3.1 Students learn to explain why the concentration of water in cells should be maintained within a narrow range for optimal function.
It follows that a fixed concentration of substrate and enzymes is necessary for reactions to proceed at an ideal rate. 3.2 Students learn to explain why the removal of wastes is essential for continued metabolic activity. 3.3 Students learn to identify the role of the kidney in the excretory system of fish and mammals. 3.4 Students perform a first-hand investigation of the structure of a mammalian kidney by dissection, use of a model or visual resource and identify the regions involved in the excretion of waste products.
Renal dialysis is similar to kidney function except that essential substances passively filtered from the blood are replaced by adding them to the blood.
Active animals produce considerable quantities of nitrogenous wastes that must be removed quickly. 3.7 Students learn to distinguish between active and passive transport and relate these to processes occurring in the mammalian kidney. In the first part of the nephron after the Bowmana€™s capsule, called the proximal tubule (see below), many of these molecules are a€?pumpeda€? back into the blood vessels as they wrap around the tubule.
The way the kidney filters the blood is analogous to a student tidying his desk by throwing everything onto the floor, then replacing only the materials he needs on the desk. 3.8 Students learn to explain how the processes of filtration and reabsorption in the mammalian nephron regulate body fluid composition. The material collected in the Bowmana€™s capsule then passes into the proximal tubule where selective (active) reabsorption of all the glucose, amino acids, vitamins and hormones occurs.
The filtrate then passes down and up the loop of Henle in the medulla (inner) part of the kidney. The distal (distant from the glomerulus) convoluted tubule is mainly responsible for the regulation of potassium, pH (acidity) and calcium concentration in the body.
From the distal tubule, the filtrate passes to the collecting tubule which joins other tubules, connects to the ureter and transports the urine to the bladder. 3.9 Students learn to outline the role of the hormones, aldosterone and ADH (anti-diuretic hormone) in the regulation of water and salt levels in blood. You will know that tea and coffee increase the amount of urine produced - they are diuretics.
Sense organs in the pituitary gland detect falls in osmotic pressure caused by a reduction of blood volume.
A range of other sensors (including stretch receptors in the atria of the heart) detect falls in blood pressure due to dehydration and loss of salts from the blood. Aldosterone and ADH are both hormones that increase the reabsorption of water and sodium ions from the filtrate in the tubules of the nephron.
3.11 Students learn to 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. Work extra hard and reduce your social activities so that you can maintain your standard and avoid getting into trouble with parents or teachers?
Do the same amount of work as usual and keep up your social life but tolerate the lower assessment ranking and criticisms you are bound to get? Estuaries are places where the salinity of water changes during the day as the tides move in or out. If you can handle these concepts, it would be in your interest to find out the meaning of the words a€?osmoregulatorsa€? and a€?osmoconformersa€? so that you can improve the quality of your answers to questions on this dot point. 3.12 Students analyse information from secondary sources to compare and explain the differences in urine concentration of terrestrial mammals, marine fish and freshwater fish. Marine fish have no trouble getting enough minerals - the oceana€™s water is full of minerals.


Freshwater fish have the opposite problem - water tends to move into their cells by osmosis and minerals tend to diffuse out. 3.14 Students process and analyse information from secondary sources and use available evidence to discuss processes used by different plants for salt regulation in saline environments.
3.15 Students perform a first-hand investigation to gather information about structures in plants that assist in the conservation of water. 3.16 Students learn to describe adaptations of a range of terrestrial Australian plants that assist in minimising water loss. In the photograph of an Acacia sp seedling below, you can see that the first leaf to form was a bipinnate (compound) leaf.
In the next photograph, the leaves of a Casuarina sp (She-Oak) are shown to be reduced to tiny brown scales - the stems are acting as leaves.
The leaves of Banksia serrata have a thick cuticle (Cu), tough sclerencyma (tough support tissue Sl) and most obviously, stomates in deep pits which have many hairs. 3.A A  Plants and animals regulate the concentration of gases, water and waste products of metabolism in cells and in interstitial fluid. Osmosis and diffusion are passive - no energy is required from the organism.A  Active transport requires the expenditure of energy. In the first part of the nephron after the Bowmana€™s capsule, called the proximal tubuleA  (see below), many of these molecules are a€?pumpeda€? back into the blood vessels as they wrap around the tubule.A  This process requires energy because the materials must pass against a diffusion gradient.
The material collected in the Bowmana€™s capsule then passes into the proximal tubule where selective (active) reabsorption of all the glucose, amino acids, vitamins and hormones occurs.A A  Most of the mineral ions and water are also reabsorbed here.
It is important to keep the volume and salt concentration of blood at a constant level.A  The hormones aldosterone and ADH (anti-diuretic hormone) control blood volume and salt concentration.
You will know that tea and coffee increase the amount of urine produced - they are diuretics.A  ADH and aldosterone do the opposite - they reduce the volume of urine produced by the kidney.
2.Do the same amount of work as usual and keep up your social life but tolerate the lower assessment ranking and criticisms you are bound to get?
Organisms that live in aquatic environments have the same a€?choicea€?.A A  If the water becomes more or less salty than usual, they can either work hard to maintain homeostasis or they can tolerate the change (and compensate in some way - just like you might keep a low profile). Freshwater fish have the opposite problem - water tends to move into their cells by osmosis and minerals tend to diffuse out.A  As a result, to help overcome these problems, freshwater fish produce large volumes of very dilute urine. This dot point will be (has been) covered in practical lessons.A A  Refer to your Practical Record Book.
The leaves of Banksia serrata have a thick cuticle (Cu), tough sclerencyma (tough support tissue Sl) and most obviously, stomates in deep pits which have many hairs.A A  The hairs slow the movement of air and hence reduce the rate of water loss from the pits and hence from the stomates. 1.1 Students learn to identify the role of enzymes in metabolism, describe their chemical composition and use a simple model to describe their specificity on substrates. Most people would know that some animals (like frogs, snakes and lizards) are a€?cold-bloodeda€? and that when the weather is cold, these animals are less active than when ita€™s warm. Each enzyme has a unique shape - it is this shape that means it will make just one reaction go. Enzymes are not usually used up in chemical reactions - they can be used over and over, so they can be present in tiny amounts.
Enzymes are difficult to study in high school but there is one in saliva that we can study. Explain why our bodies need to make large amounts of digestive enzymes (like pepsin) but only tiny amounts of other enzymes (like hexokinase, which is present in every cell and catalyses the breakdown of glucose to glucose 6-phosphate). This experiment is important to addressing the skills outcome H11 (a€?A student justifies the appropriateness of a particular investigation plana€?). I hope you have a picture of many chemical reactions occurring in your own body right now, each one occurring because of the presence of tiny amounts of enzymes. So, it is important that the temperature and acidity in your body has to be kept at the right level.


Maybe you can think of some changes that occur in your body when the temperature gets too low! The first step to prevent your death is for your body to recognise the change in your body temperature. I have only considered what happens when there is a danger of you over-heating but there are many aspects of your body that have to be kept constant - for example, oxygen, sugar and water levels in the blood.
Nerve impulses travel very quickly, and travel from one small part of the body to another small part. Hormones travel relatively slowly in blood, from an endocrine gland to a number of target organs. An example might be the hormone adrenalin, travelling from the adrenal glands above the kidneys to skin (constricting blood vessels), the pacemaker in the brain (increasing heart rate), the liver (increasing the level of glucose in the blood) and many other organs.
At the Mid-Atlantic ridge, a€?black smokersa€? raise the temperature of the ocean above 100oC without the water boiling (because of the very high pressure). There are other organisms that thrive in temperatures close to the freezing point of water. The temperatures at which organisms are found and the range over which they can survive is because of the enzymes in their bodies. A Grylloblattid - (Grylloblatta bifratrilecta) an insect related to crickets and cockroaches that lives in snow. Leta€™s make our ectotherm the impressive but relatively harmless (if left alone) Red-bellied Black Snake (Pseudechis porphyriacus). Comparing our ectoderm (Black Snake) and endoderm (Wombat) it is clear that both have behaviours and bodies that help them to survive extremes. Your textbook does not give any examples of plants responding to temperature change - only adaptations to temperature extremes -so Eucalypts have drooping leaves which helps them to avoid overheating when the Sun is high; deciduous trees drop their leaves which helps them to avoid frost damage. Responses of plants to temperature change are not common but there has been great interest from horticulturalists over several hundreds of years in the ability of Rhododendron spp to curl their leaves in response to temperature change. Most people would know that some animals (like frogs, snakes and lizards) are a€?cold-bloodeda€? and that when the weather is cold, these animals are less active than when ita€™s warm.A  Why is this? Enzymes are not usually used up in chemical reactions - they can be used over and over, so they can be present in tiny amounts.A  But most importantly, they only work under special conditions - a narrow temperature range and a narrow pH (acidity) range.
That usually doesna€™t happen because things happen in your body to cool your body.A  You sweat, surface veins open up so that blood flows closer to the cooling air, and you breathe more often releasing warm our from your lungs. This is a practical investigation involving second-hand research.A  Before you start it, you should read these notes.
I have only considered what happens when there is a danger of you over-heating but there are many aspects of your body that have to be kept constant - for example, oxygen, sugar and water levels in the blood.A  For each, there are receptors that detect the changes and a control centre (usually in the brain) that counteracts the change. Nerve impulses travel very quickly, and travel from one small part of the body to another small part.A  An example might be from a fingertip to a very small part of the brain when we touch something.
There are other organisms that thrive in temperatures close to the freezing point of water.A  For example, there are bacteria-like cells that grow on snow turning it red (to produce a€?watermelon snowa€?). On the other hand, individual organisms can generally survive in a fairly narrow range.A  For example, tropical fish die in cold water, yet antarctic fish would die in tropical waters. Choose an ectothermic animal species, an endothermic animal species and a plant species.A  Dona€™t forget the advice about second-hand research, especially to acknowledge your sources.
Your textbook does not give any examples of plants responding to temperature change - only adaptations to temperature extremes -so Eucalypts have drooping leaves which helps them to avoid overheating when the Sun is high;A  deciduous trees drop their leaves which helps them to avoid frost damage. However, because it can maintain its body temperature within a narrow range, wombats can remain active over a much wider temperature range.



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