Plant Growth and Development MCQ Quiz in मल्याळम - Objective Question with Answer for Plant Growth and Development - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

Concept:

• Photoperiodism or photoperiod response is a physiological reaction of organisms to the length of day or night.
• It is basically a developmental response of plants to the relative lengths of light and dark periods, for their flowering.
• According to photoperiodism plants can be classified into Short-day plants, Long day plants & Day-neutral plants.

Explanation:

• Short day plants - These plants give flowers on exposure to photoperiod equal to or shorter than their critical day length. Flower initiation takes place when days are short less than ten hours.
  E.g. rice, Jowar, green gram, black gram, etc.
• Long day plants -  These plants give flowers on exposure to photoperiod longer than their critical day length. Require long days more than ten hours for floral ignition.
  E.g. Wheat, Barley
• Day-neutral plants - These plants do not require any specific light period for flowering. The rate of the flowering initiation depends on how short or long the is photoperiod. Shorter the days, more rapid initiation of flowering in short days plants. The longer the days more rapid are the initiation of flowering in long days plants. E.g. Cotton, sunflower

Thus, ​Plants that flowers under the photoperiods, less than the critical day length are called Short-day plants.

The correct answer is Kinetin, synthetic auxin and natural auxin

Explanation:

• The plant growth regulators (PGRs) are small, simple molecules of diverse chemical composition.
• They could be indole compounds (indole-3-acetic acid, IAA); adenine derivatives (N⁶ -furfurylamino purine, kinetin), derivatives of carotenoids (abscisic acid, ABA); terpenes (gibberellic acid,GA₃) or gases (ethylene, C₂H₄).
• Auxins like IAA and indole butyric acid (IBA) have been isolated from plants (natural auxin)
• NAA (naphthalene acetic acid) and 2, 4-D (2, 4-dichlorophenoxyacetic)
  are synthetic auxins.

Therefore, the examples of Kinetin, synthetic auxin and natural auxin are N⁶-furfuryl amino purine, 2, 4-dichlorophenoxy acetic acid and indole-3 acetic acid respectively. 

The correct answer is Linear curve

Explanation:

• Arithmetic growth refers to a pattern of growth where a quantity increases by a constant amount over equal time intervals.
• This type of growth can be represented graphically as a straight line, indicating a constant rate of change.
• An example of arithmetic growth is the elongation of a root at a constant rate over time.

Fig: Constant linear growth, a plot of length L against time t

Mathematically, it is expressed as,

L_t = L₀ + rt

• L_t = length at time ‘t’
• L₀ = length at time ‘zero’
• r = growth rate / elongation per unit time.

Concept:

• Growth is defined as an increase in protoplasm at the cellular level.
• But it is difficult to measure the amount of protoplasm directly.
• So, growth is measured based on different parameters.

Explanation:

• Plant growth is unique as its growth is indeterminate. The plant can grow throughout its life.
• The rise in fresh weight, dry weight, and increase in size, area, volume and cell count are some of the ways by which growth can be monitored.
• A single maize root apical meristem can produce more than 17,500 new cells each hour, while cells in watermelon can swell up to 3,50,000 times their original size.
• Growth in the former is shown as a rise in cell count, whereas growth in the latter is shown as an increase in cell size.
• A pollen tube's growth is measured in terms of length, whereas a dorsiventral leaf's growth is measured by an increase in surface area.
• So, growth can be measured as an increase in cell size, increase in cell number and increase in length and weight as well.

So, the correct answer is option 4, All of the above.

Additional Information

• ​In general, the growth of an organism is represented graphically by an S-shaped curve which is also known as the sigmoidal curve.
• The sigmoidal curve of the growth pattern is divided into 3 phases:
• Namely the Lag phase, Log phase or exponential phase, and stationary or plateau phase.
• It is represented as follows:

Concept:

• Plant hormones or phytohormones are plant growth regulators that regulate the growth, development, reproduction, and death of the plant.
• There are different plant hormones such as ethylene, auxin, cytokinin, gibberellin, abscisic acid, etc.

Corrected Table:

Explanation:

• Auxin - 
  • ​It is a plant hormone responsible for apical dominance.
  • Apical dominance is a process where the growth of lateral roots is inhibited due to the presence of auxin.
  • It also controls xylem differentiation.
  • Indole acetic acid (IAA) is the naturally occurring auxin.
  • Auxins such as 2,4-D acts as a weedicide and can be used to form weed-free lawns.
• Abscisic acid - 
  • ​It is known as the stress hormone.
  • It causes abscission of plant organs, plant growth inhibitor, promotes dormancy, and works antagonistically to gibberellic acid/gibberellin.
  • It helps in stomata closure in response to water stress, increasing the tolerance of plants to water stress.
• Ethylene - 
  • ​It is a gaseous hormone that regulates both growth and senescence.
  • It promotes fruit ripening, senescence, abscission of plant organs (mainly leaves), breaking of seed dormancy, etc.
• Gibberellin -
  • It is a plant growth regulator that has many physiological effects.
  • Gibberellin plays a role in flowering, increases the length of the internode, delays senescence, and promotes rosette formation in cabbages.
  • Bolting is the term used to describe the abrupt and increased internodal growth that occurs in rosette plants and is followed by flowering after the application of gibberellins.
  • Gibberellins thus promote bolting.
• Cytokinin -
  • It is another plant hormone that regulates plant growth and development.
  • It was first isolated from autoclaved herring sperm DNA.
  • It promotes cell division, formation of leaves, formation of chloroplast, delays the process of senescence, etc.

Concept: 

• Plant growth regulators (PGRs) are defined as small, simple molecules of diverse chemical composition.
• They are also described as plant hormones or phytohormones.
•  PGRs are classified into two broad groups based on their functions in a living plant body.
• One group of PGRs is involved in growth-promoting activities, such as cell division, cell enlargement, pattern formation, tropic growth, flowering, fruiting, and seed formation.
• The PGRs of the other group plays an important role in plant responses to wounds and stresses of biotic and abiotic origin.
• A few examples of  PGRs are indole-3-acetic acid, abscisic acid, terpenes (gibberellic acid, GA3 ), or gases (ethylene, C2H4 ).

​​Explanation:

Auxin

•  Plant hormone auxin induces flowering in pineapple.

Ethylene

•  Ethylene is a gaseous plant hormone.
•  Ethylene also helps in the synchronization of flowering and fruit set up in a pineapple.
•  Therefore, auxin and ethylene can be applied to artificially induce flowering in pineapple plants throughout the year to increase yield.

Gibberellin 

• Speeds up the malting process.
• Gibberellins, cause fruits like apples to elongate and improve their shape and also delay senescence. 
• Thus, the fruits can be left on the tree longer so as to extend the market period.

Cytokinin

• Cytokinin helps to overcome apical dominance. 
• It also helps to produce new leaves, chloroplasts in leaves, lateral shoot growth, and adventitious shoot formation.

Abscisic acid

• Abscisic acid is responsible for seed dormancy and inhibition of seeds.

Thus, the correct answer is option 1.

The Correct Answer is Hypogeal. 

• There are two types of germination: 
• Epigeal Germination: In this type of germination, the hypocotyl elongates rapidly and arches upwards pulling the cotyledons which move above the soil.
• An example of a plant with epigeal germination is the common bean (Phasoleus Vulgaris). 
• Hypogeal Germination: In this type of germination, the epicotyl elongates and the cotyledons remain below the soil.
• In peas and corn (maize) the cotyledons (seed leaves) remain underground (e.g., hypogeal germination), while in other species (beans, sunflowers, etc.)​
• Another example of a plant with hypogeal germination is the pea (Pisum sativum). 

Explanation:

• The plant growth regulators (PGRs) are small, simple molecules of diverse chemical composition.
• They could be indole compounds (indole-3-acetic acid, IAA); adenine derivatives (N6 -furfurylamino purine, kinetin), derivatives of carotenoids (abscisic acid, ABA); terpenes (gibberellic acid,GA3) or gases (ethylene, C2H4).
• Adenine derivatives are a class of plant hormones that include cytokinins. These compounds are derived from the adenine molecule, which is one of the four nucleotides in DNA and RNA.
• Cytokinins are involved in various plant growth processes such as cell division, shoot and root growth, and the delay of senescence (aging).
• Kinetin is one of the most well-known cytokinins and was the first to be discovered. It is used in tissue culture to stimulate cell division.

Other Options:

• ABA (Abscisic Acid): This is a plant hormone involved in many plant developmental processes, including seed dormancy, leaf senescence, and response to environmental stress. It is a derivative of carotenoids.
• Auxin: This is another class of plant hormones that play a critical role in the regulation of plant growth and development, particularly in cell elongation and the directional growth of roots and shoots. 
• GA (Gibberellins): These are a group of plant hormones that regulate growth and influence various developmental processes, including stem elongation, germination, and flowering. It is classified as a terpene.

The correct answer is a,d correct and b,c incorrect

Explanation:

• Ethylene is used to initiate flowering and for synchronising fruit-set in pineapples.
• It also induces flowering in mango.
• The most widely used compound as source of ethylene is ethephon.
• Ethephon in an aqueous solution is readily absorbed and transported within the plant and releases ethylene slowly.
• Ethephon hastens fruit ripening in tomatoes and apples and accelerates abscission in flowers and fruits (thinning of cotton, cherry, walnut).
• It promotes female flowers in cucumbers thereby increasing the yield.

The correct answer is Abscisic acid

Concept:

• F. Skoog's Experiment: Demonstrated that certain substances, when combined with auxin, could stimulate the proliferation of callus tissue from plant stem segments.
• F. Skoog and his co-workers observed that from the internodal segments of tobacco stems the callus (a mass of undifferentiated cells) proliferated only if, in addition to auxins the nutrients medium was supplemented with one of the following: extracts of vascular tissues, yeast extract, coconut milk or DNA. Miller et al. (1955), later identified and crystallised the cytokinesis promoting active substance that they
  termed kinetin.

Explanation:

• Extract of Vascular tissues: Contains cytokinins, which work synergistically with auxin to promote cell division and callus formation.
• Coconut milk: Rich in cytokinins, which are key to callus proliferation when combined with auxin.
• Abscisic acid: Correct choice. Abscisic acid is generally involved in stress responses and inhibiting growth, not promoting callus formation with auxin.
• Yeast Extract: Contains various growth-promoting compounds, including vitamins and amino acids, which can stimulate callus formation when used with auxin.