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Maintaining a balance (Plants and animals regulate the concentration of…
Maintaining a balance
Plants and animals regulate the concentration of gases, water and waste products of metabolism in cells and in interstitial fluid
1. explain why the concentration of water in cells should be maintained within a narrow range for optimal function
Water maintains and controls:
- body temperature, pH,substrate concentration
- excretion of wastes
- transportation of nutrients
Changes in water concentration will lead to a disruption in the functioning of the enzymes and metabolism.
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4. Explain why the process of diffusion and osmosis are inadequate in removing dissolved nitrogenous wastes in some organisms
Diffusion
- Diffusion is too slow and would cause the build up of nitrogenous wastes (causing):
-increase toxicity
-slow down metabolic reactions
-take up too much space in organism
- Diffusion does not work when concentration gradients are the same
-nitrogenous wastes will not be able to be be removed the body.
Osmosis
- Too much water is lost in urine.
-If urine contains a large number of
nitrogenous wastes, water
will be drawn into the urine by osmosis,
to dilute the wastes and try to equalise
the concentration of the fluid inside the
urine
- Too slow
5. Distinguish between active and passive transport and relate these to process occurring in the mammalian kidney
Passive transport includes the process of diffusion and osmosis where no energy input is required from the cell. Molecules move along a concentration gradient.
Active transport requires cellular energy to move molecules ( sodium ions, glucose, amino acids, and hydrogen ions across he nephron wall) against the concentration gradient.
-glucose and amino acids are reabsorbes by kidney cells
-sodium pump mechanism operates in the tubules of the kidney allowing transportation of urine back to kidney cells- conservation of water and salts
6. explain how the process of filtration and reabsorption in the mammalian nephron regulate body fluid composition
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7. Outline the role of ADH (antidiuretic hormone) in the regulation of water and salt levels in blood
ADH- Antidiuretic hormone is a hydrating agent that reabsorbs the water into the body.
Function: Released by the pituitary gland , acts to make the walls of the collecting ducts more permeable to the water.
- Periods of water stress, osmotic receptors in the hypothalamus detect low water levels in the blood. - send messages to the hypothalamus
- Pituitary release ADH to make the walls of the collecting ducts more permeable to the water., water moves in the blood by diffusion
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Function: produced in the adrenal gland in the adrenal cortex. The release of aldosterone makes the walls of the distal convoluted tubule more permeable to sodium ions. Water follows by osmosis
- In high blood salt concentrations, negative feedback results in the release of less adolsterone and more water and salts are retained in the urine.
Role: stimulates secretion of potassium ions into the nephron, stabilises blood pressure and maintains blood levels
8. define enantiostasis as the maintenance of metabolic and physiological functions in response to variations in the environment and discuss its importance to estuarine organisms in maintaining appropriate salt concentrations
Enantiostasis is the maintenance of metabolic and physical functions in response to variations in the environment such as fluctuations.
Osmoconformers - organisms that can modify salt concentrations in their body to match fluctuations in external conditions. they have a broad range of salinity and have varied solute concentrations . These include marine invertebrates and algae. For example Sharks use trimethylamine oxide to regulate osmotic pressure in cells to match surroundings. ( the environment)
Osmoregulators- organisms that maintain a constant salt concentration in their bodies despite environmental fluctuations. There bodily fluids all similar to those in a marine environment. For example, salmon drink cautiously in salt through their gills water and eliminate salt through their gills, absorb salt excreting very dilute urine.
9. describe adaptions of a range of terrestrial Australian plants that assist in minimising water loss
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