Phases of plant growth MCQs With Answer

Introduction

Understanding the phases of plant growth is essential for B.Pharm students studying pharmacognosy, plant physiology, and drug development from botanical sources. This concise guide explains seed dormancy and germination, seedling establishment, vegetative and reproductive phases, flowering, fruiting, and senescence, while linking key physiological controls such as plant hormones (auxin, gibberellin, cytokinin, ABA, ethylene), photoperiodism, vernalization, and environmental influences. Emphasis on secondary metabolite production during specific growth stages helps relate plant growth to pharmaceutical quality and yield. Mastering these concepts prepares you for practical applications in herbal drug sourcing, cultivation timing, and quality control. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which phase directly follows seed dormancy when environmental conditions become favorable?

• Seedling establishment
• Vegetative phase
• Germination
• Reproductive phase

Correct Answer: Germination

Q2. During germination, which process initially softens the seed coat to allow radicle emergence?

• Photoperiod sensing
• Imbibition
• Senescence
• Vernalization

Correct Answer: Imbibition

Q3. Which plant hormone is primarily responsible for breaking seed dormancy and promoting germination?

• Abscisic acid (ABA)
• Ethylene
• Gibberellin (GA)
• Cytokinin

Correct Answer: Gibberellin (GA)

Q4. Abscisic acid (ABA) is best known for which role in seed physiology?

• Promoting flowering
• Inducing dormancy and stress tolerance
• Stimulating cell elongation
• Causing fruit ripening

Correct Answer: Inducing dormancy and stress tolerance

Q5. The vegetative phase is characterized predominantly by which of the following?

• Seed maturation
• Flower and fruit development
• Leaf and stem growth, biomass accumulation
• Fruit ripening and seed dispersal

Correct Answer: Leaf and stem growth, biomass accumulation

Q6. Which meristematic region is mainly responsible for primary growth (lengthening) of shoots?

• Intercalary meristem
• Lateral meristem
• Apical meristem
• Cork cambium

Correct Answer: Apical meristem

Q7. Which phenomenon explains directional growth of a plant toward light?

• Hydrotropism
• Gravitropism
• Phototropism
• Thigmotropism

Correct Answer: Phototropism

Q8. Auxin is most directly involved in which of these processes?

• Stomatal closure during drought
• Promotion of cell elongation and apical dominance
• Induction of leaf abscission
• Regulation of seed dormancy

Correct Answer: Promotion of cell elongation and apical dominance

Q9. Cytokinins primarily promote which activity in plant tissues?

• Cell division (cytokinesis)
• Fruit ripening
• Leaf senescence
• ABA synthesis

Correct Answer: Cell division (cytokinesis)

Q10. Photoperiodism affects which major developmental transition in many plants?

• Seed coat formation
• Transition from vegetative to reproductive (flowering)
• Root hair initiation
• Leaf cuticle development

Correct Answer: Transition from vegetative to reproductive (flowering)

Q11. Vernalization is a requirement for some plants to flower after exposure to which condition?

• Prolonged cold
• High salinity
• Extended drought
• Continuous light

Correct Answer: Prolonged cold

Q12. Which hormone is closely associated with fruit ripening and leaf abscission?

• Gibberellin
• Auxin
• Ethylene
• Cytokinin

Correct Answer: Ethylene

Q13. Secondary metabolites important for pharmaceuticals (alkaloids, flavonoids) are often most abundant during which growth stage?

• Seed dormancy
• Vegetative and early reproductive stages, depending on compound
• Late senescence only
• Only during seed germination

Correct Answer: Vegetative and early reproductive stages, depending on compound

Q14. Apical dominance is primarily regulated by a balance between which hormones?

• ABA and ethylene
• Auxin from apex and cytokinins from roots
• Gibberellin and brassinosteroids
• Salicylic acid and jasmonic acid

Correct Answer: Auxin from apex and cytokinins from roots

Q15. Which environmental factor most strongly influences vernalization and seed stratification requirements?

• Light quality
• Soil pH
• Temperature duration (cold period)
• Wind exposure

Correct Answer: Temperature duration (cold period)

Q16. The transition to reproductive phase often involves upregulation of which class of genes?

• Photosystem II genes
• Flowering integrator and MADS-box transcription factors
• Ribosomal RNA genes
• Cell wall degradation enzymes

Correct Answer: Flowering integrator and MADS-box transcription factors

Q17. Which process contributes to increased cell size during vegetative growth?

• Cell differentiation only
• Cell elongation driven by turgor and cell wall loosening
• Programmed cell death
• Stomatal closure

Correct Answer: Cell elongation driven by turgor and cell wall loosening

Q18. Gibberellins are commonly applied in agriculture to achieve which effect?

• Induce seed dormancy
• Promote stem elongation and break dormancy in seeds
• Accelerate leaf senescence
• Inhibit flowering

Correct Answer: Promote stem elongation and break dormancy in seeds

Q19. Which nutrient deficiency typically limits vegetative growth most directly?

• Iron deficiency affecting chlorophyll synthesis
• Excess potassium
• Low sodium only
• Excess manganese

Correct Answer: Iron deficiency affecting chlorophyll synthesis

Q20. In pharmacognosy, why is the timing of harvest important for herbal drug quality?

• It determines seed coat hardness only
• Secondary metabolite concentration and composition vary with growth stage
• Harvest timing only affects root length
• It only influences water content, not active compounds

Correct Answer: Secondary metabolite concentration and composition vary with growth stage

Q21. Which growth regulator is often involved in delaying leaf senescence?

• Ethylene
• Cytokinin
• Abscisic acid
• Jasmonic acid

Correct Answer: Cytokinin

Q22. Photomorphogenesis refers to plant development influenced by:

• Gravity alone
• Pathogen signals
• Light quality, quantity and duration
• Soil microbial communities

Correct Answer: Light quality, quantity and duration

Q23. Which structure initiates new lateral roots and contributes to root branching during the seedling phase?

• Cambium
• Pericycle cells
• Cork
• Endodermis only

Correct Answer: Pericycle cells

Q24. Gravitropism in roots is primarily controlled by:

• Auxin redistribution leading to differential cell elongation
• Ethylene accumulation in shoots
• Light-driven chlorophyll synthesis
• Soil moisture gradients only

Correct Answer: Auxin redistribution leading to differential cell elongation

Q25. Which phase is most associated with the mobilization of seed endosperm reserves?

• Senescence
• Seedling establishment and early germination
• Reproductive phase
• Vegetative maturity

Correct Answer: Seedling establishment and early germination

Q26. In biennial plants, which sequence of phases is typical?

• Germination → flowering → vegetative growth
• Germination → vegetative growth year 1 → vernalization/winter → flowering year 2
• Seed dormancy only for two years
• Immediate flowering in the first season

Correct Answer: Germination → vegetative growth year 1 → vernalization/winter → flowering year 2

Q27. Which compound class increases in many medicinal plants under elicitation during growth to boost defense metabolites?

• Primary metabolites like glucose only
• Secondary metabolites such as alkaloids, phenolics, terpenoids
• Structural polysaccharides only
• Inorganic ions

Correct Answer: Secondary metabolites such as alkaloids, phenolics, terpenoids

Q28. Flower induction by long-day plants requires which photoperiodic condition?

• Short nights (long days)
• Continuous darkness
• Short days (long nights)
• No light variation

Correct Answer: Short nights (long days)

Q29. Which hormone antagonizes gibberellin effects in seed dormancy maintenance?

• Auxin
• Cytokinin
• Abscisic acid (ABA)
• Brassinosteroid

Correct Answer: Abscisic acid (ABA)

Q30. Which cellular process increases cell number during meristematic activity?

• Cell elongation
• Cell division (mitosis)
• Programmed cell death
• Transpiration

Correct Answer: Cell division (mitosis)

Q31. Senescence in leaves is commonly accompanied by which biochemical change?

• Increase in chlorophyll content
• Degradation of chlorophyll and nutrient remobilization
• Rapid cell proliferation
• Enhanced photosynthetic rate

Correct Answer: Degradation of chlorophyll and nutrient remobilization

Q32. Which measurement best indicates vegetative growth rate in controlled studies?

• Seed dormancy duration
• Relative growth rate (biomass gain per unit biomass per time)
• Final fruit color
• Number of pathogens present

Correct Answer: Relative growth rate (biomass gain per unit biomass per time)

Q33. Which of the following is a common effect of water stress on plant growth phases?

• Enhanced flowering in all species
• Inhibition of cell expansion, stomatal closure, delayed growth
• Promotion of seed germination universally
• Increased leaf area index always

Correct Answer: Inhibition of cell expansion, stomatal closure, delayed growth

Q34. Which photoreceptor mediates shade avoidance and red/far-red light responses affecting flowering?

• Cryptochrome
• Phytochrome
• Phototropin
• Chlorophyll

Correct Answer: Phytochrome

Q35. In tissue culture propagation, which phase must be induced to produce shoots from callus?

• Rooting phase
• Organogenesis regulated by auxin:cytokinin ratio favoring cytokinins
• Seed dormancy
• Senescence

Correct Answer: Organogenesis regulated by auxin:cytokinin ratio favoring cytokinins

Q36. Which process in reproductive phase directly leads to formation of seeds?

• Pollination and fertilization
• Leaf senescence
• Root elongation
• Stomatal opening

Correct Answer: Pollination and fertilization

Q37. Which cellular component expands to drive turgor-dependent cell enlargement?

• Mitochondrial DNA
• Central vacuole
• Cellulose microfibrils only
• Plasmodesmata

Correct Answer: Central vacuole

Q38. Ethylene biosynthesis increases in response to wounding and contributes to which growth-related process?

• Seed germination
• Fruit ripening and abscission
• Meristem activation
• Increased nitrogen fixation

Correct Answer: Fruit ripening and abscission

Q39. Which anatomical change characterizes secondary growth in woody plants?

• Activity of vascular cambium producing secondary xylem and phloem
• Increase in stomatal density only
• Loss of apical meristem function
• Thinning of the cortex only

Correct Answer: Activity of vascular cambium producing secondary xylem and phloem

Q40. Which experimental treatment can break physiological seed dormancy in many species?

• Applying abscisic acid
• Cold stratification or gibberellin application
• Removing endosperm entirely
• Exposing seeds to continuous darkness

Correct Answer: Cold stratification or gibberellin application

Q41. Which regulatory molecule mediates systemic signaling from roots to shoots under nutrient deficiency?

• Chlorophyll
• Mobile RNAs, hormones (cytokinins), and peptides
• Cell wall lignin only
• Stored starch granules

Correct Answer: Mobile RNAs, hormones (cytokinins), and peptides

Q42. Which factor can shift metabolic allocation toward secondary metabolite production?

• Optimal, non-stress conditions always
• Biotic or abiotic stress and elicitor treatments
• Complete nutrient sufficiency only
• Low light and complete waterlogging only

Correct Answer: Biotic or abiotic stress and elicitor treatments

Q43. Which hormone class is most involved in promoting cell wall loosening for expansion?

• Gibberellins and auxins
• ABA only
• Ethylene only
• Salicylic acid

Correct Answer: Gibberellins and auxins

Q44. Apical meristem identity for flowering is typically controlled by which signal integration?

• Soil microbes only
• Integration of photoperiod, vernalization, gibberellins and endogenous signals (FT protein)
• Water uptake exclusively
• Leaf senescence signals only

Correct Answer: Integration of photoperiod, vernalization, gibberellins and endogenous signals (FT protein)

Q45. Which method is commonly used to assess seed viability before sowing?

• Measuring fruit sugar only
• Tetrazolium staining or germination tests
• Counting stomata
• Observing leaf color of parent plant

Correct Answer: Tetrazolium staining or germination tests

Q46. Which process is essential for determining flowering time in short-day plants?

• Long uninterrupted light periods
• Long nights exceeding a critical duration
• High soil nitrogen only
• Continuous watering

Correct Answer: Long nights exceeding a critical duration

Q47. Which growth phase is most critical for attaining maximum biomass for herbal drug yield?

• Late senescence only
• Peak vegetative stage for many leafy medicinal plants
• Dormant seed phase
• Immediately after seed dispersal

Correct Answer: Peak vegetative stage for many leafy medicinal plants

Q48. Which enzymatic activity often increases during fruit ripening affecting texture?

• Cellulase and pectinase activity degrading cell wall
• DNA polymerase activity
• Rubisco activity
• ATP synthase inhibition only

Correct Answer: Cellulase and pectinase activity degrading cell wall

Q49. Which signalling molecule is linked to systemic acquired resistance and can influence growth-defense trade-offs?

• Salicylic acid
• Auxin only
• Gibberellin only
• Ethylene only

Correct Answer: Salicylic acid

Q50. For cultivation aimed at producing maximum alkaloid content, which strategy is most appropriate?

• Harvest at random growth stage
• Identify and harvest at the specific growth stage when target alkaloid peaks, guided by profiling
• Always harvest at seed maturity regardless of alkaloid profile
• Ignore environmental effects on metabolite levels

Correct Answer: Identify and harvest at the specific growth stage when target alkaloid peaks, guided by profiling

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com