Excahnge Surfaces Flashcards
Do larger animals have a low or high surface area?
-smaller surface area
Explain how the size of an organism and its structure relate to its surface area to volume ratio.
As an organism grows larger, its volume increases more rapidly than its surface area because volume is proportional to the cube of the organismβs size, while surface area is proportional to the square of its size.
As a result, larger organisms have a smaller Sa:Vol compared to smaller organisms.
This affects various physiological processes such as gas exchange, nutrient absorption, and heat exchange, as organisms with a smaller surface area to volume ratio may struggle more with these processes.
Describe how larger organisms increase their surface area to volume ratio.
Larger organisms increase their surface area to volume ratio through various adaptations such as folding, branching, or specialized structures.
What are cell surrounded by?and function?
1-tissue fluid which maintains our internal environment.
2-Once substances are exchanged, they are distributed into the tissue fluid so all cells are supplied and can remove their waste products.
What gets exchanged?
Respiratory gases - oxygen, carbon dioxide
βNutrients - glucose, amino acids, fatty acids, etc
βExcretory products - urea, carbon dioxide, etc
β Heat
How do these exchanges happen?
- Passively - no metabolic energy is required - diffusion or osmosis
- Actively - using metabolic energy - active transport
Work out surface area and volume of a cube?
SA = 6s2
Vol = s3
What features have Organisms evolved to ensure efficient exchange can occur?
- Flattened shape
- Specialised exchange surfaces to increase SA:Vol ratio
- Mass transport system
What are the Features of specialised exchange systems?
- Large SA:Vol ratio
- Thin
- Selectively permeable
- Movement of environmental medium
- Transportsystem
These three organisms live in the same environment and have evolved in different ways. Using your knowledge on exchange with the environment and SA:Vol ratio, identify and explain which organism will struggle the most to maintain its warmth. (4 marks)
- Arctic Hare
- Larger ears
- Increases SA:Vol ratio
- More heat is lost
Polar Bear Arctic Fox
Work out the Sa and vol of s sphere?
SA = 4πr2
Vol=4/3πr3
Diffusion equation:
Diffusion is proportional to surface area * concentration gradient/thickness of membrane
Name 3 factors which affect the rate of diffusion.
Concentration gradient
Temperature
Sa
What are single celled organisms?
Single-celled organisms are small and therefore have a large SA:Vol ratio
Describe how single-celled organisms exchange gases
Oxygen can be absorbed by diffusion across their body surface and carbon dioxide can be released in the same way.
Example of single-celled organisms?and do they have a high or low metabolic rate?they have evolved to do what?
-Insects
-are very active organisms meaning they have a relatively high metabolic rate.
-They have evolved to reduce water loss whilst maintaining a highly adapted exchange system.
What gas system do insects use?
Tracheal system
How is the fish gas exchange system better than the humans?
In fish, blood leaving has more oxygen than water leaving
- (But) in humans, blood leaving has less oxygen than air leaving
Difference in oxygen (concentration) between artery and vein is greater in fish than in humans
(So) fish remove a greater proportion from the oxygen they take in
Describe and explain the advantages of the counter current principles in gas exchange across a fish gill
1.Water and blood flow in opposite directions
2. Maintains diffusion/concentration gradient of oxygen
Oxygen concentration always higher (in water)
Diffusion happens along length of lamellae/filament/gill/capillary
Describe the Path way taken by oxygen from alveolus to the blood
-Across the alveolar epithelium
-Endothelium / epithelium of capillary;
Explain 2 ways in which the structure of fish gills are adapted for effective gas exchange.
1-lamella increase the Sa:Vol ration
2-thin surface so short diffusion pathway
Describe the processes involved in the absorption and transport of digested lipid molecules from the ileum into lymph vessels
1.Micelles contain bile salts and fatty acids/monoglycerides
- Make fatty acids/monoglycerides (more) soluble (in water)
- Fatty acids/monoglycerides absorbed by diffusion
- Triglycerides (re)formed (in cells)
Or chylomicrons form - Vesicles move to cell membrane
