plant form and function Flashcards
where are stomata found on a leaf
They are on the bottom because no direct sunlight, so less evaporation
what are stomata and what are their functions
opening in plants that allows CO2 in and reduces water loss across their stomata
how do plants reduce water loss across their stomata
When there isn’t enough water guard cells will close to reduce water loss.
Plants also have trichome which are hair like projections on the epidermis of the lead. They trap water droplets and this reduces transpiration
what are the steps in the opening of the stoma?
- when sunlight hits the leave it activates potassium ions to go into the stoma (through active transport so ATP is needed)
- osmosis occurs, so also goes into the guard cells
- reaches a limited epansion in length
- so the guard cells start also bulging outwards
how does the stoma close at night
diffusion of water and K+ ion out of the cell causes the guard cells to shrivel
transpiration vs translocation
transpiration is the evaporation of water through leaves.
Translocation is the transportation of sugar in plants
what is the function of phloem?
allows for rapid sucrose transport from leaves to stem and roots
what is phloem made of?
sieve tubes that are living cells with perforated cross walls and no nucleus, ribosomes or cytoskeleton
why do sieve tubes lack so much?
so it’s not blocking water and sugar
describe companion cells and their function
have a nucleus and are next ot the sieve tube. give sugar to the sieve tube
how does sucrose translocation occur?
sucrose is either pushed up or down depending on tugor pressure
true or false. the plant expends its own energy for transpiration to occur
false. uses 0 of its own energy
cohesion vs adhesion
cohesion is attraction between water mols
adhesion is water attraction to structures around them
what are the steps of translocation?
- active transport of sucrose from companion cell to sieve tube
- sucrose diffusion across plamsodesmata
- osmosis of water
- tugor pressure increases.
- sucrose pushed up or down
what is transpiration
one way transfer of water and minerals when the plant expends o energy of its own. uses energy of sun as evaporation process
where does transpiration occur
through dead xylem
tracheid’s and vessels. explain the similarities and differences
the both transport water in all vascualr plants, but vessels are only found in flowering plants
why are vessels better than tracheid’s
because they have no cross walls, so water goes through it easier
a newly discovered plant has no stomata. Would you predict the plant to have a cuticle on the surface if its leaves? Why?
wouldn’t have a cuticle, so that it can breathe, but is more vulnerable to water loss
-NON-VASCULAR PLANTS DON’T HAVE CUTICLE
which one would have greater adhesion: tracheid or vessels? why?
tracheids because it has more SA for adhesion
what is meristem tissue?
tissue that consists of cells that are capable of growth throughout the life of a plant.
what it a terminal bud and what is the advantage
meristem tissue found at the top of a plant. allows for growth in length.
axillary buds description and advantage
(armpit of plant) meristem tissue on sides of plant.
Advantage: more SA for sun exposure, more photosynthesis; flower can come out of it and allow for sexual reproduction therefore more genetic variation
what is root meristem and what is the advantage?
meristem tissue found in roots, increased absorption of water and minerls
more stability / mechaninal support
less likely to tip over in a storm
why do some plants grow in width?
because of a cylinder of meristem tissue in between the xylem and phloem called vascular cambium
do monocots have cambium?
no, they lost cambium; was in common ancestor of plants.
how do growth rings form?
xylem has thick walls filled with ligning therefore keeps theri shape. growth ring represents a years woth of grouth, outer ring is newest because its next to cambium.
what is the bark of a tree
dead phloem because phloem has thin cell walls they get squashed and die.
how seasonal changes affect growth rings.
fires can cause scar tissure on inside of xylem. if growht is very wide means climate was ideal. lots of sunlight and water.
Allows us to know how much CO2 was in the air. Dark and light parts represent seasonal changes. Dark part is growth that happens in summer. Light is growth in the spring. Dark in summer because cells are more compact, less rain.
What type of information is provided by growth
ring analysis?
ires can cause scar tissure on inside of xylem. if growht is very wide means climate was ideal. lots of sunlight and water.
Allows us to know how much CO2 was in the air. Dark and light parts represent seasonal changes. Dark part is growth that happens in summer. Light is growth in the spring. Dark in summer because cells are more compact, less rain.
