BIO 304 - EXAM 1 REVIEW QUESTIONS
WITH DETAILED VERIFIED ANSWERS
A plant with plenty of light and water is growing poorly,
suggesting that it has a mineral deficiency. The plants symptoms
are as follows: old leaves are bright green while new leaves are
yellowish with green veins.
a. Is the plant lacking a mobile or an immobile nutrient?
b. Pick one nutrient of the type above (mobile or immobile) and
describe the functions of that nutrient in the plant. - correct
answer- Since the deficiency is occurring within newer
leaves, we know this plant is lacking an immobile nutrient. If the
nutrient needed was mobile, it would be able to travel through
phloem to reach the new leaves.
An immobile nutrient, calcium, would cause necrosis in
meristems, deformed young leaves, and a stunted, highly
branched root system. Calcium is responsible for regulatory
functions, stabilizing cellular membranes, signal transduction,
cell wall structure, and is an enzyme cofactor.
Be able to draw and label the internal and external parts of a
leaf. What are the functions of each part? - correct answer-
epidermis-epidermal and guard cells, trichomes, and root hairs
for protection, gas and nutrient exchange
,collenchyma- primary wall with uneven thickenings, for support
xylem- tracheids, vessels, fibers dead at maturity to help
conduct water and nutrients
phloem- seive-tube elements, compantion cells, fibers (dead at
maturity), transport of sugars, amino acids, etc.
Consider a plant 20 cm tall growing in well watered soil. In a
dark and humid greenhouse, in the middle of the night, you
measure the turgor pressure of a living leaf cell of this plant
using a probe inserted in the cell. You find that the turgor
pressure is 1.9 MPa. Given the current conditions, what is your
prediction of the osmotic potential of this cell? - correct
answer- -At night and in the dark-> soil and root and leaf
solute potentials at equilibrium, well watered, can ignore solute
potential.
-only forces contributing to water potential are pressure
potential and osmotic potential, since plant is only 20 cm
- PSIw= PSIs + PSIp + PSIg + PSIm
- 0 = 0 + 1.9 MPa + 0 - 1.9 Mpa
*osmotic potential needs to be -1.9 Mpa to be at equilibrium
, Describe how plant cells synthesize cell walls - correct
answer- cell walls are synthesized by membrane-bound
proteins in phospholipid bilayer, direction of movement is
determined by pathways of microfibrils, formed by cross-
linkages of cellulose strands and pectin, with a tensile strength
stronger than steel.
Describe the major theory used to explain the movement of
water through the xylem.
a. What evidence supports this theory?
b. What are the alternate theories for xylem transport?
c. What are the reasons these alternate theories are not
accepted? - correct answer- Cohesion-Tension Theory
explains the phenomena of how water travels so high in a plant
against gravity
-water vapor diffuses out of leaf through stomata to the
atmosphere when it is open (controlled by turgor pressure)
- pressure in extracellular spaces decreases, causing a
continuous 'pull' all the way back through the plant
- supported by xylem pressure probe experiment, found that
xylem pressure decreases when light intensity increases, and
higher light intensity reduced the weight of the plant, suggesting
greater water loss via transpiration
WITH DETAILED VERIFIED ANSWERS
A plant with plenty of light and water is growing poorly,
suggesting that it has a mineral deficiency. The plants symptoms
are as follows: old leaves are bright green while new leaves are
yellowish with green veins.
a. Is the plant lacking a mobile or an immobile nutrient?
b. Pick one nutrient of the type above (mobile or immobile) and
describe the functions of that nutrient in the plant. - correct
answer- Since the deficiency is occurring within newer
leaves, we know this plant is lacking an immobile nutrient. If the
nutrient needed was mobile, it would be able to travel through
phloem to reach the new leaves.
An immobile nutrient, calcium, would cause necrosis in
meristems, deformed young leaves, and a stunted, highly
branched root system. Calcium is responsible for regulatory
functions, stabilizing cellular membranes, signal transduction,
cell wall structure, and is an enzyme cofactor.
Be able to draw and label the internal and external parts of a
leaf. What are the functions of each part? - correct answer-
epidermis-epidermal and guard cells, trichomes, and root hairs
for protection, gas and nutrient exchange
,collenchyma- primary wall with uneven thickenings, for support
xylem- tracheids, vessels, fibers dead at maturity to help
conduct water and nutrients
phloem- seive-tube elements, compantion cells, fibers (dead at
maturity), transport of sugars, amino acids, etc.
Consider a plant 20 cm tall growing in well watered soil. In a
dark and humid greenhouse, in the middle of the night, you
measure the turgor pressure of a living leaf cell of this plant
using a probe inserted in the cell. You find that the turgor
pressure is 1.9 MPa. Given the current conditions, what is your
prediction of the osmotic potential of this cell? - correct
answer- -At night and in the dark-> soil and root and leaf
solute potentials at equilibrium, well watered, can ignore solute
potential.
-only forces contributing to water potential are pressure
potential and osmotic potential, since plant is only 20 cm
- PSIw= PSIs + PSIp + PSIg + PSIm
- 0 = 0 + 1.9 MPa + 0 - 1.9 Mpa
*osmotic potential needs to be -1.9 Mpa to be at equilibrium
, Describe how plant cells synthesize cell walls - correct
answer- cell walls are synthesized by membrane-bound
proteins in phospholipid bilayer, direction of movement is
determined by pathways of microfibrils, formed by cross-
linkages of cellulose strands and pectin, with a tensile strength
stronger than steel.
Describe the major theory used to explain the movement of
water through the xylem.
a. What evidence supports this theory?
b. What are the alternate theories for xylem transport?
c. What are the reasons these alternate theories are not
accepted? - correct answer- Cohesion-Tension Theory
explains the phenomena of how water travels so high in a plant
against gravity
-water vapor diffuses out of leaf through stomata to the
atmosphere when it is open (controlled by turgor pressure)
- pressure in extracellular spaces decreases, causing a
continuous 'pull' all the way back through the plant
- supported by xylem pressure probe experiment, found that
xylem pressure decreases when light intensity increases, and
higher light intensity reduced the weight of the plant, suggesting
greater water loss via transpiration
