Plant Structures and their Functions

• Photosynthesis is the process by which plants make their food from sunlight
• Chloroplasts in plant cells use light energy to turn carbon dioxide and water into glucose and oxygen
• Word equation for photosynthesis: CO2 + H2O → C6H12O6 + O2
• To balance the equation, put a 6 in front of everything apart from glucose: 6CO2 + 6H2O → C6H12O6 + 6O2
• Glucose is important for the plant as it's the starting point to make other necessary substances
• Photosynthesis is an endothermic reaction, meaning it takes in energy from the sun
• Limiting factors for photosynthesis include temperature, light intensity, and carbon dioxide concentration
• Temperature affects enzyme activity, light intensity is needed for photosynthesis, and carbon dioxide is essential for glucose production
• Xylem is used to transport water in plants
• Water in xylem only moves up the plant due to the structure of the cells
• Xylem cells are dead to prevent water usage before reaching the rest of the plant
• Lignin in xylem provides support and prevents bursting under high pressure
• Transpiration is the process of water movement through the plant via xylem
• Factors affecting transpiration
• Warmth, wind, and light intensity can increase transpiration rate
• Transpiration increases when water easily evaporates from leaves
• Phloem is used to transport sugars in plants
• Sugars in phloem can move in both directions within the plant
• Phloem cells are living and need companion cells to stay alive
• Translocation is the process of sugar transport through phloem
• Stomata are tiny holes in leaves for gas and water exchange
• Guard cells control the opening and closing of stomata based on water content
• Leaf structure includes waxy cuticle, upper epidermis, palisade cells, spongy mesophyll, and lower epidermis with stomata
• Auxins are plant hormones that control growth
• Auxins make shoots grow towards light (positively phototropic) and against gravity (negatively gravitropic)
• Auxins stop root growth and make roots grow against light (negatively phototropic) but with gravity (positively gravitropic)
• Other plant hormones
• Gibberellins control seed germination
• Ethene controls fruit ripening
• Gibberellins can be used to produce fruit all year round, and ethene can ripen fruits for sale