Chapter 11: Plants Flashcards
plants
- multicelled, eukaryotic, photosynthetic autotrophs
- cell walls made of cellulose
- surplus carb: starch
alteration of generations
- one generation is gametophyte, where the cells are haploid
- alternate generation is sporophyte generation, where cells are diploid
bryophytes
- nonvascular: no xylem and phloem
- absorb water through diffusion from the air
- lack tissue necessary for tall plant
tracheophytes
- vascular: have xylem and phloem
- can support tall plants
- roots: absorb water and support plant
- leaves increase photsynthetic surface
- sporophyte generation is dominant
- seedless plants reproduce by spores (ferns)
- seed plants
a. gymnosperms: cone-bearing
b. angiosperms: flowering (monocots and dicots)
seedless tracheophytes
- homosporous: produce with only one type of spore which develops into a bisexual gametophyte
- restricted to moist habitat, but can grow tall
seed tracheophytes
-heterosporous: produce two kinds of sportes, megaspores (develop into female gametophytes) and microspores (develop into male gametophytes)
gymnosperms: conifers
- first seeded plants on earth
- seed are not enclosed by fruit, but are exposed on modified leaves that form cones
- depend on wind for polliniation
angiosperms: flowering plants
- animals polinate
- after fertilization, ovary become fruit and ovule becomes the seed
- fruit protects dormant seed and aids in dispersal
monocots
- one cotyledon (seed leaves)
- scattered vascular bundles in stem
- parallel leaf venation
- floral parts usually in 3s
- fibrous roots
dicots
- two cotyledons
- vascular bundles in stem in a ring
- netlike leaf venation
- floral parts in 4s or 5s
- taproots
how plants survive on land
- cell wall: made of cellulose, supports cells who are no longer supported by a watery environment
- roots
- stomates: exchange photosynthetic gases and close to minimize water loss
- waxy coating: made of cutin
- seeds and pollen
- xylem (water and nurients) and phloem (food)
apical meristem
-tips of the root and buds of the shoots source of primary growth (elongation of the plant down in the soil and up in the air)
meristem
-continually divides and generates new cells
lateral meristem
-increase in thickness (woody plants)
vascular bundles
- AKA veins
- vascular tissue that runs the length of the stem in strand
- xylem on the inside, phloem on the outside, meristem tissue between
- located in the mesophyll
guard cells
-modified epidermal cells that contain chloroplasts, photosynthetic, control the opening of stomates
mesophyll layer
-holds the most chloroplasts
bundle sheath cells
-separate vascular bundles from the rest of the mesophyll
transpirational pull
- fluid in xylem can be pulled up against gravity without energy
- ability for roots to regulate the uptake of nutrients
transpiration
-evaporation of water from leaves that causes tension in the xylem
transpirational pull-cohesion tension theory
-for each molecule of water that evaporates from a leaf by transpiration, another water molecule is drawn in at the root to replace it
vegetative propogation
-part of the plant gives rise to another plant that is identical to the parent
pollination
- one pollen grain containing 3 haploid nuclei (one tube nucleus, 2 sperm nuclei) lands on stigma of the flower
- pollen grain absorbs moisture and sprouts, producing a pollen tube that burrows down the style into the ovary
- two sperm nuclei travel to the ovary where they enter the nuclei through the micropyle
double fertilization
- one sperm fertilizes the egg, making a 2n embryo
- one sperm fertilizes the polar bodies, making a triploid (3n) endosperm (food for the growing embryo
- ovule becomes the seed
- ovary becomes the fruit
- monocots: food reserves remain in the endosperm
- dicot: food reserves of endosperm transported to cotyledons
seed structure
-seed coat, embyo, cotyledon/endosperm
embryo structure
- hypocotyl: becomes lower part of stem
- epicotyl: becomes upper part of stem
- radicle (embryonic root): first organ to emerge from germinating seed
dormancy
-seeds do not start growing until environmental cue is met
germination
- imbibition: absorprtion of water, causing the seed to crack
- enzymes are activated
- RNA directs synthesis of proteins
- complete when radicle emerges from seed coat
gametophyte (n)
-produces gametes by mitosis, which fuse together to form 2n zygotes
sporophyte (2n)
-produces haploid spores by meiosis, which each form a new gametophyte
signal transduction pathways
-amplify hormonal signal and connect it to specific cell responses (hormones affect growth, development, and responses to environmental signaling)
auxins
- plant hormone that controls phototropisms due to uneven distribution of auxin
- enhances apical dominance
- used in human chemicals and pesticides
cytokinins
- stimulate cytokinesis and cell division
- produced in roots
gibberellins
-promote stem and leaf elongation
abscisic acid (ABA)
- inhibits growth
- enables plants to withstand drought
- promotes seed dormancy
ethylene
- promotes fruit ripening
- facilitates apoptosis
- promotes leaf abscission (leaf dies and falls from plant)
tropism
-growth of a plant towards or away from a stimulus
thigmotropisms
-touch
geotropisms
-same as gravitropisms
positive tropism
-growth towards a stimulus
negative tropism
-growth away from a stimulus
photoperiod
-relative length of day and night that plants use to detect the time of year
photoperiodism
-physiological response to the photoperiod
long-day plants
- flower when the light period is longer than a certain number of hours
- short-night plant
short-day
- flower when the light period is shorter than a certain number of hours
- long-night plant
day-neutral
-flower regardless of the length of the day
phytochrome
-keeps track of the length of day and night depending on the presence of different types of phytochromes
