SA & Exchange Flashcards
(16 cards)
explain 2 ways in which the structure of fish gills is adapted for efficient gas exchange. (2)
- many filaments and lamellae so large SA
- 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)
- blood and water flow in opposite directions
- blood is always passing water with a higher oxygen conc
- conc gradient maintained along whole length of gill
Tubifex worm are small, tin animals that live in water. They have no specialised gas exchange or circulatory system.
Name the process by which oxygen reaches the cells inside the body of a tubifex worm. (1)
diffusion
Tubifex worm are small, thin animals that live in water. They have no specialised gas exchange or circulatory system.
Using the information provided, explain how two features of the body of the tubifex worm allow efficient gas exchange. (2)
- thin so short diffusion pathway
- small and long so large SA:vol ratio
Tubifex worm are small, tin animals that live in water. They have no specialised gas exchange or circulatory system.
Most species of tubifex worms live at the bottom of ponds, lakes and rivers where the partial pressure of oxygen is low . Pollution of water by sewage can cause the p.p of oxygen to fall below 0.2kPa.
The graph shows the oxyhaemoglobin dissociation curve for a species of tubifex worm found in river polluted with sewage. the graph shows p.p of oxygen against % saturation of haemoglobin with oxygen, and the curve is very steep and right over the the left.
The species of tubifex worm in the graph has 50% saturation at 0.08kPa.
Explain how this enables the species to survive in water polluted with sewage. (2)
- 50% saturation at 0.08kPa which is lower than 0.2kPa
- oxygen is used for respiration
Tubifex worm are small, tin animals that live in water. They have no specialised gas exchange or circulatory system.
Most species of tubifex worms live at the bottom of ponds, lakes and rivers where the partial pressure of oxygen is low . Pollution of water by sewage can cause the p.p of oxygen to fall below 0.2kPa.
The graph shows the oxyhaemoglobin dissociation curve for a species of tubifex worm found in river polluted with sewage. the graph shows p.p of oxygen against % saturation of haemoglobin with oxygen, and the curve is very steep and right over the the left.
Species of tubifex worm that lives in ponds, lakes and rivers cannot survive seawater.
Use your knowledge of w.p to explain why they cannot survive in seawater. (2)
- worms w.p will be higher than the seawater
- water will move out of the worm by osmosis
describe the relationship between size and SA:VOL ratio of organisms. (1)
as size increases SA:VOL ratio decreases
the scientist used units of micrometer mole for the rate of oxygen uptake.
suggest why he used this unit. (1)
measures small uptake
the scientist decided to use SA:MASS, rather than ratio of SA:VOL. he made this decision for practical reasons.
Suggest one practical advantage of measuring the masses of frog eggs, tadpoles and adults compared with measuring their volumes. (1)
easier because irregular shape/ less distress/ quicker
Explain why oxygen uptake is a measure of metabolic rate in organisms. (1)
oxygen is used in respiration which provides ATP
describe and explain the advantage of the counter-current principle in gas exchange across a fish gill. (3)
- maintains conc gradient of oxygen
- blood and water flow in opposite directions
- diffusion along whole length of lamellae
Uronema marinum is a single-celled eukaryotic organism. Figure 3 is a photograph of the organism through an optical microscope.
Explain why it is not possible to determine the identity of the structures labelled X using an optical microscope. (1)
the resolution is too low because the wavelength of light is too long
U.marinum cells injest becateria and digest them in the cytoplasm.
Describe the role of one named organelle in digesting these bacteria. (3)
- lysosomes
- fuse with vesicle
- releases hydrolytic enzymes
In large cells of U.marinum, most mitochondria are found close to the cell-surface membrane. In smaller cells, the mitochondria are distributed evenly throughout the cytoplasm. Mitochondria use oxygen during aerobic respiration.
Use this information and you knowledge of the SA:VOL ratio to suggest an explanation for the position of mitochondria in large U.marinum cells. (2)
-large cells have smaller SA:VOL ratio
- takes longer for oxygen to diffuse to mitochondria
Describe how the structure of the insect gas exchange system:
- provides cells with sufficient oxygen
-limits water loss
Explain your answers. (5)
- spiracles allow diffusion of oxygen
- oxygen diffuses from air through spiracles, along trachea and traqueoles to cells
-spiracles have valves so that they can close to reduce water loss Explain - traqueoles walls are thin providing short diffusion distance
- traqueoles are highly beached so large SA for exchange
- hairs around spiracles reduce water loss
- cuticle impermeable so reduce water loss
Describe how gas exchange occurs in singles-celled organisms and explain why this method cannot be used by large, multicellular organisms. (3)
- diffusion across cell surface membrane
- large organisms have a smaller SA:VOL ratio
- diffusion pathway would be too long
