Plant tissues, organs, and systems Flashcards
nucleus
animal/plant cells - controls activities of the cell - holds the cell’s dna
cytoplasm
animal/plant cells - organelles are suspended in this jelly-like substance where chemical reactions (metabolism) occur
cell-membrane
animal/plant cells - semi-permeable membrane which controls what can enter and exit the cell
cell wall
plant cells - supports the cell - gives it structure
mitochondria
animal/plant cells - powerhouse of the cell - where aerobic respiration occurs
ribosomes
animal/plant cells - protein synthesis
chloroplasts
plant cells - where photosynthesis occurs - contain chlorophyll
adaptations of a leaf
upper epidermis is mostly transparent to allow light to reach palisade cells; air spaces allow for faster diffusion; waxy cuticle prevents water loss and infection; stomata control movement of gases
what are the names of different cells/tissues in a leaf
cuticle, upper/lower epidermis, palisade mesophyll, spongy mesophyll, guard cells, stomata
what are guard cells
specialised lower epidermis cells which control the opening and closing of stomata
examples of cells in plants
root hair cells, guard cells
examples of tissues in plants
epidermis, spongy mesophyll, palisade mesophyll, xylem, phloem, meristem
organs in plants
roots, leaves, flowers, fruits, seeds, stem
organ system in plants
transpiration, translocation
what is the function of a flower
reproduction - attracts pollinators (brightly coloured, nectar, scent)
function of seeds
reproduction, growth
function of leaves
photosynthesis
function of stem
keeps plant upright to absorb light, transport in xylem and phloem
function of roots
active transport of minerals, osmosis of water
composition of xylem
made of dead cells - no end walls; less obstruction to movement of water; flows in hollow tube - one way flow - transports water and minerals - walls stiffened with lignin
composition of phloem
2 way flow - transports water and food (glucose and sucrose, fatty acids, oils, amino acids) - cells have end walls with perforations; sieve plates - companion cells; change flow direction; active transport; full of mitochondria
meristem tissue
unspecialised cells - growth - found in tips of roots and shoots
transpiration
process where water evaporates and diffuses out through stomata - pulls more water up plant from root - transpiration stream (some water used in photosynthesis)
what quality of water enables transpiration to occur
water is polar - molecules stick together - water is pulled up in transpiration stream
factors affecting rate of transpiration
light intensity, wind speed, humidity, temperature
how does light intensity affect rate of transpiration
makes stomata open if brighter - lower LI, stomata close. if stomata open - transpiration is faster as water can diffuse out of leaves
how does wind speed affect rate of transpiration
higher wind speed - faster transpiration - will blow air with high water concentration away - becomes dilute - steeper concentration gradient - diffuse faster
how does temperature affect rate of transpiration
high temperature - particles have higher kinetic energy - evaporate faster as molecules break apart and become gas - as particles move faster
how does humidity affect rate of transpiration
high humidity - slow transpiration - if air is concentrated with water (humid) - shallow concentration gradient
process of transpiration
osmoses from soil into root hair cell (dilute to concentration solution) - move down concentration gradient. moves to root cell. moves through xylem - transpiration stream - pulls more water up. moves to spongy mesophyll - lower epidermis - stomata. diffuse and evaporate out - high water conc in cells - low in air - moves down conc gradient
plant adaptations to reduce water loss
rolled leaves, sunken stomata, spikes not leaves, hairs on leaves, shallow & widespread roots, fewer stomata, thick waxy cuticle
how do rolled leaves and sunken stomata reduce water loss
rolled leaves - reduce exposure of stomata to air, reducing evaporative water loss. sunken stomata - reduces air movement over stomata, creating humid microclimate, reducing evaporation rate.
how do spikes not leaves reduce water loss
prevent animals from eating plant - spines break up airflow - reduces evaporation - trapped air can create a buffer zone with slightly more moist air. spines also help collect water from fog.
how do hairs on leaves reduce water loss
trap air close to leaf - creates microclimate around leaf - as leaf loses water microclimate becomes humid - hairs prevent this from being blown away - humidity - slower transpiration rate
how do shallow, widespread roots reduce water loss
spread wide to collect surface water from wide area of land
how do fewer stomata reduce water loss
less stomata - less places for water to evaporate/diffuse out of leaf
how does a thick waxy cuticle reduce water loss
stops vapour escaping through epidermis - shiny to reflect heat - lower temperature - slower transpiration
translocation
transportation of food substances produced in photosynthesis, to places where they are needed eg storage organs (bulbs and tubers), developing seeds, growing parts of a plant
what is the part of a plant which produces food called
a source
what is the part of a plant which store/use food called
sink
process of translocation
pressure flow - at source sugar moves into phloem cells through active transport - water follows through osmosis - water creates turgor pressure in sieve elements, forcing sugars down towards sinks, at sinks sugars actively removed and water follows, so high water potential and low turgor pressure is created
