8-1 Why Some Multicellular Organisms Need A Transport System (Cambridge AS & A Level Biology, 9700)

Summary

This chapter introduces the transport system in mammals, emphasizing the necessity for such a system in multicellular organisms. It compares unicellular organisms, which can easily receive oxygen through diffusion, to multicellular organisms, where cells deep within struggle to get oxygen due to distance. To address this, mammals evolved a transport system consisting of blood, blood vessels, and the heart, which work together to efficiently deliver oxygen and nutrients to cells, minimizing diffusion distance and enhancing survival. The lesson outlines the key components and importance of this system for maintaining cellular health in complex organisms.

Takeaways

• 🦠 Transport systems in mammals are distinct from those in fish and insects.
• ❓ A key question is: What is a transport system and why is it necessary?
• 🧫 Unicellular organisms, made of one cell, can easily receive oxygen through diffusion.
• 🧬 Multicellular organisms, composed of many cells, have cells deep within that can't easily receive oxygen.
• 🏃‍♂️ The main function of the transport system is to minimize the distance for diffusion, allowing oxygen and nutrients to reach cells efficiently.
• 🩸 The transport system evolved to include cavitations filled with liquid to facilitate the distribution of oxygen and other nutrients.
• 💧 This liquid, or medium, is blood, which is transported through blood vessels to reach all cells in the body.
• ❤️ The heart acts as a pump, moving blood through the vessels to ensure constant circulation.
• 🚛 The transport system consists of three main components: blood, blood vessels, and the heart.
• 🌟 Without a transport system, cells in multicellular organisms would struggle to get necessary substances and remove waste, highlighting its critical role in survival.

Q & A

What is the main topic discussed in Chapter 8 of the lesson?

The main topic discussed is the transport system in mammals, focusing on the need for and components of the transport system.

Why is the transport system in mammals important?

The transport system is important because it helps transport essential substances, like oxygen, to cells in multicellular organisms, minimizing the distance for diffusion and ensuring that all cells receive nutrients and oxygen.

What is the difference between unicellular and multicellular organisms regarding oxygen diffusion?

In unicellular organisms, oxygen can easily diffuse directly into the cell. In multicellular organisms, especially cells located deep within, oxygen has difficulty reaching them due to the greater distance, necessitating a transport system.

What problem arises in multicellular organisms that unicellular organisms do not face?

In multicellular organisms, the problem is that cells located far from the surface cannot easily receive oxygen or nutrients due to the long diffusion distance, unlike unicellular organisms where diffusion occurs easily across a single cell.

How does the transport system solve the problem of diffusion in multicellular organisms?

The transport system solves this problem by using a liquid medium (blood) to transport substances like oxygen through blood vessels, driven by a pump (the heart), reducing the diffusion distance to cells.

What are the three main components of the transport system in mammals?

The three main components are blood (the medium for transporting substances), blood vessels (which contain the blood), and the heart (which acts as the pump to move the blood).

Why is it important to have blood vessels in the transport system?

Blood vessels are important because they contain the blood, preventing it from leaking out and ensuring that it is directed to the cells that need oxygen and nutrients.

How does the heart contribute to the transport system?

The heart acts as a pump, continuously pushing the blood through the blood vessels, ensuring that oxygen and other nutrients are transported efficiently to all cells.

What happens to cells in multicellular organisms if they don’t receive oxygen due to the lack of a transport system?

If cells in multicellular organisms do not receive oxygen because of the lack of a transport system, they will die due to oxygen deprivation.

How does the transport system help minimize diffusion distances in multicellular organisms?

The transport system minimizes diffusion distances by transporting oxygen and other substances through blood, reducing the distance between the source of the substance and the cells that need it.