9.3 reproduction in flowering plants

2. Distinguish between
pollination:transfer of pollen grains from the anther to the stigma
fertilization:fusion of male and female gametes
seed dispersal:mechanisms for distributing seeds way from the parent plant
4.Explain the conditions needed for the germination of a typical seed
evolution of the seed:key adaption of plants to terrestrial life
seed dormancy increases the chance that germination will occur at appropriate time
environmental cues
1. oxygen and water
1.needed by all seeds to germinate
2.to initiate inhibition an activate cellular respiration
b. desert
1.substantial rainfall
2.washing inhibtors from seed coat
c.chaparral
1.fire
2.intense heat
d.temperate&subarctic zones
1.extended exposure to cold
e.passage through animal digestive tract
1.exposure to digestive enzymes
2.wearing down of seed coat
-length of dormancy-varies from days to decades
5.outline the metabolic processes during of germination of a starchy seed
-imbibition-absoprtion of water due to low pwater potential in dry seed causing seed to swll and rupture seed coat which triggers metabolic changes in the embryo which resumes growth
-gibberllic acid is releases by embryo which diffues throughout seed reaching the aleurone the oter layer of the seed
-amylase-a digestive enxyme is released by the aleurone when trggerd by GA
-endosperm starch is hyrdoloized into maltose by amylase
-cotyledon absorbs maltose from endosperm into embryo
-seedling grows from embryo fueld by the nergy from maltose, stored lipids and proteins also hyrdrolized allowing for growth and development of embryo
6. Explain how flowering is controlled in long day and short day plants including the role of phytochrome
-phytichrome is a pigment that exists in plants in two forms:
Ps. abosrbs white/red light
Pfr. abosrbs dark/far red ight
in white or red light Pr is converted to Pfr
in far red light or in darkness, Pfr gradually reverts to Pr
pfr acts as a promoter of flowering in long day plants
pfr acts as an inhibtor of flowering in short day plants