Plant Test (cap 8, 28-21) Flashcards
how does a sperm fertilize an egg in a plant
pollen lands on stigma-pollen tube forms and two sperm go down the tube opening (micropyle) of the ovary in the carpel. one sperm fertilizes the forming the zygote, the other sperm combines with two polar nuclei of the embryo sac forming a triploid cell that develops into endosperm-food for growing embryo
what is “alternation of generation” of a flowering plant
alternating between the sporophyte (diploid) stage and the gametophyte (haploid) stage in plants
double fertilization
two sperm used for fertilization
what is self-incompatibility in plants
ability of a seed plant to reject its own pollen and sometimes the pollen of closely related individuals
explain how a seed germinates. what is the order of events
- seed takes in water (ambition) due to a low water potential; seeds expands and ruptures coat
- gibberillins (hormone) break dormancy
- enzymes begin digesting the endosperm or cotyledons and nutrients go to growing regions of embryo
- radicle (embryonic root emerges)
- shoot tip breaks through the soil: eudicot: (get hook first) light causes hypocotyl to straighten, cotyledons separate and epicotyl spreads leaves. monocot: coleoptile pushes up through the soil-grows straight up, shoot then grows up through coleoptile
ethylene
fruit ripening, helps leaf abscission, senescence (programmed cell death in plants)
auxin
stimulates stem elongation, promotes lateral and adventitious root growth, regalates fruit development, retards leaf abscission
gibberellins
stimulate stem elongation, pollen development, pollen tube growth and seed development and germination
abscisic acid
inhibits growth; closes stomata during drought, promotes seed dormancy, inhibits germination
brassenosteroids
promote cell expansion and cell division in shoots, promotes root growth (low conc.), inhibits root growth (high conc.) promotes seed germination
know what phytochrome are
photoreceptors that absorb mostly red light
what are concerns people have with genetically modified crops
allergens; transgene escape (ex: creating supersedes); effect on non-target organisms
what causes short-day and long-day plants to flower
- response to light based on phytochromes
- red wavelength of 660nm increased germination; far-red light (730)nm inhibited germination
- last light determines the seed response
- reversible-phytochrome switches Pr in dark switches to Pfr in light
what causes a plant to grow towards the light
auxin-elongates the cells by creating proton pumps that lower pH of cell wall which activates enzymes (expansins) to break the cell wall so more water comes in and expands cell
effect of light on plants
etiolation: adaptations for growing in darkness de0etiolation: in which shoots and roots grow normally
mesophyll cells:
can be spongy or palisades. the main cells that conduct photosynthesis
guard cells
regulate the opening and closing of the stomata. if they are turgid=stomata is open (a lot of water) if they are flaccid=stomata is closed (not a low of water)
tracheids
xylem cells that conduct water. they are dead cells
sieve tube cells
phloem cells that conduct sugar and other organic compounds up and down the plant
companion cells
cells that are connected by plasmodesmata to the sieve use cells. also found in the phloem part. help keep the sieve cells alive with their nucleus and ribosomes
vessel elements
associated with tracheas. in the xylem. shorter and wider than the tracheas. dead cells at maturity. tubes aligned end to end. they will feed water into the tracheas.
what does mychorrizal fungi do for plants
increases surface area for water uptake. supplies with minerals absorbed from the soil. stimulates root growth to the plant. creates antibiotic for the plant
what things will help uptake water in a plant
root hairs bc it increases surface area for water absorption
bulk flow which is a difference in pressure potential in the plant
transpiration because of adhesion/cohesion of water causing the water to be pulled up
casparian strip that forces water and minerals into the vascular cylinder
what is the function of xylem
transport water and minerals up the plant
what is the function of phloem
transports sugars and organic nutrients up and down the plant
how do substances move in the xylem
root hairs bc it increases surface area for water absorption
bulk flow which is a difference in pressure potential in the plant
transpiration because of adhesion/cohesion of water causing the water to be pulled up
casparian strip that forces water and minerals into the vascular cylinder
how do substances move in the phloem
goes from source-where its made-to sink-where it is used-. the sieve tube elements are loaded up with elements with sugar, water will follow which causes pressure which will move sugar to the sinks
what are the effects of closing stomata
no CO2 can come in. no water can go out.
what is nitrogen fixation
conversion of atmospheric nitrogen into ammonia by bacteria
how does water potential affect the movement of water in a plant
water moves from a high water potential to a low water potential
what elements would be beneficial to radioactively label
label the CO2 and H2O in order to figure out where the substances will end up and where they are coming from in the first place
what does the light do in the light dependent reactions
energy is absorbed to excite the electrons in the chlorophyll pigments in the photosystems. it also laces water (breaks water aparT)
what happens to water in the light dependent reactions
it gets laced (broken apart) and the oxygen becomes a waste while the hydrogen and electrons are used as the source of filling the hole of the electron that got excited from the chlorophyll molecules in PS2
what happens to the excited electrons in the light dependent reactions
in PS2 the excited electrons are hit by water and falls down the electron transport chain and ends up in the hole of the excited electron in PS1. then the electron falls down another electron chain and gets picked up by NADP+ (electron carrier) which causes it to form NADPH and eventually is carried to the calvin cycle
what are photosystems 1 and 2
reaction center complexes that has chlorophyll in it and other electron acceptor molecules. they are considered light capturing systems. in light dependent reactions.
what is the electron acceptor for PS1 and PS2
PS1=NADP+
PS2=chlorophyll molecule in PS1
what waste product is given off at light dependent reactions
oxygen
what molecules go from the light dependent reactions to the Calvin Cycle
ATP and NADPH
what molecule goes into the calvin cycle
carbon dioxide
what happens when carbon is “fixed” in the calvin cycel
it means that the carbon dioxide is attaching to a five carbon compound (RuBP) that is already in the cycle. this is done using the enzyme rubisco
what gets regenerated in the calvin cycle
RuBP
what is the product of the cycle (calvin)
G3P (two G3Ps=glucose molecule)
where do the photosynthesis reactions happen
light dependent=thylakoid membranes of the chloroplast
calvin cycle-the stroma
what are the effects of different wavelengths of light on photosynthesis
plants absorb blue-violet and red wavelengths to use for photosynthesis
green and yellow tend to be reflected
how can CAM plants handle photosynthesis
they open their stomata at night to prevent water loss. they store the organic nutrients at night. then they use the organic nutrients during the day
how can C4 plants handle photosynthesis
carbon fixation happens in the mesophyll cells (where normal photosynthesis happens) the second part of the calvin cycle happens int he bundle sheath cells where it can finish the process
