Exchange Exam Qs Flashcards
Why might mitochondria be found close to the cell surface membrane in larger cells?
Larger cells have a smaller surface area to volume ratio
So it takes longer for oxygen to diffuse to mitochondria as diffusion pathway longer
What is the advantage of larger animals having a specialised system to facilitate oxygen uptake
Larger organisms have smaller surface area: volume ratio
So specialised system overcomes long diffusion pathway
Describe how environmental conditions result in gills (system on outside of body)
Water has lower oxygen partial pressure/ concentration
So outside system gives large surface area in contact with water
Water is denser than air, so water supports the systems/ gill
Why does a mouse have higher metabolic rate than a horse
Mouse smaller so has larger surface area to volume ratio
Mouse has faster heat loss than horse in relation to body size
So faster rate of respiration releases heat
Describe the relationship between size and surface area to volume ratio of organisms
As size increases, surface area to volume ratio decreases
Explain why oxygen uptake is a measure of metabolic rate in organisms
Oxygen is used in respiration WHICH is a metabolic process/ chemical reaction
Tubifex worm have no specialised gas exchange or circulatory system.
Name the process by which oxygen reaches the cells inside the body of a tubifex worm
Simple diffusion
Describe and explain one feature of reg alveolar epithelium well adapted as a surface for gas exchange
(Don’t refer to surface area or gas exchange)
Single layer of flattened cells
Reduces diffusion pathway
Permeable
So allows diffusion of oxygen/ carbon dioxide
Tidal volume = volume of air inhaled and exhaled
How would reduced tidal volume affect the exchange of co2 between blood and alveoli
Less co2 exhaled out of lung
So reduced concentration gradient between blood and alveoli
So less movement of co2 out of blood/ more stays in 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 maintained along the lamella
Describe and explain the mechanism that causes the lungs to fill up with air
Diaphragm muscle contracts and external intercostal muscles contact
Causes volume increase and pressure decreases
Air moves down a pressure gradient, enters from higher atmospheric pressure
Why does a scientist stain lungs with haematoxylin solution (stains DNA blue) rather than iodine (stains starch blue black)
Animal/ lung tissue does not contain starch
Haemotoxylin makes nucleus visible
Explain why death of alveolar epithelium cells reduces gas exchange in the 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
Maintains diffusion gradient of oxygen, oxygen conc always higher in water
So diffusion can occur along whole length of lamellae
Suggest and explain one way the leaf growth of xerophytic plants would be different from the leaf growth of sunflowers
Lower and slower growth due to smaller number of stomata for gas exchange
OR
Growth can continue at low water potentials due to adaptations involved in photosynthesis
Why do plants grown in soil with very little water grow slowly
Stomata close to retain water
Less carbon dioxide taken up
So less photosynthesis
So less glucose produced for growth
Describe the pathway taken by an oxygen molecule from an alveolus to the blood
Across alveolar epithelium
Of capillary
Explain how one feature of an alveolus allows efficient gas exchange to occur
Alveolar epithelium is one cell thick
So creates a short diffusion pathway
Describe the gross structure of the human gas exchange system and how we breathe in and out
- Name structures in correct order: trachea, bronchi, bronchioles, alveoli
- breathing in- diaphragm contracts and external intercostal muscles contract
causes volume to increase and pressure decrease in thoracic cavity
pressure decreases to below atmospheric pressure, resulting in air rushing in - breathing out- diaphragm relaxes and internal intercostal muscles relax and lung tissues elastic so recoils
causes volume decrease and pressure increase in thoracic cavity
to above atmospheric pressure so air rushes out
explain three ways which an insects tracheal system is developed for efficient gas exchange
- tracheoles have thin walls so short diffusion distance to cells
- highly branched/ large number of tracheoles so large surface area for gas exchange
- trachea provide tubes full of air so enable fast diffusion
- fluid in the end of tracheoles that moves out into tissues during exercise so faster diffusion through air to gas exchange surface
- body can be moved by muscles o move air so maintains diffusion
why might larvae who actively hunt prey have gills, and larvae who dont actively hunt not have gills?
hunting larvae have higher metabolic and respiratory rate
so uses/ needs more oxygen
explain two ways in which the structure of the gills is adapted for efficient gas exchange
- many lamellae/ filaments so larger surface area
- thin surface so short diffusion pathway
explain how the counter current mechanism in fish gills ensures the maximum amount of oxygen passes into the blood flowing through the gills
water and blood flow in opposite directions
blood always passing water with higher oxygen concentration
diffusion gradient maintained throughout length of the gill
if water and blood flowed same direction, equilibrium would be reached
scribe processes involved in absorption and transport of digested lipid molecules from the ileum into lymph vessels
micelles contain bile salts and fatty acids/ monoglycerides
bring fatty acids to lining of ileum, make them more soluble
fatty acids absorbed by diffusion
triglycerides reform in cells
vesicles move to cell membrane
explain function of ATP hydrolase at carrier protein facilitating Na+ and K+ pump
ATP=ADP+Pi releases energy
energy allows ions to be moved against a concentration gradient by active transport
explain how the movement of Na+ out of the cell allows absorption of glucose into the cell lining the ileum
maintains a concentration gradient for Na+ from ileum into cell
Na+ moving in by (facilitated diffusion OR co-transport), brings glucose with it
describe the role of micelles in the absorption of fats into the cells lining the ileum
- micelles include bile salts and fatty acids
- they make the fatty acids more soluble in water
- bring/ release fatty acids to the lining of the ileum
- maintain higher conc of fatty acids to the lining of the ileum
- fatty acids absorbed by diffusion
describe the role of enzymes in the digestion of proteins in a mammal
- hydrolysis of peptide bonds
- endopeptidases act in the middle of protein/ polypeptide, produces shorter polypeptides
- endopeptidases act at end of polypeptide, produce amino acids
- dipeptidase acts on dipeptide, between 2 amino acids, producing single amino acids
which process do fatty acids and glycerol enter the intestinal epithelial cell by
diffusion
advantage of lipid droplet and micelle formation
droplets increase surface area for lipase action
so faster hydrolysis of triglycerides
micelles carry fatty acids and glycerol through membrane to intestinal epithelial cell
how do cells lining the ileum of mammals absorb glucose by cotransport with sodium ions
sodium ions actively transported from ileum cell to blood
maintains/ forms diffusion gradient for sodium o enter cells from gut
glucose enters by facilitated diffusion with sodium ions
give the pathway a red blood cell takes when travelling from kidney to the lungs
do not include descriptions of pressure changes in the heart or role of valve
- renal vein
- vena cava to right atrium
- right ventricle to pulmonary artery
explain how water from tissue fluid is returned to the circulatory system
plasma proteins remain
creates water potential gradient
water moves to blood by osmosis
returns to blood by lymphatic system
