Maintaining a Balance Tips

[mitochondria]

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1. Be familiar with enzymes, know that most enzymes are very specific with what substrate they act on. The enzyme-substrate complex is like a "key and lock".

2. Identify that enzymes only work under certain conditions (such as pH, substrate concentration and temperature) and will be denature or destroyed if the temperature is too high.

3. Biology ideas are often link, knowing that enzymes are made up of proteins and that they only work under certain conditions, you will be able to deduce that a stable internal environment must be kept - homeostasis.

4. Homeostasis - detect change (by receptors) --> feedback via peripheral nervous system --> centrol nervous system (brain) --> signal is sent to effectors via the peripheral nervous system again --> change is counteract --> negative feedback --> start from the beginning*

5. Know where chemical exchanges occur, cell is the one of the exchange sites for most chemicals listed in the syllabus (9.2.2) and most are carried in plasma. O2 and small amount of CO2 are carried in haemoglobin of RBC. Draw a table with headings such as "Substance", "Tissue" and "Carried by" as headings.

6. Do not try to *remember* wordy things about arteries, veins and capillaries. Remember their structure first and then work out their differences.

7. Know the adaptive advantage of haemoglobin --> this one is a biggie

8. Oxygen is needed for aerobic respiration in living cells. CO2 when dissolved in H2O is slightly acidic, the plasma is mostly H2O -- enzymes only work under certain conditions, therefore the removal of CO2 is essential in keeping a relatively stable pH. Also, CO2 is slightly to cells and a large amount of CO2 can kill them.

9. Xylum carries main H2O and ions; passive transport occurs in the xylum; know that capillary action (+adhesion and cohesion) and transpiration helps the transportation of materials in xylem.

10. Phloem carries organic materials (in other words, nutrients); materials are active transported in phloem.

11. Know what are symplastic loading and apoplastic loading. Symplast: the system of which protoplasts (the living unit of cells, i.e. nucleus + cytoplasm) are interconnected by plasmodesmata. Apoplast: the system of interconnected cell walls and the water that exist between them

12. Be able to draw the transverse and longitudinal sections of phloem and xylem

13. STYDY YOUR PRACS AND KNOW THEM WELL. The test for CO2 using limewater (CaCO3), know the chemistry of this. As discussed previously, know the blood cells prac well and their sizes: RBC ~7 microns in diameter and ~1 micron thick; WBC, have different shapes, vary from ~14-25 microns in diameter.

14. Some blood products and their uses: RBC (anaemia, blood lost); platelets (leukemia, cancer treatment which affects platelet-production); Immunoglobins (infection, people who cannot produce them); plasma (blood loss - to restore blood pressure)

15. Artificial blood: perflurochemicals and artificial haemoblobins can be used. Here's a useful link from Scientific American Artificial Blood

16. Identify that wastes can poision cells and slow down diffusion of waste outside the cell.

17. When wastes build up, osmosis will only increase the concentraion of H2O inside cells and kill them, besides, it can only move H2O so it will not remove the wastes within cells. On the other hand, diffusion is slow, and it is not selective. Also, it depends on the concentration gradient. So they are not adequate for the removing wastes.

18. Filtration: a non-selevtive process involves high pressure, occurs in the glomerulus. Reabsorption active transport; reuseable substances are transported back to the plasma. Secretion

19. ADH: Antidiuretic Hormone, made in the hypothalamus and stored in the prosterior pituitary gland, it stimulates water reabsorption in the kidney. Aldosterone: produced in the adrenal cortex and regulates salt concentration, therefore, also water concentration. See aldosterone and ADH

19. Enantiostasis: Maintenance of metabolic and physiological functions (as distinct from states), in response to variations in the environment. from science support document/syllabus Make sure you are able to compare structurally, environmentally the difference between marine and freshwater fish.

20. Understand why nitrogenous wastes produced by different type of organisms are different by relating to their environment, particularly the availability of water. Usually the more readily available water is, the more dilute the nitrogenous waste is being excret. *Pee hierarchy* - from least availability of water to most (excuse me *ahem*) uric acid --> urea --> ammonia

21. Have some examples of Australian plants and animals homeostasis. For example, Red Kangaroo, Hopping Mice, Eucalyptus, Cactus. Hint: basically any species you name have certain ways to adapt to temperature change or to adapt to water availability, (if you are really not sure in the exam - hopefully not) just name an Australian example you know and "write things" (so tempted to say "cra* on") about it... here are some common adaptions for animals: hide in shades; have large SA:V ratio to lose/absorb heat; pant; sweat; large ears, large body parts to store water/fat.. etc. For plants: hangs leaves vertically, have a waxy cuticle to prevent water loss, shiny surface to reflect sunlight (reduce the amount of heat it can absorb), bulgy parts to store water, thin leaves, leaves has small SA:V ratio; hair to reduce water loss by transpration; close and open stomas...


Important terms: enzyme, substrate, pH, homeostasis, xylem, phloem, symplast, apoplastic, osmosis, diffusion, filtration, reabsorption, secretion, kidney (and its components), enantiostasis, renal dialysis


Good luck everyone Better go and reserve my first-to-post places in other two catagories now.. meeeeee tireeeeed... hehee.. i'll just stick something don't delete them babydoll!

[moo/pokie]

that's very long...but helpful

[honky tonk]

Thanks mitochondria.

It seems I have to work on haemoglobin advantages and blood products.. I know nothing about them.

[tempco]

OK, here I go.

Advantages of Haemoglobin

• The presence of haemoglobin increases the oxygen carrying capacity of blood 100 times (In comparison to oxygen being dissolved in blood plasma).
• This ability to transport large quantities of oxygen gives mammals a considerable adaptive advantage.
• It means more oxygen is available for respiration, and more energy can be released.

Blood Products

• Red Blood Cells - Used to increase the amount of oxygen that can be carried to the body's tissue. Given to people with anaemia.
• Platelets - Given to people who have cancer of the blood or lymph.
• Plasma - Used to treat people with clotting disorders. eg. Haemophilia.
• Immunoglobulin - Used to treat people who have difficulty fighting infections.
• White Blood Cells - Used occasionally to treat life threatening infections when the cell count is very low or the white blood cells are not working properly.

Hope that helps (and is what you're looking for )!

[xiao1985]

also on adaptive adv of haemoglobin:

it is only loosely attached to oxygen, so it is very easy to disattach it, -> supply to cells that need oxygen

each haemoglobin consists of 4 haem units, which means that each heamoglobin is capable of bindin (hence transportin) 4 oxygen molecules around the body. but then again, it sorta repeats how it is 100 effecient in terms of carryin oxygen than o2 in dissolved form...

[*~Dazed~*]

hey thanks mito that was good... nice little summary there too...

hey do you think its necessary to be able to draw an artery, vein and capillary... because i find that the diagrams of artery and vein look the same and i dont know how to distingusih between them

[xiao1985]

i dunt fink u need to draw em, as long as u noe the difference between the three: artery very muscular (with the exception of pulmonary artery (? spellin??) i fink), cuz it needs to withstand huge pressure from the pumpin of the heart; veins, are usually flexible, so that they can be fitted betweent the muscles etc, also wif valves to prevent deoxygenated blood from backflowin (again wif the exception of pulmonary vein), and capilaries are very thin (the wall of capilary is usually one cell thick) to maximise the diffusion of oxygen

[tempco]

The main difference is the thickness of the muscle lining.. if you do have to draw it, make sure you make the muscle layer substantially thicker in the artery, when compared to the vein.

[sneaker]

Is this point in the summary to do with theories of moovement of substances in xylem or phloem? Could someone please explain?

11. Know what are symplastic loading and apoplastic loading. Symplast: the system of which protoplasts (the living unit of cells, i.e. nucleus + cytoplasm) are interconnected by plasmodesmata. Apoplast: the system of interconnected cell walls and the water that exist between them

[Nearlyfinished!]

mitochondria, you are truely a legend! I didn't really need help with this topic but the people who do, READ IT!!!!! It will help.

[lemonade]

Originally posted by sneaker
Is this point in the summary to do with theories of moovement of substances in xylem or phloem? Could someone please explain?

11. Know what are symplastic loading and apoplastic loading. Symplast: the system of which protoplasts (the living unit of cells, i.e. nucleus + cytoplasm) are interconnected by plasmodesmata. Apoplast: the system of interconnected cell walls and the water that exist between them

sneaker, apoplastic and symplastic loading occurs in the phloem

[cassiekate]

"12. Be able to draw the transverse and longitudinal sections of phloem and xylem"

About this, I can't seem to find any good diagrams of the xylem and phloem - can anyone help?

[tempco]

Originally posted by mitochondria
13. STUDY YOUR PRACS AND KNOW THEM WELL. The test for CO2 using limewater (CaCO3), know the chemistry of this.

Can someone please post up the chemistry behind this? I'm a bit blank on this, so any help would be great!

[dark_angel]

Originally posted by NekkidSerpent
Can someone please post up the chemistry behind this? I'm a bit blank on this, so any help would be great!

i'm not exactly doin bio this yr, but im accelerating in chem and the reaction to test wether carbon dioxide is present is by passing it through calcium hydroxide (limewater) to produce calcium carbonate and water.

CO2(g) + Ca(OH)2 (aq) ----> CaCO3(s) + Water

[tempco]

Thanks!