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

Whose water potential is less than water potential of root hair during water absorption (by root hair)?

  1. Gravitational water

  2. Pure water

  3. Vacuolar sap

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

For water to move into the root hair via osmosis, the water potential inside the root hair (specifically the vacuolar sap) must be lower than that of the 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

Rate of water absorption can be increased through 

  1. Decreased transpiration

  2. Decreased ion absorption

  3. Increased photosynthesis

  4. Increased transpiration
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The rate of transpiration is high on a bright sunny day. The water is lost from guard cell which leads to decrease in the water potential of guard cell as compared to the surrounding cell. To stabilize the water potential in the guard cell water rushes from the neighbouring cell which creates a cohesion pull in the xylem vessels to pull the water up to the guard cell. Thus, the rate of water absorption increases when the transpiration is high. 
So, the correct answer is option D.
Multiple choice biology transport in plant transport of water and minerals conduction of water and minerals absorption of water and minerals in plants

Roots play insignificant role in absorption of water in

  1. Sunflower

  2. Pistia

  3. Pea

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

Pistia is a hydrophyte where absorption of water by root is insignificant   It floats on the surface of the water, its roots hanging submersed beneath floating leaves. 

So the correct option is "pistia".

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

The transpiration-driven ascent of xylem sap depends mainly upon _______ property of water.

  1. Cohesion

  2. Adhesion

  3. Surface tension

  4. All of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

There is a continuous column of water from root through the stem and into the leaves. The water column is present in tracheary elements. The column of water does not fall down under the impact of gravity because forces of transpiration provide both energy and necessary pull. Cohesion, adhesion and surface tension-keep the water in place.

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 statements is incorrect?

  1. Endodermis is impervious to water due to the presence of suberized Casparian strips

  2. Xylem vessels and tracheids, being non-living, are parts of the apoplast

  3. Ascent of sap is best explained by root pressure theory

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cohesion tension theory(Cohesion-tension and transpiration pull theory) explains the ascent of sap best. It was put forward by Dixon and Jolly in 18941894. It was further improved by Dixon in 19141914. Therefore, the theory is also named after him as Dixon's theory of ascent of sap. Today most of the workers believe in this theory.

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

Choose the correct answers from the alternatives given.
Pressure on a plant cell wall caused by the osmotic movement of water is called

  1. Osmotic pressure

  2. Wall pressure

  3. Turgor pressure

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

When a plant cell is placed in the hypotonic solution, it causes endosmosis i.e. movement of surrounding water into the cell. This creates a turgor pressure against the rigid walls due to the entry of water.

Osmotic pressure is the hydrostatic pressure developed in a solution when it is separated from the pure solvent by a semi-permeable membrane in a rigid vessel.
Hence, the correct answer is 'Turgor pressure'.

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

Choose the correct answers from the alternatives given.
During the day most plants lose .......... and take up .......... 

  1. Carbon dioxide; oxygen

  2. Oxygen; water

  3. Water; oxygen

  4. Water; carbon dioxide
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

During the day time, plants lose a lot of water in the form of water vapour due to the process of transpiration. Whereas it takes up carbon dioxide through stomata to carry out photosynthesis.

Hence,the correct answer is 'Water; carbon dioxide'.

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

The most important factor for absorption of water in plants is?

  1. Living cell

  2. Force of capillarity

  3. Imbibition

  4. Cohesive force of water
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

While living cells and imbibition play roles, the force of capillarity (and the cohesive-adhesive properties of water) is the primary driver for the movement of water through the xylem in plants.

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

Which is not true regarding active water absorption?

  1. Require energy

  2. Occurs only when transpiration is slow

  3. Living cells are essential

  4. Force develops in shoot
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • Active absorption of water occurs in root cells which utilizes the metabolic energy released through respiration. It is of two types. Osmotic absorption is when water is ab­sorbed from the soil into the xylem of the roots according to the osmotic gradient. And Non-osmotic absorption is when water is absorbed against the osmotic gradient. Usually, transpiration is passive absorption but when it is low active absorption occurs. 
  • It takes place in living cells.
  • The force for passive absorption develops in shoot not of active absorption. 

So, the correct answer is 'Force develops in shoot'.
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 would not contribute to water uptake by plant cell?

  1. an increase in the water potential $\Psi $ of the surrounding solution

  2. a decrease in pressure on the cell exerted by the wall

  3. the uptake of solutes by the cell

  4. an increase in tension on the surrounding solution.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Plant absorb water from the soil by osmosis. Root hair cells are adapted for this by having a large surface area to speed up osmosis. The absorbed water is transported through the roots to the rest of the plant where it's used for different purposes. It's a reactant used in photosynthesis.

So, the correct option is 'an increase in the water potential of the surrounding 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 helps to move the water from root to xylem vessels?

  1. Stem cells

  2. Root cells

  3. Soil

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
In plants, transpiration is the process by which water and solutes are taken up by the roots and transported via the xylem to the leaves. 
The water passes from the soil to the root by osmosis. The long and thin shape of root hairs maximizes surface area and water passes from the soil to the root hairs. The next stage in the transpiration stream is water passing into the xylem vessels. The water either goes through the cortex cells (between the root cells and the xylem vessels) or it bypasses them – going through their cell walls. After this, the water moves up the xylem vessels to the leaves through diffusion.
So, the answer is B.
Multiple choice biology transport in plant transport of water and minerals conduction of water and minerals absorption of water and minerals in plants

Identify the vascular tissues in plants.

  1. Xylem

  2. Phloem

  3. Stem

  4. Both A and B
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Vascular tissue is an arrangement of multiple cell types in vascular plants which allows for the transport of water, minerals, product and of photosynthesis to be transported throughout the plant. There are two types of vascular tissues of a plant namely, xylem and phloem.
So the correct answer is 'Both A and B'.
Multiple choice biology transport in plant transport of water and minerals conduction of water and minerals absorption of water and minerals in plants

For absorption of water, the roots act as 

  1. Sucking organs

  2. Osmotic system

  3. Manometer

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

Osmosis occurs when there is a concentration gradient and water flows out from the region of high water potential to lower water potential. So for absorption of water roots act as an osmotic system because there is high er solute concentration (water) in the soil as compared to the roots due to which water is absorbed by the roots by osmosis.

So the correct answer is 'Osmotic system'.

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

Osmotic potential and pressure potential of three cells, a, b, c located in different parts of an actively transpiring plant are: 

Cell O.P (MPa) P.P. (MPa)
a -0.87 0.44
b -0.92 0.34
c -0.68 0.27

Which ones are root hair, root cortical and mesophyll cells respectively?

  1. a, b, c

  2. a, c, b

  3. c, a, b

  4. b, c, a
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  • Osmosis occurs only through the semi-permeable membrane. Osmosis is a gradient dependent process, osmosis is different from diffusion as it is characterized by a semi-permeable membrane.
  • Net direction and rate of osmosis depend on both pressure gradient and concentration gradient.
So, the correct answer is 'c, a, b'.