BIO 2601 PART 2- FINAL EXAM QUESTIONS AND ANSWERS FULLY SOLVED LATEST UPDATE 2025-2026
tell me about the water molecule - Answers- highly polar cuz oxygen is negative while hydrogen is
postitive
- a universol solvent, cuz it dissolved in all biological systems
- has a high large thermal capacity
- expands upon freezing
-high surface tension
-cohesion, adhesion
-tensile strength
hyperosmotic meaning - Answersmore solute is on the outside of the cell, causing a higher conc of water
inside the cell, causing the water to leave the cell creating shrinkage
hypoosmotic meaning - Answersmore solute is on the inside of the cell, causing a higher water conc on
the outside causing water to move inside the cell and expand it
cell turgor in plants - Answersthe positive pressure in plant cells that keep them turgid, so its like gaurd
cells for the stomata
ressurrection plants - Answersthese plants can survive total dehydration, they can recover in hours once
they get water back (ex, ferns, lichens, mosses, etc.)
Tardigrades - Answersthese can survive outer space, low temps, full solar uv radiation
basically the worst conditions it can survive
they do this by making their metabolic rate so slow and basically like shutting it down
how do solutes move - Answersthrough diffusion: goes from high to low concentration through a
permable membrane
how does water move - Answersthrough osmosis: through a semi permable membrane, solutes set up
an osmotic gradient causing water to move due to osmotic pressure, going to the higher solute
concentration
- never gonna get to equillibrum tho cuz the solutes cant move through the semi permable membrane
and cuz of gravity
how does water cross biological membranes - Answersthe water is going to move to the higher solute
concentration by slow diffusion through the membrane bilayer or faster diffusion through the
aquaporins which is a gated channel specific to water only
,chemical potential - Answersadding solutes to one side will raise its chemical potnetial and decrease the
water chemical potential because cuz the other side would all be water and no solute
water potential - Answersis a special case of chemical potential and has four main contributing factors
1)solutes - the free energy gradients (negative number)
2) pressure- pressure by squeezing one side, causing a free energy gradient to go from higher pressure
to lower pressure
3)heat (temp) - increasing kinetic energy will increase pressure so the water will move from the heated
and rapid moving side, to the other side
4)gravity- one membrane above the other is gonna set a energy gradient, causing it to move downwards
the water potential equation - Answerswater potential = sum of component potentials, where the solute
is gonna be negative and the rest r positive values
now in biological systems, temp and gravity ptiential are neglible
so really its water potential = solute + pressure potential
so if the soltue potential is bigger than pressure potential, then water potential will be a negative value
where do cells gets water from - Answersfor plants, they get it from the root
for animals, they get it from drinking water
water can also come from the food so metabolic water
and bound water which is water molecules bound to fuel molecules such as glycogen
whats the problem w living in salter water - Answerswater is gonna wanna leave the plant due to
osmotic gradients, but there are self defense mechanisms for that
ex, mangrove trees
how does metabolic water work - Answersin the cellular metoblism equation, we see one mole of
gluocose gives us 6 molecules of h20,
,lipids give us 2x more water, than carbs and proteins
how do pressure gradients drive fluid transport - Answersanimals use positive pressure to push the
fluids through their pipes
plants use negative pressure to pull fluids up into their roots and leaves
but in both cases, fluids move from higher to lower pressures,
Soil water potential equation - Answerssolute water potential (negative) + pressure water potential
(negative) + temp water potential (posititve) + gravity water potential (pos/neg) = soil water potential
the pressure water potential is the most dominant in this equation
how does a plant get water from the soil - Answers- there are root hairs to increase the surface area of
the root
- the water is taken up by the root hairs and root tips, not really the root tho cuz the epidermis isnt
permable to water
- water is then absorbed by the roots, creating a pressure gradient
why do plants need vascular transport - Answers- they need it to carry sugars from the leaves to other
tissues
- its also used to trnasmit hormones from sites where its made, to sites where its needed
- also a way to carry nutrients and water, from the soil to the leaves
Xylem vs. Phloem - Answersthe xylem is unidirectional(stays in one direction) and moves water and
inorganic nutrients from the roots to the leaves
the phloem is multidirectional and moves the sugars, protiens and signalling molecules from their source
to the sink tissues
what r the 3 pathways of getting water into the xylem - Answers1)apoplast- it gets through the root hair
and then through the cell walls but cant get past the endodermis due to its casparian strips, so it cant
get to the xylem
2) symplasm - water gets throuhg from cell to cell through the plasmodesmata which egts across the
endodermis so it can bypass the lipid bilayer by getting through the plasmodesmata
, 3) transmembrane- water can get in through the root hair then it will go through the aquaproins from
cell to cell and also uses the aquoporin to bypass the caparian strip
the two types of xylem cells - Answers1) tracheids- long, narrow, have holes(pits) in them, so that the
water can go through tracheid to tracheid
2)vessel elements- have perforation plates which are like holes at the top and bottom, and pits on the
side walls, faster mouvement of water
explain the mechanism of negative pressure - Answersthere is evaportation in the leaves which creates
tension, which causes water to be pulled up from the roots and so the negtive pressure has to be strong
enough to the get the water to travel all the way to the leaves
what r the 3 mechanisms that r used to facilitate negative pressure - Answers1) root pressure- when
there is solute pumped in the xylem, the plant sets up an osmotic gradient to get water to move into the
xyelm whcih then causes a lower water potential so water moves in but cant move out due to casparian
strip, and so this causes root pressure that builds up in the xylem and to move all the way up, however
root pressure only provies 0.1 MPa, and we need 2 to reach the top of a tree
2)capillary force- inversely proportional to diameter, so the broader the root, the smaller the force, but
still not enough for a tree
3)cohesion-tension theory- a continous column of water moving from the soil to the leaves, with a
continous negative pressure, with a driving force from the transpiration of the stomata so evaporation
from the leaf basically
what r the two ways that breaks the column of water in the xylem - Answers1)cavitation - disolved gases
form bubbles under tension(frozen water, damage to xylem) in the water column
2)embolism- large gas bubbles that come together to block the path of water
how do we cope with cavitation - Answersthere is the buldge called the torus and it moves when there is
air pressure put upon it, and this repevents an embolism from being put together
what about plants with no torus? - Answersthese plants perforation plates isntead which are kinda like
drainers and cant prevent air bubble from getting through
how is an embolism repaired - Answersat night- transpiration stops so so the driving force stops, so the
gas bubbles go back into solution
spring- tension is elimaintated causing gas to redissolve
yearly - new layers of xylem every year , so if there is a xylem they just replace
why is the phloem able to flow in both directions - Answerscuz the contents of the phloem will always
flow from source to sink,
tell me about the water molecule - Answers- highly polar cuz oxygen is negative while hydrogen is
postitive
- a universol solvent, cuz it dissolved in all biological systems
- has a high large thermal capacity
- expands upon freezing
-high surface tension
-cohesion, adhesion
-tensile strength
hyperosmotic meaning - Answersmore solute is on the outside of the cell, causing a higher conc of water
inside the cell, causing the water to leave the cell creating shrinkage
hypoosmotic meaning - Answersmore solute is on the inside of the cell, causing a higher water conc on
the outside causing water to move inside the cell and expand it
cell turgor in plants - Answersthe positive pressure in plant cells that keep them turgid, so its like gaurd
cells for the stomata
ressurrection plants - Answersthese plants can survive total dehydration, they can recover in hours once
they get water back (ex, ferns, lichens, mosses, etc.)
Tardigrades - Answersthese can survive outer space, low temps, full solar uv radiation
basically the worst conditions it can survive
they do this by making their metabolic rate so slow and basically like shutting it down
how do solutes move - Answersthrough diffusion: goes from high to low concentration through a
permable membrane
how does water move - Answersthrough osmosis: through a semi permable membrane, solutes set up
an osmotic gradient causing water to move due to osmotic pressure, going to the higher solute
concentration
- never gonna get to equillibrum tho cuz the solutes cant move through the semi permable membrane
and cuz of gravity
how does water cross biological membranes - Answersthe water is going to move to the higher solute
concentration by slow diffusion through the membrane bilayer or faster diffusion through the
aquaporins which is a gated channel specific to water only
,chemical potential - Answersadding solutes to one side will raise its chemical potnetial and decrease the
water chemical potential because cuz the other side would all be water and no solute
water potential - Answersis a special case of chemical potential and has four main contributing factors
1)solutes - the free energy gradients (negative number)
2) pressure- pressure by squeezing one side, causing a free energy gradient to go from higher pressure
to lower pressure
3)heat (temp) - increasing kinetic energy will increase pressure so the water will move from the heated
and rapid moving side, to the other side
4)gravity- one membrane above the other is gonna set a energy gradient, causing it to move downwards
the water potential equation - Answerswater potential = sum of component potentials, where the solute
is gonna be negative and the rest r positive values
now in biological systems, temp and gravity ptiential are neglible
so really its water potential = solute + pressure potential
so if the soltue potential is bigger than pressure potential, then water potential will be a negative value
where do cells gets water from - Answersfor plants, they get it from the root
for animals, they get it from drinking water
water can also come from the food so metabolic water
and bound water which is water molecules bound to fuel molecules such as glycogen
whats the problem w living in salter water - Answerswater is gonna wanna leave the plant due to
osmotic gradients, but there are self defense mechanisms for that
ex, mangrove trees
how does metabolic water work - Answersin the cellular metoblism equation, we see one mole of
gluocose gives us 6 molecules of h20,
,lipids give us 2x more water, than carbs and proteins
how do pressure gradients drive fluid transport - Answersanimals use positive pressure to push the
fluids through their pipes
plants use negative pressure to pull fluids up into their roots and leaves
but in both cases, fluids move from higher to lower pressures,
Soil water potential equation - Answerssolute water potential (negative) + pressure water potential
(negative) + temp water potential (posititve) + gravity water potential (pos/neg) = soil water potential
the pressure water potential is the most dominant in this equation
how does a plant get water from the soil - Answers- there are root hairs to increase the surface area of
the root
- the water is taken up by the root hairs and root tips, not really the root tho cuz the epidermis isnt
permable to water
- water is then absorbed by the roots, creating a pressure gradient
why do plants need vascular transport - Answers- they need it to carry sugars from the leaves to other
tissues
- its also used to trnasmit hormones from sites where its made, to sites where its needed
- also a way to carry nutrients and water, from the soil to the leaves
Xylem vs. Phloem - Answersthe xylem is unidirectional(stays in one direction) and moves water and
inorganic nutrients from the roots to the leaves
the phloem is multidirectional and moves the sugars, protiens and signalling molecules from their source
to the sink tissues
what r the 3 pathways of getting water into the xylem - Answers1)apoplast- it gets through the root hair
and then through the cell walls but cant get past the endodermis due to its casparian strips, so it cant
get to the xylem
2) symplasm - water gets throuhg from cell to cell through the plasmodesmata which egts across the
endodermis so it can bypass the lipid bilayer by getting through the plasmodesmata
, 3) transmembrane- water can get in through the root hair then it will go through the aquaproins from
cell to cell and also uses the aquoporin to bypass the caparian strip
the two types of xylem cells - Answers1) tracheids- long, narrow, have holes(pits) in them, so that the
water can go through tracheid to tracheid
2)vessel elements- have perforation plates which are like holes at the top and bottom, and pits on the
side walls, faster mouvement of water
explain the mechanism of negative pressure - Answersthere is evaportation in the leaves which creates
tension, which causes water to be pulled up from the roots and so the negtive pressure has to be strong
enough to the get the water to travel all the way to the leaves
what r the 3 mechanisms that r used to facilitate negative pressure - Answers1) root pressure- when
there is solute pumped in the xylem, the plant sets up an osmotic gradient to get water to move into the
xyelm whcih then causes a lower water potential so water moves in but cant move out due to casparian
strip, and so this causes root pressure that builds up in the xylem and to move all the way up, however
root pressure only provies 0.1 MPa, and we need 2 to reach the top of a tree
2)capillary force- inversely proportional to diameter, so the broader the root, the smaller the force, but
still not enough for a tree
3)cohesion-tension theory- a continous column of water moving from the soil to the leaves, with a
continous negative pressure, with a driving force from the transpiration of the stomata so evaporation
from the leaf basically
what r the two ways that breaks the column of water in the xylem - Answers1)cavitation - disolved gases
form bubbles under tension(frozen water, damage to xylem) in the water column
2)embolism- large gas bubbles that come together to block the path of water
how do we cope with cavitation - Answersthere is the buldge called the torus and it moves when there is
air pressure put upon it, and this repevents an embolism from being put together
what about plants with no torus? - Answersthese plants perforation plates isntead which are kinda like
drainers and cant prevent air bubble from getting through
how is an embolism repaired - Answersat night- transpiration stops so so the driving force stops, so the
gas bubbles go back into solution
spring- tension is elimaintated causing gas to redissolve
yearly - new layers of xylem every year , so if there is a xylem they just replace
why is the phloem able to flow in both directions - Answerscuz the contents of the phloem will always
flow from source to sink,
