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Difficulty: HardReproductive Systems and Processes in Organisms

A flower collected from a tropical rainforest canopy possesses a deeply tubular corolla, secretes copious amounts of dilute nectar at the base of the floral tube, produces red unscented petals, and displays sturdy floral structures. Which of the following agents is primarily adapted to pollinate this flower?

  1. Sunbirds, which possess long slender beaks to reach nectar in deep corolla tubes and rely on visual cues rather than olfactory senses.Answer
  2. B
    Wind currents, which require long pendulous filaments, light powdery pollen, and large feathery stigmas exposed outside the perianth.
  3. C
    Nocturnal moths, which are attracted to strong sweet aromas and dull white or pale petals that reflect light at night.
  4. D
    Bees, which require broad landing platforms, sweet floral scents, and ultraviolet nectar guides on shallow open corollas.

Answer

Sunbirds, which possess long slender beaks to reach nectar in deep corolla tubes and rely on visual cues rather than olfactory senses.
The combination of a deep tubular corolla, red coloration, unscented petals, and high production of dilute nectar is characteristic of bird pollination (ornithophily). Sunbirds have long slender beaks capable of probing deep floral tubes, excellent perception of red light, and high caloric needs satisfied by nectar, while requiring no floral scent due to their weak olfactory sense.

Step-by-Step Solution

1
Analyze the floral characteristics presented in the stem.
Identified key features: deeply tubular corolla, high volume of dilute nectar, red color, sturdy floral parts, and absence of fragrance.
Floral syndromes correspond directly to the sensory capabilities and morphological features of specific pollinator groups.
2
Evaluate pollinator sensory and physical match for the floral features.
Birds (such as sunbirds or hummingbirds) possess keen vision for red wavelengths, weak senses of smell (hence unscented flowers), long bills adapted to reach deep corollas, and require high volumes of dilute nectar to satisfy high metabolic demands.
Red tubular unscented flowers with copious dilute nectar are classic adaptations for ornithophily (bird pollination).
3
Differentiate from alternative pollination syndromes (anemophily, phalaenophily, melittophily).
Wind pollination lacks nectar and petals; moth pollination requires night-visible white petals and strong scents; bee pollination requires scent, landing platforms, and colors visible in the UV spectrum rather than deep unscented red tubes.
Matching structural adaptations eliminates insect and wind vectors.

Key Concept

Floral structural adaptations and pollination syndromes in angiosperms
Estimated Time:1m 30s
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Topics

Reproductive Systems and Processes in Organisms

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