topic 9: reproduction in angiospermophytes 9.3

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