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Exchange and Transport (flipped for write mode)
Terms in this set (38)
-Oxygen used in respiration
-So oxygen concentration gradient established
-So oxygen diffuses in
Explain the movement of oxygen into the gas exchange system of an insect when it is at rest.
-trachea and bronchi and bronchioles
-down diffusion gradient-down pressure gradient
-across alveolar epithelium
Describe how oxygen in the air reaches capillaries surrounding alveoli in the lungs. Details of breathing are not required.
-hydrolysis of peptide bonds
-endopeptidases break polypeptides into smaller chains
-exopeptidases remove terminal amino acids
-dipeptidases break down dipeptides into amino acids
Describe how proteins are digested in the human gut.
-atrium has a higher pressure than the ventricle (due to filling) causing atrioventricular valves to open
-ventricle has a higher pressure than the atrium (due to filling / contraction) causing the atrioventricular valves to close
-ventricle has higher pressure than aorta causing semiluminar valves to open
-higher pressure in aorta than ventricle (as heart relaxes) causing semiluminar valve to close
-contraction causes increase in pressure
Explain how the heart muscle and the heart valves maintain a one-way flow of blood from the left atrium to the aorta.
-narrows size of lumen
An arteriole contains muscle fibres. Explain how these muscle fibres reduce blood flow to capillaries.
-contraction of the ventricles causes high blood / hydrostatic pressure
-this forces water out of the capillaries
Explain the role of the heart in the formation of tissue fluid
-water potential becomes more negative as sugars enter phloem
-water enters phloem by osmosis
-increased volume of water causes increases pressure
One theory of translocation states that organic substances are pushed from a high pressure in the leaves to a lower pressure in the roots. Describe how a high pressure is produced in the leaves
-at source sucrose is actively transported into the phloem/sieve tubes by companion cells
-lowers water potential in phloem and water enters by osmosis-produces a high hydrostatic pressure
-mass flow towards sink-at sink sugars are unloaded
Describe the processes involved in the transport of sugars in plant stems.
-at source, sugars actively transported into phloem
-by companion cells
-lowers water potential of sieve tube and water enters by osmosis
-increase in pressure causes mass movement towards sink
Describe the mass flow hypothesis for the mechanism of translocation in plants
-waxy cuticle reduces evaporation
-hairy leaves trap water vapour so decrease water potential gradient
Other than the distribution of stomata, suggest and explain two xerophytic features the leaves of this plant might have
Name the structure through which gases enter and leave the body of an insect.
Name the small tubes that carry gases directly to and from the cells of an insect.
-Many lamellae so large surface area
-Thin so short diffusion pathway
Explain two ways in which the structure of fish gills is adapted for efficient gas exchange.
-water and blood flow in opposite directions
-blood always passing water with a higher oxygen concentration
-diffusion gradient maintained throughout length of gill
Explain how the counter current mechanism in fish gills ensures the maximum amount of the oxygen passes into the blood flowing through the gills.
-large surface area provided by lamellae makes diffusion efficient
-thin epithelium between water and blood-countercurrent flow
-maintains gradient as blood always passing water with a higher concentration of O2
-circulation replaces blood saturated with oxygen
-ventilation replaces water (as oxygen removed)
A fish uses its gills to absorb oxygen from water. Explain how the gills of a fish are adapted for efficient gas exchange.
-contraction of the internal intercostal muscles
-relaxation of the external intercostal muscles
-causes decrease in volume of the thoracic cavity
-air pushed down pressure gradient
Describe and explain the mechanism that causes forced expiration.
-trachea, bronchi, bronchioles, alveoli
- diaphragm contracts and external intercostal muscles contract
-volume increase and pressure decrease in thoracic cavity
-diaphragm relaxes and internal intercostal muscles contract
-volume decrease and pressure increase in thoracic cavity (resulting in air moving out)
Describe the gross structure of the human gas exchange system and how we breathe in and out
-Endopeptidases hydrolyse internal peptide bonds OR exopeptidases hydrolyse external peptide bonds
-more ends for exopeptidases
Suggest and explain why the combined actions of endopeptidases and exopeptidases are more efficient than exopeptidases on their own.
-Hb in A has a greater affinity for O2
-becomes more saturated at same ppO2
-able to supply enough O2 to its tissues
Species A lives in water containing a low partial pressure of oxygen. Species C lives in water with a high partial pressure of oxygen. The oxygen haemoglobin dissociation curve for species A is to the left of the curve for species C. Explain the advantage to species A of having haemoglobin with a curve in this position.
-B has a greater rate of respiration
-Hb dissociates more readily
Species A and B live in the same place but B is more active. Suggest an advantage to B of having an oxygen haemoglobin dissociation curve to the right of that for A.
-first oxygen binds to Hb causing a change in shape
-allows more oxygen to bind easily
Explain how changes in the shape of haemoglobin result in the S-shaped (sigmoid) oxyhaemoglobin dissociation curve
-Hb has a lower affinity for oxygen / oxygen unloads more readily
-for rapid respiration
The oxygen dissociation curve for haemoglobin shifts to the right during vigorous exercise. Explain the advantage of this shift.
-valves stop backflow
In a healthy person, blood moves in one direction as it passes through the heart. Give two ways in which this is achieved.
Explain how the highest blood pressure is produced in the left ventricle.
-many more capillaries
-cross sectional area of capillaries much greater
Although the speed of blood flow in an arteriole is greater than speed of blood flow in a capillary, blood does not accumulate in the arterioles. Explain why.
-short pathway between blood and outside of the capillary
Other than causing slow blood flow, explain one advantage of capillaries being narrow.
-to carry oxygen
-to the heart muscle/tissue
What is the function of the coronary arteries?
-fluid in tissue fluid
The volume of blood leaving the capillary network into the veins is less than the volume of blood entering from the arteries. Explain why
-high blood pressure = high hydrostatic pressure
-increases outward pressure from arterial end of capillary
-so more tissue fluid formed
High blood pressure leads to an accumulation of tissue fluid. Explain how.
-water has left the capillary
-proteins in blood too large to leave capillary
-giving higher concentration of proteins
The water potential of the blood plasma is more negative at the venule end of the capillary than at the arteriole end of the capillary. Explain why.
-hydrostatic pressure higher than osmotic effect
-pushes out water
The hydrostatic pressure of the blood at the arteriole end of the capillary helps to form tissue fluid. Explain how.
-high blood / hydrostatic pressure
-forces water out
-large proteins remain in capillary
-Return: low water potential in blood due to proteins
-water enters blood by osmosis
Describe how tissue fluid is formed and how it is returned to the circulatory system.
-so easier flow
Suggest and explain one other way in which sieve cells are adapted for mass transport.
-mitochondria release energy
-for active transport against concentration gradient
Suggest and explain one other way in which companion cells are adapted for the transport of sugars between cells.
-transpiration/evaporation of water molecules through stomata
-lowers water potential of mesophyll/leaf cells
-water molecules pulled up xylem (creating tension)
-water molecules cohere/stick together by H bonds
-forming continuous water column
-adhesion of water molecules to wall of xylem
Describe the cohesion-tension theory of water transport in the xylem.
-mouse has a larger SA:V ratio
-so faster heat loss
-faster rate of respiration releases heat
Use your knowledge of surface area to volume ratio to explain the higher metabolic rate of a mouse compared to a horse
-starch digested to maltose by amylase
-maltose digested to glucose by maltase
-digestion of sucrose is a single step /only one enzyme
The concentration of glucose in the blood rises after eating a meal containing carbohydrates. The rise is slower if the carbohydrate is starch rather than sucrose. Explain why
-aorta is closer to the heart so pressure is high
-aorta has elastic tissue
-aorta has stretch/recoil
The rise and fall in blood pressure in the aorta is greater than in the small arteries. Suggest why.
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