EXCHANGE SURFACES Test Exam Questions And Answers Verified 100% Correct

EXCHANGE SURFACES Test Exam Questions And Answers Verified 100% Correct What is at the end of the tracheoles in insects? - ANSWER tracheal fluid oxygen diffuses faster in air than it does in water so tracheal fluid is a barrier to oxygen diffusion when insect is active more SA of muscle is exposed so more O2 can diffuse structure of gills - ANSWER gills composed of thousands of filaments. each filament is covered in lamallae lamallae are thin so diffusion pathway of O2 from water into blood is short and they increase SA large SA, good blood supply operculum (bony flap) protects gills What do fish need to maintain for efficient gas exchange? - ANSWER Continuous flow of water over the gills explain process of ventilation in fish - ANSWER water is constantly pushed over gill filaments for constant supply of O2: - fish mouth opens, buccal cavity lowered, increases volume of buccal cavity - pressure now lower in buccal cavity than outside pressure so water flows in - fish mouth closes, buccal cavity raised, increased pressure pushes water into gill cavity (has lower pressure) - pressure builds up in gill cavity which forces open the operculum and water is pushed out *when buccal cavity is lowered has effect of forcing operculum shut What is counter current flow in fish - ANSWER - water flowing over gills and blood in gill filaments flow in different directions - it ensures that all the way across the gill filament, blood constantly meets water with higher O2 conc than it has, maintains diffusion gradient How do fish slow the movement of water to allow more time for gas exchange? - ANSWER Tips of adjacent gill filaments overlap How does a countercurrent exchange system help fish with gas exchange? - ANSWER Maintains steep concentration gradient 3.1.1 EXCHANGE SURFACES - ANSWER 3.1.1 EXCHANGE SURFACES 3.1.2 TRANSPORT IN ANIMALS - ANSWER 3.1.2 TRANSPORT IN ANIMALS purpose of transport systems - ANSWER - supply nutrients + oxygen - remove waste products - hormone circulation - temp maintenance - immune responses Why do multi-cellular animals need transport systems? - ANSWER - metabolic demands high → greater demand for oxygen + waste removal - SA:V ratio smaller as animals get bigger so diffusion distances bigger - diffusion pathway increases as size of animal increases → need short diff. pathway to supply cells efficiently if relied on diffusion would be too slow Which circulatory system is found in insects? - ANSWER Open - pumped straight from heart into body cavity How it works: - open body cavity = haemocoel - insect blood = haemolymph → transports waste + food - haemocoel = low pressure - haemocoel has direct contact with tissues + cells → where exchange take place between haemolymph + cells - haemolymph then returns to the heart - don't rely on circulatory system to transport O2/CO2 what is a closed circulatory system? - ANSWER blood confined to blood vessels and has no direct contact with cells distribution of blood to diff tissues can be adjusted Which circulatory system is found in fish? - ANSWER single closed how it works: - blood travels only once through the heart for each complete circulation of the body - O2 poor blood pumped from atrium to ventricle - O2 poor transported to gill capillaries to get oxidised - O2 rich blood transported to body capillaries and O2 gets used up - back to heart (2 chambers) How can fish so active with an inefficient single closed system? - ANSWER usually blood returns to heart slowly which limits exchange process → less active but fish have have countercurrent gaseous system that means they can take up lots of O2 also don't maintain body temp reduces metabolic demand Which circulatory system is found in mammals? - ANSWER double closed how it works: - blood is pumped from the right side of heart to the lungs to pick up O2 + unload CO2 - blood flows back through left side of the heart and pumped out to be transported to body tissues - returns to heart extra: - blood travels x2 - 4 chambered heart