what advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration
Terrestrial organisms have the advantage that they get oxygen directly from air, which has much more oxygen than water, so they can obtain it more easily and efficiently for respiration.
Quick Scoop
One-line answer
A terrestrial organism breathes air, which contains a much higher concentration of oxygen than water, so it does not need to breathe as fast or develop very specialized structures to obtain enough oxygen for respiration.
What’s different in their oxygen source?
- Terrestrial organisms take in oxygen directly from the atmosphere.
- Aquatic organisms depend on oxygen dissolved in water.
- Air contains about 21% oxygen, while dissolved oxygen in water is much lower (often less than 1%).
Think of it like this: land animals are “breathing from a full tank,” while aquatic animals are “breathing from a much smaller tank.”
The real advantage for terrestrial organisms
Because air has much more oxygen than water:
- Terrestrial animals can get sufficient oxygen without breathing very fast.
- Aquatic animals must move a lot more water across their gills and often have a faster breathing rate to get the same amount of oxygen.
- Terrestrial organisms generally do not need as many complex adaptations just to extract enough oxygen, whereas aquatic organisms need specialized structures like gills and continuous water flow.
In simple exam language, you can write:
A terrestrial organism breathes oxygen directly from air, which has a much higher oxygen content than water, so it can obtain oxygen more easily and does not need to breathe as fast as an aquatic organism.
Mini comparison table (for revision)
| Feature | Terrestrial organism | Aquatic organism |
|---|---|---|
| Source of oxygen | Oxygen from air/atmosphere | [1][5][7][9][3]Dissolved oxygen in water | [5][7][3]
| Oxygen availability | High (about 21% in air) | [7][1]Low (much less than 1% in water) | [1][5][7]
| Breathing rate | Usually slower, sufficient oxygen even with normal breathing | [9][5][7]Often faster, to compensate for low dissolved oxygen | [3][5][7]
| Main advantage | Easier and more efficient uptake of oxygen for respiration | [5][7][9][1][3]No such advantage; must work harder to get enough oxygen | [7][3][5]
How to phrase it in an exam (2–3 lines)
Terrestrial organisms obtain oxygen directly from the air, which contains a much higher concentration of oxygen than water. Therefore, they can get sufficient oxygen for respiration more easily and do not need to breathe as rapidly as aquatic organisms, which rely on limited dissolved oxygen in water.
TL;DR:
Air has far more oxygen than water, so land organisms get oxygen more easily
and efficiently, while aquatic organisms must work harder and breathe faster
to obtain enough oxygen for respiration.
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