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 transpiration major activities of living organisms biology

Which of the following is not the purpose of transpiration process?

  1. Supplying water for photosynthesis

  2. Maintaining shape and structure of plants

  3. Translocation of sucrose from source to sink

  4. Cooling the leaf surfaces
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Transpiration is the process of loss of water through the aerial parts of the plant. It depends upon the amount of humidity level of the atmosphere.

When there is a high level of moisture then there is no concentration gradient between leaf and the atmosphere there is a minimum loss of water through transpiration. 
So, the correct answer is 'Translocation of sucrose from source to sink'.

Multiple choice transpiration major activities of living organisms biology

Which of these is not the goal of transpiration?

  1. Prevention of loss of water

  2. Helping in the absorption and transportation process

  3. Supplying water for photosynthesis

  4. Keeping the plant cool
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Transpiration helps in the absorption of carbon dioxide gas from the atmosphere and its transportation.

It also helps in maintaining the temperature of the plant by releasing water which gets evaporated taking away the heat of the plant.
Transpiration leads to water loss so it cannot prevent loss of water.
So the correct answer is 'Prevention of loss of water'.

Multiple choice transpiration major activities of living organisms biology

Maximum water loss occurs through

  1. Lenticles

  2. Hydathodes

  3. Stomata

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

Water is essential for plants, it absorbs water from the soil through roots. However, plants absorbs much water, but only a small amount of water is used for their growth and metabolism. Persisting 97 - 99.5% of absorbed water is lost by transpiration. Transpiration is the process of elimination water in the form of water vapour from the aerial parts such as leaves, flowers and stem. The leaves contains tiny pores called stoma which helps in the gas exchange of oxygen and carbon dioxide. More the stoma (pores) on the leaves result in the increase in the transpiration via stomata. The leaf with the bigger surface area will transpire more when compared to the lower surface area. Each stomata is gaurded by guard cells which helps in the opening and closing of stomata. When stomata are open, transpiration rates increase; when they are closed, transpiration rates decrease.

So, the correct answer is option C.

Multiple choice transpiration major activities of living organisms biology

In hot summer day, plant cooling occurs due to

  1. Transport of water from root to all parts of the plants.

  2. Loss of liquid water

  3. Water loss from entire plant

  4. Loss of water vapour from foliar surface
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In hot summer days when loss of water vapour occurs from foliar surface because these are the main site of water loss or transpiration and directly exposed to sunlight.

There is no effect on cooling of plants due to transport of water from root to all parts of the plant or water loss from entire plant.

Multiple choice transpiration major activities of living organisms biology

Plant cooling occurs due to 

  1. Assimilation

  2. Guttation

  3. Photorespiration

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

Transpiration is the evaporation of the water from the stomata of the plants. The water absorbed by the roots is transported up to the leaves where stomata are present. Stomata open during the daytime and increasing temperature results in loss of water in the form of vapours. This is similar to the sweating process that occurs in humans. It cools the plants during high temperature.

Assimilation is the use of minerals by plants.
Guttation is oozing out of water in liquid form during night-time.
Photorespiration is a deviation in photosynthesis when the concentration of oxygen increases.
Transpiration is evaporation of water due to increased temperature during daytime.
So, the correct answer is 'Transpiration'.

Multiple choice transpiration major activities of living organisms biology

Choose the correct answers from the alternatives given.
According to transpiration pull-cohesion theory of ascent of sap, water is pulled upward through the xylem. The cause of the pull is 

  1. Transpiration

  2. Guttation

  3. Root pressure

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

Water is pulled upwards through the plants due to transpiration. Transpiration is the loss of water in the form of water vapour through stomata. The model that explains this translocation of water is called Cohesion-tension transpiration pull model of water transport. Less than one percent of water reaching the plant is used in photosynthesis and plant growth.

Hence, the correct answer is'Transpiration'.

Multiple choice transpiration major activities of living organisms biology

Which of the following is not a function of transpiration?

  1. Uptake of water

  2. Evaporation of water

  3. Uptake of minerals

  4. Excretion of minerals
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Evaporation of water and uptake of minerals and water is a function of transpiration.

Transpiration causes water to take up the heat of the organs or the energy from sunlight and convert into water vapour causing evaporation of water.
Transpiration pull helps in ascent of xylem sap and hence helps in transportation of water and minerals.
Since water vapours are lost through transpiration, the minerals are left behind as they cannot evaporate along with water.
So the correct answer is 'Excretiom of minerals'.

Multiple choice transpiration major activities of living organisms biology

Transpiration is unavoidable evil because of

  1. Structure of leaf and harmful effect

  2. Beneficial and harmful effect

  3. Maintenance of turgidity for growth

  4. Gaseous exchange for photosynthesis and respiration
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Stomata are the aperture which is mainly present at the dorsal surface of the leaf. It is meant for gaseous exchange but it also allows the loss of water through transpiration. Loss of water can lead to wilting, serious dessication and often the death of a plant if there is a shortage of water. 

Thus, the correct answer is an option D.

Multiple choice transpiration major activities of living organisms biology

A negative effect of transpiration is

  1. Development of water stress

  2. Increase in mineral absorption

  3. Maintenance of leaf temperature

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

Transpiration is the process of loss of water through the aerial parts of the plant. It depends upon the amount of humidity level of the atmosphere.

When there is a high level of moisture then there is no concentration gradient between leaf and the atmosphere there is a minimum loss of water through transpiration. It is a necessary evil as it develops water stress.
So, the correct answer is 'Development of water stress'.

Multiple choice transpiration major activities of living organisms biology

Choose the correct answers from the alternatives given.
The rate of transpiration in plants is more when

  1. Atmosphere is dry

  2. Temperature is high

  3. Atmosphere is humid

  4. Atmosphere is dry and temperature is high
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Dry atmosphere means lack of moisture content in the air. Due to this, air has a lot of capacity to hold water and thus the rate of transpiration increases.

Similarly, high temperatures evaporate the water at a much higher rate thus again increasing the rate of transpiration. Humid atmosphere already contains a lot of moisture and can not hold more water and thus transpiration rate decreases.
Hence, the correct answer is 'Atmosphere is dry and the temperature is high'.

Multiple choice transpiration major activities of living organisms biology

Choose the correct answers from the alternatives given.
Loss of water from the plants in the form of vapour state is known as

  1. Guttation

  2. Imbibition

  3. Transpiration

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

  • Water loss from the leaves in the form of water vapour through the openings called stomata is called transpiration.
  • Imbibition is a phenomenon that refers to the absorption of one substance by another, usually uptake of water by a plant or a seed.
  • Guttation is excretion of xylem sap on the tips of some plants through pores called hydathodes.
  • Translocation is the movement of the material from the source to sink inside the plant. Example, movement of starch from leaves to roots or other plant parts.
Hence, the correct answer is 'Transpiration'.

Multiple choice biology excretion in living organisms excretion - plants excretion in plants excretion - animals

Aquatic plants excrete metabolic wastes through

  1. Transpiration

  2. Shedding of leaves

  3. Diffusion

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

Aquatic plants respire and dispose of wastes by diffusion. Diffusion is a process by which oxygen and nutrients dissolve in water and reach aquatic plants. The waste materials diffuse out of the plants as diffusion takes place from higher concentration to lower concentration. Shedding of leaves occurs in deciduous trees. The process of getting rid of excess water in form of water vapour is called transpiration. 

So, the correct answer is 'Diffusion'.

Multiple choice biology excretion in living organisms excretion - plants excretion in plants excretion - animals

Which of the following is excreted by the plant roots?

  1. Water

  2. Oxygen

  3. Organic acids

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

Plant roots excrete a variety of organic compounds to the soil such as sugars, amino acids, organic acids and phenols. Organic acids are usually present in root exudates and they seem to be part of a nutrient mobilization strategy. For example, oxalic acid is most efficient for phosphorus mobilization, while citric and malic acids are more efficient with iron. Water, oxygen and calcium carbonate are not excreted by plant roots.