IB Biology Topic B4.2.11 Adaptations of Plant Form for Harvesting Light Revision Notes (SL/HL)

IB Biology Topic B4.2.11 Adaptations of Plant Form for Harvesting Light Revision Notes (SL/HL) | RevisionDojo

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Harvesting Light: Plant Form Is Shaped by the Race for Sunlight

In a forest, dense vegetation means light is the resource plants compete hardest for.
This competition has produced different forms of plant structure that each capture light in a different way.
More captured light means more photosynthesis, so form that reaches or exploits light is favoured by natural selection.

Canopy Trees: Growing Tall to Reach the Light

The canopy is the uppermost layer of the forest, where light is most abundant.
Trees tall enough to reach it get direct sunlight while shading out competitors below.

Tall trunks
1. Trees invest heavily in height, growing straight, tall trunks to reach the canopy.
2. Thick, woody trunks resist collapse and withstand strong winds.
Broad crowns and leaf arrangement
1. Once in the canopy, trees spread their crowns wide to expose the largest leaf area to light.
2. Leaves are positioned in a mosaic that reduces self-shading, so upper leaves do not block those below.

Example

The kapok tree (Ceiba pentandra) is an emergent that grows over 60 metres tall, towering above the rainforest canopy for uninterrupted sunlight.
This height needs a massive root system, often with buttress roots, for stability.

Climbers: Reaching the Canopy Without Building a Trunk

Height is a trade-off: it wins light but costs energy and makes trees vulnerable to wind.

Lianas are woody vines that use existing trees for support, reaching the canopy without building their own thick trunk.

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Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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Harvesting Light: Plant Form Is Shaped by the Race for Sunlight

In a forest, dense vegetation means light is the resource plants compete hardest for.
This competition has produced different forms of plant structure that each capture light in a different way.
More captured light means more photosynthesis, so form that reaches or exploits light is favoured by natural selection.

Canopy Trees: Growing Tall to Reach the Light

The canopy is the uppermost layer of the forest, where light is most abundant.
Trees tall enough to reach it get direct sunlight while shading out competitors below.

Tall trunks
1. Trees invest heavily in height, growing straight, tall trunks to reach the canopy.
2. Thick, woody trunks resist collapse and withstand strong winds.
Broad crowns and leaf arrangement
1. Once in the canopy, trees spread their crowns wide to expose the largest leaf area to light.
2. Leaves are positioned in a mosaic that reduces self-shading, so upper leaves do not block those below.

Example

The kapok tree (Ceiba pentandra) is an emergent that grows over 60 metres tall, towering above the rainforest canopy for uninterrupted sunlight.
This height needs a massive root system, often with buttress roots, for stability.

Climbers: Reaching the Canopy Without Building a Trunk

Height is a trade-off: it wins light but costs energy and makes trees vulnerable to wind.

Lianas are woody vines that use existing trees for support, reaching the canopy without building their own thick trunk.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic B4.2.11: Adaptations of Plant Form for Harvesting Light Notes

Harvesting Light: Plant Form Is Shaped by the Race for Sunlight

Canopy Trees: Growing Tall to Reach the Light

Climbers: Reaching the Canopy Without Building a Trunk

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Harvesting Light: Plant Form Is Shaped by the Race for Sunlight

Canopy Trees: Growing Tall to Reach the Light

Climbers: Reaching the Canopy Without Building a Trunk

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics