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Difficulty: HardReproductive Systems and Processes in Organisms

A botanist observes an angiosperm flower species in which the anthers mature and release pollen several days before the stigma of the same flower becomes receptive. The flower also features large, scented petals with nectaries at its base. Which reproductive phenomenon is demonstrated by this flower, and what is its primary biological advantage?

  1. Protandry, which enforces cross-pollination by preventing self-fertilization within the flower.Answer
  2. B
    Protogyny, which ensures rapid self-pollination before visiting insects can remove pollen.
  3. C
    Anemophily, which uses scented petals and nectaries to attract wind currents for pollen transport.
  4. D
    Cleistogamy, which keeps the floral bud permanently closed to guarantee cross-pollination by insect vectors.

Answer

Protandry, which enforces cross-pollination by preventing self-fertilization within the flower.
Protandry is a temporal form of dichogamy where anthers release pollen prior to the stigma becoming receptive in the same flower. This structural and physiological adaptation prevents autogamy (self-pollination) and ensures outcrossing (cross-pollination) via insect vectors attracted by the bright, scented petals and nectar.

Step-by-Step Solution

1
Analyze the temporal sequence of maturation of the reproductive organs.
The anthers (male organs) mature and shed pollen before the stigma (female organ) is receptive.
Temporal separation of male and female organ maturation within the same flower is termed dichogamy. Specifically, male-first maturation is known as protandry.
2
Determine the functional significance of protandry combined with floral features (scented petals, nectaries).
Scented petals and nectaries attract insect pollinators (entomophily), while protandry prevents pollen of the flower from fertilizing its own ovules.
Preventing self-fertilization forces pollen transfer between different individual plants, promoting outcrossing and genetic variation.

Key Concept

Dichogamy and mechanisms promoting cross-pollination in angiosperms
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Topics

Reproductive Systems and Processes in Organisms

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