nutrition in plants Flashcards
how do plants absorb sunlight?
chlorophyll is a pigment in plants that absorbs sunlight
what conditions are essential for photosynthesis?
- sunlight
- carbon dioxide
- chlorophyll
- suitable temperature
- water
word equation for photosynthesis
https://images.app.goo.gl/F8os9Q98HWCZcCJi6
how is carbon dioxide absorbed into the leaf?
carbon dioxide diffuses into the leaf via diffusion through tiny pores called stomata found mostly on the underside of the leaf
factors affecting rate of photosynthesis
- light intensity
- carbon dioxide concentration
- temperature
does light intensity increase the rate of photosynthesis?
https://drive.google.com/file/d/1_JruDktbAtes4QbvkrF6bIKHJw1hwksS/view?usp=drivesdk
how does carbon dioxide concentration affect the rate of photosynthesis?
https://drive.google.com/file/d/1DlemmqNm3_VqtRNjRHusHjQGifWjiyZm/view?usp=drivesdk
how does temperature affect the rate of photosynthesis?
https://drive.google.com/file/d/1FiMxL68xjMdya1VHSCHU9ZFM61zFJmMe/view?usp=drivesdk
function of cuticle
- provides protection for the leaf by acting as a barrier against infection
- prevents excessive loss of water by evaporation as it forms a waterproofing layer
function of upper epidermis
- closely packed cells that do not contain chloroplast and therefore do not photosynthesise
- small number of guard cells and associated stomata may be present
function of palisade mesophyll
- two or three layers of vertically arranged cylindrical cells that contain a high amount of chloroplasts
- site for the highest rate of photosynthesis
the arrangement of the palisade cells in this layer, with their high concentration of chloroplast, maximises the use of available sunlight to manufacture food via photosynthesis
function of spongy mesophyll
- loosely arranged, irregularly shaped cells with large intercellular air spaces between them
- contain chloroplasts and are able to carry out photosynthesis
- cells are used as storage sites for starch
- vascular bundles containing phloem and xylem tissues are found in this layer
function of lower epidermis
- similar to the upper epidermis, it is covered by a layer of cuticle but contains a high number of guard cells and stomata
function of guard cells
- bean shaped cells that provide openings (stomata) to the external environment for the purpose of gaseous exchange and transpiration
- guard cells also contain chloroplast and are able to carry out photosynthesis
- during daylight hours, guard cells produce glucose, increase amount of potassium ions in the cells and draw water in due to their lower water potential. the cells have thicker cell walls facing the stomatal openings and as they expand and become turgid, the stoma enlarges to allow more CO2 in for photosynthesis
- At night, guard cells do not photosynthesise. Thus, their water potential increases and water is lost from the cells. This causes the cells to become flaccid and decreases the size of the stoma, decreasing water loss.
describe the intake of carbon dioxide
CO2 enters the leaf through the stomatal openings of the leaf by diffusion. This results in the formation of a concentration gradient with low CO2 in the leaf as compared to the surroundings. Thus, CO2 from the surroundings diffuses into the intercellular air spaces of the leaf.
- The CO2 in the leaf dissolves in the thin layer of water covering the mesophyll cells and diffuses into the cell for photosynthesis to occur.
describe the intake of water and mineral salts
- water and mineral salts enter the leaf through the xylem tissue found within the vascular bundle
- both water and mineral salts are absorbed by the root hairs and transported to the leaf through the xylem tissue
importance of photosynthesis
- as a food source for animals
- glucose can be converted into other products such as starch, fats and proteins
- maintains the balance of CO2 and O2 in the air
function of petiole
holds leaf in position to absorb maximum light energy
how is the lamina adapted to its function?
THIN lamina provides a short diffusion distance for gases and enables light to reach all mesophyll cells
BROAD lamina provides a large surface area for maximum absorption of light
function of waxy cuticle on upper and lower epidermis
reduces water loss through evaporation from the leaf
why are there more chloroplasts in upper palisade tissue?
more light energy can be absorbed near the leaf surface
why are the veins containing xylem and phloem situated close to mesophyll cells?
xylem transports water and mineral salts to mesophyll cells
phloem transports sugars away from the leaf
