Transport in Plants Practice Questions - DPP for NEET

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DPP /CB11
1. (d)
2. (c) Osmosis is the movement of solvent particles  from a
region of low solute concentration to a region of high
solute concentration through a selectively  permeable
membrane.
3. (b) 4. (c)
5. (d) The factors which affect the rate of transpiration are light –
stomatal opening, temperature – increases rate of
transpiration, humidity – low humidity increases the rate of
transpiration whereas high humidity exerts an opposite effect
i.e. decreases the rate, wind – high wind causes stomatal
closure, thereby, reducing the rate of transpiration in plants.
6. (a) Osmotic potential is the potential of a solution to cause
water movement into it across a semi- permeable membrane.
Water potential is the tendency of water to leave a system.
7. (d) Turgor pressure is the pressure that develops in a cell due
to osmotic diffusion of water  inside  it and is responsible
for pushing the membrane against cell wall. Stomata open
under conditions of increased turgor pressure of guard cells
and stomata gets closed under conditions of decreased
turgor pressure of guard cells. When turgid, they swell and
bend outward. As a result, the stomatal aperture opens.
When they are flaccid, the tension from the wall is released
and stomatal aperture closes.
8. (b) Active transport involves movement of ions against
concentration gradient involves the expenditure of energy.
Diffusion involves the movement  of solute particles from
region of higher concentration to a region of lower
concentration. Pinocytosis is cell drinking. Brownian
movement is the random to and fro movement of atoms
and molecules.
9. (c)
10. (d) A solution having more solutes as compared to solution
having less number of solutes : former is known as
hypertonic and latter hypotonic. Hence, solution outside
the cytoplasm has more solutes (higher concentration) and
are hypertonic. If two solutions have same solute
concentration then they are isotonic.
11. (b)
12. (a) During sodium-potassium pump, the concentration of sodium
ions will be about 14 times more in extra cellular fluid (outside)
and concentration of potassium ions will be about 28-30
times more in axoplasm (inside). Thus, 3Na
+
 and 2K
+ 
are
transported during the process.
13. (a) In rainy season, door gets swelled due to the phenomenon
of imbibition. It is the process of absorption of water
without forming a solution.
14. (c) Cell placed in a hypotonic solution becomes turgid due to
endosmosis. Water exerts a pressure on the walls of the
cell called turgor pressure. Cell wall being a rigid and hard
structure also exerts a pressure on Cytoplasm in response
to Turgor pressure when TP = WP, DPD = 0 (No net
exchange of water).
15. (a) The pure water, at atmospheric pressure has zero water
potential. The addition of any solute particles reduces the
free energy of water. Thus, the water potential will be negative.
16. (b)
17. (b) Water logging of soil makes it physiologically dry because
this condition does not allow oxygen to enter the soil.
18. (c) 19. (b) 20. (b)
21. (b) The absorption of water still occurs when concentration of
outer soil water is more than root hair cell sap.
22. (d)
23. (b) With increasing humidity, the rate of transpiration decreases
linearly, because the high saturation of water vapour in the
atmosphere prevents the evaporation of more water from
the leaf interior to the exterior.
24. (b) 25. (b)
26. (d) If we cut a small soft-stemmed plant on a day, when there is
plenty of atmospheric moisture, early in the morning we will
soon see drops of solution ooze out of the cut stem; this
comes out due to the positive root pressure. If we fix a
rubber tube to the cut stem as a sleeve we can actually collect
and measure the rate of exudation, and also determine the
composition of the exudates. Root pressure is a positive
pressure that develops in the xylem sap of the root of some
plants. It is a manifestation of active water absorption. Root
pressure is observed in certain seasons which favours
optimum metabolic activity and reduce transpiration. It is
more during rainy season in the tropical countries and during
spring in temperate habitats.
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DPP /CB11
1. (d)
2. (c) Osmosis is the movement of solvent particles  from a
region of low solute concentration to a region of high
solute concentration through a selectively  permeable
membrane.
3. (b) 4. (c)
5. (d) The factors which affect the rate of transpiration are light –
stomatal opening, temperature – increases rate of
transpiration, humidity – low humidity increases the rate of
transpiration whereas high humidity exerts an opposite effect
i.e. decreases the rate, wind – high wind causes stomatal
closure, thereby, reducing the rate of transpiration in plants.
6. (a) Osmotic potential is the potential of a solution to cause
water movement into it across a semi- permeable membrane.
Water potential is the tendency of water to leave a system.
7. (d) Turgor pressure is the pressure that develops in a cell due
to osmotic diffusion of water  inside  it and is responsible
for pushing the membrane against cell wall. Stomata open
under conditions of increased turgor pressure of guard cells
and stomata gets closed under conditions of decreased
turgor pressure of guard cells. When turgid, they swell and
bend outward. As a result, the stomatal aperture opens.
When they are flaccid, the tension from the wall is released
and stomatal aperture closes.
8. (b) Active transport involves movement of ions against
concentration gradient involves the expenditure of energy.
Diffusion involves the movement  of solute particles from
region of higher concentration to a region of lower
concentration. Pinocytosis is cell drinking. Brownian
movement is the random to and fro movement of atoms
and molecules.
9. (c)
10. (d) A solution having more solutes as compared to solution
having less number of solutes : former is known as
hypertonic and latter hypotonic. Hence, solution outside
the cytoplasm has more solutes (higher concentration) and
are hypertonic. If two solutions have same solute
concentration then they are isotonic.
11. (b)
12. (a) During sodium-potassium pump, the concentration of sodium
ions will be about 14 times more in extra cellular fluid (outside)
and concentration of potassium ions will be about 28-30
times more in axoplasm (inside). Thus, 3Na
+
 and 2K
+ 
are
transported during the process.
13. (a) In rainy season, door gets swelled due to the phenomenon
of imbibition. It is the process of absorption of water
without forming a solution.
14. (c) Cell placed in a hypotonic solution becomes turgid due to
endosmosis. Water exerts a pressure on the walls of the
cell called turgor pressure. Cell wall being a rigid and hard
structure also exerts a pressure on Cytoplasm in response
to Turgor pressure when TP = WP, DPD = 0 (No net
exchange of water).
15. (a) The pure water, at atmospheric pressure has zero water
potential. The addition of any solute particles reduces the
free energy of water. Thus, the water potential will be negative.
16. (b)
17. (b) Water logging of soil makes it physiologically dry because
this condition does not allow oxygen to enter the soil.
18. (c) 19. (b) 20. (b)
21. (b) The absorption of water still occurs when concentration of
outer soil water is more than root hair cell sap.
22. (d)
23. (b) With increasing humidity, the rate of transpiration decreases
linearly, because the high saturation of water vapour in the
atmosphere prevents the evaporation of more water from
the leaf interior to the exterior.
24. (b) 25. (b)
26. (d) If we cut a small soft-stemmed plant on a day, when there is
plenty of atmospheric moisture, early in the morning we will
soon see drops of solution ooze out of the cut stem; this
comes out due to the positive root pressure. If we fix a
rubber tube to the cut stem as a sleeve we can actually collect
and measure the rate of exudation, and also determine the
composition of the exudates. Root pressure is a positive
pressure that develops in the xylem sap of the root of some
plants. It is a manifestation of active water absorption. Root
pressure is observed in certain seasons which favours
optimum metabolic activity and reduce transpiration. It is
more during rainy season in the tropical countries and during
spring in temperate habitats.
27. (c) Cohesion tension theory (Cohesion-tension and transpiration
pull theory) explains the ascent of sap best. It was put forward
by Dixon and Jolly in 1894. It was further improved by
Dixon in 1914. Therefore, the theory is also named after him
as Dixon's theory of ascent of sap. Today most of the workers
believe in this theory.
28. (a) Sap will flow from high to low pressure areas in the plant.
Adding sugars to the sap causes water to enter the phloem,
thus increasing pressure. Removing sugars causes water to
leave the phloem, thereby reducing pressure.
29. (c) The water potential is the sum of the osmotic potential
(usually negative) and the pressure potential (usually
positive), so WP = –0.24 + 0.16 = –0.08 mPa.
30. (a) Guttation is caused by root pressure. It is only important to
the movement of water in quite small plants.
31. (d) As leaf cells lose water, they release abscisic acid, which
causes potassium ions to leave guard cells, decreasing their
pressure potential and closing stomata.
32. (b) As carbon dioxide is fixed into organic acids at night the pH
decreases; metabolism of these acids during the day (with
the carbon dioxide going into the citric acid cycle) causes the
pH to increase.
33. (a) Choices b, c, and d are true for phloem transport only.
34. (c) Sugar molecules diffuse through the symplast of mesophyll
cells, are pumped into the apoplast near a vein, re-enter the
symplast of a companion cell, and then move into a sieve
tube element.
35. (a) The intercellular spaces and cell walls of the plant constitute
the apoplast.
36. (a) Transpiration causes tension.
37. (d) Abscisic acid, light, and carbon dioxide levels all regulate
stomatal opening and closing.
38. (a) Stomatal regulators work by activating and deactivating the
proton pump in guard cells.
39. (d) 40. (c) 41. (c) 42. (a)
43. (b) The tension created by the evaporation of water from leaf
surfaces generates a pull on the water column that moves
water and nutrients up the xylem from the roots to the leaves.
44. (c) 45. (d)