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in Botany
The osmotic potential of a solution is directly related to:
ATemperature only
BSolute concentration and temperature
CPressure only
DVolume of solvent only
Correct Answer:
B. Solute concentration and temperatureExplanation:
Osmotic potential (Ψs) = -iCRT, where it depends on solute concentration (C) and absolute temperature (T).
Which type of phloem tissue is responsible for translocation of sugars in plants?
ASieve tube members only
BCompanion cells only
CSieve tube members with companion cells
DPhloem fibers
Correct Answer:
C. Sieve tube members with companion cellsExplanation:
Sieve tube members conduct sugars while companion cells provide ATP and metabolic support for active transport.
The process by which plants lose water as water vapour through stomata is called:
AGuttation
BTranspiration
CImbibition
DExudation
Correct Answer:
B. TranspirationExplanation:
Transpiration is the loss of water vapour from aerial parts of plants, primarily through stomata during daytime.
In the light-dependent reactions, the splitting of water molecules produces oxygen, hydrogen ions, and:
ANADP+
BNADPH
CElectrons
DATP alone
Correct Answer:
C. ElectronsExplanation:
Water photolysis (2H2O → O2 + 4H+ + 4e-) releases electrons that are transferred through electron transport chains.
The enzyme RuBisCO catalyzes the fixation of CO2 by combining it with:
AGlyceraldehyde-3-phosphate
BRibulose-1,5-bisphosphate
CPhosphoenolpyruvate
DPyruvate
Correct Answer:
B. Ribulose-1,5-bisphosphateExplanation:
RuBisCO (Ribulose-1,5-bisphosphate carboxylase/oxygenase) catalyzes CO2 fixation with RuBP in the Calvin cycle.
Which of the following plants exhibits CAM (Crassulacean Acid Metabolism) photosynthesis?
AWheat
BRice
CPineapple
DMaize
Correct Answer:
C. PineappleExplanation:
CAM plants like pineapple, cactus, and agave fix CO2 at night into organic acids and release during day for photosynthesis.
The pulling force that moves water upward in xylem vessels is primarily due to:
ARoot pressure alone
BCapillary action alone
CTranspirational pull (tension) in xylem
DGravitational force
Correct Answer:
C. Transpirational pull (tension) in xylemExplanation:
Cohesion-tension theory explains that water is pulled upward due to transpirational pull creating negative pressure in xylem.
In the nitrogen cycle, the conversion of atmospheric N2 into ammonia is carried out by:
ANitrosomonas
BRhizobium
CNitrobacter
DThiobacillus
Correct Answer:
B. RhizobiumExplanation:
Rhizobium bacteria in root nodules of legumes fix atmospheric nitrogen into ammonia through nitrogenase enzyme.
When a plant wilts despite adequate soil moisture, this condition is called:
APermanent wilting point
BIncipient wilting
CPhysiological wilting
DHydration stress
Correct Answer:
C. Physiological wiltingExplanation:
Physiological wilting occurs when transpiration rate exceeds water absorption rate, though soil moisture is sufficient.
The double fertilization process in angiosperms results in the formation of:
ASeed coat and cotyledon
BEndosperm and embryo
CFruit and seed
DOvule and nucellus
Correct Answer:
B. Endosperm and embryoExplanation:
Double fertilization: one sperm fuses with egg nucleus (embryo), other fuses with polar nuclei (endosperm - 3n).
