9.3 Reproduction in Angiospermophytes Flashcards Preview

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Flashcards in 9.3 Reproduction in Angiospermophytes Deck (7)
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1

Define pollination

The transfer of pollen grains from the mature anther to the receptive stigma (usually of another plant) often facilitated by animals, wind or water movement

2

Define fertilisation

Fusion of the male gamete in the pollen grain with the female gamete in the ovule to form a zygote

3

Outline seed dispersal

Fertilised ovules form seeds which move away from the parental plant before germination, reducing competition for resources. Seed dispersal mechanisms include fruit, wind, water and animals

4

Define germination

The process by which a seed emerges from a period of dormancy and starts to sprout

5

Outline three factors which a seed requires for germination

• Temperature for the optimal function of enzymes
• Oxygen for aerobic respiration (seed needs ATP to grow)
• Water to metabolically activate the cells

(TOW)

6

Outline the metabolic processes during germination of a starchy seed

• Water is absorbed, which causes the formation of gibberellin in the embryo's cotyledon
• Gibberellin stimulates the production of amylase, which catalyses the breakdown of starch to maltose
• Maltose is transported to the embryo, where it is either hydrolysed to glucose (for energy) or polymerised to cellulose (for cell wall formation)

7

Explain how flowering is controlled in long day and short day plants

• Flowing is affected by light
• Phytochrome exists in two forms, Pr which absorbs red light and Pfr which absorbs far-red light
• Pfr is active form, Pr is inactive form
• Daylight converts Pr to Pfr
• In darkness, Pfr gradually reverts back to Pr
• Pfr acts as promoter of flowering in long-day plants
• In long day plants, flowing induced by dark periods shorter than a critical length because enough Pfr remains at the end of short nights to stimulate flowering
• Pfr acts as inhibitor of flowering in short-day plants
• Short-day plants induced to flower by dark periods longer than a critical length because at end of long nights enough Pfr has been converted to Pr to allow flowering to occur