mineral nutrition
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What is the difference between autotrophy and heterotrophy in plants?
• Autotrophy: The ability to use light energy to produce organic compounds from carbon and minerals (e.g., plants, green algae, and green bacteria). • Heterotrophy: The dependence on organic compounds supplied by other organisms for nutrition.
What is the difference between organic and inorganic nutrition in plants?
• Organic nutrition: Involves the uptake of carbon, oxygen, and hydrogen to produce carbohydrates, proteins, lipids, and nucleic acids. • Inorganic nutrition (also called mineral nutrition): Involves the uptake of mineral nutrients from the soil.
What are the key components of soil?
• Soil is a dynamic and heterogeneous substrate containing solid, liquid, and gaseous phases. • Nutrients are contained in colloids, forming micelles. • Soil colloids are generally negatively charged, so they retain positively charged ions and leach negatively charged ions like nitrate.
How do roots adapt to nutrient uptake in the soil?
• Roots develop length, density, and complexity based on soil properties and nutrient availability. • Nutrient transport occurs by passive diffusion or facilitated transport, which may require energy.
How are nutrients transported inside plants?
• Symplastic transport: Nutrients move through plasmodesmata from one cell to another until reaching the xylem. • Apoplastic transport: Nutrients travel through the apoplast until the Casparian band, then are transported into the root cells to enter the xylem.
What are the main types of nutrient transport in plants?
• Simple diffusion: Movement of ions down their concentration gradient without energy (e.g., CO₂, O₂, NH₃). • Facilitated transport: No energy required, but relies on channel and carrier proteins to assist ion movement. • Active transport: Requires ATP to move ions against their concentration gradient (e.g., ATPase-proton pumps).
What happens when plants experience nutrient deficiencies or toxicity?
• Deficiencies: Lead to symptoms like yellowing leaves (chlorosis) due to lack of nitrogen, potassium, iron, or phosphorus. • Toxicity: Can occur from excessive uptake of minerals, disrupting plant growth. • Fertilization is a common solution to correct deficiencies.
How do plants optimize nutrient uptake through relationships with other organisms?
• Mutualism: Both partners benefit (e.g., plants and nitrogen-fixing bacteria). • Symbiosis: One partner benefits, and the other may be neutral or also benefit. • Soil is a complex ecosystem with bacteria and fungi that affect plant health.
What are mycorrhizae, and how do they benefit plants?
• Mycorrhizae are fungal associations with plant roots that improve nutrient uptake, especially phosphorus. • Types of mycorrhizae: Ectomycorrhizae: Fungal sheaths around roots but no cell penetration. Endomycorrhizae: Fungi penetrate root cortical cells. Ectendomycorrhizae: Features of both ecto- and endo-mycorrhizae.
How do plants benefit from their association with bacteria?
• Plants provide carbohydrates to bacteria, and in return, bacteria supply mineral nutrients (e.g., nitrogen fixation). • Rhizobium bacteria form a symbiotic relationship with legume roots, creating root nodules where nitrogen fixation occurs.
How does nitrogen fixation occur in plants?
• Rhizobium bacteria in legumes use ATP to reduce N₂ to NH₃, which is then processed into glutamine by glutamine synthetase. • Cyanobacteria (e.g., Anabaena) also fix nitrogen in specialized cells called heterocysts, often in ferns or rice fields.