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Questions and Answers
Why can't diffusion alone adequately transport substances in larger organisms?
What is the primary reason multicellular organisms require a specialized transport system?
What characterizes a mass transport system in vertebrates?
Which type of circulation involves blood traveling through the heart twice during one complete circuit of the body?
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What aspect of multicellular organisms reduces the efficiency of diffusion?
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What is the effect of increasing the size of an organism on the surface area to volume ratio?
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What is a key feature of a mass transport system?
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Which of the following best describes an open circulatory system?
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What characterizes single circulation systems in organisms like fish?
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Why do birds and mammals require more oxygen compared to fish?
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What is a limitation of diffusion in large organisms?
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What is a primary function of circulatory systems in all vertebrates?
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What is the main advantage of a closed circulatory system over an open circulatory system?
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Study Notes
Transport of substances
- Organisms need to get substances into and out of their cells for survival
- Diffusion is one way; movement of molecules down a concentration gradient (high to low concentration)
- Diffusion is sufficient for unicellular organisms
- Surface area to volume ratio (sa:vol) is important for diffusion; a large sa:vol allows substances to move quickly
- In large organisms, the sa:vol decreases, making diffusion alone insufficient.
- Multicellular organisms need specialised transport systems like lungs and a circulatory system
Mass Transport Systems
- Structures in some animals (and all vertebrates) that carry substances around the body
- Overcomes the limits of diffusion
- Still relies on diffusion locally
Features of Mass Transport Systems
- Exchange surfaces for picking up and releasing substances
- A system of vessels to carry substances
- Mechanisms to ensure substances move in the right direction
- Mechanisms to ensure substances move fast enough
- A suitable transport medium (e.g., blood)
- Ability to adapt the rate of transport as needed
Types of Circulatory Systems
- Open circulatory system: Blood flows freely in large open spaces (e.g., insects)
- Closed circulatory system: Blood contained within vessels, allowing for higher pressure and directed flow (e.g., mammals)
Single vs. Double Circulation
- Single circulation: Blood travels through the heart once per cycle (e.g., fish)
- Double circulation: Blood passes through the heart twice per cycle (e.g., mammals)
- Single circulation leads to lower pressure and slower blood flow in the body
- Mammals and birds need a higher oxygen supply than fish, leading to the evolution of double circulation for faster and more efficient transport of oxygenated blood.
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Description
Explore the mechanisms of substance transport in organisms through this quiz. Learn how diffusion operates differently in unicellular and multicellular organisms, and discover the specialized systems required for efficient transport in larger bodies. This quiz covers the concepts of surface area to volume ratio, mass transport systems, and their features.
