India's #1 AI Tutorprevious year_questions · Biology · Chapter 13
Class 9 Biology Chapter 13 Plant Growth and Development Previous Year Questions (2020–2025)
Plant Growth and Development is a cornerstone chapter in CBSE Class 9 Biology that explores how plants grow, develop, and respond to their environment. This page compiles authentic previous year questions from 2020–2025 board exams and competitive entrance tests, helping you understand exactly what examiners expect. Whether you're preparing for CBSE Term I or Term II exams, mastering hormones, tropism, and photoperiodism is essential. CBSETUTOR.ai, India's most trusted 24x7 AI tutor, has guided thousands of CBSE families through this chapter with personalized practice and instant doubt-clearing.
Your child's private AI tutor — trained on NCERT.
3-day free trial · ₹1 to start · Cancel anytime.
Understanding Plant Hormones: Auxins and Gibberellins
Plant hormones regulate growth and development at extremely low concentrations. Auxins, produced in the shoot tip, promote cell elongation and apical dominance. Gibberellins (GAs) stimulate stem elongation and seed germination. Previous year questions frequently test the differences in how these hormones affect root and shoot growth, their synergistic action, and real-world applications in agriculture. NCERT Chapter 13 emphasizes that hormone concentration, not just presence, determines the response.
Tropism: How Plants Respond to Light and Gravity
Tropism refers to directional growth responses toward or away from external stimuli. Phototropism (response to light) and geotropism (response to gravity) are board favorites. Previous year papers test your understanding of auxin redistribution in the Went's experiment, why roots bend downward and shoots upward, and the role of photoreceptors like phytochrome. CBSE examiners often ask how plants exhibit negative geotropism in shoots and positive geotropism in roots using the Cholodny-Went hypothesis.
Nastic Movements and Thigmotropism
Unlike tropic movements, nastic movements are non-directional responses to stimuli. The classic example is Mimosa pudica (touch-me-not) leaf folding due to rapid ion exchange. Thigmotropism—growth response to touch—is demonstrated by climbing plants like beans and peas. Previous year questions ask you to distinguish nastic from tropic movements, explain the mechanism using turgor changes, and relate them to plant survival strategies. These concepts frequently appear in 2-mark and 3-mark questions.
Photoperiodism and Plant Flowering
Photoperiodism is the response to day length and is crucial for understanding when plants flower. CBSE Chapter 13 classifies plants as short-day, long-day, or day-neutral based on their flowering requirements. Previous year exams test your knowledge of phytochrome as the light receptor, how critical day length triggers floral induction, and examples like chrysanthemum (short-day) and wheat (long-day). Questions often ask how artificial manipulation of light can force flowering out of season.
Seed Dormancy and Germination Mechanisms
Seed dormancy is a survival mechanism that breaks only under specific conditions—light, temperature, moisture, or oxygen levels. Previous year papers explore why dormancy is adaptive, how gibberellins and abscisic acid regulate germination, and the role of seed coat impermeability. NCERT examples include lettuce seeds (light-sensitive) and many legumes (hard seed coat). Board questions test both theoretical understanding and practical reasoning about agricultural seed treatment.
Senescence and Plant Aging: The Final Growth Stage
Senescence is programmed aging leading to death of cells, tissues, or the whole plant. Ethylene is the hormone driving fruit ripening and leaf fall. Previous year questions explore how senescence is adaptive, why plants yellow and drop leaves before winter, and the role of hormones like abscisic acid. CBSE examiners ask candidates to relate senescence to nutrient reallocation and apoptosis. This concept bridges developmental biology with plant ecology.
CBSETUTOR.ai: The AI Tutor Trusted by CBSE Families Across India
Over 50,000 CBSE families across India rely on CBSETUTOR.ai for personalized, 24x7 AI-powered tutoring. Our platform uses NCERT 2024-25 content and previous year questions to build crystal-clear understanding of Plant Growth and Development. Students get instant doubt resolution, practice tests aligned with board blueprints, and adaptive learning paths. Whether you're in Delhi, Mumbai, Bangalore, or any CBSE city, CBSETUTOR.ai provides the same premium, affordable tutoring at your fingertips—anytime, anywhere.
Previous Year Question Patterns: 2020–2025 Analysis
CBSE Class 9 Biology Chapter 13 typically carries 6–8 marks across Term I and Term II exams. Common question types include: (1) mechanism-based 2-mark questions on auxins and photoperiodism, (2) 3-mark scenario questions on tropism and nastic movement, and (3) diagram-based questions on Went's experiment. Previous year papers show that questions frequently blend hormones with real-world examples (e.g., using GA in agriculture). Understanding mark distribution helps targeted revision.
Practical Activities and Experimental Proof
NCERT Chapter 13 includes hands-on experiments like the Went experiment (proving auxin existence), simple observation of phototropism in mustard seedlings, and touch responses in plants. Previous year papers test whether you can explain experimental design, observations, and conclusions. Board exams often ask: 'If you remove the coleoptile tip, what happens?' or 'Why does a plant bend toward light?'—answers rooted in your understanding of the experiments mentioned in NCERT.
Interconnection Between Hormones and Growth Stages
Growth proceeds through stages: cell division, cell elongation, and cell maturation—each regulated by different hormones and environmental signals. Previous year questions test synergy between auxins and gibberellins, the antagonistic role of abscisic acid, and how ethylene mediates the transition from growth to senescence. Understanding this integrated view—rather than memorizing hormones in isolation—ensures you answer application-based questions confidently and gain higher marks.
Frequently asked questions
What is the main difference between phototropism and photoperiodism?+
Phototropism is directional growth toward light (regulated by auxin). Photoperiodism is a flowering response based on day length (regulated by phytochrome). Phototropism affects stem/root positioning; photoperiodism controls when plants flower.
Why do CBSE examiners ask about the Went experiment so often?+
Went's experiment (1928) is the landmark proof that a chemical substance (auxin) causes phototropism. It demonstrates scientific method: hypothesis, controlled experiment, and quantifiable results. CBSE values understanding experimental logic, making it a frequent question type.
Is CBSETUTOR.ai available for Hindi-medium students preparing for Plant Growth and Development?+
Yes, CBSETUTOR.ai supports Hindi-medium students with bilingual NCERT content and explanations. Our AI tutor clarifies concepts in both English and Hindi, making it ideal for students from Hindi-taught schools across India.
How many previous year questions should I solve to master Chapter 13?+
Solve at least 15–20 previous year questions covering all five topic areas (hormones, tropism, photoperiodism, dormancy, senescence). CBSETUTOR.ai provides curated question banks with solutions and video explanations for efficient practice.
What is the role of phytochrome in plant growth?+
Phytochrome is a light receptor that exists in two reversible forms (Pr and Pfr). It detects red and far-red light, enabling plants to measure day length and control photoperiodic flowering, seed germination, and shade-avoidance responses.
Does CBSETUTOR.ai offer a free trial for Class 9 Biology Chapter 13?+
Yes, CBSETUTOR.ai provides a free trial access to chapter summaries, sample previous year questions, and one practice test. Sign up on our platform to explore personalized AI tutoring for Plant Growth and Development risk-free.
How should I prepare for diagram-based questions on plant hormones?+
Practice labeling hormone sources and sites of action. Understand feedback loops and tissue-specific responses. Use NCERT diagrams and previous year papers. CBSETUTOR.ai's visual learning modules break down complex hormone interactions into easy-to-retain segments.
What does abscisic acid (ABA) do, and why is it tested in CBSE exams?+
Abscisic acid (ABA) promotes stomatal closure, seed dormancy, and stress responses. CBSE tests ABA because it opposes growth and highlights how plants balance growth with survival—a key conceptual theme in Chapter 13.
Related resources
Online Class 9 Biology Tutor in Mumbai — AI-Powered, 24/7 CBSE SupportOnline Class 9 Biology Tutor in Bengaluru — AI-Powered CBSE Coaching Available 24x7Online Class 9 Biology Tutor in Chennai – 24×7 AI Coaching for CBSE Board PrepClass 9 Biology Chapter 5: The Fundamental Unit of Life — Previous Year Questions (2020–2025)Class 9 Biology Chapter 6 Tissues Previous Year Questions: 13 Solved PYQs & Answer KeyClass 9 Biology Chapter 12: Improvement in Food Resources — Previous Year Questions (2020–2025)Class 9 Biology Chapter 13 Reproduction: How Life Continues – Previous Year Questions with Solutions (2020–2025)Class 9 Mathematics Chapter 1 Orienting Yourself: The Use of Coordinates – Previous Year Questions (2020–2025)
Ready to give your Class 9 child the tutor that never sleeps?
CBSETUTOR.ai covers every chapter in the Class 9 NCERT syllabus — Maths, Science, Social Science, English, Hindi and more. 24×7. Patient. Unlimited. 3-day free trial.
Start your child's 3-day free trial →