Biology

Plant Transport and Physiology

2,012 Questions

Access a comprehensive set of questions on plant transport mechanisms and physiological adaptations. Topics include water movement, translocation of food, and plant responses to external stimuli. These biology questions are essential for medical entrance exams and other science competitive tests.

Xylem and phloem transportTranspiration and evaporationPlant adaptationsGeotropic and phototropic responsesWater absorption by rootsRespiration in roots

Plant Transport and Physiology Questions

Multiple choice apical dominance auxins and gibberellins growth and development plant growth and development biology

To get a carpet like grass, lawns are mowed regularly, this is done to

  1. Remove the shoot apical meristem

  2. Remove the axillary buds

  3. Accelerate the growth of terminal bud

  4. Both (b) and (c)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The lawn is mowed regularly to remove apical meristem, and prevent vertical growth of the grass and enhance the growth of lateral buds whose growth is hindered due to apical dominance. This helps the grass get a spreading or carpet like appearance.

So, the correct answer is 'Remove the shoot apical meristem'

Multiple choice biology transport in plant transport of water and minerals conduction of water and minerals absorption of water and minerals in plants

The structures present in the roots to absorb water and minerals are 

  1. Epidermal appendages

  2. Epidermal extensions

  3. Hypodermis

  4. Endodermis
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • Root hairs are the lateral epidermal extensions or tubular outgrowths in the roots (zone of maturation) of plants.
  • The root hairs penetrate into the soil and prevent harmful microbes from entering the plant through the xylem vessels.
  • They increase the surface area for absorption of water and nutrients from the soil.
  • So, the correct answer is 'Epidermal extensions'.
Multiple choice biology transport in plant transport of water and minerals conduction of water and minerals absorption of water and minerals in plants

Select the correct sequence of passive absorption path of water in a plant

  1. Soil $\rightarrow $ Root hair $\rightarrow $ Epidermis $\rightarrow $ Secondary cortex $\rightarrow $ Endodermis $\rightarrow $ Pericycle $\rightarrow $ Metaxylem
  2. Soil $\rightarrow $ Root hair $\rightarrow $ Cortex $\rightarrow $ Passage cells $\rightarrow $ Pericycle $\rightarrow $ Root protoxylem $\rightarrow $ Root Metaxylem
  3. Soil $\rightarrow $ Epidermis $\rightarrow $ Cortex $\rightarrow $ Endodermis $\rightarrow $ Pericycle $\rightarrow $ Root metaxylem $\rightarrow $ Root protoxylem $\rightarrow $ Root hair
  4. Soil $\rightarrow $ Epidermis $\rightarrow $ Cortex $\rightarrow $ Pericycle $\rightarrow $ Endodermis $\rightarrow $ Root protoxylem
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Option (A)
Soil $\rightarrow$ Root hair $\rightarrow$ Epidermis $\rightarrow$ Secondary cortex $\rightarrow$ Endodermis $\rightarrow$ Pericycle $\rightarrow$ Metaxylem.
The absorption of water by plants is essential for various metabolic activities. Soil water enters into the cortical cells through root hairs to reach the xylem of roots to maitain the supply of water.
Multiple choice biology transport in plant transport of water and minerals conduction of water and minerals absorption of water and minerals in plants

At low temperature water absorption decreases due to
(I) An increase in the viscosity of water and protoplasm. 
(II) A decrease in the permeability of cell membranes.
(III) A decrease in the metabolic activities of root cells. 
(IV) A check in the growth and elongation of roots.

  1. I and II are correct

  2. I and III are correct

  3. I, II and III are correct

  4. All are correct
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

At low temperature, there will be physical changes in water and also water absorption, both due to active and passive means will decrease. There will be an increase in viscosity of water and decrease in respiration in roots. The decreased respiration will lead to reduced supply of ATP. Hence, active absorption will decrease. Also, growth of roots will suffer due to decrease in rate of metabolism. The cell membrane will become less permeable and there will be lesser movement of solutes across them. As temperature rises, the lipids become more fluidic and permit movement of more solutes across the membrane.

Multiple choice biology transport in plant transport of water and minerals conduction of water and minerals absorption of water and minerals in plants

In poorly aerated soil, the rate of water absorption will

  1. Increase

  2. Decrease

  3. Remains the same

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Poorly aerated soil, particularly when it is deficient in oxygen, retards absorption of water from the soil. Accumulation of $CO _2$ in the soil also inhibits absorption.

Multiple choice biology transport in plant transport of water and minerals conduction of water and minerals absorption of water and minerals in plants

Root cap plays no role in the absorption of water in a plant, because

  1. Its cells are loosely arranged.

  2. It has no root hairs.

  3. It has no connection with xylem tissue.

  4. Its cells are dead.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Root hairs are unicellular extensions of root epidermis or epiblema. They increase the surface area for absorption and are involved with absorption of water. Root cap typically lacks root hairs and hence not involved in absorption process.

Multiple choice biology transport in plant transport of water and minerals conduction of water and minerals absorption of water and minerals in plants

Maximum absorption of water by a root occur in the region of

  1. Cell division

  2. Cell elongation

  3. Cell maturation

  4. Cell division and root cap together
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In a typical dicot root; root hairs are present in the zone of cell maturation. Root hairs are unicellular extensions of root epidermis, called as epiblema, which absorb water due to increased surface area for absorption. Zone of cell division, zone of elongation and root cap generally lack root hairs.

Multiple choice biology transport in plant transport of water and minerals conduction of water and minerals absorption of water and minerals in plants

During absorption of water by roots, the water potential of cell sap is lower than that of

  1. Pure water and soil solution

  2. Neither pure water nor soil solution

  3. Pure water but higher than that of soil solution

  4. Soil solution but higher than that of pure water
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Water flows from higher water potential to lower water potential. Water potential of pure water is zero. As solutes are dissolved in it, the water potential decreases. More the dissolved solutes, lower will be the water potential. Water potential of all the solutions is always negative. Hence, water flows from higher water potential (i.e., less negative water potential) towards a lower water potential (i.e., more negative water potential). It is clear that absorption of water will occur if water potential of cell sap is lower than pure water and soil solution.

Multiple choice biology transport in plant transport of water and minerals conduction of water and minerals absorption of water and minerals in plants

Which of the following statement(s) is/are incorrect?

  1. Water and salts are taken simultaneously by root hairs.

  2. Plants absorb one thing at a time either water or inorganic salt.

  3. Plants absorb excess quantity of water.

  4. All of the above.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

It is wrong to believe that water absorption and absorption of mineral salts are two unrelated processes. In fact the active uptake of ions is partly responsible for the water potential gradient in roots, and therefore for the uptake of water by osmosis. Some ions also move into the epidermal cells passively. Since soil has less concentration of minerals; most of the minerals are absorbed actively.

Multiple choice biology transport in plant transport of water and minerals conduction of water and minerals absorption of water and minerals in plants

Lignin and cellulose have affinity for water. This is called

  1. Adhesion

  2. Cohesion

  3. Root pressure

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

  • The attraction between the molecules of dissimilar substances is termed as adhesion. 
  • Walls of tracheid and vessels of xylem are made up of lignin and the cellulose. Hence due to the adhesive force, they have a close affinity for water.
  • So, the correct answer is option A.

Multiple choice biology transport in plant transport of water and minerals conduction of water and minerals absorption of water and minerals in plants

Root hair absorbs water from soil through

  1. Turgor pressure

  2. Ion exchange

  3. Osmosis

  4. DPD
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Root hair absorbs water from soil through osmosis. Water will be absorbed by root hairs by osmosis as the environment in the soil is hypotonic. This kind of absorption takes place passively. The water can easily move from the region of higher concentration to the low concentration without expenditure of energy. The cell membrane of the root cells acts as a semipermeable membrane. It passes the epidermis, cortex, endodermis, casparian strip and pericycle and protoxylem and metaxylem.

So, the correct answer is option C.

Multiple choice biology transport in plant transport of water and minerals conduction of water and minerals absorption of water and minerals in plants

Loss of water taken place through.

  1. Stomata, cell wall of mesophyll cells and hydathodes

  2. Stomata and cell wall of mesophyll cells

  3. Stomata and hydathodes

  4. Cell wall of mesophyll cells and hydiahodes
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Water loss in plants occurs through transpiration (stomata), cuticular transpiration, and guttation (hydathodes). The cell wall of mesophyll cells is the site where evaporation starts, making option A the most comprehensive.