Maintaining A Balance

Question 1

Identify pH as the way of describing the acidity of a substance.

Answer 1

pH is a measure of how basic or acidic a solution is. Calculated using pH probe or universal indicator.

Question 2

Explain why maintenance of a constant internal environment is important for optimal metabolic efficiency.

Answer 2

Metabolism is affected by enzymes and hence functioning of an organism. They work best with a limited range of environmental conditions and their efficiency is affected greatly by certain factors which include temp, pH and substrate concentration.

• when factors are outside of this range activity is decreased.
• Enzymes become de-natured.
• therefore temp and pH need to remain constant.

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Question 3

Describe homeostasis as the process by which organisms maintain a relatively stable internal environment.

Answer 3

Organisms maintain a constant internal state regardless of external changes. Two stages: detecting change and counteracting change.

Question 4

Explain that homeostasis consists of two stages:

• Detecting changes from the stable state.
• Counteracting changes from the stable state.

Answer 4

Detecting changes- Any change that provokes a response is a stimulus. E.g. Light, sound. E.g. Internal: co2 levels, wastes. Receptors detect stimuli e.g. Patch of sensitive cells, complex organs like eye or ear.
Counteracting changes- after receptors detect changes, organisms can react to the change. This will counteract the change to ensure the stable state is maintained.
Effectors bring about responses to stimuli. E.g. Muscles or glands. Glands bring about changes by secreting chemical substances.
Stimulus-receptor-control centre-effector-response.
Temp-thermoreceptor-

Question 5

Outline the role of the nervous system in detecting and responding it environmental changes.

Answer 5

Nervous system is an organ system containing a network of specialised cells called neurons that coordinate the actions of an animal and transmit signals between different parts of the body.
Central nervous system- control centre for the bodies responses and coordinates these. Consists of brain (specifically hypothalamus) and spinal cord where it receives information, interprets and initiates response.
Peripheral nervous system: branching system of nerves that connects receptors and effectors. The system transmits messages from the central nervous system and back. Acts as a communication channel. E.g. Too cold, muscles contract.

Question 6

Identify the board range of temperatures over which life is found compared with the narrow limits for individual species.

Answer 6

-life is found over a broad range of temps e.g. -40 degrees to 150 degrees.
Individual species can only survive in a narrow temp range e.g. Humans 27-43 degrees.

Question 7

Compare responses of named Australian ectothermic and endothermic organisms to changes in the ambient temperature and explain his these responses assist temperature regulation.
Analyse information from sources to describe adaptations and responses that have occurred in Australian organisms to assist temperature change.

Answer 7

Ectotherms: have limited ability to control their body temperature due to cellular activities generating little heat. Their body temp rises and falls with the ambient temperature.
E.g. Eastern brown snake. Too cold: Behavioural- basks in sun. Physiological- hibernates to stay away from the cold and decrease metabolism.
Too hot: behavioural, seeks shade.
Endotherms: organisms whose metabolism generates enough heat to maintain an internal temperature independent of the ambient temperature. E.g. Fairy penguin. Too cold: behavioural: huddle together to reduce surface area. Structural: feathers stick out, trap in warm layer of air.
Too hot: swim (behavioural), feathers close to skin (structural) minimum air trapped to the skin.

Question 8

Identify some responses of plants to temperature change.

Answer 8

Increase I’m temp: evaporative cooling-open stomata- transpiration- cooling.
Turgod response- wilting, decrease SA exposed to sun.
Decrease, water between cells freezes: cells produce antifreeze. Tulips flower when exposed to cold temps.

Question 9

Gather, process and analyse information from secondary sources and use available evidence to develop a model of a feedback mechanism.

Answer 9

Stimulus (increase in co2 in blood)- receptor (receptors in aorta)- control system (hypothalamus)- effector (rib muscles and diaphragm)-negative feedback (co2 levels reduced).

Question 10

Test to see effect of increased temp, pH and substrate concentration on enzyme.

Answer 10

Temp: -set up water baths with different temps e.g. 20, 30, 45 and 60. Place potato in h2o2/ detergent solution. See which one has highest froth.
pH- soak potato in solutions of different pHs. E.g. 1, 3, 7, 10. Place potato in h2o2/detergent mixture. Measure which had highest froth.
Substrate concentration: change water/detergent conc. e.g. 0/100, 25/75, 50/50, 75/25, 100,0.
Place potato in each, record height of froth.
SAFETY hydrogen peroxide is poisonous, cannot be ingested.
Hot plate can reach very high temps.

Question 11

How oxygen, carbon dioxide, lipids, salts, water, nitrogenous wastes, other products of digestion.

Answer 11

Oxygen- oxyhemoglobin.
Carbon dioxide- 70% carbonic acid, 23% red blood cells carbohaemoglobin and 7% dissolves in plasma.
Water- solvent in plasma, 60% plasma volume.
salts- ions dissolved in the plasma of the blood.
Lipids- changed into triglycerides then transported as chylomicrons wrapped in a coat of protein. Released in lymph.
Nitrogenous wastes- urea, ammonia, creatine, Uris acid. Dissolved in plasma of the blood

Question 12

Compare structure of arteries, capillaries and veins.

Answer 12

Arteries- thick walled, elastic, muscular. Carries blood away from the heart, stress is put on it from pressure from hearts pumps. Muscle fibres which contract and relax.
Veins- thinner walls than arteries, elastic, wider diameter.
Capillaries- one cell thick, surround tissue cells providing a very large surface area over which exchange of materials between body cells can occur.

Question 13

Describe the main changes in the chemical composition of blood as it moves around the body and identify tissues in which these changes occur.

Answer 13

YOU ALREADY KNIE THIS BECAUSE YOURE A FUCKING GENIUS BRIANNA.

Question 14

Outline the need for oxygen in living cells and explain why the removal of carbon dioxide from the cell is essential.

Answer 14

• cells require oxygen for the process of respiration.
• carbon dioxide is a waste product of respiration and must be removed in order to maintain normal pH balance of the blood. By removing carbon dioxide it prevents a build up of carbonic acid which increases pH which would therefore increase breathing rate and depth.

Question 15

Describe current theories about the processes responsible for the movement of materials through plants in xylem and phloem tissue.

Answer 15

Phloem: source and sink.
Xylem: transpiration stream theory.

Question 16

Perform first-hand investigation to demonstrate the effect of dissolved carbon dioxide on the pH of water.

Answer 16

Set up test tube with marble chips+HCL, connected with a rubber stopper. The rubber stopper should connect to another test tube with water.

• pH of water started at 7, ended at 2.
• Co2 made water acidic.

Question 17

Perorm first-hand investigation using a light microscope and prepared slides to gather information to estimate the size of red and white blood cells and draw scales diagrams of each.

Answer 17

RBC: 7.5-8 microns, WBC: 10microns.

Question 18

Analyse information from secondary sources to identify current technologies that allow measurement of oxygen saturation and carbon dioxide concentrations in blood and describe and explain the conditions under which these technologies are used.

Answer 18

Pulse oximetry: small clip attached to person’s finger. Emits different wavelengths to determine saturation levels. Large difference between the red light absorbed by haemoglobin compared to oxyhaemoglobin, hence can be analysed to give a reading. Advantages: cheap, non-invasive. When used: asthma attacks, surgery when under anaesthesia.
Arterial blood gas: measure pH, 02 and CO2 saturation levels.
Blood is drawn from artery where O2 and co2 levels measured before entering body tissues.
Advantages: accurate measurement if gases in the blood. When used: critically ill patients.

Question 19

Analyse information from secondary sources to identify the products extracted from donated blood and discuss the uses of these products.

Answer 19

RBC: increase oxygen carrying capacity.
WBC: fight off serious bacterial infections.
Intragram: boost immune system after bone marrow transplant.
Cryoprecipitate: massive bleeding.

Question 20

Analyse info and present info from secondary sources to report in progress in the production of artificial blood and use available evidence to propose reasons why such research is needed.

Answer 20

Problems with real blood: shortage, has to be matched, can carry diseases, limited shelf life.
Replacement: perflurochemicals.
-synthetic and inert
-cheap to produce
-can dissolve 5 times more oxygen than blood.
-completely sterile.
-free of biological materials, therefore no risk of infections. But must be combined with other materials to mix in with the bloodstream (e.g. Lecithin).

Question 21

Choose equipment or resources to perform a first-hand investigation to gather first-hand data to draw transverse and longitudes sections of phloem and xylem.

Answer 21

1. In 100ml beaker filled with water add 3-5 drops of red food colouring into solution. Should change to dilute red colour.
2. Place celery stick in beaker, leave overnight, so coloured water can seep into the plant sections to rise through the xylem vessels, hence staining them strongly. Some also travelled down the phloem vessels.
3. Using sharp razor blade very thin slices were cut from across the stalk (for transverse section) and from the length of the stalk (for longitudal section).
4. Suitable slices were then prepared as wet mounds and viewed under a microscope.

Phloem vessels are usually closer to the outer edge of the stem. Bundles of xylem tissue Re clearly visible because they contain coloured water. Together=vascular bundle.

Question 22

Explain why the concentration of water in cells should be maintained within a narrow range for optimal function.

Answer 22

Water makes up 70-90% of organisms and is the solvent of Ll metabolic reactions in living cells and sometimes directly takes part in the reaction e.g. Respiration.

Question 23

Explain why the removal of wastes is essential for continued metabolic activity.

Answer 23

-as a result of metabolism many waste products are formed:
E.g. Process of deamination- (amino acids and proteins are broken down into ammonia) which ammonia can make the pH of the cell alkaline and is very toxic.
co2 can form carbonic acid, decreasing pH.

Question 24

Identify the role of the kidney in the excretory system of fish and mammals.

Answer 24

Plays a central role in homeostasis, forming and excreting urine while maintaining osmoregulatory.
-osmoregulation: the physiological processes that an organism uses to maintain water balance, to compensate for water loss, avoid water gain and maintain the proper osmotic concentration (osmolarity) of the body fluids.
-removes wastes
-maintains salt levels.
E.g. Freshwater fish, lots of h2o in environment, needs to conserve salt levels. Excretes dilute urine in large quantities.
E.g.2. Marine fish, lots of salt in environment, h20 levels need to be conserved, excretes concentrated urine in small concentrations.
Insects: Uric acid.

Question 25

Explain why the process of diffusion and osmosis are inadequate in removing dissolved nitrogenous wastes in some organisms.

Answer 25

• diffusion is very slow.
• osmosis on,y deals with water, not solutes.
• the organism is generally too big to rely on just these methods.

Question 26

Distinguish between active and passive transport and relate these to processes occurring in the mammalian kidney.
Explain how the processes of filtration and reabsorption in the mammalian kidney nephron regulate body fluid composition.

Answer 26

Active transport: uses energy specifically from the mitochondria. In kidney: secretion of toxins.
Passive transport: doesn’t use energy from cell specifically the mitochondria. Reabsorption of nutrients.

Question 27

The kidney process.

Answer 27

1. Blood comes in from aorta via renal artery.
2. This splits up into arterioles leading to a nephron.
3. Blood passes through bundled capillary known as the glomerulus. Ultra filtrator. Only small molecules e.g. Urea, salts, water, amino acids, glucose pass out of blood stream as e.g. Red blood cells are too large to get through.
4. Filtrate passes through the proximal consulted tubule (twisting and turning). Here, there is active transport of glucose and amino acids and some other substances into the surrounding tissue where it re-enters the blood. H2o moves out via passive diffusion.
5. Loop of henle. Here, at the ascending limb, sodium ions are actively transported into the surrounding tissue the medulla, this makes it very salty. Cl- ions follow it (the Na+).
6. The descending limb (same limb as collecting duct) may be permeable to water or may not be. If it is permeable, water is passively reabsorbed into the surrounding tissue. Concentrated urine is excreted and so water is conserved. If the wall is impermeable, no water is reabsorbed and dilute urine is excreted The permeability of the wall of the collecting tubule to water is altered by anti-diuretic hormone.

Question 28

Outline the role if the hormones, aldosterone and ADH (anti-diuretic hormone) in the regulation of water and salt levels in blood.

Answer 28

ADH: released from pituitary gland. If e.g. The body is dehydrated, ADH increases the permeability to water in the distal tubule and collecting duct. Results in concentrated urine being formed and an increase in blood volume. Water is also conserved.
Aldosterone: released from the adrenal gland. A decrease in concentration of sodium ions in the bloodstream leads to a decrease in blood volume and causes secretion of the hormone aldosterone. It increases the permeability of the nephron to sodium particularly in the ascending limb of the loop of Henle. Reabsorption of sodium ions from the nephron into the surrounding kidney tissue and capillaries occurs, resulting in the retention (conservation) of salt by the body (less salt is lost in urine). With no aldosterone, the salt concentration in the urine is higher.

Question 29

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.
Process and analyse information from secondary sources and use available evidence to discuss processes used by different plants for salt regulation in saline environments.

Answer 29

Maintenance of metabolic and physiological functions in an organism experiencing variations in its environment.
E.g. Mangroves- rhizophora mangrove- accumulates
Saltbush- excluder. It actively transports excess sodium and chloride ions into bladder cells situated on the tips of hairs on surface of leaves. When bladder cell reaches capacity, it bursts, releasing salt into the environment b

Question 30

Describe adaptations of a range of terrestrial Australian plants that assist in minimising water loss.
Performs first-hand investigation to gather information about structures in plants that assist in the conservation of water.

Answer 30

Eucalypt- waxy cuticle and leaves hanging vertically.
Water can’t escape, reduce SA to sun.
Cacti- shallow roots- absorbs overnight condensation.

Question 31

Gather, process and analyse information from secondary sources to compare the process of renal dialysis with the function of the kidney.

Answer 31

Similarities- blood is cleaned (N) wastes are removed.
-use a membrane
-conc. of urine is controlled.
Differences- time efficiency: kidney=30 min, dialysis=3-6hrs.
Method: kidney= non-invasive. Dialysis=invasive.

Question 32

Present information to outline the general use of hormone replacement therapy in people who cannot secrete aldosterone.

Answer 32

-inadequate aldosterone may lead to Addison’s disease, where the adrenal cortex is unable to secrete sufficient (or in severe cases any) aldosterone. Results in very low levels of Na+ and high K in blood.
-symptoms include weakness, dizziness, nausea, no appetite.
-treated with flurocortisone.
Advantages- addresses symptoms quick, easy to do.
Disadvantages- synthetic (needs to be made), expensive, needs to be taken for your whole life.

Question 33

Analyse information from secondary sources to compare and explain the difference in urine concentration of terrestrial mammals, marine fish and freshwater fish.

Answer 33

Terrestrial mammal- components: conc. urine containing urea, salts, wastes and water. Explanation: wastes are excreted dissolved in water.
Freshwater fish- large quantities if dilute urine. With ammonia. Explanation: absorbs lots of water.
Marine fish: small quantities of concentrated urine. Urea. Explanation: needs to conserve water. Urine contains high levels of non-toxic wastes.

Question 34

Identify the role of enzymes in metabolism, describe their chemical composition and use simple model to describe their specificity on substrates.

Answer 34

Metabolism- sum total of all chemical reactions within an organism.
Anabolic- building up of larger organic compounds from simpler ones.
Catabolic- breaking down of complex organic compounds from simpler ones.
Specificity- highly specific in their action, each acting on one substrate only. Due to the shape of the active site matching the shape of substrate material. One substrate can split or two substrates can join.
Models- lock and key: substrate fits exactly into active site of the enzyme. Enzyme has rigid and up changing shape.
Induced fit- the binding of the substrate to the enzyme induces a temporary change in shape of enzyme. Shape of the new enzyme better accommodates the shape of the substrate and a reaction occurs.