Question 1

   Question: Movement and accumulation of ions across a membrane against their concentration gradient can be explained by

   Options: 

       A. Facilitated Diffusion

       B. Passive Transport

       C. Active Transport

       D. Osmosis

   Correct Answer: C

   Year: [NEET 2023]

   Solution: Movement and accumulation of ions across a membrane against their concentration gradient can be explained by active transport. It uses energy to transport molecules from lower concentration to a higher concentration.

   Step Solution:

    1.  Observe the direction of ion movement: "against their concentration gradient."

    2.  Recall that moving substances "uphill" from low to high concentration requires metabolic energy.

    3.  Identify the transport mechanisms: Passive transport (Diffusion, Osmosis, Facilitated Diffusion) always moves substances "downhill" (along a gradient).

    4.  Conclusion: Only Active Transport utilizes ATP energy to move ions against a gradient.

   The difficulty level: Easy

   The Concept Name: Active Transport

   Short cut solution: Against gradient + Energy required = Active Transport.

Question 5

   Question: During symport two different molecules move across the membrane :

   Options: 

       A. in same direction with the help of different carriers located at a common site

       B. in same direction with the help of different carriers located at different sites in the same cell

       C. in same direction with the help of same carrier

       D. in opposite direction with the help of same carrier

   Correct Answer: C

   Year: [NEET 2023 mpr]

   Solution: Symport is a type of transport mechanism that occurs in a cell's membrane. In symport, two different molecules or ions are transported across the membrane in the same direction, but they are co-transported by the same carrier protein.

   Step Solution:

    1.  Define the prefix "sym-", which means "together" or "same."

    2.  Identify the number of molecules involved: Two different molecules.

    3.  Determine the direction: Same direction.

    4.  Identify the vehicle: A single/same carrier protein facilitates the move.

   The difficulty level: Easy

   The Concept Name: Symport (Cotransport)

   Short cut solution: Sym = Same direction; Anti = Opposite direction.

Question 7

   Question: When a carrier protein facilitates the movement of two molecules across the membrane in same direction, it is called :

   Options: 

       A. Symport

       B. Uniport

       C. Transport

       D. Antiport

   Correct Answer: A

   Year: [NEET Re-2022]

   Solution: Symport is the type of transportation where the two molecules move simultaneously in the same direction using carrier protein.

   Step Solution:

    1.  Analyze the query: Two molecules moving in the same direction.

    2.  Differentiate terms: Uniport (one molecule), Antiport (two molecules, opposite directions).

    3.  Select the term corresponding to "same direction" movement for two molecules.

   The difficulty level: Easy

   The Concept Name: Membrane Transport (Symport)

   Short cut solution: 2 molecules + Same direction = Symport.

Question 9

   Question: Which type of substance would face difficulty to pass through the cell membrane?

   Options: 

       A. Substance soluble in lipids

       B. Substance with hydrophobic moiety

       C. Substance with hydrophilic moiety

       D. All substance irrespective of hydrophobic and hydrophilic moiety

   Correct Answer: C

   Year: [NEET Re-2022]

   Solution: (The source lists C as the answer). Hydrophilic substances (water-loving) have difficulty passing through the non-polar, hydrophobic lipid bilayer of the cell membrane.

   Step Solution:

    1.  Identify the composition of the cell membrane: Primarily a lipid bilayer.

    2.  Recall the property of lipids: They are hydrophobic (non-polar).

    3.  Identify the property of the substance: Hydrophilic (polar/water-loving).

    4.  Apply "like dissolves like": Hydrophilic moieties cannot easily dissolve in or pass through the hydrophobic core of the membrane.

   The difficulty level: Easy

   The Concept Name: Membrane Permeability

   Short cut solution: Hydrophobic membrane repels Hydrophilic (water-loving) substances.

Question 15

   Question: Which of the following is not a feature of active transport of solutes in plants ?

   Options: 

       A. Requires ATP

       B. Occurs against concentration gradient

       C. Non-selective

       D. Occurs through membranes

   Correct Answer: C

   Year: 

   Solution: Active transport is uphill transport. This transport takes place against the electrochemical potential gradient and requires additional input of energy that chiefly comes from hydrolysis of ATP. It is highly selective.

   Step Solution:

    1.  List the known features of Active Transport: Requires energy (ATP), "uphill" movement (against gradient), and involves specific carrier proteins.

    2.  Evaluate the term "highly selective": Transport proteins only allow specific molecules/ions to pass.

    3.  Identify the incorrect statement: Non-selective is incorrect because active transport is highly selective.

   The difficulty level: Easy

   The Concept Name: Features of Active Transport

   Short cut solution: Carrier proteins = Specificity = Selectivity. (So "Non-selective" is wrong).

Question 17

   Question: Active and passive transports across cell membrane differ in :

   Options: 

       A. Passive transport is non-selective

       B. Passive transport is along the concentration gradient while active transport is due to metabolic energy.

       C. Active transport is more rapid

       D. Passive transport is confined to anions while active transport in confined to cations.

   Correct Answer: A

   Year: 

   Solution: Active transport is selective for a particular ion... sodium/potassium channel... Passive transport is non-selective it occurs along the concentration gradient so this kind of channel allow to transport of many types of ions across the membrane.

   Step Solution:

    1.  Recall the primary difference in selectivity: Active transport uses specific pumps.

    2.  Recall the primary difference in energy: Active uses ATP; Passive uses the natural gradient.

    3.  Identify the source's chosen distinction: It highlights that passive transport (like simple diffusion) lacks the specific "particularity" of active transport channels.

   The difficulty level: Medium

   The Concept Name: Selective Permeability/Transport

   Short cut solution: Active = Specific (Selective); Passive = General (Non-selective).

Question 30

   Question: Which of the following criteria does not pertain to facilitated transport?

   Options: 

       A. Transport saturation

       B. Uphill transport

       C. Requirement of special membrane proteins

       D. High selectivity

   Correct Answer: B

   Year: 

   Solution: Facilitated transport or facilitated division is the spontaneous passage of molecules or ions across a biological membrane passing through specific transmembrane integral proteins... importantly, neither channels nor carrier proteins require energy to facilitate the transport of molecules; they enable molecules to move down their concentration gradients (downhill transport).

   Step Solution:

    1.  Identify the nature of Facilitated Transport: It is a form of diffusion.

    2.  Recall the rule of diffusion: Movement is always from high to low concentration (downhill).

    3.  Assess the options: Saturation, proteins, and selectivity are all features of protein-mediated transport.

    4.  Conclusion: Uphill transport is an active process and does not happen in facilitated diffusion.

   The difficulty level: Easy

   The Concept Name: Facilitated Diffusion

   Short cut solution: Facilitated = Diffusion = Downhill only.

Question 42

   Question: Passive absorption of minerals depends on

   Options: 

       A. temperature

       B. temperature and metabolic inhibitor

       C. metabolic inhibitor

       D. humidity

   Correct Answer: A

   Year: 

   Solution: Rate of salt absorption increases when temperature increases but to a certain limit... Rate of diffusion of ions and molecules increases at enhanced temperature due to their increased kinetic activity. Thus passive salt absorption will increase.

   Step Solution:

    1.  Define passive absorption: It is driven by diffusion.

    2.  Identify the physics of diffusion: Movement depends on the kinetic energy of particles.

    3.  Relationship: Kinetic Energy $\propto$ Absolute Temperature ($T$).

    4.  Conclusion: Increased temperature enhances the rate of passive absorption.

   The difficulty level: Medium

   The Concept Name: Factors affecting Diffusion

   Short cut solution: Temperature $\uparrow$ = Kinetic Activity $\uparrow$ = Passive Diffusion $\uparrow$.

Question 45

   Question: The movement of ions against the concentration gradient will be

   Options: 

       A. active transport

       B. osmosis

       C. diffusion

       D. all of the above

   Correct Answer: A

   Year: 2000

   Solution: Active transport involves movement of materials across the membrane against the concentration gradient of the solute particles. It requires energy in the form of ATP and carrier molecules.

   Step Solution:

    1.  Identify the movement: "Against the concentration gradient."

    2.  Analyze "Diffusion" and "Osmosis": These are passive and move with the gradient.

    3.  Analyze "Active transport": It specifically pumps ions against a gradient using ATP.

   The difficulty level: Easy

   The Concept Name: Active Transport

   Short cut solution: Against gradient = Active Transport.