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

Water absorbed by the roots reaches the leaves and is used in producing food for the entire plant.

  1. True

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

The leaves prepare food for the plant, using water and carbon dioxide during photosynthesis. The roots have root hair. The roots hair increase the surface area of the root for the absorption of water and mineral nutrients dissolved in the water.

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

Ascent of sap is best explained by.

  1. Mass (bulk) flow

  2. Pulsation theory

  3. Root pressure

  4. Cohesion-tension transpiration pull
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The cohesion-tension theory is a theory of intermolecular attraction that explains the process of water flow upwards (against the force of gravity) through the xylem of plants. Transpiration pull, utilizing capillary action and the inherent surface tension of water, is the primary mechanism of water movement in plants.
Answer is D.

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 major driving force in the movement of water in the xylem is 

  1. Osmotic pressure

  2. gravitational pull

  3. transpiration pull

  4. Diffussion pressure
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The movement of water in the xylem is explained by the cohesion-tension theory. According to this theory, the water moves up in the xylem via the force of transpiration which is created because of the evaporation of water from the leaves of the plant.

So, the correct answer is 'transpiration pull'.
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

Read the following statements regarding transaction and select the correct option
I. Transpiration is the loss liquid droplets from the plant
II. Low atmospheric pressure inhibits transpiration
III. Transpiration maintains the shape and structure of plant parts
IV. Cuticular transpiration takes place only during day time

  1. I &II only

  2. I, II &III only

  3. III only

  4. None of the statements are true
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • The process of loss of water from the aerial part of the plant in the form of vapor is known as transpiration.
  • It is of three types:-
(i) Cuticle transpiration (loss of water from cuticles),
(ii)Lenticular transpiration (loss of water from lenticels)
(iii)Stomatal transpiration (loss of water from stomata)
  •  Atmospheric pressure, humidity, and temperature are some factor that affects transpiration.
So, the correct option is 'None of the statements are true'.
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

Read the following statements and identify the incorrect difference between transpiration pull and root pressure.

Transpiration pull Root pressure
$(1)$ Acts as main driving force for translocation of water in tall trees It establishes chain of water molecules in xylem of tall trees
$(2)$ Its magnitude is maximum during day time Its magnitude is maximum during early morning and night
$(3)$ It generates a strong positive water potential in xylem It is a negative hydrostatic pressure developed in xylem
$(4)$ It is manifestation of passive water absorption It generates from active water absorption
  1. $1$
  2. $2$
  3. $3$
  4. $4$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Statement 1 is incorrect because transpiration pull is the driving force for water movement, while root pressure is a minor contributor. The description in the table for statement 1 is swapped or incorrectly attributed.

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

A pressure that is responsible for pushing up water to small height in the stem is?

  1. Positive root pressure

  2. Turgor pressure

  3. Pressure gradient

  4. Negative root pressure
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Root pressure is a positive pressure that develops in the xylem of roots and can push water up to small heights in the stem.

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 plants can absorb water in the form of vapour from its atmosphere?

  1. All xerophytes

  2. Low transpiring cacti

  3. Succulent plants

  4. Epiphytes and lichen
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Epiphytes are the plants growing on other plants. They have hanging roots having velamen tissue, which can directly absorb moisture from atmosphere. 

Lichens are not plants but symbiotic associations between fungi and algae. They do not have well developed roots but the thallus making up their body can directly absorb moisture from atmosphere.

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

Movement of sap through the plant is facilitated by

  1. Absorption by roots and gravitational force

  2. Gravitational force and pull due to transpiration

  3. Pull due to transpiration and absorption by roots

  4. Weight of sap and gravitational force
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The movement of sap in plants is primarily driven by the transpiration pull (cohesion-tension theory) and the absorption of water by roots.

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

Capillary action can cause

  1. Water uptake in tall plants

  2. Water uptake in small plants

  3. Both of the above

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

Water tends to rise up inside the narrow tubes by capillary action. This is because of the cohesive force of the water molecules. Because of this water rises up in the xylem vessel to some distance up dragging other water molecules present below them this capillary rise cannot take up water to tall plants though this may be possible in very small plants. Thus, the correct answer is option B.

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 movement of sap within the xylem is increased by

I. Water movement into guard cell's vacuoles.
II. Humidity increases in the surrounding air.
III. Root endodermis prevents ions from entering the xylem.

  1. I only

  2. II only

  3. I and III

  4. II and III

  5. I, II, and III
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The upward movement of water from the root to aerial parts of the plant body is called ascent of sap or translocation of water. This movement takes place through the xylem due to positive root pressure and is increased by the movement of water into the guard cells vacuoles. Thus, 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

A sufficient atmospheric pressure required to push the water upto the top of tall plants must be

  1. 2 atm

  2. 6 atm

  3. 20 atm

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

Taller plants like Eucalyptus need higher pressure to raise the water up. While the value of root pressure ranges from 2.5 atmospheres. A pressure of about 20 atm. is required to raise the water to tops of tall trees.

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 statement is/are  not true :-
A.In CAM plants stomata open during dark and remain closed during the day
B.Role of $Na^{+}$ in stomatal opening is now universally accepted
C.The water potential of root cells is higher than the water potential of soil
D.Capillary theory is the most accepted theory of water movement through plants
E.The walls of xylem vessels made up of ligno-cellulose have strong affinity for water molecules.

  1. B ,C and E only

  2. B ,C and D only

  3. A ,B and C only

  4. B and C only

  5. A and E only
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Statement B is false (Na+ role is not universally accepted), C is false (water potential of root cells is lower than soil), and D is false (Cohesion-tension theory is the most accepted, not capillary theory).

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

Force for passive water absorption develops in

  1. Xylem

  2. Aerial parts

  3. Root

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

The force for passive water absorption originates in the aerial parts of the plant due to loss of water in transpiration. This creates a tension or low water potential of several atmospheres in the xylem channels. 

Thus, the correct answer is option (B). 

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 which forces water upwards into tracheary elements of xylem in the root region is

  1. Transpiration

  2. Root pressure

  3. Turgor pressure

  4. Imbibition pressure
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. During low transpiration there is no transpiration pull that time root pressure increases and water moves upwards in xylem elements

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

Force for active water absorption is present in

  1. Xylem

  2. Aerial parts

  3. Root

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

Active water absorption is the absorption of water due to forces present in the root. Living cells in active metabolic condition are essential for this. Auxins are known to enhance water absorption (even from hypertonic solution) while respiratory inhibitors reduce the same.

Thus, the correct answer is option (C).