nutrition and transport in flowering plants Flashcards
use of chlorophyll
-absorbs light energy and converts it into chemical energy for the formation of carbohydrates and its subsequent uses
function of things in leaf
-waxy cuticle to reduce water loss on upper surface of leaf
-upper epidermal cells contain no chloroplast, prevent water loss and stop unwanted organisms or substances from entering
-palisade cell contains lots of chloroplasts to help them perform photosynthesis, closely pack together to maximise light absorption
-cells in spongy mesophyll layer are not closely packed creating intercellular air spaces to enable gas to move in and out
-stomata allow gases to diffuse in and out of the leaves, formed by two guard cells
how to stoma work
-they have chloroplasts for photosynthesis, increase k plus and glucose concentration, lowering water potential in the guard cell causing water to diffuse into the cell through osmosis, becoming turgid and swollen
-thick inner wall and thin out wall allows it to curve and open the stoma
-close under dry or low humidity to protect leaf from drying out
function of xylem
-conducts water and dissolved mineral salts from soil to stem and leaves with empty hollow tubular lumen without protoplasm or cross wall reducing resistance to water flowing though the xylem
-provides mechanical support preventing collapse of xylem vessels as walls are thickened with lignin that is hard and rigid
function of phloem
-moves organic solutes like glucose and amino acids through leaves to whole plant
-companion cells have mitochondria which provides energy needed for the companion cells to load sugars from mesophyll layers to sieve tubes by active transport
-holes in the sieve plates allow rapid flow of manufactured food substances through the sieve plates.
entry of water into a plant
-sap in root hair cell is a concentrated solution of sugar and salts, hence has lower water potential than soil solution and hence water enters the cell through osmosis
-entry of water dilutes the sap, and now has a higher water potential than that of next cell so water passes by osmosis from root hair cell to inner cell, this process continues until water moves up the xylem vessels up the plant
structure of root hair cell
-long narrow tubular extension increase SA:V ratio for absorption
-large vacuole to take in water
-high conc of sugar, salts and amino acids in cell sap
-mitochondria present to release energy for active transport of mineral ions
why are most forms of life dependent on photosynthesis
Most forms of life depend on photosynthesis because it is the primary process that produces energy and oxygen, which are essential for survival, providing energy required by nearly all organisms for growth
state the equation of photosynthesis
6co2 + 12H20 under chlorphyll and light energy gives C6H12O6 and 6O2
describe how carbon dioxide enters the mesophyll cell
during day with sunlight, the guard cells have chloroplast to undergo photosynthesis and hence opens, carbon dioxide diffuses into the cell and into the mesophyll layer
investigate and discuss the effects of varying light intensity, carbon dioxide concentration and temperature on the rate of photosynthesis
as light intensity increase, rate of photosynthesis increase until carbon dioxide becomes the limiting reagent
-temperature is not an important limiting reagent in photosynthesis
-CO2 concentration is an important limiting reagent, large change in photosynethis
what is cambium pith and cortex epidermis
divides the xylem and phloem cells in a vascular bundle, can divide and differentiate to form new xylem cells and phloem tissues, giving rise to the thickening of the stem
cortex and pith both store food substances like starch
-epidermis is outer layer of the stem that greatly reduce evaporation of water from the stem
