AQA A Level Biology Surface Area to Volume ratio Flashcards
What is the significance of the surface area to volume ratio (SA:V) in organisms?
It affects the rate of diffusion, heat loss, and exchange of materials with the environment.
Why do smaller organisms have a higher surface area to volume ratio?
They have a larger surface area relative to their volume, which allows for faster diffusion of substances.
How does surface area to volume ratio affect heat loss in organisms?
High SA:V ratio: Faster heat loss, common in smaller organisms. Low SA:V ratio: Slower heat loss, common in larger organisms.
Why do larger organisms require specialized exchange surfaces?
Their low SA:V ratio makes diffusion alone too slow to meet their metabolic needs.
How do organisms adapt to overcome limitations of a low surface area to volume ratio?
Developing specialized exchange surfaces (e.g., lungs, gills). Efficient transport systems (e.g., circulatory systems).
What are some adaptations in small organisms to reduce heat loss?
Small organisms often have a compact shape and high metabolic rate to maintain body temperature.
How does shape affect the surface area to volume ratio?
Compact shapes have a lower SA:V ratio, reducing heat loss. Elongated or thin shapes have a higher SA:V ratio, increasing diffusion efficiency.
Why do large animals often have lower metabolic rates relative to body mass?
To reduce heat loss, as they have a lower SA:V ratio and lose heat more slowly.
Why do small mammals need a higher metabolic rate than larger mammals?
To compensate for rapid heat loss due to their high SA:V ratio.
What adaptations do larger organisms have to increase their effective surface area?
Flattened shape to reduce diffusion distance. Development of specialized exchange surfaces such as alveoli or gills.
How does surface area to volume ratio impact gas exchange in single-celled organisms?
Their high SA:V ratio allows efficient diffusion of gases directly across their surface.
Why is diffusion alone insufficient for larger organisms?
Their low SA:V ratio means diffusion would be too slow to supply necessary substances to all cells.
