Mineral Transport Practice Questions
20 free Mineral Transport practice questions for the NCERT Biology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Unlike water, most minerals cannot be absorbed by the roots passively because:
- A Minerals exist as ions that cannot cross lipid bilayers without protein carriers
- B The concentration of minerals in the soil is usually higher than in the root cell sap.
- C Minerals are too large to pass through the pores in the cell wall.
- D Root hairs lack the membrane proteins needed for mineral transport.
Correct answer: Minerals exist as ions that cannot cross lipid bilayers without protein carriers
Minerals exist in the soil as ions which cannot cross lipid bilayers without assistance. Additionally, the concentration of minerals in the soil is usually lower than in the root, requiring energy for uptake against a gradient.
The active uptake of ions from the soil into the root cells is responsible for:
- A Decreasing the osmotic potential of the root hair cells
- B Creating a water potential gradient that draws water in passively
- C Lowering the turgor pressure inside the root hair cells
- D Preventing the movement of water toward the xylem vessels
Correct answer: Creating a water potential gradient that draws water in passively
Active transport of ions into the root vascular tissue lowers the water potential inside. This creates a gradient that allows water to follow the minerals into the root via osmosis.
Which of the following acts as 'control points' where a plant adjusts the quantity and types of solutes that reach the xylem?
- A Epidermal cells
- B Cortical cells
- C Endodermal cells
- D Pericycle cells
Correct answer: Endodermal cells
Endodermal cells have transport proteins embedded in their plasma membranes. Because of the Casparian strip, all solutes must pass through these membranes, allowing the plant to selectively regulate mineral entry.
The movement of ions into the 'free space' or 'outer space' of the cell without the expenditure of metabolic energy is known as:
- A Rapid water loss by transpiration pulling the xylem sap
- B Active secretion of water molecules into the xylem
- C Active ion uptake into vascular tissues drawing water by osmosis
- D Passive diffusion of sugar from phloem into the xylem
Correct answer: Active ion uptake into vascular tissues drawing water by osmosis
As various ions from the soil are actively transported into the vascular tissues of the roots, water follows (its potential gradient) and increases the pressure inside the xylem. This positive pressure is called root pressure.
During the uptake of ions, the 'inner space' refers to the:
- A Cell wall and intercellular spaces
- B Cytoplasm and vacuole
- C Space between the epidermis and cortex
- D Xylem vessel lumen
Correct answer: Cytoplasm and vacuole
In plant physiology, the 'inner space' refers to the symplast, which includes the cytoplasm and vacuole. Movement into this space is generally active and requires the expenditure of metabolic energy.
What is the primary cause of 'Root Pressure' in plants?
- A Rapid transpiration from leaf surfaces
- B Active secretion of water into the xylem
- C Active absorption of ions into the vascular tissues followed by water
- D Passive diffusion of sugars from the phloem
Correct answer: Active absorption of ions into the vascular tissues followed by water
As various ions from the soil are actively transported into the vascular tissues of the roots, water follows (its potential gradient) and increases the pressure inside the xylem. This positive pressure is called root pressure.
In which condition is root pressure most easily observed in plants?
- A During peak sunlight with high wind and low humidity
- B When evaporation is low and soil moisture is high
- C In very tall trees such as coastal Sequoia redwoods
- D During periods of prolonged severe drought
Correct answer: When evaporation is low and soil moisture is high
Root pressure is most observable when transpiration is low (such as at night or early morning) and soil moisture is high. Under these conditions, the positive pressure pushes water out of specialized leaf openings.
The loss of water in the form of liquid droplets around special openings of veins near the tip of leaves is called:
- A Transpiration
- B Guttation
- C Evaporation
- D Bleeding
Correct answer: Guttation
Guttation is the result of positive root pressure. It occurs through specialized structures called hydathodes when the rate of water absorption exceeds the rate of transpiration.
Chief sinks for the mineral elements in plants are:
- A Mature leaves and older bark tissue
- B Apical meristems, young leaves, and developing fruits
- C Xylem vessels, tracheids, and fibres
- D Rhizosphere soil surrounding the root tips
Correct answer: Apical meristems, young leaves, and developing fruits
Minerals are transported to the parts of the plant that have the highest metabolic demand. These include growing regions (meristems), young leaves, developing flowers, fruits, and seeds.
Which of the following minerals is not easily remobilized from older senescing leaves to younger parts of the plant?
- A Nitrogen (N)
- B Phosphorus (P)
- C Calcium (Ca)
- D Potassium (K)
Correct answer: Calcium (Ca)
Calcium is a structural component of the cell wall (middle lamella) and is not easily remobilized. Elements like nitrogen, phosphorus, and potassium are readily exported from old leaves before they fall.
Analysis of xylem exudates shows that nitrogen is mainly carried in the form of:
- A Atmospheric nitrogen gas ($N_2$) dissolved in water
- B Inorganic ions like nitrate ($NO_3^-$) and nitrite ($NO_2^-$)
- C Organic forms such as amino acids and amides
- D Ammonia gas ($NH_3$) produced by root decomposition
Correct answer: Organic forms such as amino acids and amides
While some nitrogen travels as inorganic ions, much of it is converted into organic forms like amino acids within the roots before being transported through the xylem. Similarly, small amounts of P and S are carried as organic compounds.
The concept that xylem only transports water/minerals and phloem only transports organics is no longer strictly accurate because:
- A Xylem can also transport sugars to roots during summer dormancy.
- B Small amounts of material are exchanged between xylem and phloem.
- C Phloem is the primary transporter of nitrogenous ions in all seasons.
- D Xylem is composed entirely of metabolically active living cells.
Correct answer: Small amounts of material are exchanged between xylem and phloem.
Chemical analysis reveals that there is an exchange of materials between xylem and phloem. Both organic and inorganic solutes can be found in both tissues, though they have primary roles.
The layer of cells containing the Casparian strip is the:
- A Epidermis
- B Endodermis
- C Pericycle
- D Hypodermis
Correct answer: Endodermis
The endodermis is the innermost layer of the root cortex. Its cell walls are impregnated with suberin (Casparian strip), which acts as a barrier to the apoplastic movement of water and minerals.
What happens to the rate of mineral absorption if the roots are deprived of oxygen?
- A It increases because ions move faster with less oxygen interference.
- B It stays unchanged because mineral uptake is a purely physical process.
- C It decreases because active transport depends on ATP from aerobic respiration.
- D It increases sharply because the plant shifts to anaerobic stress metabolism.
Correct answer: It decreases because active transport depends on ATP from aerobic respiration.
Because most mineral uptake is an active process requiring metabolic energy (ATP), aerobic respiration in root cells is essential. Lack of oxygen inhibits ATP production, thus slowing down active mineral transport.
Translocation of minerals through the xylem is characterized as:
- A Unidirectional (Upwards)
- B Radial only
- C Multidirectional
- D Downward from leaves to roots
Correct answer: Unidirectional (Upwards)
In the xylem, the flow of water and minerals is unidirectional, moving from the roots to the stems and leaves, primarily driven by the transpirational pull.
Ions are absorbed from the soil by both passive and active transport, but ______ transport accounts for the majority of the uptake.
- A Passive (no energy needed)
- B Active (energy-driven)
- C Facilitated (channel-mediated)
- D Osmotic (water-driven)
Correct answer: Active (energy-driven)
While some passive movement occurs, the majority of mineral uptake is active because the concentration of minerals in soil is lower than in the root cells and ions cannot cross membranes without energy.
Specific proteins in the membranes of ______ cells actively pump ions from the soil into the cytoplasm of epidermal cells.
- A Cortex
- B Root hair
- C Xylem
- D Endodermis
Correct answer: Root hair
Root hair cells (epidermal cells) have specialized carrier proteins that use energy to pump ions from the soil into the cell, initiating the transport process.
Remobilization of minerals occurs primarily during:
- A During early seed germination
- B Leaf senescence (aging)
- C During periods of high transpiration
- D At the peak of active photosynthesis
Correct answer: Leaf senescence (aging)
Before leaves fall off (senescence) in deciduous plants or during the aging of older leaves, minerals like N, P, K, and Mg are moved to younger, growing parts of the plant.
Which of the following statements about root pressure is FALSE?
- A It is a positive pressure.
- B It can push water up to the tops of very tall trees.
- C It provides a modest push in the overall process of water transport.
- D It helps in re-establishing continuous water chains in xylem.
Correct answer: It can push water up to the tops of very tall trees.
Root pressure is a positive pressure but it is not strong enough to account for water movement in tall trees. Its main role is re-establishing the water column and providing a small push in smaller plants.
Mineral ions reach the xylem through which of the following pathways?
- A Through the apoplast pathway only
- B Through the symplast pathway only
- C Via apoplast or symplast, but must enter the symplast at the endodermis
- D Only through the cell walls of endodermal cells
Correct answer: Via apoplast or symplast, but must enter the symplast at the endodermis
Minerals can move through the cortex via the apoplast or symplast. However, the Casparian strip at the endodermis blocks the apoplast, forcing all minerals to enter the symplast to reach the xylem.