Mix Examples-Plant Growth and Development Questions in English

(D) $I.$ Incorrect: Cytokinins actually delay the senescence of leaves and prevent chlorophyll degradation,rather than suppressing its synthesis.
$II.$ Correct: Auxins are responsible for apical dominance,where the terminal bud inhibits the growth of lateral buds.
$III.$ Correct: Gibberellins are well-known for promoting internodal elongation and shoot growth.
$IV.$ Correct: Abscisic acid $(ABA)$ plays a crucial role in seed development and maturation,helping seeds withstand desiccation and other environmental stresses by inducing dormancy.
Therefore,statements $II, III,$ and $IV$ are correct.

(D) Sleep movements in plants,also known as nyctinasty,are nastic movements that occur daily in response to changes in environmental stimuli such as light and darkness. These movements are primarily driven by changes in turgor pressure within the pulvinus cells. Since these movements occur in response to both light (day) and dark (night) conditions,the correct answer is both $(a)$ and $(b)$.

(C) $IAA$ (Indole-$3$-Acetic Acid) is an indole compound,not a terpene.
$GA$ (Gibberellic Acid) is a terpene.
Therefore,the pair Terpenes - $IAA$ is incorrectly matched.

(D) $I.$ Cytokinins are known to delay leaf senescence by promoting nutrient mobilization.
$II.$ Auxins are primarily responsible for apical dominance,where the apical bud inhibits the growth of lateral buds.
$III.$ Ethylene is primarily associated with fruit ripening and senescence,not seed germination. Gibberellins are the hormones that promote seed germination.
$IV.$ Abscisic acid $(ABA)$,not Gibberellins,is responsible for the abscission (falling) of leaves and fruits. Therefore,statements $I$ and $II$ are correct.

(C) Stomatal movements are primarily regulated by phytohormones that influence turgor pressure in guard cells.
$III.$ $Zeatin$ is a type of cytokinin,which promotes the opening of stomata.
$IV.$ $ABA$ (Abscisic acid) is a stress hormone that induces the closure of stomata,especially under water-deficit conditions.
Therefore,$Zeatin$ and $ABA$ are the two hormones involved in regulating stomatal movements.

(D) $6$-furfuryl amino purine is a cytokinin known as Kinetin. It was discovered by Miller et al. from autoclaved herring sperm $DNA$.
$2,4$-dichlorophenoxy acetic acid $(2,4-D)$ is a well-known synthetic auxin.
Indole-$3$-acetic acid $(IAA)$ is the most common natural auxin found in plants.
Therefore,the correct sequence is $A-$ Kinetin,$B-$ Synthetic auxin,$C-$ Natural auxin.

(C) $I.$ Kinetin is a modified form of adenine (a purine) obtained from autoclaved herring sperm $DNA$,making the statement correct.
$II.$ $ABA$ (Abscisic acid) is not present in all lower plants; for example,it is absent in many algae and some bryophytes,making the statement incorrect.
$III.$ $A$ low ratio of cytokinin to auxin (high auxin,low cytokinin) promotes root initiation,while a high ratio promotes shoot formation,making the statement correct.
$IV.$ $ABA$ is synthesized via the mevalonic acid pathway (terpenoid pathway) in plastids,not through glycolysis,making the statement incorrect.
Therefore,statements $I$ and $III$ are correct.

(B) Auxins (e.g.,$IAA$,$IBA$) are acidic in nature.
Gibberellins $(GA)$ are acidic in nature.
Abscisic acid $(ABA)$ is acidic in nature.
Cytokinins are basic in nature.
Therefore,$I$ (Auxin),$III$ $(GA)$,and $IV$ $(ABA)$ are acidic.

(C) In plant tissue culture,the balance between auxin and cytokinin is crucial for organogenesis. Auxin promotes root initiation,while cytokinin promotes shoot development. Together,these hormones stimulate cell division in the callus,allowing for the growth and differentiation of plant tissues.

(B) The correct matches are as follows:
$a.$ Ethephon is a source of ethylene, which is a gaseous plant hormone. Thus, $a \rightarrow (ii)$.
$b.$ $GA$ (Gibberellic Acid) is chemically derived from terpenes. Thus, $b \rightarrow (i)$.
$c.$ Zeatin is a naturally occurring cytokinin found in plants. Thus, $c \rightarrow (iv)$.
$d.$ $IAA$ (Indole$-3-$acetic acid) is the most common natural auxin. Thus, $d \rightarrow (iii)$.
Therefore, the correct sequence is $a(ii), b(i), c(iv), d(iii)$.

(B) $a.$ Weedicide: $2, 4-D$ is a synthetic auxin used as a weedicide.
$b.$ Bolting: $GA_3$ (Gibberellic acid) promotes bolting (internode elongation just prior to flowering) in rosette plants.
$c.$ Thinning of cotton: Ethylene is used to promote thinning of cotton flowers and fruits.
$d.$ Lateral shoot growth: Cytokinin promotes lateral shoot growth by overcoming apical dominance.
Therefore,the correct matching is: $a(iv), b(i), c(iii), d(ii)$.

(A) Ethylene is a gaseous plant hormone that promotes senescence and abscission of plant organs,especially leaves and fruits. $ABA$ (Abscisic Acid) also acts as an inhibitor of plant growth and metabolism,and it plays a significant role in promoting the abscission of leaves and fruits. Therefore,both hormones are responsible for promoting the abscission of plant organs.

(A) In plant tissue culture,the ratio of Auxin (like $IAA$) and Cytokinin is the primary factor determining cell differentiation and morphogenesis. $A$ high Auxin to Cytokinin ratio promotes root development,while a high Cytokinin to Auxin ratio promotes shoot development. Therefore,the combination of Cytokinin and $IAA$ (an Auxin) is the key regulator.

(D) Plant growth regulators like $IAA$ (Indole$-3-$acetic acid),$C_2H_4$ (Ethylene),and $CK$ (Cytokinins) are known to influence sex expression in plants. Specifically,the application of these hormones can promote the development of female flowers in various plant species.

(D) The correct biosynthetic precursors for plant hormones are as follows:
$1$. Tryptophan is the precursor for Auxin (Indole$-3-$acetic acid).
$2$. Methionine is the precursor for Ethylene.
$3$. $tRNA$ (specifically adenine derivatives in $tRNA$) is the precursor for Cytokinin.
$4$. Violaxanthin is a carotenoid,which is the precursor for Abscisic Acid $(ABA)$,not $GA_3$ (Gibberellic Acid). Gibberellic Acid is derived from Acetyl $CoA$ via the mevalonic acid pathway.
Therefore,the incorrect match is Violaxanthin $\rightarrow$ $GA_3$.

(D) The correct matches are as follows:
$a.$ Auxin helps in xylem differentiation $(iii)$.
$b.$ Cytokinin is known for nutrient mobilisation $(iv)$.
$c.$ Ethylene promotes root hair formation $(i)$.
$d.$ $ABA$ (Abscisic Acid) plays a role in seed development $(ii)$.
Therefore,the correct sequence is $a(iii), b(iv), c(i), d(ii)$.

(D) Essential oils are concentrated hydrophobic liquids containing volatile aroma compounds from plants.
These compounds are primarily composed of terpenes,terpenoids,and other aromatic volatile organic substances.
They are responsible for the characteristic scent and flavor of plants and are widely used in perfumes,cosmetics,and aromatherapy.
Therefore,the correct option is $D$.

(B) Seed germination is the process by which a seed develops into a new plant. The essential factors required for seed germination are:
$1$. Moisture (Water): It is necessary for the activation of enzymes and the softening of the seed coat.
$2$. Oxygen: It is required for cellular respiration to provide energy for the growing embryo.
$3$. Suitable Temperature: Enzymes involved in germination are temperature-sensitive and require an optimal range to function.
Light is generally not required for the initial process of germination in most seeds,although it may be necessary for later stages of plant development (photosynthesis). Therefore,the correct combination is $II, III$ and $IV$.

(C) Colchicine is a poisonous chemical, isolated from the seeds and bulbs of the autumn crocus $(Colchicum)$ $autumnale$.
It blocks spindle fiber formation during cell division and thus inhibits the movement of sister chromatids to the opposite poles.
The resulting restitution nucleus includes all the chromatids.
As a result, the chromosome number of the cell is doubled, which leads to polyploidy.

(C) Plants that exhibit characteristics of mesophytes during the rainy season (when water is abundant) and adapt to xerophytic conditions during the summer (when water is scarce) are known as trophophytes.
These plants are adapted to seasonal changes in water availability.

(C) Clayey soils consist of hydrated silicates of aluminium,and the size of the soil particles is less than $0.002 \; mm$.
Clayey soils are the least porous,compact soils with good water-holding capacity but very little aeration.

(N/A) phase of growth which is maximum and fastest is the Exponential phase.
$(b)$ Apical dominance as expressed in dicotyledonous plants is due to the presence of more Auxins in the apical bud than in the lateral ones.
$(c)$ In addition to auxin,a Cytokinin must be supplied to the culture medium to obtain a good callus in plant tissue culture.
$(d)$ Leaves of vegetative plants are the sites of photoperiodic perception.

(N/A) Gibberellic acid $(GA)$ is used to increase the length of the stem,thereby increasing the yield of sugarcane.
$(b)$ Cytokinins are used to promote lateral shoot growth by overcoming apical dominance.
$(c)$ Ethylene is used to initiate sprouting in potato tubers.
$(d)$ Abscisic acid $(ABA)$ acts as a growth inhibitor and is responsible for inhibiting seed germination.

(D) $IAA$ (Indole$-3-$acetic acid) is primarily synthesized in the shoot tips and apical buds of the plant.
$(b)$ Gibberellins are synthesized in young leaves,developing seeds,and root tips.
$(c)$ Cytokinins are primarily synthesized in regions of rapid cell division,such as root tips and developing shoot buds.

(C) The correct matches are as follows:
$P$. Indole compounds: $IAA$ (Indole$-3-$acetic acid) is an indole compound. $(P-I)$
$Q$. Adenine derivatives: Kinetin is a cytokinin, which is an adenine derivative. $(Q-IV)$
$R$. Carotenoid derivatives: $ABA$ (Abscisic acid) is derived from carotenoids. $(R-II)$
$S$. Terpenes: $GA_3$ (Gibberellic acid) is a terpene. $(S-III)$
$T$. $C_2H_4$: This is the chemical formula for Ethylene. $(T-V)$
Therefore, the correct sequence is $(P-I), (Q-IV), (R-II), (S-III), (T-V)$.

(D) Plant growth regulators (PGRs) are classified based on their physiological effects on plant growth.
$1$. Plant Growth Promoters: These are involved in growth-promoting activities such as cell division,cell enlargement,pattern formation,tropic growth,flowering,fruiting,and seed germination. Examples include Auxins,Gibberellins,and Cytokinins.
$2$. Plant Growth Inhibitors: These play a role in growth-inhibiting activities such as dormancy and abscission. They also respond to wounds and stresses of biotic and abiotic origin. Abscisic acid $(ABA)$ is the primary growth inhibitor. Ethylene is a unique $PGR$ that can act as both a promoter and an inhibitor,but it is largely categorized as an inhibitor in the context of abscission and senescence.

(D) Ethylene is a gaseous plant hormone primarily associated with fruit ripening and promoting senescence. Its functions include:
$II -$ Initiates flowering in pineapple.
$III -$ Initiates germination in peanut seeds.
$IV -$ Synthesized in large amounts by ripening fruits.
Abscisic Acid $(ABA)$ is known as a stress hormone. Its functions include:
$I -$ Induces closure of stomata during water stress.
$V -$ Plays an important role in seed development,maturation,and dormancy.
Thus,the functions for Ethylene are $II, III, IV$ and for Abscisic Acid are $I, V$. The correct option is $D$.

(A) The process of soaking grains like rice or barley in water to induce germination is known as $Malting$. $Malting$ is a crucial step in the brewing and food industry where the grain is allowed to germinate,which activates enzymes like amylase to break down starches into sugars. $Gibberellins$ play a key role in this process by promoting the synthesis of these hydrolytic enzymes.

(C) In plant tissue culture,the formation of callus (an unorganized mass of cells) from an explant is primarily controlled by the balance of two major plant growth regulators: Auxin and Cytokinin.
Auxins promote root initiation,while Cytokinins promote shoot initiation.
$A$ specific ratio of these two hormones is essential to induce and maintain the growth of callus in a culture medium.

(A) Statement $A$ is correct: Auxins are known to induce parthenocarpy in many plants.
Statement $B$ is correct: Plant growth regulators (PGRs) can act as promoters (e.g.,auxins,gibberellins,cytokinins) or inhibitors (e.g.,abscisic acid) of growth.
Statement $C$ is correct: Dedifferentiation (the process where mature cells regain the capacity to divide) is a necessary step before redifferentiation (where cells mature into specific tissues) can occur.
Statement $D$ is incorrect: Abscisic acid $(ABA)$ is a plant growth inhibitor,not a promoter.
Statement $E$ is incorrect: Apical dominance refers to the phenomenon where the apical bud inhibits the growth of lateral buds,not promotes it.
Therefore,statements $A, B,$ and $C$ are correct.

(C) Statement $A$ is correct: Ethylene promotes root growth and root hair formation,thus helping the plants to increase their absorption surface.
Statement $B$ is correct: Natural cytokinins are synthesized in regions where rapid cell division occurs,such as root apices,developing shoot buds,and young fruits.
Statement $C$ is incorrect: $2,4-D$ ($2,4$-dichlorophenoxyacetic acid) is a synthetic auxin used as a herbicide to kill dicotyledonous weeds. It does not affect mature monocotyledonous plants. The statement incorrectly claims it kills monocots and spares dicots.
Since $A$ and $B$ are correct and $C$ is incorrect,the option stating 'only $C$ is incorrect' is the right answer.

(C) Statement-$I$ is incorrect because spraying sugarcane crop with $\text{Gibberellins}$ $(\text{GA})$ increases the yield by $20$ tonnes per acre,not $\text{IAA}$ (Indole$-3-$acetic acid).
Statement-$II$ is correct because plants like cotton,coriander,and larkspur show heterophylly due to different phases of life (juvenile vs. mature),which is known as developmental heterophylly.

(D) $E. \text{ Kurosawa}$ discovered the growth-promoting factor $Gibberellin$ from the fungus $Gibberella \ fujikuroi$,which causes 'bakanae' (foolish seedling) disease in rice. $Cytokinins$ were discovered by $Skoog$ and $Miller$ (as $Kinetin$ from herring sperm $DNA$). Therefore,the pair $E. \text{ Kurosawa} - \text{Fungus} - \text{Cytokinins}$ is incorrect because $E. \text{ Kurosawa}$ is associated with $Gibberellins$,not $Cytokinins$.

(D) The correct answer is $D$.
Bioassays are tests used to measure the biological activity of a substance.
$A$: Auxins are commonly tested using the Avena curvature test,which measures apical dominance or stem elongation.
$B$: Gibberellins are tested using the barley endosperm test,which measures seed germination.
$C$: Cytokinins are tested using the tobacco pith culture or chlorophyll retention test,which measures cell division.
$D$: Ethylene is typically tested using the triple response test in pea seedlings. Parthenocarpy in tomato is a physiological effect of ethylene,but it is not a standard bioassay for measuring ethylene activity. Therefore,this pair is incorrect.

(C) Ethylene inhibits flowering in most plants,with the notable exception of pineapple,where it promotes flowering.
Abscisic acid $(ABA)$ is known to inhibit flowering in long-day plants,while it can stimulate flowering in certain short-day plants.
Therefore,both Ethylene and Abscisic acid are recognized for their inhibitory roles in the flowering process of various plant species.

(C) The morphogenic differentiation in plant tissue culture is primarily regulated by the balance between cytokinin and auxin.
$A$ low ratio of cytokinin to auxin promotes root development.
$A$ high ratio of cytokinin to auxin promotes bud and shoot development.
Therefore,the interaction between these two hormones is critical for organogenesis.

(B) The correct matches are as follows:
$1$. $(a)$ Tryptophan is the precursor for the synthesis of $(iv)$ Auxin (Indole$-3-$acetic acid).
$2$. $(b)$ Mevalonic acid is a key precursor in the biosynthetic pathway of $(iii)$ Gibberellins.
$3$. $(c)$ Kinetin is a type of $(i)$ Cytokinin.
$4$. $(d)$ Dormin is another name for $(ii)$ Abscisic acid,which promotes dormancy.
Therefore,the correct matching is $(a)-(iv), (b)-(iii), (c)-(i), (d)-(ii)$.

(C) The correct matching is as follows:
$(a)$ Auxins: These are known to induce parthenocarpy in fruits like orange,lemon,and grapes. Thus,$(a)-(ii)$.
$(b)$ Gibberellins: These are known to produce male flowers on female plants (e.g.,in Cannabis). Thus,$(b)-(i)$.
$(c)$ Cytokinin: These hormones help in overcoming apical dominance by promoting the growth of lateral buds. Thus,$(c)-(iv)$.
$(d)$ Abscisic acid: It acts as an antitranspirant by inducing stomatal closure and helps plants in stress tolerance. Thus,$(d)-(iii)$.
Therefore,the correct sequence is $(a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)$.

$(A)$ The chemical nature of plant growth regulators is as follows:
$1$. Abscisic acid $(ABA)$ is a derivative of carotenoids $(A-iii)$.
$2$. Gibberellins $(GA)$ are chemically terpenes $(B-iv)$.
$3$. Kinetin is a modified form of adenine, which is a purine derivative $(C-i)$.
$4$. Auxin, specifically Indole$-3-$acetic acid $(IAA)$, is an indole derivative $(D-ii)$.
Therefore, the correct matching is $A-iii, B-iv, C-i, D-ii$.

(D) The correct answer is $D$ ($I$ and $V$).
Statement $I$ is incorrect because Kinetin is a derivative of adenine,which is a purine,not a pyrimidine.
Statement $II$ is correct; decapitation (removal of shoot tips) is used in tea plantations to promote lateral branching.
Statement $III$ is correct; ethylene is a gaseous plant hormone.
Statement $IV$ is correct; Gibberellic acid $(GA)$ is used to speed up the malting process in the brewing industry.
Statement $V$ is incorrect because Abscisic acid $(ABA)$ acts as a growth inhibitor,not a growth promoter.

(C) The correct sequence is as follows:
$1$. Gibberellin: It is known to hasten the maturity period in juvenile conifers.
$2$. Auxin: It plays a crucial role in controlling xylem differentiation.
$3$. Abscisic acid $(ABA)$: It increases the tolerance of plants to various kinds of stress,which is why it is also known as the 'stress hormone'.

(D) . $2,4-D$ is a synthetic auxin used as a herbicide $(III)$.
$B$. $GA_3$ (Gibberellic acid) is used in the brewing industry to speed up the malting process $(I)$.
$C$. Kinetin is a cytokinin that promotes nutrient mobilisation $(IV)$.
$D$. $ABA$ (Abscisic acid) stimulates stomatal closure during water stress $(II)$.
Therefore,the correct match is $A-III, B-I, C-IV, D-II$.