B6 - Organisms exchange substances with their environment Flashcards
(12 cards)
Describe and explain how fish maintain a flow of water over their gills.
- Mouth open/ opercular valve shuts
- Floor of mouth lowered
- Water enters due to decreased pressure/ increased volume
- Mouth closes/ opercular valve opens
- Floor raised results in increased pressure/ decreased volume
- High/ increased pressure force pushes water over the gills
Describe and explain how the structure of the mammalian breathing system enables sufficient uptake of oxygen in the blood.
- Alveoli provide large surface area
- Walls of alveoli are thin to provide short diffusion pathway
3.Wall of capillary are thin and close to alveoli so provides a short diffusion pathway - Walls of capillaries and alveoli have flattened cells
- Cell membrane permeable to gases
- Many blood capillaries provide a large surface area
- Intercostal muscles ventilate lungs, maintaining diffusion/ concentration gradient
- Cartilage rings keep airways open
Describe how the structure of the insect gas exchange system: (explain your answers)
- provides cells with sufficient oxygen
- limits water loss
- Spiracles, trachea and tracheoles
- Spiracles allow diffusion (of oxygen) OR diffusion through trachea/tracheoles
- Tracheoles are highly branched so large surface area (for exchange of gases)
- Tracheal walls are thin so provides a short diffusion pathways OR tracheoles are close to cells so short diffusion distance
- Tracheal walls are permeable to oxygen
- Cuticle are impermeable so reduce water loss
- Spiracles close to prevent water loss
- Hairs around spiracles reduce water loss
Describe how humans breathe in and out.
Breathing in:
1. Diaphragm muscles contract6 and diaphragm flattens
2. External intercostal muscles contract and ribcage pulled up/out
3. Causing volume increase and pressure decrease in thoracic cavity (to below atmospheric pressure)
Breathing out:
4. Diaphragm muscles relax and diaphragm moves up/out
5. External intercostal muscles relax and ribcage moves down/in OR internal intercostal muscles contract so ribcage moves down/in
6. Causing volume to decrease and pressure increases in thoracic cavity (to above atmospheric pressure)
Describe and explain how the lungs are adapted to allow rapid exchange of oxygen between air in the alveoli and blood in the capillaries around them.
- Many alveoli/ folded alveoli walls provide a large surface area
- many capillaries provide a large surface area
(3. So diffusion is fast) - Alveoli or capillary wall/ epithelium/ lining are thin so diffusion distances pathway is short between alveoli and blood.
- Flattened squamous epithelium
- creates short diffusion pathways
(7. So fast diffusion rate) - ventilation/ circulation
- maintains a diffusion/ concentration gradient
(10. So fast diffusion)
Describe the gross structure of the human gas exchange system and how we breathe in and out.
- Named structures - trachea, bronchi, bronchioles, alveoli
- Above structures labelled in correct positions in diagram
Breathing in:
3. Diaphragm contracts and external intercostal muscles contract (ribs move up/out)
4. Causing volume increase and pressure decrease in thoracic cavity (to below atmospheric pressure)
Breathing out:
5. Diaphragm relaxes and internal intercostal muscles contract (ribs move down/ in)
6. Causing volume decrease and pressure increase in thoracic activity (to above atmospheric pressure, causing air to move out of the lungs)
Describe the processes involved in the absorption and transport of digested lipid molecules from the ileum into lymph vessels.
- Micelles contain bile salts and fatty acids/ monoglycerides
- Makes fatty acids soluble in water Or maintains a higher concentration of fatty acids in cell lining of the ileum
- Fatty acids/ monoglycerides absorbed by diffusion
- Triglycerides are formed in cells
- Vesicles move to cell membrane (via exocytosis)
The epithelial cells that line the small intestine are adapted for the absorption of glucose. Explain how.
- Microvilli provide a large increased surface area
- Many mitochondria produce ATP/ release energy (for active transport)
- Carrier proteins for active transport
- Channel/ carrier proteins for facilitated diffusion
- Co-transport of sodium ions and glucose through sodium/glucose carrier proteins
- Membrane-bound enzymes digest disaccharides to produce glucose
Describe the process involved in the absorption of the product of starch digestion.
- Glucose moves into epithelial cell with sodium
- Via sodium/glucose carrier protein
- Sodium is removed by active transport/ Na+-K+ pump
- Into the blood
- maintaining low concentration gradient of sodium in epithelial cell
- Glucose moves 9into blood
- By facilitated diffusion
Describe the role the enzyme of the digestive system in the complete breakdown of starch
- Amylase enzyme added to starch
- Converts starch into maltose
- Maltase enzyme added to maltase
- Maltose is converted into glucose
- Hydrolysis
- Glycosidic bonds
Describe how proteins are digested in the human gut.
- Hydrolysis of peptide bonds
- Endopeptidases break polypeptides into smaller chains
- Exopeptidases remove terminal amino acids
- Dipeptidases hydrolyses/ break down dipeptides into single amino acids
Glucose is absorbed from the lumen of the small intestine into epithelial cells. explain how the transport of sodium ions is involved in the absorption of glucose by epithelial cells.
- Na+ ions leave the epithelial cell and enter blood
- Transported out by active transport/ sodium-potassium pump/ via carrier protein using ATP
- So Na+ concentration in epithelial cell is lower than in the lumen of the gut
- Na+ ions enter by facilitated diffusion
- glucose is absorbed with sodium ions against their concentration gradient/ diffusion gradient/ glucose is absorbed down an electrochemical gradient
