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 transport in plant homeostasis in plants regulation of stomatal opening stomata

Stomata opens by

  1. Increasing solute concentration in guard cells.

  2. Weakening of cell walls of guard cell to allow them to stretch.

  3. Increasing water potential of guard cells.

  4. Decreasing the solute concentration of guard cells.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Stomata opens by increasing solute concentration in guard cells. The guard cells contain chloroplasts, so they can manufacture food by photosynthesis. The epidermal cells don't have chloroplast. Due to the presence of chloroplast, guard cell synthesizes glucose during the day time by the process of photosynthesis and so its osmotic potential increases and it withdraws water from the epidermal cell and turns turgid and the stomata opens and transpiration takes place.

So, the correct answer is option A.

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

The opening and closing of stomata in leaves of mesospheric plants is regulated by.

  1. Changes in $CO _2$, K$+$ ions, and ABA concentration with simultaneous changes in the turgidity/flaccidity of guard cells

  2. Changes in the starch-sugar concentration in the guard cell
  3. Changes in the $H^+$ concentration in the guard cells

  4. Differential thickening of walls of the guard cells
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Stomatal movement is primarily regulated by K+ ion flux, CO2 concentration, and ABA levels, which change the turgor pressure of guard cells.

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

Choose the correct answers from the alternatives given.
Stomata open when guard cells

  1. Sense an increase in CO2 in the air spaces of the leaf

  2. Flop open due to a decrease in turgor pressure
  3. Become more turgid due to an influx of $K^+$ followed by the osmotic flow of water

  4. Accumulate water by active transport
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When the concentration of the potassium ions and malate ions increase guard cells form potassium malate and stores it in vacuoles of the guard cells. This increases the osmotic concentration and hence water enters the guard cells by endosmosis. The turgor pressure of the guard cells increases due to endosmosis which finally leads to the opening of the stomata.

Hence,the correct answer is 'Become more turgid due to an influx of $K^+$ followed by the osmotic flow of water'.

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

Choose the correct answers from the alternatives given.
Which of the following changes in the cell sap of the guard cells is responsible for keeping stomata open during day time?

  1. Decrease in osmotic pressure but increase in turgor pressure

  2. Increase in osmotic pressure but decrease in turgor pressure

  3. Increase in both osmotic and turgor pressures

  4. Decrease in both osmotic and turgor pressures
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The increased concentrations of potassium ions are balanced by malate ions that form potassium malate. This is stored in the vacuoles of the guard cells, increasing the osmotic concentration. Hence, the water enters the guard cells by endosmosis. The turgor pressure of the guard cells also increases due to this endosmosis causing the stomata to open.

Hence, the correct answer is 'Increase in both osmotic and turgor pressures'.

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

As the guard cells become turgid, outward stretching of their inner walls, open the stomata.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When guard cells become turgid the inner wall cannot move in vertical direction or along the longitudinal axis. Neither it can move or stretch on inner side. This is because of extra cellulose deposition on inner wall and radial microfibrils emerging from the inner wall.
So as guard cells become turgid and pressure builds up, the outer wall is pushed outside, which pulls the inner wall towards outside, or radially outwards. This opens the stomatal pore.

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

The correct hypothesis to explain opening of stomata during night in succulent plants is

  1. $CO _2$ used, pH increases and results in the accumulation of sugars.
  2. $CO _2$ accumulates, reduces pH and stimulates enzymes to bring about accumulation of sugars.
  3. Low $CO _2$ concentration, accumulation of organic acids resulting in the increased concentration of cell sap.
  4. Increases in $CO _2$ concentration brings conversion of organic acids into starch resulting in an increased uptake of $K^+$ and water.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Scotoactive stomata are the stomata, which open in dark and close during the day time. Scotoactive stomata occur in succulents, e.g., cactus and bryophyllum. Succulents perform crassulacean acid metabolism or CAM in their photosynthesis. Nishida explained, that in succulents during night there is accumulation of organic acids, whereas, during day time the organic acids breakdown releasing carbon dioxide, which keeps stomata closed. During night, because of formation of organic acids carbon dioxide is consumed and concentration of carbon dioxide is less.

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

Choose the correct answers from the alternatives given.
Stomata are usually open

  1. Whenever there is excess water in the soil

  2. At night, when the plant requires a supply of oxygen

  3. During the day, when the plant requires a supply of carbon dioxide

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

Stomata are tiny openings present on the epidermis of the leaves and young stem. These structures help in transpiration as well as uptake of carbon dioxide. The carbon dioxide is utilised in the process of photosynthesis. Since carbon dioxide is not utilised during the night, its concentration increases which inhibit the uptake of the potassium ions and closing of stomata takes place.

Hence,the correct answer is 'During the day, when the plant requires a supply of carbon dioxide'.

Multiple choice biology mineral nutrition in plants nutrients and nutrition essential and non-essential mineral elements transport in the xylem of plants hydroponics hydroculture

Which of the following is not a role played by Potassium in plant growth?

  1. Translocation of carbohydrates

  2. Maintaining anion-cation balance

  3. Opening and closing of stomata

  4. Synthesis of proteins

  5. Maintaining turgidity of cells
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Potassium is involved in stomatal opening, enzyme activation, and protein synthesis, but it is not directly responsible for the translocation of carbohydrates; that is primarily the role of Boron.

Multiple choice biology mineral nutrition in plants nutrients and nutrition essential and non-essential mineral elements transport in the xylem of plants

Which statement is wrong

  1. Plant take very little amount of minerals element from soil

  2. Plant absorb one thing at a time either water or minerals salt

  3. Root hair absorb water and minerals together

  4. Minerals absorption primarily takes place by active method
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Plants absorb water and mineral salts simultaneously through root hairs, not sequentially. The statement that plants absorb one thing at a time is incorrect because absorption of water and minerals occurs concurrently through the same root tissues. Mineral absorption does primarily occur through active transport methods.

Multiple choice biology biology : an introduction introduction to organization of life signs of life what is living?

Stomata can be related to which of the following activity

  1. Locomotion

  2. Excretion

  3. Movement

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

Stomata are pores found on the surface ie. epidermis of the leaf. These are used for the exchange of gases and releasing water by the process of transpiration. In some plants, calcium salts are also excreted through these pores. So the correct option is B "excretion".

Multiple choice biology anatomy of flowering plants theories of meristematic cell development theories of shoot apical meristem development shoot and root apex

Heaping of earth around base of stem in Potato is meant for.

  1. Preventing exposure of roots

  2. Providing extra support to delicate stem

  3. Inducing development of more auxiliary shoots

  4. Making more water available
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Heaping soil around the base of the potato stem, known as earthing up, encourages the development of more underground stems (stolons) from the axillary buds, which then swell to form tubers.

Multiple choice biology anatomy of flowering plants theories of meristematic cell development theories of shoot apical meristem development shoot and root apex

Choose the correct answers from the alternatives given.
Which of the following functions is not shared by both the root system and the shoot system of a plant?

  1. Absorb water

  2. Transport water

  3. Transport inorganic nutrients

  4. Transport organic nutrients
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The root system forms the underground system of the plant that absorbs water from the soil along with various organic and inorganic nutrients. It exerts the root pressure due to which the absorbed water is transported to the shoot system.

The shoot system forms the upper part of the plant part. It transports the absorbed water and nutrients to different plant parts.
Hence, the correct answer is 'Absorb water'.

Multiple choice biology anatomy of flowering plants theories of meristematic cell development theories of shoot apical meristem development shoot and root apex

Choose the correct answers from the alternatives given :
Plant roots function to

  1. anchor the plant

  2. store the products of photosynthesis

  3. produce hormones that stimulate stem growth

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

Root is the most important organ of a plant which generally lies below the soil in the vascular plants.

The main functions of the root are:
a. It anchors the plants in soil and thus provides mechanical support to plants to stand upright.
b. Photosynthesis products are usually stored in roots. eg. Raddish, carrots etc.
c. Roots synthesize certain hormone that helps in the growth of the plant.

So the correct answer is "All of the above"

Multiple choice biology selection and evolution theory of natural selection natural selection evidence for evolution

State whether the following statements are true or false .
Osmosis is concerned with the movement of water only and cannot directly affect the movement of dissolved substances into the roots and through the plant.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Osmosis is the movement of solvent from its higher concentration to its lower concentration across a semipermeable membrane. It does not affect the solute particles and does not facilitate their movements. Thus osmosis does not affect the movement of dissolved substances into roots and through the plant.


So the correct answer is 'True'