NCERT Exemplar Solutions for Class 11 Biology Chapter 15 Plant Growth and Development
The NCERT Exemplar Solutions for Class 11 Biology Chapter 15, Plant Growth and Development, focus on how plants grow, differentiate, and respond to environmental stimuli. Unlike animals, plants grow throughout their life due to the presence of meristems. This chapter introduces growth phases, conditions affecting growth, differentiation, dedifferentiation, redifferentiation, plant hormones, photoperiodism, and seed dormancy. The NCERT Exemplar questions help students develop conceptual clarity and apply their knowledge to real-life examples, making them useful for both board exams and entrance tests like NEET.
The chapter begins with the characteristics of plant growth, emphasizing that growth is irreversible, measurable, and often indeterminate. Students learn about primary growth in roots and shoots, and secondary growth in woody plants. Exemplar questions often test the differences between these types of growth and their significance in plant development. Phases of growth—lag phase, log or exponential phase, and stationary phase—are explained with a graphical representation. Exemplar problems may involve interpreting growth curves, calculating growth rates, and linking these with physiological processes in plants.
The chapter also covers factors affecting growth, including internal and external conditions. Temperature, light, water, and nutrients play a major role in growth regulation. Exemplar questions may require students to analyze how these factors influence seed germination or flowering. One of the most significant parts of the chapter is plant growth regulators (PGRs), also known as plant hormones. Students study auxins, gibberellins, cytokinins, abscisic acid (ABA), and ethylene, along with their functions and applications. Exemplar questions often test knowledge of their roles in processes like apical dominance, seed germination, fruit ripening, and stress responses. For example, students may be asked why gibberellins are used to increase sugarcane yield or how ethylene accelerates fruit ripening.
The chapter also explains differentiation, dedifferentiation, and redifferentiation, which highlight how cells change their structure and function during plant development. Exemplar questions in this section may involve reasoning-based problems, asking students to apply these concepts to tissue culture or secondary growth. Photoperiodism and vernalization are introduced as environmental factors influencing flowering. Photoperiodism refers to the response of plants to the relative length of day and night, while vernalization involves the promotion of flowering by cold treatment. Exemplar problems often test classification of plants as short-day, long-day, or day-neutral based on experimental data. Another important concept is seed dormancy, which ensures that seeds remain inactive until favorable conditions for germination appear. Exemplar questions frequently involve identifying the factors breaking dormancy, such as light, temperature, or mechanical scarification. To prepare effectively, students should review NCERT diagrams illustrating growth curves, hormone pathways, and photoperiodic responses. Since many Exemplar questions are application-based, practicing them strengthens analytical skills and improves exam readiness. In summary, NCERT Exemplar Solutions for Class 11 Biology Chapter 15 Plant Growth and Development provide students with a clear understanding of how plants grow and adapt. By practicing these questions, learners gain confidence, improve their problem-solving skills, and strengthen their foundation for higher-level biology and competitive exams.