Prepare for NEET with Botany-specific practice questions. Covering all major Botany chapters, this is perfect for your NEET Biology needs.
In an experiment, a researcher selectively removes histone H4 from chromatin. Which of the following is the MOST likely immediate consequence?
Increased condensation of the chromatin fiber.
Enhanced binding of RNA polymerase to promoter regions.
Specific activation of a subset of genes.
Significant destabilization of the nucleosome core and loss of DNA wrapping.
In a recalcitrant seed, which physiological factor is PRIMARILY responsible for its inability to withstand desiccation?
Presence of germination inhibitors that prevent metabolic slowdown
Lack of protective proteins that stabilize cellular components during drying
High sensitivity of cellular membranes to dehydration damage
Rapid depletion of stored reserves during the early stages of desiccation
Lipid rafts are specialized microdomains within the cell membrane. Which of the following statements about their composition and function is INCORRECT?
They are enriched in cholesterol and sphingolipids.
They are involved in signal transduction and membrane trafficking.
They exhibit reduced fluidity compared to the surrounding membrane.
They are primarily composed of unsaturated phospholipids and peripheral membrane proteins.
The fluidity of the cell membrane is influenced by several factors. Which of the following would DECREASE membrane fluidity?
Increased proportion of unsaturated fatty acids
Shorter fatty acid chain length
Increased cholesterol content at high temperatures
Decreased cholesterol content at low temperatures
Imagine a U-shaped tube with a selectively permeable membrane separating two solutions. Side A contains a 0.2M sucrose solution, and Side B contains a 0.1M NaCl solution. Initially, the levels are equal. Considering the dissociation of NaCl and the non-penetrating nature of sucrose and NaCl, which side will have a higher level at equilibrium?
Side A
Side B
The levels will remain equal
The membrane will rupture
A researcher is studying facilitated diffusion of a novel solute 'X' across a cell membrane using an artificial lipid bilayer system. They observe that increasing the concentration of X on one side of the membrane increases the rate of transport, but only up to a certain point. Beyond this point, further increases in X concentration do not affect the transport rate. Which of the following BEST explains this observation?
The membrane has reached its maximum permeability for X.
The solute X is being actively transported at higher concentrations.
Saturation of the carrier proteins
The solute X is inhibiting its own transport through feedback regulation.
In a hypothetical cell, the facilitated diffusion of a solute 'Y' is observed to be significantly faster than predicted by simple diffusion models. However, the transport rate plateaus at high concentrations of Y. Which of the following is the MOST likely explanation for this observation?
The cell membrane is selectively permeable to Y.
The solute Y is transported via carrier proteins.
The solute Y is undergoing active transport.
The cell is modifying Y during transport.
Which of the following statements regarding facilitated diffusion is INCORRECT?
It requires transport proteins.
It is a passive process and does not require energy.
It can move molecules against their concentration gradient.
Transport proteins involved can become saturated.
A dry wooden block and a dry gelatine block of equal mass are placed in water. The gelatine block imbibes considerably more water than the wooden block. This difference is primarily attributed to:
The higher density of wood compared to gelatine.
The greater number of hydrophilic colloids in gelatine compared to wood.
The presence of lignin in wood, which repels water.
The lower osmotic potential of gelatine compared to wood.
Which of the following scenarios would result in the LEAST efficient water absorption by a plant's roots?
Slightly acidic soil with optimal nutrient availability
Well-aerated soil with moderate water content
Low soil temperature coupled with high humidity
High soil salinity coupled with low soil oxygen levels
