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Topic 9: Reproduction in Angiospermophytes 9.3
Draw and label a diagram showing the structure of a dicotyledonous animal-
pollinated flower• Limit the diagram to: sepals, petals, anther,
filament, stigma, style and ovary
Distinguish between pollination, fertilization, and dispersal
Draw and label a diagram showing the external and internal structure of a named dicotyledonous
seed
• Testa (seed coat), hypocotyl (embryonic shoot), radicle (embryonic root), cotyledons (seed leaves) Pisum sativum (common pea)
Explain the conditions needed for seed germination
• Water = rehydration of dry tissue
• Oxygen = aerobic cell respiration
• Suitable temperatures for enzymatic activity
Outline the metabolic events during the germination of a starchy seed
• Stage 1 – water absorption• Stage 2 – gibberelin (growth hormone) produced by
cotyledons = growth hormone• Stage 3 – gibberelin stimulates amylase production =
chem. breakdown of starch into maltose in food stores of the seed
• Stage 4 – maltose transported to radicle and plumulue• Stage 5 – maltose converted to glucose = E or
synthesis of materials for growth (e.g. cellulose)• Stage 6 – cessation once leaves and sun connect
Explain how flowering is controlled in long-day and short-day plants, including the role of
phytochrome
• Key points:– Phytochrome is a light absorbing pigment– Phytochrome exists in two interchangeable forms:
phytochrome red (Pr) and far-red (Pfr).– Only Pfr is biologically active
– ****Pfr is a promoter of flowering in long-day plants and it inhibits flowering in short-day plants
Draw a similar presentation for Long-day (short-night) plants