Nutrition & Transport in Flowering Plants

• In plants, xylem vessels conduct water and mineral salts upwards, from roots to leaves
• Thick lignified walls in xylem vessels prevent their collapse
• Phloem translocates sucrose and amino acids from leaves to other parts of the plant
• Water flows from root hair cells to xylem by osmosis
• Water movement in plants is facilitated by osmosis and transpiration
• Transpiration, affected by factors like light intensity, wind, temperature, and humidity, creates a transpiration pull in plants
• Photosynthesis in plants requires light, carbon dioxide, chlorophyll, a suitable temperature, and water
• Photosynthesis produces glucose and oxygen, which can be converted into amino acids and proteins
• Importance of photosynthesis:

  • Provides food
  • Stores energy from the sun as chemical energy
  • Maintains the balance of oxygen and carbon dioxide in the atmosphere
• Stomata are natural openings on the surface of a plant leaf bordered by two bean-shaped guard cells, allowing gaseous and water exchange only when the guard cells are turgid

  
• Phloem is a plant tissue that transports sugars and nutrients from leaves to the rest of the plant, with sieve tubes as the main cells connected by sieve plates for nutrient passage

  
• A diagram of a dicotyledonous stem shows the arrangement of vascular bundles, cortex, pith, and epidermis

  
• Chloroplasts, responsible for photosynthesis, contain chlorophyll that absorbs light energy to convert carbon dioxide and water into glucose and oxygen
• In photosynthesis, glucose can be used immediately for cellular respiration, stored as starch, converted into amino acids, or used for protein synthesis
• The rate of photosynthesis increases with temperature, with high light intensity always resulting in a higher rate compared to low light intensity
• Guard cells control stomatal size, opening in light for photosynthesis and closing in the dark; they swell and become turgid in light, leading to stomatal opening
• Xylem transports water and mineral salts from roots to other plant parts, providing mechanical support, while phloem conducts manufactured food
• Xylem's adaptations include being dead and hollow to reduce water flow resistance and having lignin-thickened walls for mechanical support
• Plants intake carbon dioxide through stomata, where it dissolves into the spongy mesophyll cells, and water is absorbed by roots, moving up the xylem due to transpirational pull
• The cell sap of root hair cells has lower water potential than the soil solution, causing water to move into the root hair cells and then up the xylem to the leaf cells
• The structure of a leaf includes the lamina for light absorption, mid-rib and veins for water transport, and petiole for sunlight exposure, with internal features like cuticle, epidermis, mesophyll, and vascular bundles
• The palisade mesophyll contains the highest number of chloroplasts in a leaf, followed by the spongy mesophyll and guard cells with the lowest number
• Transpiration is the consequence of gaseous exchange in plants, influenced by factors like air movement, temperature, humidity, and light intensity
• Translocation in phloem involves the transport of food, mainly sucrose, with companion cells regulating the flow of sugars and other nutrients
• The dicotyledonous leaf's cellular and tissue structure includes chloroplast distribution for photosynthesis, stomata for gaseous exchange, and vascular bundles for transport
• Root hair cells are adapted for water and ion uptake, with chlorophyll in chloroplasts converting light energy into chemical energy for carbohydrate formation
• Photosynthesis is crucial for life on earth as it converts light energy into chemical energy, producing glucose for plant energy and oxygen as a byproduct
• Most life forms depend on photosynthesis, where chlorophyll absorbs light energy to form carbohydrates essential for life processes
• Light intensity, carbon dioxide concentration, and temperature act as limiting factors on the rate of photosynthesis, affecting the overall process
• Transpiration involves the movement of water between plant cells and the environment, regulated by factors like water potential, air movement, and temperature
• Water is transported into roots and through xylem vessels to leaves by transpiration pull, with variations in air movement, temperature, humidity, and light intensity affecting transpiration rate
• Wilting occurs due to factors like reduced water uptake, leading to loss of turgidity in plant cells and subsequent drooping
• The graph on the relationship between the relative rate of photosynthesis and temperature shows higher rates with increasing temperature, especially under high light intensity conditions
• Glucose produced by photosynthesis can be used immediately for cellular respiration, stored as starch, converted into amino acids, or used for protein synthesis, essential for cell growth and function
• Excess glucose can be converted into starch and stored in leaves or other organs, serving as a reserve energy source for plants when needed
• Glucose can react with nitrates and other mineral salts from the soil to form amino acids, crucial for protein synthesis and cell growth in plants
• Proteins synthesized from amino acids are essential for the formation of new protoplasm, the living material of cells, supporting cell growth and function
• The structure of a plant leaf enables efficient photosynthesis, with adaptations like a large surface area, thin lamina for gas exchange, and vascular bundles for nutrient transport
• The plant's transport system ensures leaves receive raw materials for photosynthesis and distributes the products of photosynthesis for overall plant growth and function
• Photosynthesis is vital for maintaining life on earth as it converts light energy into chemical energy, producing glucose for plant energy and oxygen for the atmosphere