Question 1

What is the significance of exchange surfaces in biological systems?

Accepted Answer

Exchange surfaces are crucial in biological systems as they facilitate the transfer of materials such as gases, nutrients, and waste products between an organism and its environment. In the Edexcel A Levels Biology B curriculum, understanding the characteristics of effective exchange surfaces, such as large surface area, thin barriers, and a concentration gradient, is essential for comprehending how organisms maintain homeostasis and efficient metabolic processes.

Question 2

How do the structures of alveoli in the lungs optimize gas exchange?

Accepted Answer

Alveoli are tiny air sacs in the lungs that provide a large surface area for gas exchange. Their thin walls, composed of a single layer of epithelial cells, minimize the diffusion distance for oxygen and carbon dioxide. Additionally, the rich capillary network surrounding each alveolus ensures a constant blood supply, maintaining a steep concentration gradient essential for efficient gas exchange. This topic is a key component of the Exchange and Transport section in the Edexcel A Levels Biology B syllabus.

Question 3

Why is the transport system in plants different from that in animals?

Accepted Answer

Plants and animals have evolved different transport systems due to their distinct lifestyles and metabolic needs. In plants, the transport system consists of xylem and phloem, which move water, minerals, and nutrients. In contrast, animals have a circulatory system with a heart and blood vessels to transport oxygen, nutrients, and waste products. The Edexcel A Levels Biology B curriculum explores these differences, emphasizing how each system is adapted to meet the organism's specific requirements.

Question 4

What role does the circulatory system play in the transport of substances in animals?

Accepted Answer

The circulatory system in animals is responsible for transporting oxygen, nutrients, hormones, and waste products throughout the body. It consists of the heart, blood, and a network of blood vessels. The heart pumps blood, ensuring that oxygen and nutrients reach cells while waste products are carried away for excretion. This system's efficiency is vital for maintaining homeostasis, a concept explored in the Exchange and Transport section of the Edexcel A Levels Biology B curriculum.

Question 5

How do fish gills facilitate efficient gas exchange in aquatic environments?

Accepted Answer

Fish gills are specialized organs that allow efficient gas exchange in water. They have a large surface area due to numerous filaments and lamellae, which are thin and richly supplied with blood vessels. The counter-current exchange mechanism in gills maximizes oxygen uptake and carbon dioxide removal by maintaining a gradient where water and blood flow in opposite directions. This adaptation is crucial for survival in aquatic environments and is studied under the Exchange and Transport topic in the Edexcel A Levels Biology B syllabus.

Exchange and transport

Quiz

Frequently Asked Questions