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 plant physiology mineral absorption transport of food, water and minerals mineral transport theories of translocation transport in the phloem of plants

Most widely accepted theory of carbohydrate translocation is

  1. Mass flow theory

  2. Root pressure theory

  3. Imbibition theory

  4. Transpiration theory
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

(A) Mass flow theory proposes the transportation of food in the plants.

(B) Root pressure theory proposes the transportation of water in the plants through the root pressure.
(C) Imbibition theory proposes water transportation through pipes.
(D) Transpiration theory proposes water transportation due to the evaporation from the upper surface of the leaves.
So, the correct answer is 'Mass flow theory'.

Multiple choice botany plant physiology mineral absorption transport of food, water and minerals mineral transport theories of translocation transport in the phloem of plants

Cohesion transpiration pull theory of ascent of sap was proposed by 

  1. Munch

  2. Stephen Hales

  3. Dixon and Joly

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

Cohesion transpiration pull theory was proposed by Dixon and Jolly. They proved that cohesion and adhesion support continuity of water columns and provide strength like a steel wire, transpiration pulls water columns towards leaves which causes ascent of sap.

So, the correct answer is 'Dixon and Jolly'.

Multiple choice botany plant physiology mineral absorption transport of food, water and minerals mineral transport theories of translocation transport in the phloem of plants

According to mass flow hypothesis
(a) Sucrose is moved into the companion cells and then into the sieve tube by passive transport.
(b) Inside the phloem, an osmotic pressure gradient is generated that facilitates the mass movement in the phloem.
(c) Water in the adjacent xylem moves into the phloem by active process

  1. (a) and (c) are correct

  2. (b) and (c) are incorrect

  3. (a) and (c) are incorrect

  4. (a) and (b) are correct
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice botany plant physiology mineral absorption transport of food, water and minerals mineral transport theories of translocation transport in the phloem of plants

Leaf photosynthates are transported to other parts of higher plants through

  1. Cambium

  2. Pith

  3. Xylem

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

Phloem is involved in transport of sugars. Phloem cells are living cells, which carry out the physiological process of sugar transport in higher plants.

Multiple choice botany plant physiology mineral absorption transport of food, water and minerals mineral transport theories of translocation transport in the phloem of plants

How many of the following features are related to Dixon and Jolly model of water transport in plants?
a. Cohesion between water molecules
b. Transpiration pull
c. Pushing of water by negative root pressure
d. Surface tension
e. Pushing of water by positive root pressure.

  1. $4$
  2. $5$
  3. $2$
  4. $3$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Dixon and Jolly model (Cohesion-Tension theory) relies on cohesion, adhesion, surface tension, and transpiration pull. Pushing by root pressure is not part of this specific model.

Multiple choice botany internal structure of root, stem and leaf internal structure of monocot leaf internal structure of leaf (dicot and monocot) anatomy of leaf internal structure of dicot leaf

Isobilateral leaves have stomata on

  1. Both upper and lower surfaces

  2. Upper surface only

  3. Lower surface only

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

In isobilateral leaves or monocot leaves, stomata are present on both upper or adaxial epidermis as well as lower epidermis or abaxial epidermis.

So, the correct option is ‘Both upper and lower surfaces’.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

Na is an essential element for ....

  1. C3 plant

  2. C4 plant

  3. both (a) and (b)

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sodium (Na) is an essential micronutrient specifically required by C4 plants for processes like the regeneration of phosphoenolpyruvate (PEP) through the pyruvate-phosphate dikinase pathway, whereas C3 plants do not require it.

Multiple choice water potential water potential and pressure plant water relation transport in plants biology

Cell A and cell B are adjacent plant cells. In cell A, $\psi s$ = - 20 bars and $\psi _p$ = 8 bars. In cell B, $\psi _s$ = - 12 bars and $\psi _p$ = 8 bars. Then ______________.

  1. Water moves from cell A to cell B

  2. There is no movement of water between cell A and cell B

  3. Water moves from cell B to cell A

  4. Equal amount of water is simultaneously exchanged between cell A and cell B
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Water potential (Psi_w) = Psi_s + Psi_p. For cell A: -20 + 8 = -12 bars. For cell B: -12 + 8 = -4 bars. Water moves from higher potential (-4) to lower potential (-12), so from B to A.

Multiple choice water potential water potential and pressure plant water relation transport in plants biology

0.5 M sucrose develops a pressure of 15 bars  in an osmometer. Which of the following statement is wrong for such a solution ______________.

  1. That its osmotic potential is-15 bars

  2. That its water potential is-15 bars

  3. That its pressure potential is-15 bars

  4. That its osmotic potential is+15 bars
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The pressure potential is usually positive.

So the incorrect option is C.

Multiple choice water potential water potential and pressure plant water relation transport in plants biology

Water will move from the root hair through cortex if the water potentials are _________________________.

  1. Root hair- $0$, Cortex-$0$, Xylem-$0$
  2. Root hair-$-2$, Cortex-$-1$, Xylem-$0$
  3. Root hair-$0$, Cortex-$-1$, Xylem-$-2$
  4. Root hair-$0$, Cortex-$+1$, Xylem-$+2$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

If a difference in water potential exists between the two regions, spontaneous movement of water will take place, provided the movement can occur between them. The direction of flow will be energetically down hill, that is from the region of higher water potential(root hair) to the region of lower water potential(xylem) via cortex from less negative water potential (e.g., - $1$ kPa) to more negative water potential (e.g., - $2$ kPa).

So, the correct answer is 'Root hair-0,, Cortex-−1, Xylem−2'

Multiple choice water potential water potential and pressure plant water relation transport in plants biology

If a cell A with DPD $=5$ bars is connected to cells B, C and D, whose OP and TP are respectively $5$ and $5$, $10$ and $4$, and $8$ and $3$, the flow of water will be _______________.

  1. C to A, B and D

  2. A and D to B and C

  3. A to B, C and D

  4. B to A, C and D
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

DPD of cell A=5A=5 bars
DPD of cell B=5−5=0B=5−5=0 bars
DPD of cell C=10−4=6C=10−4=6 bars
DPD of cell D=8−3=5D=8−3=5 bars
As cell B has the lowest value of DPD, therefore water will move from cell B to cells A, C and D.

Multiple choice water potential water potential and pressure plant water relation transport in plants biology

Choose the correct answers from the alternatives given :
Water potential is generally most negative in

  1. the soil solution

  2. mesophyll cell walls

  3. xylem sap of roots

  4. xylem sap of leaves
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Water potential is generally most negative in mesophyll cell walls because water evaporates from the mesophyll cells into the air spaces in the leaf. If the air surrounding the leaf has less water vapor than the air in the intercellular spaces, water vapor will leave the leaf through stomata. Order of water to move through the plant from the soil to the air ( a process called transpiration).

W.P root ---> W.P stem ---> W.P leaf ---> W.P atmosphere.
So, the correct option is 'mesophyll cell walls'.

Multiple choice biology water a precious resource water cycle earth's energy budget bio-geo chemical cycles in nature solar energy and its applications

Water enters atmosphere by

  1. Filtration

  2. Evaporation

  3. Evapo-transpiration

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

Water enters the atmosphere primarily through evaporation from water bodies and transpiration from plants. Together, these processes are known as evapotranspiration, but evaporation is the most fundamental term for water entering the atmosphere from the surface.