Exam Questions Flashcards
(25 cards)
Explain the advantage for larger animals of having a specialised system that facilitates oxygen uptake.
Larger organisms have a smaller surface area:volume ratio. So they can overcome long diffusion pathways.
Mammals such as a mouse and a horse are able to maintain a constant body temperature. Use your knowledge of surface area to volume ratio to explain the higher metabolic rate of a mouse compared to a horse.
Mouse are smaller so they have a larger surface area to volume ratio. Thus they have more heat loss. Therefore faster rate of metabolism releases heat.
Describe the relationship between size and surface area to volume ratio of organisms.
As size increases, ratio of surface area to volume decreases.
Explain why oxygen uptake is a measure of metabolic rate in organisms.
Oxygen used in respiration, which provides energy.
Describe and explain 2 features of the alveolar epithelium that makes the epithelium well adapted as a surface for gas exchange. Do not refer to surface area or moisture in your answer.
Single layer of cells so reduces diffusion pathway. Also, it is permeable so it allows for the diffusion of oxygen and carbon dioxide.
Suggest and explain how a reduced tidal volume affects the exchange of carbon dioxide between the blood and the alveoli.
Less carbon dioxide exhaled out of lungs so reduced concentration gradient and slower movement of carbon dioxide out of blood.
Explain how the counter-current principle allows efficient oxygen uptake in the fish gas exchange system.
Blood and water flow in opposite directions. Concentration gradient is maintained along the length of the lamella.
Describe and explain the mechanism that causes lungs to fill with air.
Diaphragm contracts and external intercostal muscles contract. This causes volume increase and pressure decrease. Air moves down a concentration gradient.
Explain why death of alveolar epithelium cells reduces gas exchange in
human lungs.
Reduced surface area. Increased distance for diffusion. Reduced rate of gas exchange.
Describe and explain the advantage of the counter-current principle in gas
exchange across a fish gill.
Water and blood flow in opposite directions. This maintains a concentration gradient of oxygen. Diffusion along length of lamellae.
Use your knowledge of gas exchange in leaves to explain why plants
grown in soil with very little water grow only slowly.
Stomata close so less carbon dioxide uptake for less photosynthesis.
Describe the pathway taken by an oxygen molecule from an alveolus to the
blood.
Across alveolar epithelium . Epithelium of capillary.
Explain how one feature of an alveolus allows efficient gas exchange to
occur.
Alveolar epithelium is one cell thick so it has a short diffusion distance.
Describe the gross structure of the human gas exchange system and how we breathe in and out.
There is the trachea, bronchi, bronchioles and alveoli. When we breathe in, diaphragm contract and EIM contract. This causes an increase in volume and decrease in pressure in the thoracic cavity. When we breathe out, diaphragm relaxes and IIM contract. This causes a decrease in volume and increase in pressure in the thoracic cavity.
Explain three ways in which an insect’s tracheal system is adapted for
efficient gas exchange.
Tracheoles have thin walls so short diffusion distance to cells.
There are a large number of tracheoles so there is a large surface area for gas exchange.
Tracheae provide tubes full of air so fast diffusion.
Explain two ways in which the structure of fish gills is adapted for efficient gas exchange.
Many lamellae and filaments so large surface area. Thin surface so short diffusion pathway.
Explain how the counter current mechanism in fish gills ensures the maximum amount of the oxygen passes into the blood flowing through the
gills
Water and blood flow in opposite directions. Blood always passes water with a higher oxygen concentration. Diffusion gradient is maintained throughout the length of the gill.
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.
Fatty acids are more soluble in water.
Fatty acids are absorbed by diffusion.
Triglycerides are reformed in cells.
Vesicles move to cell membrane.
The movement of Na+ out of the cell allows the absorption of glucose into
the cell lining the ileum
Maintains a conc gradient for Na+. Na+ moving in by co-transport brings glucose with it.
Explain the function of ATP hydrolase.
Releases energy and allows ions to be moved against a concentration gradient.
Describe the role of micelles in the absorption of fats into the cells lining
the ileum.
Micelles include bile salts and fatty acids. They bring fatty acids to the lining of the ileum. The fatty acids are absorbed by diffusion.
Describe the role of enzymes in the digestion of proteins in a mammal.
Peptide bonds are hydrolysed. Endopeptidases act in the middle of the protein. Exopeptidases act on the ends of the protein. Dipeptidases act between two amino acids.
Explain the advantages of lipid droplet and micelle formation.
Droplets increase surface area so faster hydrolysis of triglycerides. Micelles carry fatty acids and glycerol to intestinal epithelial cell.
How is the Golgi Apparatus involved in the absorption of lipids.
Modified triglycerides. Combines triglycerides with proteins. Forms vesicles.
