Chapter 1: पौधों में पोषण (Nutrition in Plants) – Detailed NCERT Class 7 Science Notes
Welcome to the detailed notes for Chapter 1: Nutrition in Plants पौधों में पोषण from NCERT Class 7 Science. This chapter is about how plants obtain their food and nutrients. It focuses on the process of photosynthesis and explains how plants get energy from the sun, absorb water, and use various nutrients from the soil to survive and grow.
In this post, we will cover the concepts in detail, breaking them down with real-life examples and flowcharts for better understanding. Let's dive into the study material.
Table of Contents:
- Introduction to Nutrition in Plants
- What is Photosynthesis?
- Role of Chlorophyll
- How Do Plants Obtain Water?
- The Importance of Sunlight
- Other Nutrients for Plants
- Types of Nutrition in Plants
- MCQs for Practice
1. Introduction to Nutrition in Plants
Plants are autotrophic organisms, which means they can produce their own food using natural resources like sunlight, water, and carbon dioxide. Unlike animals, which depend on other organisms for food, plants can manufacture food through the process of photosynthesis.
Nutrients are essential for the growth and development of plants. While plants can make their own food, they also need certain minerals and elements from the soil to grow properly.
2. What is Photosynthesis?
Photosynthesis is the process by which plants prepare their food. This process occurs mainly in the leaves of the plant, which contain a green pigment called chlorophyll.
During photosynthesis, plants take in carbon dioxide (CO₂) from the air and water (H₂O) from the soil through their roots. In the presence of sunlight, these ingredients are converted into glucose (C₆H₁₂O₆), a type of sugar that plants use as food. Oxygen (O₂) is released as a by-product.
Here’s the photosynthesis equation:
This means:
- Carbon dioxide (CO₂) from the air + Water (H₂O) from the soil + Sunlight = Glucose (food) for the plant + Oxygen (O₂).
3. Role of Chlorophyll
Chlorophyll is a green pigment present in plant leaves. It absorbs light energy from the sun and helps in the process of photosynthesis. Without chlorophyll, plants wouldn’t be able to convert sunlight into food. It is the reason plants appear green.
Chlorophyll absorbs mostly red and blue light and reflects green light, which is why we see plants as green. The energy absorbed by chlorophyll is used to break down water molecules and release oxygen.
4. How Do Plants Obtain Water?
Plants absorb water through their roots. The water then travels upwards through the plant via a system of tissues known as xylem. The absorbed water is vital for the process of photosynthesis because it is one of the key ingredients in making glucose.
The root hairs of the plant increase the surface area for water absorption, ensuring the plant gets enough water for its needs.
Real-life Example: When you water a plant, the water travels from the soil through the roots, into the stem, and eventually to the leaves where photosynthesis takes place.
5. The Importance of Sunlight
Sunlight is the most important factor for photosynthesis. Without sunlight, plants would not be able to make food. During photosynthesis, sunlight is absorbed by the leaves and converted into chemical energy, which is then used to create glucose.
Plants use their chlorophyll to absorb sunlight. The energy from sunlight is used to convert carbon dioxide and water into glucose and oxygen.
Real-life Example: A plant in a dark room will not grow as well as a plant placed in direct sunlight, showing how important sunlight is for the plant’s survival.
6. Other Nutrients for Plants
While sunlight, water, and carbon dioxide are the main factors for photosynthesis, plants also require other nutrients from the soil to grow. These nutrients include:
- Nitrogen (N): Important for leaf growth.
- Phosphorus (P): Essential for root development and flowering.
- Potassium (K): Helps with overall growth, disease resistance, and fruit development.
Plants absorb these nutrients from the soil through their roots. Fertilizers are often used to provide these essential nutrients to plants.
Real-life Example: Garden fertilizers contain nitrogen, phosphorus, and potassium to help plants grow better by replenishing the soil with these essential nutrients.
7. Types of Nutrition in Plants
There are two types of nutrition in plants:
Autotrophic Nutrition: This is the type of nutrition that plants follow. They make their own food through photosynthesis, using sunlight, carbon dioxide, and water.
Heterotrophic Nutrition: Some plants, like carnivorous plants (e.g., Venus flytrap), obtain nutrition by capturing and digesting insects. This happens because they grow in soils that are low in nutrients.
Real-life Example: The Venus flytrap catches insects with its specialized leaves that snap shut when triggered by the movement of an insect. The plant then digests the insect to obtain nitrogen and other nutrients.
8. MCQs for Practice
Here are some Multiple-Choice Questions (MCQs) to test your understanding of Nutrition in Plants:
What is the main pigment involved in photosynthesis?
- a) Melanin
- b) Chlorophyll
- c) Carotenoids
- d) Hemoglobin
Answer: b) Chlorophyll
What is produced during photosynthesis?
- a) Water
- b) Glucose and Oxygen
- c) Carbon dioxide and Oxygen
- d) Nitrogen and Glucose
Answer: b) Glucose and Oxygen
Which part of the plant absorbs water?
- a) Leaves
- b) Flowers
- c) Roots
- d) Stem
Answer: c) Roots
Which of the following is required for photosynthesis?
- a) Sunlight
- b) Carbon dioxide
- c) Water
- d) All of the above
Answer: d) All of the above
Where does photosynthesis take place in the plant?
- a) Roots
- b) Flowers
- c) Leaves
- d) Stem
Answer: c) Leaves