Biology

Plant Transport and Physiology

1,834 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 apoplast and symplastic pathway transport of water in plants water transport

Movement of water through the symplast involves crossing the 

  1. Intercellular spaces

  2. Cell wall

  3. Cell membrane

  4. More than one option is correct
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The symplast pathway involves the movement of water through the cytoplasm of cells, which requires crossing the cell membrane to enter and exit cells.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Most water flow in root occurs via apoplast as

  1. Cortical cells are living cells

  2. Cortical cells are loosely arranged

  3. Cortical cells are thin walled

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

Most of the water flow in the roots occurs via Apoplast since the cortical cells are loosely packed, and hence offer no resistance to water movement.

So, the answer is, "Cortical cells are loosely arranged".

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Apoplastic movement of water occurs exclusively through the 
(i) Intercellular spaces
(ii) Walls of the cells
(iii) Plasmodesmata
(iv) Cytoplasm

  1. i, ii and iv

  2. iii and iv

  3. i and ii

  4. ii and iv

  5. iv
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Apoplast absorption is a type of absorption where the water moves through the cell wall and intercellular spaces between the two cell. Water is absorbed by the root hair from the soil. It passes the epidermis, cortex, endodermis, casparian strip and pericycle and xylem. After reaching the xylem it is pulled up by the transpirational pull. 
So, the correct answer is option C.
Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Following are the differences between apoplast pathway and symplast pathway. Which of the given differences is/are correct?

Apoplast pathway Symplast pathway
(i) It consists of non-living parts of plant body, i.e., cell walls and intercellular spaces. It consists of living parts of plant body, i.e., protoplasts connected by plasmodesmata.
(ii) There is little resistance in the movement of water Some resistance occurs in the movement of water through symplast
(iii) It is slightly slower It is faster
(iv) Metabolic state of root directly affects apoplast pathway Metabolic state of root does not affect symplast pathway

  1. (iii) only

  2. (i) and (iii) only

  3. (iii) and (iv) only

  4. (ii) and (iii) only
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Apoplast pathway is faster while symplast pathway is slightly slower. Metabolic state of root does not affect apoplast pathway while metabolic state of root directly affects symplast pathway.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

In which of the following pathways, movement of water occurs from one cell to another cell through plasmodesmata?

  1. Apoplast pathway

  2. Symplast pathway

  3. Vacuolar pathway

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

In symplast pathway, water passes from cell to cell through their protoplasm. It does not enter cell vacuoles. The cytoplasm of the adjacent cells are connected through plasmodesmata. Symplastic movement is aided by cytoplasmic streaming of individual cells.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

The transportation of water and minerals from the root to the leaves is known as ________

  1. Capillary action

  2. Accent of sap

  3. Climbing

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

The transportation of water and dissolved minerals from the root to the leaves is known as ascent of sap. It is transported through xylem tissues. During transportation, there is large accumulation of mineral ions in the root hair cells by active transport. This results in the higher water concentration in the soil as compared to the cell sap of the root hair. Hence, water diffuses from the soil into the root hair. The root hair cells become turgid. From root hair cells, the water moves into the cortical cells. From the cortical cells, the water reaches the endodermis by osmosis. The endodermis then pushes water into the xylem tubes through passage cells.

Thus, the correct answer is 'Ascent of sap.'

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Which is shown by the experiment Ascent of sap?

  1. The food materials are transmitted by phloem

  2. Water is transmitted by phloem

  3. Water is transmitted by xylem

  4. The food material is transmitted by xylem
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The ascent of sap experiment demonstrates the absorption of water by root cells if plants and their upwards movement. The sap is the water and minerals absorbed by the roots and they are pushed upwards into the xylem and then it goes to other regions of the plant.

The upward movement of water and minerals is known as ascent of sap.
So the correct answer is 'Water is transmitted by the xylem'.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

The rate of transpiration ........... the process of ascent of sap.

  1. Increases

  2. Decreases

  3. Do not affect

  4. Increases and then decreases
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Transpiration causes the development of a pull or a negative pressure region which created a suction force to aid the ascent of sap. It increases the process of ascent of sap.

So the correct answer is 'Increases'.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

The root pressure theory considers ........... responsible for the ascent of sap.

  1. Gravitational pull

  2. Hydrostatic pressure

  3. Capillary force

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

The root pressure theory considers that hydrostatic pressure developed in the roots is responsible for pushing the water through the column. It depends on the active accumulation of minerals in the root cells which then causes passive absorption of water creating a high pressure.

It neglects the effect of gravity.
Capillary force is not the driving force in this theory.
Many small herbaceous plants only depend on root pressure for ascent of Sap.
So the correct answer is ' Hydrostatic pressure'.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Ringing experiments are performed to demonstrate

  1. Ascent of sap through both phloem and xylem.

  2. The ascent of sap through phloem and xylem parenchyma.

  3. The ascent sap through cortical cells.

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

In ringing experiment the bark of a tree is removed at a height above the soil surface as a ring. This leads to accumulation of sugars just above the ring of bark removal because sugars are transported through phloem. The ascent of sap which occurs through xylem continues normally because xylem is not part of the bark and bark consists of secondary phloem along with several other tissues.The experiment clearly demonstrates the function of xylem.

Thus, the correct answer is option D.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Mostly minerals are absorbed from the soil by the plant 

  1. By a process dependent of water absorption

  2. Only when soil solution is hypotonic to cell sap

  3. Only when soil solution is hypertonic to cell sap

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

In soil, the minerals can be present dissolved in soil solution or adsorbed on charged clay particles. Plants obtain minerals both from the soil solution (through absorption) as well as directly from clay particles (through ion exchange mechanisms). 

Mineral absorption can be active or passive. The passive mineral absorption can occur both in the direction as well as against concentration gradient. Mass flow is one mechanism through which minerals are absorbed passively against their concentration gradient. In mass flow, mineral ions are swept into root and passed into the plant parts along the current of water, caused by transpiration pull. Mineral absorption depends on water absorption because the solvent of soil solution is water. Mineral absorption can occur along with the water stream. Minerals can also be absorbed actively involving the expenditure of metabolic energy irrespective of the tonicity of the soil solution.
So, the correct answer is option A.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

The chief role of transpiration in plants is to

  1. Remove surplus water

  2. Cooling of the plant

  3. Increase ascent of sap

  4. Uptake rise of minerals
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

According to the most widely accepted theory, ascent of sap occurs through 'Cohesion Tension' or 'Cohesion Transpiration pull'. The cohesion and adhesion forces give rise to a continuous water column in xylem elements, which is lifted by the transpiration pull. Thus, ascent of sap is purely physical process and does not involves energy input.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

The main path for movement of water against the force of gravity i.e., ascent of sap in herbaceous dicots is

  1. Tracheids

  2. Vessels

  3. Sieve tubes

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

Xylem tissue is a complex permanent tissue specialized to transport water in plant body. Xylem tracheids are found in a number of plant groups like angiosperms, gymnosperms and pteridophytes. Bryophytes do not possess vascular tissues. Hence, bryophytes do not attain height. Xylem tracheids are present in pteridophytes and gymnosperms. These plant groups lack vessels. Vessels are characteristics of angiosperms only. In angiosperms, xylem vessels form the main channel for ascent of sap.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Vital theories of ascent of sap were discarded due to reasons that

  1. Living cells are involved.

  2. Metabolic activity provides energy requirements.

  3. Water continues rising even after killing of xylem parenchyma.

  4. Atmospheric pressure is involved in ascent of sap.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Vital force theories were propagated to explain the ascent of sap. These theories believed that living cells are involved in the ascent of sap e.g., relay pump theory by Godlewski, 1883 and pulsation theory by Bose, 1923. Bose believed that the inner most cortical cells pump water into the interior, that contains xylem channels. The vital force theories have been discarded because as proved by Boucherie in 1840 and Strasburger in 1891 that water rises up the stem, even when all the living cells are killed by poison or heat.