New MCQs
- Ringing/girdling experiments demonstrate
(a) phloem is responsible for translocation of food
(b) xylem is responsible for ascent of sap
(c) transpiration pull (d) both (a) and (b). - Which of the following theories gives the latest
explanation for the opening and closure of stomata?
(a) Starch-sugar conversion theory
(b) Munch theory
(c) Transpiration pull theory
(d) Active K+ transport theory - Match column-I with column-II and select the correct
option from the codes given below.
Column-I Column-II
A. Dixon and Jolly (i) Rate of transpiration
B. Stomata closure (ii) Transpiration pull
C. Potometer (iii) Only water available to
plants
D. Capillary water (iv) ABA
(a) A-(i), B-(iv), C-(ii), D-(iii)
(b) A-(ii), B-(iv), C-(i), D-(iii)
(c) A-(ii), B-(i), C-(iii), D-(iv)
(d) A-(iii), B-(ii), C-(i), D-(iv) - Which of the following statements is incorrect?
(a) Guard cells are kidney shaped in dicots and dumb
bell shaped in monocots.
(b) Free-floating hydrophytes possess epistomatic leaves.
(c) In xerophytes such as Opuntia, stomata are absent.
(d) Amphistomatic leaves are generally present in
monocots. - The transpiration-driven ascent of xylem sap depends
mainly upon _____ property of water.
(a) cohesion (b) adhesion
(c) surface tension (d) all of these - Which of the following is correct regarding the
translocation of substances in vascular tissues of plants?
(a) Organic substances, e.g., sugars are transported
upward in the xylem.
(b) Organic substances move up and down in phloem.
(c) Salts and other inorganic substances move
downward only through the xylem.
(d) Inorganic substances move upward only through
the pholem.
7. A girdled plant (upto bast) may survive for some time
but it will eventually die, because
(a) water will not move downwards
(b) water will not move upwards
(c) sugars and other organic materials will not move
downwards
(d) sugars and other organic materials will not move
upwards.
8. Guttation is the release of liquid water from veins at the
leaf margins. It is caused by
(a) transpiration
(b) high leaf pressure
(c) high root pressure
(d) clogged tracheids or vessel elements.
9. Wilting of a plant occurs when
(a) xylem is blocked
(b) phloem is blocked
(c) epidermis and few roots are removed
(d) pith is removed.
10. Translocation of minerals takes place through
(a) phloem (b) xylem
(c) cambium (d) wood parenchyma.
11. The continuity of water column in xylem is maintained
due to
(a) adhesive property of water
(b) cohesive property of water
(c) presence of air bubbles
(d) both (a) and (b).
12. Stomata of a plant open when guard cells show
(a) influx of hydrogen ions
(b) efflux of potassium ions
(c) influx of potassium ions
(d) all of these.
13. Potometer works on the principle of
(a) osmotic pressure
(b) amount of water absorbed equals the amount
transpired
(c) root pressure
(d) capillarity.
14. The rate of transpiration of a plant would gradually
increase if
(a) the relative humidity increases
(b) the relative humidity decreases
(c) the relative humidity remains unchanged
(d) the water potential gradient remains unchanged.