Reproduction in Angispermophytes (9.3.1-6)
9.3.2
Distinguish between pollination, fertilization,+ seed dispersal
POLLINATION: the transfer of pollen grains from the anther to stigma
FERTILIZATION: fusion of male + female gametes
SEED DISPERSAL: mechanisms for distributing seeds away from the parent plant
9.3.4
Explain the conditions needed for the germination of a typical seed:
EVOLUTION (of the seed): key adaptations of plants to terrestial life
SEED DORMANCY: increases chance that germination will occur @ appropriate time
ENVIRONMENTAL CUES:
*O2 +H2O >> needed by all plants to germinate, initiate inhibition + activate cellular respiration
*Desert >> substantial rainfall that wahses away inhibitors from seed coat (testa)
*Chaparral >> fire + intense heat
*Temperature + subarctic zones >> extended exposure to cold
*Passage thru animal digestive tract >> exposure to digestive enzymes wears down seed coat (testa)
LENGTH OF DORMANCY: varies from days -> decades
9.3.5
Outline the metabolic processes during the germinaton of a starchy seed:
*Imbibition: absorption of H2O, due to low H2O potential in dry seed and causes seed to swell, rupruring the seed coat + triggering metabolic chnages in the embryo, causing it to resume growth.*
-Gibberllic acid (GA) is released by embryo, diffuses thru-out seed, reaching aleurone, the outer layer of seed
-a-amylase (digestive enzyme) is released when aleurone triggered by GA
-endosperm starch hydrolyzed in2 maltose by digestive enzyme
-cotyledon absorbs maltose from endosperm into embryo
-seedling grows from embryo fueled by the energy fom maltose; stored lipids + proteins also hydrolyzed allowing for embryo's growth + development
9.3.6
Explain how flowering is controlled in long-day and short-day plants, including the role of phytochrome:
>phytochrome is a pigment that exists in plants in 2 forms:
1.) Pr - absorbs white/red light
2.) Pfr - absorbs dark/far-red light
>in white/red light, Pfr is converted -> Pr
>Pfr acts as a promoter of flowering in long-day plants
>it also acts as an inhibitor of flowering in short-day plants