Tag: the leaf

Quizzes (12) Questions (128)

Questions Related to the leaf

Multiple choice botany the leaf mechanism of absorption mineral absorption significance of transpiration

Choose the correct answers from the alternatives given.
Which of the following is not a part of the transpiration cohesion-adhesion theory of the ascent of xylem sap?

  1. The evaporation of water from the mesophyll cells, which initiates a pull of water molecules from neighbouring cells and eventually from the tracheids

  2. The transfer of this pull from one water molecule to the next due to the cohesion caused by hydrogen bonds

  3. The hydrophilic walls of the narrow tracheids and vessels that help to maintain the column of water against the force of gravity

  4. The use of proton pumps to create membrane potentials that facilitate the accumulation of mineral ions.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The forces of cohesion (attraction among water molecules) and adhesion (attraction between water molecules and the walls of the xylem vessels), together help to form a thin, unbroken column of water which leads to the mass flow of water in apoplastic pathways. These forces act due to the cohesive and adhesive properties of water. In plants, the capillarity is aided by the small diameter of the tracheary elements like the tracheids and the vessel elements. The proton pump has no role in the facilitation of water and minerals.

Hence,the correct answer is 'The use of proton pumps to create membrane potentials that facilitate the accumulation of mineral ions'.

Multiple choice botany the leaf mechanism of absorption mineral absorption significance of transpiration

Who said that "transpiration is a necessary evil"?

  1. Bose

  2. Steward

  3. Anderson

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

Curtis proclaimed that transpiration is a necessary evil. Stomata allows gaseous exchange. Carbon dioxide is taken in for its fixation by Calvin cycle and oxygen produced during the photolysis is given out. This gaseous exchange takes place by the process of diffusion. When the stomata open for the gaseous exchange, the water vapor is lost by the process of transpiration.

So, the correct answer is option D.

Multiple choice botany the leaf mechanism of absorption mineral absorption significance of transpiration

Grafted flower is contained in saline water because

  1. Suitable nutrient available to flower

  2. Flower remains fresh in long duration due to less transpiration

  3. The flower is protected by microbes

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

Water moves from high water potential to less water potential. Also it is assumed that transpiration loss of water equals water absorption. In saline water there will be less of transpiration loss as absorption will be less. Consequently there are less chances of wilting.

Multiple choice botany the leaf mechanism of absorption mineral absorption significance of transpiration

Generally stomata found on the lower surface of leaf. Thus, approximate percentage of transpiration through abaxial surface is

  1. 47 %

  2. 57 %

  3. 67 %

  4. 97 %
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Stomata are usually confined in more number on the lower sides of the leaves. The lower surface is called as abaxial surface and the upper surface is called as the adaxial surface. Hence, maximum percentage i.e., 80- 95% of transpiration occurs from the lower surface.

Multiple choice botany the leaf mechanism of absorption mineral absorption significance of transpiration

Which one is the driving force for the process of passive absorption of water in roots?

  1. Root pressure

  2. Transpiration in leaves

  3. Activity of aquaporins

  4. Increase in imbibition pressure in root cells
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Passive absorption is absorption by the pull from transpiration without the active involvement of root cells, The shoots and leaves of the plant experience transpiration due to evaporation of water from their surface.

So, the answer is, "Transpiration in leaves".

Multiple choice botany the leaf mechanism of absorption mineral absorption significance of transpiration

Transpiration ratio is the ratio of moles of H$ _{2}$O transpired / moles of CO$ _{2}$ fixed. This ratio is measure of

  1. The efficiency of guard cells on stomatal movement.

  2. Effectiveness of stomata is maximizing photosynthesis, while minimizing water loss.

  3. Distinguishing a xerophyte from a glycophyte.

  4. Stomatal pore size of the leaves.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Water is required to generate the reducing power, which is used to reduce carbon dioxide during photosynthesis. The water molecules are split up and oxygen released as a by-product. The protons are used to synthesize reducing power. Now all the water that is absorbed is never used up. In fact, the water that is actually used is a small fraction of water that is absorbed. Hence, transpiration ratio is calculated to find out the effectiveness of stomata in maximizing photosynthesis and minimizing loss of water.

Multiple choice botany the leaf mechanism of absorption mineral absorption significance of transpiration

Water moves up against gravity and even for a tree of $20$m height, the tip receives water within two hours. The most important physiological phenomenon which is responsible for the upward movement of water is ____________.

  1. Cohesive forces

  2. Adhesive forces

  3. Transpiration pull

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

According to transpiration pull theory, due to transpiration, the water column inside the plant comes under tension. This is called 'transpiration pull'. On account of this tension, the water column is pulled up passively from below to top of the plant(almost like a rope). A tension of one atmosphere is sufficient to pull water to a height of about $20$ meters.

So, the correct answer is 'Transpiration pull'

Multiple choice botany the leaf mechanism of absorption mineral absorption significance of transpiration

Choose the correct answers from the alternatives given.
Which of the following forces is responsible for moving water up to the tops of the tallest trees?

  1. Atmospheric pressure

  2. Root pressure

  3. Guttation

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

Loss of water from the leaves causes water stress to develop from the top of the trees which forces more and more water to rise from the roots to the leaves. The column of the water is maintained due to cohesion and adhesion forces and the water moves up due to transpiration pull.

Hence,the correct answer is 'Transpiration'.

Multiple choice botany the leaf mechanism of absorption mineral absorption significance of transpiration

Choose the correct answers from the alternatives given.
What is the action spectrum of transpiration?

  1. Blue and infra red

  2. Green and ultraviolet

  3. Orange and red

  4. Blue and red
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

An action spectrum is a graph of the rate of a physiological activity plotted against the wavelengths of light. it shows which wavelengths of light is most effectively used in a specific reaction. In photosynthesis, chlorophyll is much more efficient at the blue and red wavelengths of light to carry out photosynthesis. Since transpiration is indirectly related to photosynthesis, its action spectrum would be similar to photosynthesis.

Hence, the correct answer is 'Blue and red'.