IB Biology Topic B2.3.7 Adaptations to Increase Surface Area-to-volume Ratios of Cells Revision Notes (HL)

IB Biology Topic B2.3.7 Adaptations to Increase Surface Area-to-volume Ratios of Cells Revision Notes (HL) | RevisionDojo

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Cells Reshape Themselves to Trade Faster Across Their Membranes

A high surface area-to-volume ratio lets a cell move materials in and out fast enough to keep up with what its inside is doing.

When a cell needs a high rate of exchange or reaction, it cannot just shrink, so it evolves structural adaptations that add surface area without adding much volume.
Each adaptation below is tied to a specific job, and in every case the extra surface area is what makes that job possible.

Hint

When you see one of these structures in an exam, name the adaptation and then say what higher surface area lets the cell do.
The mark is almost always for linking the shape to a function, not for describing the shape alone.

External Projections: Reaching Out for Absorption

Some cells push out projections so that more of their membrane touches the material they need to absorb.
Microvilli
1. Microvilli are tiny finger-like projections of the cell membrane that greatly increase the surface area of the cell.
2. They give more room for transport proteins and channels, so materials cross the membrane faster.
3. They cover the epithelial cells lining the small intestine and the proximal tubule of the nephron, both sites of heavy absorption.
Root Hair Cells
1. A root hair cell grows one long, thin projection out into the spaces between soil particles.
2. This projection raises the surface area for uptake of water by osmosis and minerals by active transport, such as nitrate, phosphate, and potassium.

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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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Cells Reshape Themselves to Trade Faster Across Their Membranes

A high surface area-to-volume ratio lets a cell move materials in and out fast enough to keep up with what its inside is doing.

When a cell needs a high rate of exchange or reaction, it cannot just shrink, so it evolves structural adaptations that add surface area without adding much volume.
Each adaptation below is tied to a specific job, and in every case the extra surface area is what makes that job possible.

Hint

When you see one of these structures in an exam, name the adaptation and then say what higher surface area lets the cell do.
The mark is almost always for linking the shape to a function, not for describing the shape alone.

External Projections: Reaching Out for Absorption

Some cells push out projections so that more of their membrane touches the material they need to absorb.
Microvilli
1. Microvilli are tiny finger-like projections of the cell membrane that greatly increase the surface area of the cell.
2. They give more room for transport proteins and channels, so materials cross the membrane faster.
3. They cover the epithelial cells lining the small intestine and the proximal tubule of the nephron, both sites of heavy absorption.
Root Hair Cells
1. A root hair cell grows one long, thin projection out into the spaces between soil particles.
2. This projection raises the surface area for uptake of water by osmosis and minerals by active transport, such as nitrate, phosphate, and potassium.

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 B2.3.7: Adaptations to Increase Surface Area-to-volume Ratios of Cells Notes

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

Cells Reshape Themselves to Trade Faster Across Their Membranes

External Projections: Reaching Out for Absorption

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

Cells Reshape Themselves to Trade Faster Across Their Membranes

External Projections: Reaching Out for Absorption

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