the opposite direction
- The main way that homeostatic mechanisms work
Positive feedback - CORRECT ANSWER - - When a change in the variable occurs, the
body responds by causing more of a change in the same direction
- Rarely used in the body
- Examples: blood clotting, oxytocin release during child birth, and milk release
,Structure of the plasma membrane - CORRECT ANSWER - - Semi-permeable,
phospholipid bilayer
- Regulates passage of substances into and out of the cell
- Principal components: lipids, proteins, carbohydrates
Phospholipids in the plasma membrane - CORRECT ANSWER - - Hydrophilic head
- Hydrophobic tail
- Arranged in a double layer (bilayer) with the heads surrounded by fluid and the tails kept from
the water
Cholesterol in the cell membrane - CORRECT ANSWER - - Hydrophobic so found in the
tail
- Maintains the consistency of the cell membrane
- Strengthens it by preventing smell molecules from crossing
- Keeps the phospholipid tails from coming into contact and solidifying it to ensure the
hydrophobic tail stays fluid and flexible
Proteins in the cell membrane - CORRECT ANSWER - - Function as enzymes to speed up
chemical reactions
- Act as receptors for specific molecules or transport materials across the cell membrane
- Integral proteins are located within the lipid bilater
- Peripheral proteins are located outside the lipid bilayer
Carbohydrates in the cell membrane - CORRECT ANSWER - - Sometime attached to
proteins or lipids on the outside of the cell membrane
- Form the glycocalyx which provides cushioning and protection for the membrane, important
for cell recognition and determining if cells should be there or not, and acts as a glue to attach
cells together
Polar substances - CORRECT ANSWER - - Water soluble
, - Water, sodium, potassium
Nonpolar substances - CORRECT ANSWER - - Fat soluble
- Urea, carbon dioxide, oxygen, and alcohol
Solubility - CORRECT ANSWER - - Like dissolves like
- Polar liquids dissolve polar substances
- Nonpolar liquids dissolve nonpolar substances
What substances can easily pass through the phospholipid bilayer of cell membranes? -
CORRECT ANSWER - - Nonpolar substances will pass through easily
- Polar substances must go through a channel in the cell membrane
Disorder - CORRECT ANSWER - - Disorder increases
- Molecules want to go where there is more room for them to spread out
Diffusion - CORRECT ANSWER - - The movement of small molecules from an area of
high concentration to an area of low concentration
- Does not require ATP energy
- Consists of a solute (molecules being dissolved) and a solution (water)
- Nonpolar, small lipid-soluble molecules will easily pass through the lipid bilayer
Osmosis - CORRECT ANSWER - - The unassisted diffusion of water across a selective
permeable membrane
- Water will go through an aquaporin (a pore) and will move from where there is more water to
where there is less water (high to low) OR movement of water from an area of low solute
concentration to an area of high solute concentration
- Happens when the membrane is not permeable to the solutes
(CSCC - SU18) UPDATED Exam Questions
and CORRECT Answers
Homeostasis - CORRECT ANSWER - The body's ability to maintain internal stability,
even in the face of external change
Components of a homeostatic mechanism - CORRECT ANSWER - - Control center:
usually found in the hypothalamus of the brain, contains the "set point" for the variable, receives
info from the receptors and sends instructions to effectors
- Receptors: detect or sense the variable and send that info to the control center
- Effectors: receive instructions from the control center and carry them out to get the variable
back to normal
Examples of homeostatic mechanisms - CORRECT ANSWER - - The maintenance of
body temperature
- Blood glucose levels
- Blood sodium levels
- Blood pressure
Negative feedback - CORRECT ANSWER - - When a change in the variable occurs, the
body responds by causing a change in the opposite direction
- The main way that homeostatic mechanisms work
Positive feedback - CORRECT ANSWER - - When a change in the variable occurs, the
body responds by causing more of a change in the same direction
- Rarely used in the body
- Examples: blood clotting, oxytocin release during child birth, and milk release
,Structure of the plasma membrane - CORRECT ANSWER - - Semi-permeable,
phospholipid bilayer
- Regulates passage of substances into and out of the cell
- Principal components: lipids, proteins, carbohydrates
Phospholipids in the plasma membrane - CORRECT ANSWER - - Hydrophilic head
- Hydrophobic tail
- Arranged in a double layer (bilayer) with the heads surrounded by fluid and the tails kept from
the water
Cholesterol in the cell membrane - CORRECT ANSWER - - Hydrophobic so found in the
tail
- Maintains the consistency of the cell membrane
- Strengthens it by preventing smell molecules from crossing
- Keeps the phospholipid tails from coming into contact and solidifying it to ensure the
hydrophobic tail stays fluid and flexible
Proteins in the cell membrane - CORRECT ANSWER - - Function as enzymes to speed up
chemical reactions
- Act as receptors for specific molecules or transport materials across the cell membrane
- Integral proteins are located within the lipid bilater
- Peripheral proteins are located outside the lipid bilayer
Carbohydrates in the cell membrane - CORRECT ANSWER - - Sometime attached to
proteins or lipids on the outside of the cell membrane
- Form the glycocalyx which provides cushioning and protection for the membrane, important
for cell recognition and determining if cells should be there or not, and acts as a glue to attach
cells together
Polar substances - CORRECT ANSWER - - Water soluble
, - Water, sodium, potassium
Nonpolar substances - CORRECT ANSWER - - Fat soluble
- Urea, carbon dioxide, oxygen, and alcohol
Solubility - CORRECT ANSWER - - Like dissolves like
- Polar liquids dissolve polar substances
- Nonpolar liquids dissolve nonpolar substances
What substances can easily pass through the phospholipid bilayer of cell membranes? -
CORRECT ANSWER - - Nonpolar substances will pass through easily
- Polar substances must go through a channel in the cell membrane
Disorder - CORRECT ANSWER - - Disorder increases
- Molecules want to go where there is more room for them to spread out
Diffusion - CORRECT ANSWER - - The movement of small molecules from an area of
high concentration to an area of low concentration
- Does not require ATP energy
- Consists of a solute (molecules being dissolved) and a solution (water)
- Nonpolar, small lipid-soluble molecules will easily pass through the lipid bilayer
Osmosis - CORRECT ANSWER - - The unassisted diffusion of water across a selective
permeable membrane
- Water will go through an aquaporin (a pore) and will move from where there is more water to
where there is less water (high to low) OR movement of water from an area of low solute
concentration to an area of high solute concentration
- Happens when the membrane is not permeable to the solutes
