NCERT Exemplar Solutions for Class 11 Biology Chapter 13 Photosynthesis in Higher Plants
The NCERT Exemplar Solutions for Class 11 Biology Chapter 13, Photosynthesis in Higher Plants, provide a detailed insight into one of the most vital physiological processes in plants. Photosynthesis is the process by which green plants capture solar energy and convert it into chemical energy in the form of glucose. This chapter covers the history, mechanisms, and significance of photosynthesis, along with advanced topics such as C3, C4, and CAM pathways. The NCERT Exemplar questions are designed to test higher-order thinking and application-based skills, making them crucial for both board exams and competitive exams like NEET. The chapter begins with a historical perspective, including experiments by scientists like Joseph Priestley, Jan Ingenhousz, and Julius von Sachs, which demonstrated the importance of carbon dioxide, sunlight, and chlorophyll in photosynthesis. Exemplar questions often require students to analyze these classical experiments and connect them with the modern understanding of photosynthesis.
One of the core sections of the chapter is the structure of the chloroplast, the site of photosynthesis. Students learn about thylakoids, grana, and stroma, along with the distribution of pigments like chlorophyll a, chlorophyll b, and carotenoids. Exemplar problems frequently involve identifying pigments through absorption and action spectrum experiments, including the famous work of T.W. Engelmann. The chapter then explains light reactions or the photochemical phase. This involves the absorption of light, excitation of electrons, and electron transport through photosystems I and II. Students also study photophosphorylation (cyclic and non-cyclic), the production of ATP and NADPH, and the splitting of water to release oxygen. Exemplar questions in this section often test diagram-based understanding of Z-scheme electron transport and differences between cyclic and non-cyclic photophosphorylation. Another significant concept is the dark reaction or biosynthetic phase, where carbon dioxide is fixed to form glucose. The Calvin cycle, also known as the C3 pathway, is explained in detail with its three stages—carboxylation, reduction, and regeneration. Exemplar problems may include solving numerical questions on ATP and NADPH requirement per glucose molecule formed.
The chapter also covers alternative pathways such as the C4 pathway and CAM pathway, which are adaptations in plants growing under high light intensity, temperature, or water stress. Exemplar questions often ask students to compare C3 and C4 plants in terms of anatomy, efficiency, and photorespiration. Photorespiration is another important section, where oxygen acts as a competitor to carbon dioxide at the enzyme RuBisCO, leading to energy loss. Students are asked to explain how C4 plants reduce photorespiration and why they are more efficient in hot and dry climates. To master this chapter, students should thoroughly review diagrams of the Z-scheme, chloroplast structure, Calvin cycle, and C4 cycle provided in the NCERT textbook. Solving NCERT Exemplar questions ensures clarity of concepts, enhances analytical thinking, and prepares students for complex application-based problems. In conclusion, NCERT Exemplar Solutions for Class 11 Biology Chapter 13 Photosynthesis in Higher Plants offer a structured approach to mastering one of the most important topics in plant physiology. By practicing these solutions, students gain confidence to tackle both theoretical and problem-based questions effectively in exams.