Table of Contents
Revision Notes – Chapter 1- Nutrition in Plants
Nutrition in Plants
1. Nutrition in Plants
- Definition- The process by which plants obtain and use substances for growth, development, and metabolic activities.
- Importance- Essential for energy, building materials, and nutrients for photosynthesis, respiration, reproduction, health, and resistance to diseases.
Also Check – Chapter 1- Nutrition in Plants -Class 7 – Detailed Notes
2. Types of Nutrients
- Macronutrients- Required in large quantities.
- Carbon (C)- For building organic compounds.
- Hydrogen (H) and Oxygen (O)- Formation of water and organic compounds.
- Nitrogen (N)- Synthesis of proteins, enzymes, chlorophyll.
- Phosphorus (P)- Energy transfer, DNA, RNA, ATP synthesis.
- Potassium (K)- Osmoregulation, enzyme activation, protein synthesis.
- Calcium (Ca)- Cell wall formation, membrane stability, enzyme activation.
- Magnesium (Mg)- Component of chlorophyll, essential in photosynthesis.
- Micronutrients- Needed in smaller quantities.
- Iron (Fe), Zinc (Zn), Copper (Cu), Manganese (Mn), Molybdenum (Mo), Boron (B), Chlorine (Cl)- Crucial for enzyme activation, electron transport, and metabolic reactions.
Also Check – Nutrition in Plants – Class 7 Questions with Answers Worksheet
3. Mineral Requirements for Plant Growth
- Each mineral nutrient serves specific functions.
- Deficiencies can lead to problems like stunted growth, yellowing of leaves, poor root development, and reduced disease resistance.
Photosynthesis
4. Photosynthesis
- Definition- Process where green plants, algae, and some bacteria convert sunlight into chemical energy (glucose).
- Process- Involves light-dependent reactions and light-independent reactions (Calvin cycle).
- CO2 and H2O are converted into glucose (C6H12O6) and oxygen (O2).
- Takes place in chloroplasts of plant cells.
5. Chlorophyll in Photosynthesis
- Chlorophyll- Green pigment in chloroplasts, captures light energy from the sun.
- Absorbs light in the blue and red regions and reflects green light.
- Arranged in photosystems for converting light energy into chemical energy.
6. Sunlight in Photosynthesis
- Role- Primary energy source for photosynthesis.
- Absorption- Chlorophyll pigments absorb light, mainly in red and blue wavelengths; green light is mostly reflected.
- Energy Conversion- Light energy is transformed into chemical energy in the form of ATP and NADPH.
- Importance- Essential for oxygen production and conversion of light energy to chemical energy stored in glucose.
Also Check – NCERT Solutions for Class 7 Science Chapter 1: Nutrition In Plants
Plant Processes
7. Stomata and Gas Exchange
- Structure- Tiny openings on plant surfaces, surrounded by guard cells.
- Function- Control entry of CO2 for photosynthesis and exit of O2 and H2O vapour.
- Mechanism- Stomata open when guard cells are turgid and close when flaccid.
Also Check – What are the function of Stomata
8. Transpiration
- Process- Loss of water vapour through leaves, mainly via stomata.
- Functions-
- Cooling the plant through evaporative cooling.
- Creating a transpiration pull for upward movement of water and minerals.
- Nutrient transport and maintenance of cell turgidity.
- Relation to Photosynthesis- Opens stomata for CO2 entry, leading to water loss but necessary for photosynthesis.
9. Absorption of Water and Minerals
- Roots’ Role- Crucial in absorbing water and minerals from the soil.
- Root Hairs- Increase surface area for absorption.
- Water Absorption- Through osmosis, driven by concentration gradients.
- Mineral Absorption- Via active transport (against concentration gradient) and passive diffusion.
- Transport- Water and minerals are moved upwards through xylem vessels, aided by transpiration pull.
Photosynthesis Equation
10. Photosynthesis Equation
- Equation- 6CO2 + 6H2O -> C6H12O6 + 6O2
- Reactants- Carbon dioxide (CO2) and water (H2O).
- Products- Glucose (C6H12O6) and oxygen (O2).
- Process- Uses light energy to convert CO2 and H2O into glucose and oxygen.
11. Components of Photosynthesis
- Carbon Dioxide (CO2)- Obtained from air through stomata, essential for photosynthesis.
- Water (H2O)- Absorbed from soil, provides hydrogen for glucose.
- Glucose (C6H12O6)- Primary product, energy-rich molecule for metabolic processes.
- Oxygen (O2)- By-product, released into the atmosphere.
Plant Nutrition
12. Synthesis of Nutrients in Plants
- Proteins- Made from amino acids; crucial for structure, enzyme functions, cell signalling.
- Fats (Lipids)- Source of energy; involved in membrane formation, energy storage.
- Vitamins- Facilitate enzyme activity; support growth, development, defence mechanisms.
13. Importance of Nutrients for Plant Growth
- Proteins- Building blocks of cells; involved in photosynthesis, respiration, DNA replication.
- Fats (Lipids)- Energy reserve; structural integrity of cell membranes, temperature regulation.
- Vitamins- Aid in metabolic pathways, stress tolerance, synthesis of hormones.
Other Modes of Nutrition in Plants
14. Heterotrophic Nutrition
- Definition- Plants obtaining food from external sources, not capable of photosynthesis.
- Types- Parasitic, insectivorous, and saprotrophic plants.
15. Parasitic Plants
- Characteristics- Depend on host plants for nutrients; have little or no chlorophyll.
- Adaptations- Specialised roots or haustoria to penetrate host tissues.
- Examples- Mistletoe, dodder, Rafflesia.
16. Insectivorous (Carnivorous) Plants
- Habitat- Grow in nutrient-poor soils.
- Mechanism- Trap and digest insects for essential nutrients, especially nitrogen.
- Examples- Venus flytrap, pitcher plants, sundews.
17. Saprotrophic Nutrition
- Definition- Decomposing dead organic matter for nutrition.
- Role in Ecosystem- Recycle nutrients, enrich soil.
- Examples- Fungi (mushrooms, molds), certain bacteria.
18. Symbiotic Relationships in Nutrition
- Symbionts- Organisms that form beneficial relationships with plants.
- Nutrient Exchange- Provide nutrients like nitrogen, phosphorus to host plants.
- Examples- Nitrogen-fixing bacteria, mycorrhizal fungi.
19. Lichens-
- Composition- Symbiotic association between a fungus and an alga or cyanobacterium.
- Role- Contribute to soil formation and nutrient cycling in harsh environments.
Transport of Food in Plants
20. Transport of Food in Plants
- Vascular Tissues- Xylem and Phloem.
- Xylem- Transports water and minerals from roots; made of tracheary elements.
- Phloem- Transports food, mainly sugars, from leaves; consists of sieve elements and companion cells.
Translocation in Plants
21. Translocation in Plants
- Process- Movement of food substances, primarily sugars, through the phloem.
- Sources and Sinks- From sources (leaves) to sinks (growing roots, fruits, storage tissues).
- Mechanism- Pressure flow mechanism; sugars transported into sieve tubes create a pressure gradient.
- Importance- Distributes food for growth, respiration, storage; ensures even nutrient supply.
Nutrient Replenishment in Plants
22. Nutrient Absorption and Replenishment
- Absorption- Plants absorb minerals and nutrients from the soil through roots.
- Soil Depletion- Continuous nutrient uptake decreases soil nutrient availability.
- Fertilisers and Manures- Replenish soil nutrients, ensuring healthy plant growth.
23. Nitrogen Deficiency and Rhizobium Bacteria
- Nitrogen Demand- High in crop plants; leads to soil nitrogen deficiency.
- Nitrogen Fixation- Rhizobium bacteria convert atmospheric nitrogen into soluble form.
- Symbiotic Relationship- Rhizobium and leguminous plants (e.g., gram, peas, beans).
- Farmer’s Advantage- Reduces need for nitrogenous fertilisers; sustainable nitrogen source.
24. Importance of Leguminous Plants
- Role in Agriculture- Acquire nitrogen from the atmosphere, enrich soil nutrients.
- Dietary Significance- Source of legumes (dals), vital in human nutrition.
Quick Review Tips
- Focus on the functions of macronutrients and micronutrients.
- Understand the basic steps of photosynthesis and the role of chlorophyll.
- Remember the effects of nutrient deficiencies on plant health.
- Understand the roles of sunlight, stomata, and transpiration in photosynthesis.
- Familiarise with the process and importance of water and mineral absorption through roots.
- Highlight the connection between these processes and their overall impact on plant health and growth.
- Focus on the key elements of the photosynthesis equation.
- Understand the roles of CO2, H2O, glucose, and O2 in photosynthesis.
- Remember the types of nutrients synthesised by plants and their significance for growth and development.
- Understand different heterotrophic nutrition modes in plants and their specific adaptations.
- Familiarise with the role of symbiotic relationships in plant nutrition.
- Remember the functions of xylem and phloem in the transport of nutrients within plants.
- Focus on understanding the translocation process and its significance in plant growth.
- Remember the role of fertilisers and manures in nutrient replenishment.
- Recognize the importance of Rhizobium bacteria and leguminous plants in natural nitrogen fixation.
Also Check – NCERT Exemplar Solutions- Class 7 Science – Chapter 1 – Nutrition In Plants
Also Check – Class 7- Chapter 1 – Nutrition in Plants – 4 Worksheets with Answer Key
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