bio1 plant transport system

parts of the leaf

upper epidermis + cuticle

lower epidermis + stomata +guard cells

palisade mesophyll

spongy mesophyll + thin layer of water

vascular bundle

feature and function of the cuticle

thin transparent waxy layer to prevent water loss via transpiration

feature and function of the palisade mesophyll

tightly packed elongated cells contain many chloroplasts for greater rate of photosynthesis

feature and function of spongy mesophyll

loose packed irregular shaped cells that contain many intercellular air spaces for rapid diffusion of gases for quicker rate of gaseous exchange

where is chemical energy produced during photosynthesis stored in

chemical bonds of organic molecule

how does stomata open during light

-guard cell contain chloroplasts, photosynthesis produce glucose

-w.p. in guard cell decrease, water enters guarde cells via osmosis

-guard cells become turgid, bend outwards.

how does stomata close when no light

-glucose in the guard cells used up

-w.p. in guard cells increase

-water exits guard cells via osmosis

-guard ells flaccid

what controls opening and closing of stomata

turgidity of guard cells

2 functions of xylem and its adaptation

1. transports water and dissolved mineral salts upwards from roots to leaves

-empty hollow lumen with no protoplasm and cross walls between dead xylem cells to reduce resistance on the flow of water

2. provides mechanical support to the plan

-walls contain lignin to prevent collapse of the xylem vessel when exposed to high tension during transport of water and dissolved mineral salts

function and 2 adaptations of the phloem tissue

1. transport manufactured food substances (sucrose and amino acids) from leaves to other parts (translocation)

-companion cells have many mitochondria to provide sieve tube elements nutrients and energy to carry out metabolic processes

-pores in sieve plates allow sucrose and amino acids to flow through sieve tubes

why must have companion cell

-each sieve tube element requires companion cells to help it carry out metabolic processes by providing nutrients to sieve tube elements , help sieve tube with translocation and has numerous mitochondria to provide energy for AT of sugar into sieve tubes.

function of cambium

actively divide and differentiate into new xylem and phloem tissues, leading to thickening of stem

2 adaptations of root hair and their function

1. selectively permeable plasm membrane

-prevent cell sap which contains sugars amino acids and salt from leaking out, thus maintaining lower w.p. than soil

2.many mitochondria

-release energy for active transport of dissolved mineral salts into cell

word and chemical equation for photosynthesis

carbon dioxide + water —chlorophyll and light—> glucose and oxygen

6CO2 + 6H2O —chlorophyll,light—> C6H12O6 + 6CO2

what happens in the light dependent stage +photolysis

chlorophyll absorbs light energy and converts it to chemical energy

light energy splits water molecules into hydrogen atoms and oxygen (photolysis)

what happens in the light independent stage

hydrogen is used to reduce co2 to form glucose

energy for reaction comes from light dependent stage (ATP and NADPH)

what is translocation

unidirectional transport of manufactured food substance through the phloem tissues

phloem/xylem sap vs cell sap

solution found in the sieve tube/xylem lumen

any liquid found in the cell vacuole and cytoplasm

why xylem and phloem no cell sap

mature xylem and sieve tube elements have lost their vacuoles

why does stem swell during ringing experiment

removal of phloem prevents translocation of manufactured food substances to region below ring.

accumulation of manufactured food substances in region right above ring lowers wp of cells in that region

water enters region via osmosis causing swelling

where will radioactivity be detected in t.s. of stem

phloem. carbon-14 is a radioactive isotope taken up by the lead during photosynthesis, incorporated into glucose the. sucrose

radioactive sucrose in phloem cause x-ray foil to blacken, confirm sug

overall movement of water

water is loss from aerial parts of the plant during transpiration, generating a transpiration pull pulling water from the roots that entered the roots via osmosis down a concentration gradient

water movement in roots to stem

1. cell sap of root hair cell more conc (w. sugars and mineral salts)than soil solution outside. water enters by osmosis down a water potential gradient.

2. entry of water dilutes root hairs cell sap. now has higher w.p than that of next cell. water pass by osmosis from root hair cell through the cortex until it enters the xylem vessel

transpiration

loss of wv through the aerial parts of the plant mainly through stomata.

comsequence of photosynthesis

how does transpiration happen

1. during day, stomata open for gaseous exchange

2. wv lost to atmosphere by diffusion out of stomata due to lower conc of wv in atmosphere

3. water evaporates from surface of spongy mesophyll cells to replace water lost via transpiration

4. high wv conc in intercellular air spaces establishes wv conc gradient between inside leaf and atmosphere

trans pull

transpiration results in trans pull which pull water up the xylem vessel in a continuous unbroken chain

three forces during transpiration

1. transpiration pull (main pulling force)

2. capillary action (minor pulling force)

3. root pressure (minor pushing force)

how does water form in an unbroken column

cohesion prevents water column from breaking apart

adhesion prevents water column from slipping back