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 excretion in living organisms excretion - plants excretion in plants excretion - animals

How do plants get rid of their excretory products? 

  1. Shedding leaves

  2. Shedding bark

  3. Both A and B

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

Plants get rid of water by transpiration. Waste products may be stored in vacuoles or may be stored in leaves which fall off. Resine and gums are stored in xylem which are harmless to trees. When the leaves and bark are shed, the wastes are eliminated. Thus, option C is correct. 

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

Plants get rid of waste by which of the following method?

  1. Transpiration

  2. Shedding of leaves

  3. Peeling of bark

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

The waste products in the plants are stored by the vacuoles which is centrally located in a plant cell. It is filled with waste products until  the plant dies, it does not "excrete" any sort of waste. Plants also eliminate waste by its accumulation in the vacuoles of the aged leave cells which gets removed when such leaves are shed off. This process is called abscission. The excretory products include resins, gums, latex etc. Peeling of bark can also be considered as one of the excretory processes of plants.

Therefore, the correct answer is option D.

Multiple choice biology food and human health balanced diet and malnutrition balanced and unbalanced food digestive disorders diseases caused by changes in lifestyle diseases and toxic substance health and its maintenance

'Hunger signs" in plants are_____________

  1. Symptoms due to lesser water absorption in plants

  2. Sympotms due to poor photosynhesis in plants

  3. Deficiency sympoms of particular mineral nutrients

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • According to the criteria of essentiality, there are 16 essential elements for plant growth. Hunger signs are shown by plants due to the deficiency of one or more of these mineral nutrients.

So, the correct option is 'Deficiency symptoms of particular mineral nutrients'.
Multiple choice biology food and human health balanced diet and malnutrition balanced and unbalanced food digestive disorders diseases caused by changes in lifestyle diseases and toxic substance health and its maintenance

Tea yellow is a disease of tea plants produced due to the deficiency of-

  1. Nitrogen

  2. Sulphur

  3. Potassium

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

  • The yellows disease of tea, the nature of which has hitherto remained obscure, has caused serious losses to planters in Nyasaland. It is characterized by a progressive degeneration of the bush, in which the leaves become chlorotic, small, uprolled and of stiff texture, and are finally shed.It is caused due to the deficiency of Nitrogen. 

So the correct option is 'Nitrogen'.

Multiple choice

What do we call the release of water vapor by plants?

  1. transpiration

  2. sublimation

  3. precipitation

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

Transpiration is the specific biological process by which plants absorb water through roots and release it as vapor through their leaves.

Multiple choice botany leaf - external morphology venation arrangement of leaves morphology of leaf

In the leaves, veins are useful for

  1. Transport of water and minerals

  2. Mechanical support

  3. Transport of organic nutrients

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

Veins in leaves are made up of xylem and phloem. It is useful in providing mechanical support to the leaf. It also helps in transport of both water and minerals via xylem tissue and transport of organic nutrients via phloem tissue to the rest of the plant.

Thus, the correct answer is 'All of the above.'

Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

Transpiration is regulated by the movements of

  1. Epidermal cells of the leaf

  2. Subsidiary cells of the leaf

  3. Guard cells of the stomata

  4. Mesophyll tissue of the leaf
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In higher plants transpiration occurs through stomata. The stomatal pore is regulated by the turgidity of guard cells. When the guard cells are turgid the stomatal pores open. When guard cells are flaccid, stomatal pore closes.

Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

What will be the effects on stomata, if relative humidity is $100\%$ in atmosphere?

  1. Completely open

  2. Partially open

  3. No effects

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

At 100% relative humidity, transpiration is inhibited, which often leads to stomatal closure to prevent water loss or maintain turgor, but in some contexts, it is stated they remain open.

Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

Stomata opening in most of the plants is during the day instead of night because

  1. Enzymes convert starch into sugar at night.

  2. Formation of sugar increases osmotic concentration of the cell sap, which results in more absorption of water, which provides turgidity to the guard cells.

  3. The starch converts into sugar by enzymatic activity during the night and the whole process of the day becomes reversible, thus resulting in the closure of stomata.

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

Most widely accepted theory for opening and closing of guard cells is the malate or potassium ion pump theory, first proposed by Levitt, 1974. According to this theory, during day time, rise in pH of guard cells (due to photosynthesis and consequent decrease of carbon dioxide) causes hydrolysis of starch to form phospho enol pyruvate (PEP). PEP combines with carbon dioxide to form organic acids like oxalic acid. The organic acids get ionised and the proton passes out of guard cells and potassium ion is actively absorbed and accumulated. Potassium ions combine with malate and passes into small vacuoles. Chloride ions are also absorbed from outside to maintain electroneutrality. As a result of accumulation of ions there is a reduction in water potential of guard cells. The reduction in water potential causes absorption of water from adjacent cells, guard cells become turgid and stomata open.

Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

Stomata are bound by a pair of guard cells. Stomata close, when the guard cells become

  1. Turgid

  2. Flaccid

  3. Half turgid

  4. Half flaccid

  5. Small
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Opening and closing of stomata are controlled by the turgor changes in the guard cells. In the dark, the guard cells lose water, become flaccid and the stomata close. In the light, the guard cells absorb water by osmosis, become turgid and the stomata open.

Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

Malate or K$^{+}$ hydrolysis theory was given for

  1. Starch metabolism.

  2. Stomatal movement.

  3. Ascent of sap.

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

There are three more theories for mechanism of stomatal movement
(A) Hydrolysis of guard cell photosynthesis
(B) Classical starch hydrolysis theory
(C) Malate or $k^{+}$ ion pump hydrolysis.

Malate or $k^{+}$ ion pump hypothesis theory was put forward by Levitt $(1974)$. It is considered as the modern one. It states that the change in the turgor pressure of the guard cells regulates the opening and closing of stomata. 

Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

Active K$^+$ mechanism of opening and closing of the stomata was given by

  1. Darwin

  2. Leuitt

  3. Scarth

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

  • Potassium is a very important macronutrient for plants. Its ions cause the turgor movement of guard cells. 
  • The gain of potassium ions by the guard cells causes a decrease in water potential of guard cells. 
  • This makes guard cells turgid and hence they swell. Increase in turgidity of guard cells opens the stomatal pore. 
  • Movement of potassium ions from the guard cells results in the increase of water potential. It becomes flaccid and stomatal pore closes. This mechanism of stomatal opening and closing was first stated by Levitt.

The correct option is B.