Table of Contents
Autotrophic
- Definition- Autotrophic organisms are those that can synthesise their own food from inorganic substances using light or chemical energy. In plants, this process typically involves photosynthesis, where sunlight, carbon dioxide, and water are converted into glucose and oxygen.
- Explanation- Autotrophic plants capture energy from sunlight using chlorophyll and other pigments. This energy is used to convert carbon dioxide from the air and water from the soil into glucose, a form of sugar that provides energy and building material for the plant. Oxygen is released as a byproduct. This ability to produce their own food makes autotrophic plants foundational to most ecosystems.
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Chlorophyll
- Definition- Chlorophyll is a green pigment found in the chloroplasts of plants, algae, and some bacteria. It is essential for photosynthesis, the process by which these organisms convert sunlight into chemical energy.
- Explanation- Chlorophyll absorbs light primarily in the blue and red wavelengths, while reflecting green light, giving plants their characteristic green colour. The energy absorbed from light is used to initiate the chemical reactions in photosynthesis. These reactions transform carbon dioxide and water into glucose, which the plant uses for energy and growth, and release oxygen as a byproduct.
Also Check – Chapter 1- Nutrition in Plants -Class 7 – Detailed Notes
Heterotrophs
- Definition- Heterotrophic organisms are those that cannot synthesise their own food and must rely on other organisms or organic substances for nutrition.
- Explanation- Unlike autotrophs, heterotrophs obtain their energy and nutrients by consuming other organisms or organic matter. This category includes animals, fungi, and some plants and bacteria. In the case of heterotrophic plants, they may absorb nutrients from decomposing matter, or in the case of parasitic plants, directly from other living plants.
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Host
- Definition- A host is an organism that provides sustenance and support for a parasite. In the plant world, a host is typically another plant from which the parasitic plant derives water, nutrients, and essential compounds.
- Explanation- Parasitic plants attach themselves to their host plants and form connections with the host’s vascular system. This allows them to draw resources like water and nutrients directly from the host. Since parasitic plants often have little or no chlorophyll, they rely heavily on their hosts for survival and are unable to perform photosynthesis effectively.
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Insectivorous
- Definition- Insectivorous plants, also known as carnivorous plants, are those that have evolved unique adaptations to capture and digest insects or other small organisms.
- Explanation- These plants typically grow in habitats with nutrient-poor soils. To compensate for the lack of essential nutrients, particularly nitrogen, they have developed carnivorous traits. These adaptations allow them to trap and digest insects, thereby obtaining the necessary nutrients for their survival and growth. Examples include the Venus flytrap and pitcher plants.
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Nutrient
- Definition- Nutrients are substances that provide the necessary elements and compounds for the growth, development, and metabolic activities of organisms, including plants.
- Explanation- In plants, nutrients are vital as they form the building blocks of organic compounds such as carbohydrates, proteins, fats, and vitamins. Nutrients are broadly categorised into macronutrients, which are needed in larger quantities, and micronutrients, required in smaller amounts. These nutrients are essential for processes like photosynthesis, respiration, and reproduction, and contribute to the plant’s overall health and resistance to diseases and environmental stresses.
Nutrition
- Definition- Nutrition in plants refers to the process by which plants obtain and utilise essential substances for their growth, development, and metabolic activities.
- Explanation- This process involves the absorption, assimilation, and utilisation of nutrients necessary for the plant’s survival. Nutrition is a critical aspect of a plant’s life, affecting its ability to perform essential functions such as photosynthesis, respiration, and reproduction. The health, strength, and disease resistance of plants are significantly influenced by their nutritional status.
Parasite
- Definition- Parasitic plants are those that obtain their nutrients by attaching to other plants, referred to as host plants.
- Explanation- These plants form connections with the vascular system of the host plant to draw water, nutrients, and other essential compounds. Parasitic plants often have little or no chlorophyll and are unable to perform photosynthesis effectively. Their parasitic lifestyle enables them to survive in environments where nutrients are scarce, as they rely on the host for their nutritional needs.
Photosynthesis
- Definition- Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy from the sun into chemical energy in the form of glucose. It takes place in the chloroplasts of plant cells.
- Explanation- During photosynthesis, carbon dioxide (CO2) from the air and water (H2O) from the soil are converted into glucose (C6H12O6) and oxygen (O2). This process occurs in two main stages: the light-dependent reactions and the light-independent reactions (also known as the Calvin cycle). Chlorophyll, a green pigment in chloroplasts, plays a crucial role in capturing the light energy from the sun to power these reactions.
Saprotrophs
- Definition- Saprotrophic nutrition is a type of nutrition where organisms, including certain plants, obtain their food by decomposing dead organic matter. Saprotrophs, also known as decomposers, secrete enzymes that break down complex organic compounds into simpler substances.
- Explanation- After decomposing dead plants, animals, and other organic materials, saprotrophs absorb the resulting nutrients for their own growth and development. This process of nutrient recycling is essential in ecosystems, as it releases important elements back into the soil, enriching it and making nutrients available to other organisms, including plants.
Stomata
- Definition- Stomata are tiny openings on the surfaces of plant leaves and stems, surrounded by specialised cells known as guard cells.
- Explanation- Stomata play a crucial role in the exchange of gases between plants and the environment. They control the entry of carbon dioxide (CO2) for photosynthesis and the exit of oxygen (O2) and water vapour (H2O) during transpiration. When guard cells absorb water, they become turgid, causing the stomatal pore to open for the intake of CO2. Conversely, when guard cells lose water, they become flaccid, leading to the closure of the stomatal pore, thereby reducing water loss through transpiration.
