Photosynthesis – The Life Process of Plants

-

Introduction

Photosynthesis is one of the most vital biological processes on Earth. It enables green plants to manufacture their own food using sunlight, water, and carbon dioxide. This process not only supports plant life but also sustains all life on Earth by releasing oxygen and forming the base of the food chain.


---

What is Photosynthesis?

Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy stored in glucose. It takes place mainly in the chloroplasts, which contain the green pigment chlorophyll.

6CO_2 + 6H_2O + \text{Light energy} \rightarrow C_6H_{12}O_6 + 6O_2


---

Factors Required for Photosynthesis

1. Sunlight – The energy source for the entire process.


2. Water (H₂O) – Absorbed from the soil through roots.


3. Carbon Dioxide (CO₂) – Taken in from the atmosphere through stomata.


4. Chlorophyll – The green pigment that captures solar energy.




---

Structure of the Chloroplast

Chloroplasts are double-membrane organelles found mainly in mesophyll cells of leaves. Key parts:

Thylakoids – Disc-like structures where the light reaction occurs.

Grana – Stacks of thylakoids.

Stroma – Fluid-filled space where the dark reaction takes place.



---

Steps of Photosynthesis

1. Light Reaction (Photochemical Phase)

Occurs in the thylakoid membrane.

Requires light directly.

Key events:

Photolysis of water (splitting of water)

Formation of ATP and NADPH

Release of Oxygen



Mnemonic: "Oxygen is out, ATP is in!"

2. Dark Reaction (Biosynthetic Phase / Calvin Cycle)

Takes place in the stroma of the chloroplast.

Does not require light directly.

Utilizes ATP and NADPH to fix CO₂ into glucose.

Named after Melvin Calvin.



---

Importance of Photosynthesis

Provides food and energy to all organisms.

Maintains oxygen levels in the atmosphere.

Acts as a carbon sink, controlling global CO₂ levels.



---

Limiting Factors of Photosynthesis

1. Light Intensity


2. Carbon Dioxide Concentration


3. Temperature


4. Water Availability




---

Photosynthesis – NEET and CBSE Tips

Focus on chloroplast structure and functions.

Understand the difference between light and dark reactions.

Revise the Calvin cycle steps.

Practice diagrams – especially the thylakoid and stroma.

Remember the site and products of both reactions.



---

Conclusion

Photosynthesis is the foundation of life. It not only nourishes plants but also provides oxygen and energy to the entire biosphere. Mastering this topic is crucial for success in CBSE Class 11 Biology and NEET Botany.

Comments

Post a Comment

Popular posts from this blog

🌱 Plant Growth and Development: Role of Hormones in NEET & CBSE Biology

-
Image
Introduction Plant growth and development are crucial chapters in both NEET and CBSE Class 11 Biology. Understanding how plants grow and how hormones regulate this process is important not just for exams, but also for grasping key concepts in plant physiology. --- 🌿 What is Plant Growth? Growth in plants refers to an irreversible increase in size, usually accompanied by an increase in dry mass. It involves cell division (mitosis), cell elongation, and cell differentiation. Plant growth is indeterminate, meaning it continues throughout their life due to the presence of meristems (actively dividing tissues). --- 🔍 Phases of Growth 1. Meristematic Phase – cells are actively dividing. 2. Elongation Phase – cells elongate and expand in size. 3. Maturation Phase – cells differentiate and mature into specific tissues. --- 📈 Growth Curve Follows a sigmoid curve (S-shaped). Has four phases: 1. Lag Phase (slow growth), 2. Log Phase (rapid growth), 3. Declining Phase (slowdown), 4....
Read more

NEET 2025 – Cell: The Unit of Life | NCERT-Based Notes + Diagrams

-
Image
Post Content: Introduction: "Cell: The Unit of Life" is a conceptual and factual chapter. NEET 2025 can include diagram-based MCQs and questions from cell organelles and types of cells. Focus on NCERT keywords and functions. 1. Discovery of Cell Discovered by Robert Hooke in 1665 (cork cell) Cell Theory by Schleiden & Schwann Rudolf Virchow: "Omnis cellula-e-cellula" – cells arise from pre-existing cells 2. Prokaryotic vs Eukaryotic Cells Feature Prokaryote (Bacteria) Eukaryote (Plants/Animals) Nucleus Absent Present Organelles No membrane-bound Membrane-bound Ribosome Type 70S 80S Cell Wall Peptidoglycan Cellulose (plants) 3. Cell Organelles Nucleus: Double membrane, contains nucleolus and chromatin Mitochondria: Powerhouse, double membrane, has its own DNA Plastids: Chloroplast: Green, photosynthesis, has DNA Endoplasmic Reticulum (ER): Rough ER: Protein synthesis Smooth ER: Lipid synthesis Golgi Apparatus: Modifies & packages proteins Lysosome...
Read more

Plant Growth Regulators: Types, Functions, and NEET Insights

-
Image
Introduction Plant Growth Regulators (PGRs) are organic compounds that influence physiological processes in plants. These are also called phytohormones and are essential for growth, development, dormancy, flowering, fruiting, and stress responses. For NEET aspirants, understanding PGRs is crucial as they frequently appear in exams. --- Types of Plant Growth Regulators 1. Auxins Discovered by F.W. Went. Promote cell elongation, apical dominance, root initiation, and prevent premature fruit drop. Example: Indole-3-acetic acid (IAA), NAA. 2. Gibberellins Discovered from the fungus Gibberella fujikuroi. Promote stem elongation, seed germination, and break dormancy. Example: GA₃ (Gibberellic acid). 3. Cytokinins Promote cell division, delay senescence, and stimulate lateral shoot growth. Example: Kinetin, Zeatin. 4. Abscisic Acid (ABA) Known as a stress hormone. Induces seed dormancy, stomatal closure, and inhibits growth. 5. Ethylene A gaseous hormone. Promotes fruit ripening, ...
Read more