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 botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

Prolonged water-logging kills plants due to

  1. Stoppage of root respiration

  2. Dilution of soil nutrients

  3. Dilution of plant cell sap

  4. Leaching of nutrients
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Waterlogging is the saturation of soil with water which excludes air from the groundwater. If waterlogging will be prolonged then air cannot reach up to groundwater and root and it will result in the stoppage of root respiration.
So, the correct answer is 'Stoppage of root respiration'.
Multiple choice botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

Which of the following is not an important factor in the regulation of transpiration?

  1. Light

  2. Temperature

  3. Humidity

  4. Nitrogen content in the soil
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Transpiration is the evaporation of the water molecule from the upper surface of leaves.

(A) The intensity of light is directly proportional to the amount of transpiration.
(B) With the temperature increase, the transpiration also increases.
(C) Humidity also affects the rate of transpiration.
(D) The nitrogen content in the soil does not affect the regulation of transpiration.
So, the correct answer is 'Nitrogen content in the soil'.

Multiple choice botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

The principle by which blotting paper absorbs water is 

  1. Capillary action

  2. Transpiration pull

  3. Root pressure

  4. Absorptive capacity
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
(A)Capillary action is the name of force by which water or any sap is pulled upwards direct through fine fibres or tubes. Blotting paper absorbs the water through capillary action only as thin threads like structure are present in blotting paper.
(B)Transpiration pull is also the process of upward movement of sap but it occurs during the process of transpiration.
(C)Root pressure is the transverse osmotic force causing sap rise in plants.
(D)Absorptive capacity is the capacity of absorption.
So, the correct answer is 'Capillary action'.
Multiple choice botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

Passive absorption occurs due to 

  1. Tension in root

  2. Tension in xylem sap

  3. ATP

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

Passive absorption is the absorption without the use of energy or ATP.

It occurs when there is tension in xylem sap which causes concentration gradient and liquid moves without the use of energy according to the concentration gradient.
So, the correct answer is 'Tension in xylem sap'

Multiple choice botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

Water potential of root cells is higher than water potential of soil.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Water potential is the potential energy of water per unit volume taking the reference of pure water. Water potential of the soil is higher than the water potential of root cell.

So, the correct answer is 'False'.

Multiple choice botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

Which of these is a factor not related to transpiration pull?

  1. Capillarity

  2. Adhesion

  3. Cohesion

  4. Ascent of sap
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
(A) Capillarity is the motion of the liquid in a narrow passage which travels only up to a certain point where it balances the force of gravity of the column.
(B) Adhesion is the force of attraction which leads to the attraction between water and xylem molecule necessary for transpiration pull.
(C) Cohesion is the phenomenon of attraction between similar molecules, which makes water molecule remain attracted to each other while being lifted up by transpiration pull. 
(D) The suction force which makes water to move in an upward direction is the ascent of sap caused by transpiration pull.
So, the answer is, "Capillarity".
Multiple choice botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

Transpiration - cohesion tension theory operates through

  1. Active absorption

  2. Passive absorption

  3. Active and Passive absorption

  4. Apoplastic movements
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
(A) Active absorption is the absorption process when it is being driven by the force present in the root which occurs through osmosis or use of active transport to move molecules of solutes to change the water concentration gradient.
(B) The force for passive absorption originates in the aerial part of the plant due to loss of water in transpiration which causes upward motion and cohesion theory is a theory of intermolecular attraction that explains the process of upward flow of water through the xylem.
(D) Apoplastic movement is the movement of water through the apoplast between loosely packed cortical cell which occurs in the root.
So, the answer is, "Passive absorption".
Multiple choice botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

Active absorption of water by roots from the soil is mainly affected by 

  1. Tension in cell sap due to transpiration.

  2. Hydrophobic nature of root hair.

  3. Typical tissue organisation.

  4. Osmotic concentration of xylem sap.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Active absorption is the movement of water molecule along the gradient with the use of energy.

Osmotic pressure is the movement of a solute particle from low concentration to high concentration through a semi-permeable membrane.
So, the water will move from a higher concentration to a lower concentration.

So, the correct option is 'Osmotic concentration of xylem sap'.

Multiple choice botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

If a soft stemmed plant is cut horizontally near the base of its stem with a sharp blade on early morning of a humid day, drop of solution ooze through cut stem. This is due to

  1. Guttation

  2. Bleeding

  3. Transpiration pull

  4. Root pressure
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

If we cut a small soft-stemmed plant on a day, when there is plenty of atmospheric moisture, early in the morning we will soon see drops of solution ooze out of the cut stem; this comes out due to the positive root pressure. If we fix a rubber tube to the cut stem as a sleeve we can actually collect and measure the rate of exudation, and also determine the composition of the exudates. Root pressure is a positive pressure that develops in the xylem sap of the root of some plants. It is a manifestation of active water absorption. Root pressure is observed in certain seasons which favour optimum metabolic activity and reduce transpiration. It is more during rainy season in the tropical countries and during spring in temperate habitats. So, the correct answer is 'Root pressure'.

Multiple choice botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

Wall of xylem vessels are made up of lignocellulose has a strong affinity for water molecules.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Xylem vessels are made up of a substance called lignin. In some xylem vessels contains lignocellulose which is the complex structure of lignin and cellulose also present in it. They are long hollow chains of which are made up of tough long dead xylem cells. Each of the vessels is interconnected to each other through a perforation in their common walls. Xylem vessels are hydrophobic in nature i.e, cell wall shows the greater affinity for water. With the help of this particular property only xylem vessel function as transportation of water and solutes from the roots to all parts of a plant. 

So, the correct answer is option A.

Multiple choice botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

The phenomenon related to active water absorption is

  1. Transpiration

  2. Root pressure

  3. Osmotic pressure

  4. Translocation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 Root pressure is the force in root region that helps to drive water or sap upwards into tracheary elements of xylem. Water is absorbed through the root hairs from the soil. When during low transpiration there is no transpiration pull that time root pressure increases and water moves upwards in xylem elements. Root pressure is actively push up the water to small height in the stem.

So the correct answer is 'Root pressure '.

Multiple choice biology seeds - structure and germination dicot seed monocot seed structure of monocot and dicot seed

In monocots, sieve tube first appears in

  1. Stem

  2. Leaves

  3. Roots

  4. Endosperm
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In monocots, sieve tube first appears in leaves. The main function of the sieve tube is transport of carbohydrates, primarily sucrose, in the plant (e.g., from the leaves to the fruits and roots). Unlike the water-conducting xylem vessel elements that are dead when mature, sieve elements are living cells. They are unique in lacking a nucleus at maturity.

Therefore, the correct answer is option B.

Multiple choice botany living world of plants - plant physiology historical events in photosynthesis history of photosynthesis introduction to photosynthesis

Root pressure theory was supported by

  1. Dixon

  2. Stephen Hales

  3. Levitt

  4. Sachs
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Root pressure theory was proposed by Prisetley and supported by Stephen Hales. Root pressure is defined as the pressure created in the xylem of the roots when the rate of absorption is greater than the rate of transpiration. The xylem sap is hypertonic to the water present in the soil as the xylem sap has high concentration of ions. This difference in the concentration allows the movement of water from high concentration in the soil  to the low concentration in the roots which creates a hydrostatic pressure in the roots known as root pressure.
So, the correct answer is option B.

Multiple choice botany the leaf mechanism of absorption mineral absorption significance of transpiration

Choose the correct answers from the alternatives given.
One important difference between the anatomy and physiology of roots and leaves is that

  1. Unlike roots, the xylem vessels in leaves normally transport sap in both directions

  2. A waxy cuticle covers most leaves but is absent in roots

  3. Leaves, but not roots, have ground tissue consisting mainly of parenchyma cells

  4. Phloem always conducts sap away from leaves and toward roots
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The leaves are covered with waxy cuticle but roots do not possess any cuticle. Cuticle helps in preventing loss of water from the surface of the leaves. Since roots are present underground immersed in the soil they do not show transpiration and hence no cuticle is present. 

Hence, the correct answer is 'A waxy cuticle covers most leaves but is absent in roots'.