Plant Transport and Physiology

Root hairs absorb both water and mineral nutrients from soil through their large surface area. They actively take up ions via membrane transport proteins.

Transpiration pulls water up xylem vessels, creating negative pressure (tension) at the top. This reduced pressure draws water upward from roots through the transpiration-cohesion-tension mechanism.

Water enters root hairs primarily through osmosis, moving from higher water potential in soil to lower water potential in root cells. This passive transport drives water uptake.

Transpiration is the biological process where water evaporates from the leaves of plants, primarily through stomata. This creates a transpiration pull that helps draw water and minerals up from the roots. Transport refers to general movement, respiration is the release of energy from glucose, and 'all the above' is incorrect because only transpiration fits the definition.

Stomata are the tiny pores found primarily on the undersides of leaves. They open and close to regulate gas exchange (CO2 intake, O2 release) and water vapor loss. Pits are depressions in cell walls, spores are reproductive cells, and holes is too generic a term.

Translocation is the specific term for the transport of organic food materials (mainly sugars) from the leaves (where they're produced by photosynthesis) to other parts of the plant. Transpiration refers specifically to water loss, transport is too general, and photosynthesis is the sugar production process, not its transport.

Plasma membrane regulates the passage of water and dissolved substances into and out of the cell.

Transpiration is the process by which plants lose water through their leaves, primarily through small openings called stomata. This water loss occurs as water vapor, not liquid water or gas. It helps plants cool down and transport nutrients.

Stomatal transpiration occurs through stomata (tiny pores on leaf surfaces) and accounts for about 90% of total water loss in plants. Cuticular transpiration through the waxy leaf cuticle is minimal, while lenticular (through stems) and foliar transpiration are even less significant.

Wilting occurs when water transport through xylem is blocked, preventing water from reaching leaves. Without water, turgor pressure in cells drops and leaves droop. Blocking phloem would affect sugar transport, not water delivery.

Transpiration is a physiological process because it occurs through living stomatal guard cells that actively open and close. Evaporation is purely physical - water molecules escape from any exposed surface without biological control. The key difference is living tissue involvement.

Transpiration cools leaves through evaporative cooling - as liquid water evaporates from leaf surfaces, it absorbs heat energy (latent heat of vaporization). This is similar to how sweating cools human skin. Respiration and photosynthesis are metabolic processes that may produce heat, not cooling.

Levitt (1974) proposed the K+ ion exchange hypothesis for stomatal movement - K+ ions actively move into guard cells to open stomata (increasing turgor) and exit to close them. Darwin studied phototropism, Scarth worked on stomatal physiology earlier, and Khorana is known for genetic code research.

A potometer measures transpiration rate by recording water uptake by a plant cut shoot - as water is lost through transpiration, an equal amount is absorbed, moving the air bubble in the capillary tube. Auxanometer measures growth, porometer measures stomatal opening, and potentiometer measures electrical potential.