3 Exam Questions Flashcards
(43 cards)
Explain the advantage for larger animals of having a specialised system that facilitates oxygen uptake. [2]
Larger animals have smaller surface area to volume ratio
Takes longer for oxygen to diffuse due to longer diffusion pathway
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. [3]
Mouse is smaller so larger surface area to volume ratio
More heat loss
Faster rate of respiration to release heat
Describe the relationship between size and surface area to volume ratio of organisms. [1]
As size increases, ratio decreases
Explain why oxygen uptake is a measure of metabolic rate in organisms. [1]
Oxygen is used in respiration which is a metabolic process
Suggest and explain how a reduced tidal volume affects the exchange of carbon dioxide between the blood and the alveoli. [3]
Less carbon dioxide exhaled
Reduced concentration gradient between blood and alveoli
Less movement of carbon dioxide out of blood
Explain how the counter-current principle allows efficient oxygen uptake in the fish gas exchange system. [3]
Blood and water flow in opposite directions
Maintains concentration gradient of oxygen
Diffusion along length of lamellae
Describe and explain the mechanism that causes lungs to fill with air. [3]
Diaphragm and external intercostal muscles contract
Causes volume increase and pressure decrease
Air moves down pressure gradient from higher atmospheric pressure into lungs
Explain why death of alveolar epithelium cells reduces gas exchange in human lungs. [3]
Reduced surface area
Increased distance for diffusion
Reduced rate of gas exchange
Suggest and explain one way the leaf growth of xerophytic plants would be different from others. [2]
Slower growth
Due to smaller number of stomata for gas exchange
Use your knowledge of gas exchange in leaves to explain why plants grown in soil with very little water grow only slowly. [2]
Stomata close
Less carbon dioxide uptake so less photosynthesis and less glucose produced
Describe the pathway taken by an oxygen molecule from an alveolus to the blood. [2]
Across alveolar epithelium
Epithelium of capillary
Explain how one feature of an alveolus allows for efficient gas exchange to occur. [2]
The alveolar epithelium is one cell thick
Creating a short diffusion pathway
Describe the gross structure of the human gas exchange system and how we breathe in and out. [6]
Trachea, bronchi, bronchioles, alveoli
Breathing in - diaphragm and external intercostal muscles contract
Causes volume increase and pressure decrease in thoracic cavity to below atmospheric pressure so air moves in
Breathing out - diaphragm relaxes and internal intercostal muscles contract
Causes volume decrease and pressure increase in thoracic cavity to above atmospheric pressure so air moves out
Explain three ways in which an insects tracheal system is adapted for efficient gas exchange. [3]
Tracheoles have thin walls so short diffusion distance to cells
Large number of highly branched tracheoles so large surface area for gas exchange
Large number of highly branched tracheoles so short diffusion distance to cells
Explain three ways in which an insects tracheal system is adapted for efficient gas exchange. [3]
Tracheoles have thin walls so short diffusion distance to cells
Large number of highly branched tracheoles so large surface area for gas exchange
Large number of highly branched tracheoles so short diffusion distance to cells
Explain two ways in which the structure of fish gills is adapted for efficient gas exchange. [2]
Many lamellae 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. [3]
Water and blood flow in opposite directions
Blood always passing water that has higher oxygen concentration
Concentration gradient maintained though length of gill for diffusionc
Describe the processes involved in the absorption and transport of digested lipid molecules from the ileum into lymph vessels. [5]
Micelles contain bile salts and fatty acids
Maintain higher concentration of fatty acids in lining of ileum
Fatty acids absorbed by diffusion
Triglycerides 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.
Explain how. [2]
Maintains a concentration gradient for Na+ between ileum and cell
Na+ moves in by cotransport/facilitated diffusion bringing glucose with it
Describe the role of micelles in the absorption of fats into the cells lining the ileum. [3]
Micelles include bile salts and fatty acids
Release fatty acids into lining of the ileum
Maintain higher concentration gradient for diffusion
Describe the role of enzymes in the digestion of proteins in a mammal. [4]
Hydrolysis of peptide bonds
Endopeptidase acts in middle of protein to produce shorter polypeptide
Exopeptidase acts at end of protein to produce dipeptides
Dipeptidase acts on dipeptides to produce amino acids
Explain the advantages of lipid droplet and micelle formation. [3]
Droplets increase surface area for lipase action
So faster hydrolysis of lipids into fatty acids and glycerol
Micelles carry fatty acids and glycerol through membrane to epithelial cell
Suggest how the golgi is involved in the absorption of lipids. [3]
Modifies/processes triglycerides
Combines triglycerides with proteins
Packaged into vesicles for exocytosis
Cells lining the ileum of mammals absorb the monosaccharide glucose by co-transport with sodium ions.
Explain how. [3]
Sodium ions actively transported from ileum cell to blood
Maintains diffusion gradient for sodium to enter cells from gut
Glucose enters by facilitated diffusion with sodium ions;
