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 bio-chemistry absorption by roots - the processes involved osmotic relations of plant cells transport across membrane imbibition and its importance

Glucose is not stored in plants due to its ability to 

  1. Decrease osmotic pressure

  2. Increase osmotic pressure

  3. Increase turgor pressure

  4. Decrease turgor pressure
Reveal answer Fill a bubble to check yourself
B 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 'Increase osmotic pressure'.

Multiple choice bio-chemistry absorption by roots - the processes involved osmotic relations of plant cells transport across membrane imbibition and its importance

All of the following involves osmosis except

  1. Water passing from a root hair to adjacent cells.

  2. Water passing from a xylem vessel element to xylem vessel element above it.

  3. Water entering a mesophyll cell from the xylem vessel element.

  4. Water from soil entering a root hair.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Water passing from a xylem vessel element to xylem vessel element above it due to the transpiration pull exerted by the mesophyll cells. However, the transfer of water from the soil to the root is due to osmosis.

Therefore, the correct answer is option B.

Multiple choice bio-chemistry absorption by roots - the processes involved osmotic relations of plant cells transport across membrane imbibition and its importance

In root hair, water enters due to 

  1. Diffusion

  2. W.P.

  3. T.P.

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

(A) Diffusion is the movement of the water molecule from higher concentration to lower concentration.

(B) Wall pressure is the pressure applied by the cell wall against the turgor pressure.
(C) Turgor pressure is pressure applied against the wall pressure.
(D) Osmotic pressure is the pressure applied to prevent osmosis that is the movement of the water molecule from a lower solute concentration to a higher concentration through a semi-permeable membrane. Absorption of water through roots is by osmotic pressure.
So, the correct answer is 'Osmotic pressure'.

Multiple choice botany transport in plants osmotic relations of plant cells transport across membrane imbibition and its importance

Imbibition occurs due to?

  1. Increase in volume of imbibate

  2. Adsorption of imbibate by imbibant

  3. Absorption of imbibant by imbibate

  4. Loss of energy in the form of heat
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Imbibition is a special type of diffusion when water is absorbed by solids and colloids causing an enormous increase in volume. The substance that imbibes water is called imbibant, and the liquid which is imbibed is called imbibate. Imbibition occurs due to the increase in the volume of imbibate.

 Hence, the correct answer is option A.
Multiple choice botany transport in plants osmotic relations of plant cells transport across membrane imbibition and its importance

Absorption of water from soil by seeds increases the _________ thus helping seedlings to come out of soil.

  1. DPD

  2. Diffusion pressure

  3. Imbibition pressure

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

Imbibition is the initial step in the germination of the seeds. When mature seeds are sown in soil they imbibe water and swell. The water is imbibed first by seed coat and then by other tissues of embryo and endosperm. The process of imbibition is important ot initiate the seed germination. the pressure that an imbibant develops when submerged in pure imbibing liquid is called imbibition pressure.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

Stomata remain open at night in

  1. $C _3$ plants
  2. $C _4$ plants

  3. CAM plants

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

Certain plants which have Crassulacean Acid Metabolism (CAM) are known as CAM plants. They have scotoactive stomata, i.e. stomata remain open in night. These plants fix carbon dioxide during the night but form sugars only during the day when RuBisCO is active. Sedum, Kalanchoe, Pineapple, Opuntia are the examples of CAM plants. These plants also perform double carbon dioxide fixation. The carbon dioxide acceptor in CAM plants is Phosphoenol pyruvic acid (PEP) during the night and Ribulose bisphosphate is carbon dioxide acceptor during the daytime. The first stable product in case of CAM plants is Oxalo acetic acid (OAA).

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In Kranz anatomy, the bundle sheath cell have

  1. Thick walls, many intercellular spaces and no chloroplasts

  2. Thin walls, no intercellular spaces and large number of chloroplasts

  3. Thick walls, no intercellular spaces and large number of chloroplasts

  4. Thin walls, many intercellular spaces and several chloroplasts
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Kranz anatomy is found in leaves of $C _{4}$ plants. The $C _{4}$ pathway requires the presence of two types of cells i.e. mesophyll cells and bundle sheath cells. The particularly large cells around the vascular bundles of $C _{4}$ plants are called bundle sheath cells, these cells may form several layers around the vascular bundles, they are characterized by having a large number of chloroplasts, grana are absent, thick walls impervious to gaseous exchange and no extracellular spaces. This special anatomy of leaves of the $C _{4}$ plants is called Kranz anatomy. 'Kranz' means wreath and is a reflection of the arrangement of cells.
Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

Which of the following statements is characteristic feature of CAM plants

  1. Release oxygen during day

  2. Release oxygen during night

  3. Open their stomata during night

  4. Do not respire during day
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Certain plants which have Crassulacean Acid metabolism (CAM) are known as CAM plants. They have scotoactive stomata. Their stomata remain open during night. It is characteristic feature of CAM plants. These plants fix carbon dioxide during night but form sugars only during day when RuBisCO is active. Sedum, Kalanchoe, Pineapple, Opuntia are the examples of CAM plants. These plants also perform double carbon dioxide fixation. The carbon dioxide acceptor in CAM plants is Phosphoenol pyruvic acid (PEP) during night and Ribulose bisphosphate is carbon dioxide acceptor during day time. The first stable product in case of CAM plants is Oxalo acetic acid (OAA).

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

CAM helps the plants in 

  1. Reproduction

  2. Conserving water

  3. Secondary growth

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

Certain plants especially succulents which grow under extremely xerophytic conditions, fix atmospheric carbon dioxide in the dark. Since the process was first observed in the plants belonging to family Crassulaceae such as Bryophyllum, Kalanchoe, Sedum etc., it was termed crassulacean acid metabolism (CAM). Such plants are known as CAM plants. The most characteristic feature of these plants is that their stomata remain open at night but closed during the day. Thus, CAM is a kind of adaptation in succulents to carry out photosynthesis without much loss of water. This helps in conserving water in these plants. 

Thus, the correct answer is option B. 

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

Select the incorrect statement from the following.

  1. C4 pathway for CO$ _2$ fixation were discovered by Hatch and Slack.
  2. CO$ _2$ is essential for photosynthesis.

  3. Addition of sodium carbonate in water retards photosynthetic rate in Vallisneria.

  4. Phloem is the principal pathway for translocation of solutes.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Sodium bicarbonate acts as a source of carbon-dioxide to the plant which helps in the production of carbohydrates during photosynthesis acting as the carbon source for the same. Its addition in the water increases the photosynthetic rate in Vallisneria. Thus, CO2 is essential for photosynthesis. 
The C4 pathway is also known as the Hatch and Slack pathway in the name of their discoverers Hatch and Slack.
Phloem in plants acts the pathway for transport of plant solutes and metabolites whereas xylem acts as the pathway for transport of water.
The correct answer is 'addition of sodium carbonate in water retards photosynthesis rate in Vallisneria'.
Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In a CAM plant, the concentration of organic acid

  1. Increases during the day.

  2. Decreases or increases during the day.

  3. Increases during night.

  4. Decreases during any time.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Crassulacean acid metabolism is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions. In a plant using full CAM, the stomata in the leaves remain shut during the day to reduce evapotranspiration, but open at night to collect carbon dioxide. The $CO _2$ is stored as the four-carbon acid malate and then used during photosynthesis during the day. As photosynthesis occurs during night, the concentration of organic acid, which is the product of photosynthesis increases during night. Thus, option C is correct answer.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

The common feature in CAM and $C _4$ plants is

  1. Stomata open only during night

  2. Acid concentration increases during night
  3. Both $C _3$ and $C _4$ pathways occur

  4. Having Kranz anatomy
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A) Stomata are open both during the day and night in ${ C } _{ 4 }$ plants, but open only at night in CAM plants.

B) The acid in ${ C } _{ 4 }$ plants decreases at night.
C) In both CAM and ${ C } _{ 4 }$ plants, ${ C } _{ 4 }$ pathway takes place followed by ${ C } _{ 3 }$ pathway.
D) Only ${ C } _{ 4 }$ plants have Kranz anatomy.
So the correct answer is 'Both ${ C } _{ 3 }$ and ${ C } _{ 4 }$ pathways occur'.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In CAM cycle, during the formation of malic acid, stomata remains

  1. Open

  2. Closed

  3. Semi open

  4. Always closed
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

CAM method is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions. In a plant using full CAM, the stomata in the leaves remain shut during the day to reduce evapotranspiration, but open at night to collect carbon dioxide. The carbon dioxide is then stored as a four-carbon acid, malate, and then used during photosynthesis during the day. The pre-collected CO2 is concentrated around the enzyme RuBisCO, increasing photosynthetic efficiency.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In maximum plants, stomata open during day and closed at night. Its exception is

  1. Crassulacean acid metabolism plants
  2. $C _{3}$ plants
  3. $C _{4}$ plants

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

Crassulacean acid metabolism is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions. In a plant using full CAM, the stomata in the leaves remain shut during the day to reduce evapotranspiration, but open at night to collect carbon dioxide. The $CO _2$ is stored as the four- carbon acid malate, and then used during photosynthesis during the day. The pre-collected $CO _2$ is concentrated around the enzyme RuBisCO, increasing photosynthetic efficiency.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

CAM helps the plants in

  1. Reproduction

  2. Secondary growth

  3. Conserving water

  4. Disease resistance
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
CAM stands for Crassulacean Acid Metabolism. Plants having CAM have scotoactive stomata. These plants fix $CO _{2}$ during the night but form sugars only during the day (when RuBisCO is active). CAM helps plants in conserving water. These plants are succulent and they have water-storing cells. Sedum, Kalanchoe, Opuntia, etc., are the examples of CAM plants.
So, the correct answer is 'Conserving water'