Unit 3: Organisms exchange substances in their environment Flashcards
(56 cards)
Insects- Describe Abdominal Pumping (3)
1) Abdominal pumping in tubes linked to CO2 release
2) Pumping raises pressure in body
3) CO2 pushed out of body/ CO2moves down pressure gradient
Insects- Explain 3 ways in which an insects tracheal system is adapted for efficient gas exchange (5)
1) Tracheoles- thin wall- short diffusion pathway
2) Tracheoles- Highly branched- Large SA, short diffusion pathway
3) Fluid- Moves out during exercise increasing SA
4) Treacheae- Provides tubes full of air- fast diffusion
5) Body- moved by muscles to move air- maintains concentration gradient for oxygen
Lungs- Describe the gross structure of the human gas exchange system
Trachea, Bronchii, Bronchioles, Alveoli
Lungs- Describe and explain one feature of the alveolar epithelium that makes the epithelium wall adapted as a surface for gas exchange (6)
1) Flattened cells/ single layer of cells
2) Reduces diffusion pathway
3) Permeable
4) Allows diffusion of O2/CO2
5) Moist
6) Increase rate of diffusion
Lungs- Describe and explain inhaling (3)
1) Diaphragm contracts and flattens and external intercostal muscles contract, and ribcage moves up and out
2) This causes the thoracic cavity volume to increase and the pressure decrease
3) Air moves in down the pressure gradient
Lungs- Explain how one feature of an alveolus allows efficient gas exchange to occur (2)
1) Alveolar epithelium is one cell thick
2) This creates a short diffusion pathway
Describe the counter-current mechanism in fish? (3)
1) Water and blood flow in opposite directions
2) Blood always passing water with higher oxygen concentration
3) Diffusion/concentration gradient maintained along lamella/fillament/across the whole gill (equilibrium never reached)
Lungs-Describe the pathway taken by an oxygen molecule from an alveolus to the blood (2)
1) Across alveolar epithelium
2) to endothelium of capillary
Insects- Describe and explain how structure of insect gas exchange system:
Limits water loss (2)
1) Chitin in tracheae impermeable so reduce water loss
2) Spiracles close preventing water loss
Lungs- Describe how we breathe in and out (6)
In: 1) Diaphragm contracts and flattens, external intercostals muscles contract and the ribcage moves up and out
2) Causing thoracic cavity volume increase and pressure decrease
3) Air Moves in down a pressure gradient
Out: 4.) Diaphragm relaxes and internal intercostal muscles to contract and the ribs move down and in
5.) Causing thoracic cavity volume to decrease and pressure increase
6.) Causing the air to be forced out
Describe Fish Gill Anatomy
- Fish gills are stacks of gill filaments
- Each filament is covered with gill lamellae at right angles
Insects- Describe and explain how structure of insect gas exchange system:
Provides cells with sufficient oxygen (5)
1.) Spiracles -> Tracheae -> Tracheoles
2.) Open spiracles allow diffusion of oxygen
3) Tracheoles, highly branched so large SA
4) Tracheoles have thin walls so short diffusion pathway
5.) Tracheal walls are permeable to oxygen
Fish- Explain two ways in which the structure of fish gills is adapted for efficient gas exchange? (2)
1) Many Lamellae/ filaments so large SA
2) Thin surface so short diffusion pathway
Digestion- Proteins (4)
1.) Hydrolysis of peptide bonds
2) Endopeptidases break polypeptides into smaller peptide chains
3) Exopeptidases remove terminal amino acids
4.) Dipeptidases hydrolyse dipeptides into amino acids
Digestion- Compare endopeptidases and exopeptidase (3)
1) Endopeptidases hydrolyse internal peptide bonds
2) Exopeptidases remove terminal amino acids
3) More ends/increase SA from exopeptidase
Digestion- Describe the action of membrane-bound dipeptidases and explain their importance (2)
1) Hydrolyse peptide bonds to release amino acids
2) Amino Acids can cross cell membrane by facilitated diffusion
Digestion- Describe the complete digestion of starch by a mammal (5)
1) Hydrolysis
2) Of glycosidic bonds
3) Starch to maltose by amylase
4) Maltose to glucose by maltase
5) Maltase is membrane-bound
Digestion- Function of bile salts and micelles (3)
1) Bile salts emulsify lipids forming droplets which increase SA for lipase
2) So faster hydrolysis of triglycerides
3) Micelles carry fatty acids and glycerol to membrane to epithelial cell
Digestions- Describe lipid digestion (3)
1) Lipase hydrolyses triglycerides
2) Breaking ester bonds
3) Forming monoglycerides and fatty acids
Digestion- Explain the advantages of emulsification and micelle formation (3)
1) Droplets increase surface area for lipase
2) So faster hydrolysis
3) Micelles carry away fatty acids and glycerol to membrane of epithelial cell
Absorption- Describe and explain two features you would expect to find in a cell specialised for absorption (4)
1) Folded microvilli so large surface area
2) Large number of carrier proteins so faster rate of absorption/active transport
3) Large number of mitochondria so make more ATP by respiration
4) Membrane-bound digestive enzymes so maintains concentration gradient
Absorption- Describe the processes involved In absorption and transport of digested lipid molecules from the ileum into lymph vessels (5)
1) Micelles contain bile salts and fatty acids
2) Makes fatty acids more soluble in water and bring fatty acids to cell membrane of epithelial cell
3) Fatty acids absorbed by simple diffusion
4) Triglycerides reformed by SER and Golgi produces chylomicrons
5) Vesicles move to cell membrane and chylomicrons exported by exocytosis
Absorption- Describe roles of micelles in absorption of fats into cells lining the ileum (5)
1) Micelles include fatty acids and bile salts
2) Makes fatty acids more soluble in water
3) Carry fatty acids to lining of the ileum
4) Maintain higher concentration of fatty acids to lining of ileum
5) Fatty acids absorbed by diffusion
Absorption- How is the Golgi apparatus involved in absorption (3)
1) Modifies triglycerides
2) Combines triglycerides with proteins
3) Package for exocytosis
