Tag: cytokinins, ethylene and abscisic acid

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Multiple choice biology plant growth other plant hormones cytokinins, ethylene and abscisic acid plant hormones

Horizontal growth of seedlings, swelling of axis and apical hook formation in dicot seedlings is brought about by

  1. Auxins

  2. Gibberellins

  3. Ethylene

  4. Kinetin

  5. Abscisic acid
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Ethylene is a gaseous plant hormone. It is also called as ripening hormone as it stimulates ripening of fruits. It also promotes the horizontal growth of seedlings, swelling of the axis and increase curvature by apical hook formation in dicot seedlings. It inhibits stem elongation. This is called as triple response shown by ethylene.
Thus, the correct answer is option C.
Multiple choice biology plant growth other plant hormones cytokinins, ethylene and abscisic acid plant hormones

Which is not the effect of ethylene?

  1. Promotes senescence and abscission of plant organs

  2. Breaks seed and bud dormancy

  3. Brings about horizontal growth of seedlings

  4. Hastens fruit ripening

  5. Helps to overcome apical dominance
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Ethylene is a plant hormone. It is also called as ripening hormone as it hastens fruit ripening in plants. In certain plants, it breaks seed and bud dormancy and induces germination. It also causes flowers to fall from the plant and hence, promotes senescence and abscission of plant hormones. It also causes the triple response in etiolated seedlings. It inhibits stem elongation and brings about the horizontal growth of seedlings. 

Thus, the correct answer is option E.

Multiple choice biology plant growth other plant hormones cytokinins, ethylene and abscisic acid plant hormones

Ethylene promotes water absorption by increasing the root's absorption surface. It promotes:

  1. Premability of cell membrane

  2. Rormation of root hairs

  3. Concentration of cell sap

  4. All of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Ethylene promotes water absorption by increasing the root's absorption surface. It promotes the elongation of the root hairs and the root itself and it is also responsible for increasing the cell permeability in some cases. It has also been observed to increase the osmotic pressure and the concentration of cell sap.

So, the correct answer is 'all of these'.
Multiple choice biology plant growth other plant hormones cytokinins, ethylene and abscisic acid plant hormones

Artificial ripening of fruit is carried out by

  1. Auxin

  2. Gibberellin

  3. Abscisic acid

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

Ethylene is sprayed on fruits to promote artificial ripening, which is very commonly seen in fruit shops.
Ethylene is applied on fruits in the form of a spray. It acts to the fruit cell wall made of pectin or cellulose and promotes ripening.

Multiple choice biology plant growth and development other plant hormones cytokinins, ethylene and abscisic acid plant hormones

How many of the following are true regarding secondary growth in root?
A. All cambium are secondary in orgin
B. Lenticels are not formed
C. Bark is formed
D. Cork cambium is originated from outer layer of cortex

  1. Two

  2. Three

  3. One

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

In dicotyledonous plants, roots undergo secondary growth to increase in thickness by the formation of the secondary meristem. In roots, vascular bundles are radial, primary cambium is absent. During secondary growth, some of the parenchyma cells beneath each phloem group become meristematic and thus form cambium strips, which is secondary in origin. 

Lenticels can be developed by the activity of phellogen or cork cambium as transversely elongated outer cortex regions. 
In stems and roots of the woody dicots, all the cork layers together with cortical and dry secondary phloem tissue external to the innermost phellogen are called outer bark; while all the tissues external to the vascular cambium (secondary phloem, primary phloem, cortex, periderm, and tissues outside the periderm are termed bark. 
In dicot roots, cork cambium or phellogen arises in the outer cells of the pericycle. 
Hence, the except D all other options are correct. 
So, the correct answer is option B, Three. 

Multiple choice biology plant growth and development other plant hormones cytokinins, ethylene and abscisic acid plant hormones

Cycocel is a .............

  1. Wound hormone

  2. Growth hormone

  3. Rhizocaline necessary for root formation

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

 Cycocel is among the most reliable and widely used plant growth regulators on the market. Cycocel may be used on any crop in the green house or nursery including but not limited to, poinsettias, hibiscus, azzaleas and geraniums to reduce stem elongation, induce early flowering, and to produce compact plants with multiple buds per shoots.

Multiple choice biology plant growth and development other plant hormones cytokinins, ethylene and abscisic acid plant hormones

Acid deposition weakens plants by damaging their

  1. Leaves

  2. Roots

  3. Stems

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

Acid deposition primarily damages the waxy cuticle of leaves, which leads to increased water loss and susceptibility to pathogens. While it can affect soil chemistry and roots indirectly, the direct primary damage is to the foliage.

Multiple choice biology plant growth and development other plant hormones cytokinins, ethylene and abscisic acid plant hormones

Elongation of internodes is inhibited by ..............

  1. Gibberellins

  2. Morphactins

  3. Both (A) and (B)

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

Morphactins have inhibitory effect on the stem elongation. Increases concentration produced dwarfing in the plants. Morphactins are a group of substances which act on morphogenesis and modulate the expression of plants. Chemically, they are the derivatives of fluorene compounds.