BIO 2301 HUMAN PHYSIOLOGY ACTUAL
TEST PAPER 2026 COMPLETE QUESTIONS
AND SOLUTIONS
◉Components of a homeostatic mechanism. 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. Answer: - The maintenance
of body temperature
- Blood glucose levels
- Blood sodium levels
- Blood pressure
◉Negative feedback. 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. 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. 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. 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. 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. 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. 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. Answer: - Water soluble
- Water, sodium, potassium
◉Nonpolar substances. Answer: - Fat soluble
- Urea, carbon dioxide, oxygen, and alcohol
◉Solubility. 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?. Answer: - Nonpolar substances will pass
through easily
- Polar substances must go through a channel in the cell membrane
◉Disorder. Answer: - Disorder increases
- Molecules want to go where there is more room for them to spread
out
◉Diffusion. 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. 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)
TEST PAPER 2026 COMPLETE QUESTIONS
AND SOLUTIONS
◉Components of a homeostatic mechanism. 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. Answer: - The maintenance
of body temperature
- Blood glucose levels
- Blood sodium levels
- Blood pressure
◉Negative feedback. 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. 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. 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. 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. 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. 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. 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. Answer: - Water soluble
- Water, sodium, potassium
◉Nonpolar substances. Answer: - Fat soluble
- Urea, carbon dioxide, oxygen, and alcohol
◉Solubility. 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?. Answer: - Nonpolar substances will pass
through easily
- Polar substances must go through a channel in the cell membrane
◉Disorder. Answer: - Disorder increases
- Molecules want to go where there is more room for them to spread
out
◉Diffusion. 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. 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)
