Year 12 Biology Summaries
1.1
- identify the role of enzymes in metabolism, describe their chemical
composition and use a simple model to descibe their specificity on substrates.
Role of enzymes in metabolism:
 all physical and chemical processes in cells
 reaction speed = metabolic rate
 enzyme- a biological catalyst (must be present or speeds up reaction)
 reaction- biosynthetic pathway
 enzyme may change during reaction, but reverts back by end
 each enzyme acts on one compound only (substrate)
 requires certain environment to be active
 each cell makes different enzymes
Chemical composition:
 built from amino acids, linked for peptide chains
 22 types of amino acids
 linked in any sequence
 protein molecules
 folded to expose active site specific to substrate
Induced fit model
 attaches to model to change shape
Lock and key model
 substrate fits neatly into enzyme active site
 disassemble to remain the same shape
1.2
- identify the pH as a way of describing the acidity of a substance
pH Scale
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1.S.1
Lower than 7 = acidic = H+
7 = neutral = H2O
Higher than 7 = basic = OH-
pH- describes acidity/alkalinity of a substance
pH extremes cause protein structure to denature permanently
- identify data sources, plan, choose equipment or resources and perform a
first-hand investigation to test the effect of:
 increased temperature
 change in pH
 change in substarte concentrations on the activity of named
enzyme(s)
Increased / decreased temperature
 used potato and bleach (H2O2, hydrogen peroxide)
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3 test tubes: one on ice, one at room temperature, one at 60oC (approx.)
found activity highest at room temperature, hot or cold extremes reduce reaction
rates and therefore enzyme activity
therefore it is obvious there is a narrow optimum temperature range, outside of
which enzyme activity significantly decreases
Change in pH
 used potato and bleach (H2O2, hydrogen peroxide)
 tested with 2 stengths of hydrochloric acid, distilled water and 2 strengths of
sodium hydroxide
 found activity highest at a pH of 7, a cell’s natural pH
 therefore similar to the temperature results, there is a narrow optimum pH range,
outside of which enzyme activity significantly decreases
 optimum range = 7-9, neutral to mildly basic
Change in concentration
 used Bromaline and milk
 the higher the concentration of milk (the substrate), the faster the reaction with
the enzyme (Bromaline) was
1.3
- explain why the maintenance of a constant internal environment is important
for optimal metabolic efficiency
Internal maintenance & metabolic efficiency
 major changes in environment = incativity = cell death
 feedback systems monitor environment changes
 if enzyme conditions are not in the optimal range, the organism will suffer
 therefore metabolic efficiency decreases
1.4
- descibe homeostasis as the process by which organisms maintain a relatively
stable internal environment
Homeostasis
 maintain a constant internal biochemical state
 therefore metabolic and physiological functioning are maintained
 two stages: normal state and counteraction state
 if homeostasis isn’t present, cells die and the organism suffers
1.5
- explain that homeostasis consists of two stages:
 detecting changes from the stable state
 counteracting changes from the stable state
The two stages of homeostasis
 receptors always start working to detect changes that might disrupt the stable
state of homeostasis
 the counteracting stage takes measures to return the body to the stable state
1.6
- outline the role of the nervous system in detecting and responding to
environmental changes
Role of the nervous system
 stimulus  receptors  conductor (sensory nerve)  control centre (central
nervous system)  motor nerve  effector  response  back to receptors
 CNS receives information on required body adjuctments for changes
 sends instructions for appropriate feedback through motor nerves to the effector
 adjustments made, loops back to CNS to check for any further required changes
1.7
- identify the broad range of temperatures over which life is found compared
with the narrow limits for individual species
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1.8
1.S.3
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1.9
there are narrow optimum temperature ranges for each individual species
outside these ranges the organism will suffer, perhaps being killed
life on our planet is found from temperatures far below freezing to incredibly hot
these temperature ranges and the life they support demonstrates diversity and
evolution within organisms
- compare responses of named Australian ectothermic and endothermic
organisms to changes in the ambient temperature and explain how these
responses assist temperature regulation
AND
- analyse information from secondary sources to describe adaptations and
responses of Australian organisms that assist temperature regulation
echidna  hibernates when the weather gets colder  prevents losing heat
through minimal movement  behavioural adaptation
some marsupials  licks fur  helps keep cool by saliva application 
behavioural adaptation
whale  thick layer of blubber (fat) insulates against the cold waters of the
ocean  structural adaptation
small mammals  surface area to volume ratio allows to lose more heat on hot
days than a larger mammal  structural adaptation
- identify some responses of plants to temperature change
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some flowering plants withdraw the petals of the flowers in hot conditions,
exposing less surface area to the heated environment surfaces
many will lose the flowers altogether and change the colour of their leaves to
assist in absorbing heat instead of reflecting it during times of cold weather
2.1
- identify the form(s) in which each of the following is carried in mammalian
blood:
 carbon dioxide
 oxygen
 water
 salts
 lipids
 nitrogenous waste
 other products of digestion
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2.2
carbon dioxide- hydrogen carbonate ions in red cells and plasma
oxygen- oxyhaemoglobin in red cells
water- as water in plasma
salts- ions in plasma
lipids- chylomicron in plasma
nitrogenous waste- mostly urea in plasma
other products of digestion- separate molecules (glucose, amino acids etc) in
plasma
- explain the adaptive advantage of haemoglobin
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2.3
each molecule hasa 4 active sites for oxygen to attach to
dissociates more easily at higher temperatures
dissociates more readily in electrolytes than pure solution
dissociates more readily at lower pH
- compare the structure of arteries, capillaries and veins in relation to their
function
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2.S.1
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2.S.2
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arteries  thick wall, large diameter to allow high volumes of blood to be
pushed through at once, leads to and from vital organs
veins  thin wall, diameter smaller than artery but a larger number to still allow
efficient blood flow, connected to vital organs
capillaries  1 cell thick wall, very narrow but copious amounts in body, spread
from other major blood vessels to allow blood to be distributed around the body
- perform a first-hand investigation to demonstrate the effect of dissolved
carbon dioxide on the pH of water
visually, limewater turns milky with carbon dioxide, so this was used to assure
there was carbon dioxide present
when carbon dioxide is dissolved into water, the pH lowers
this means that carbon dioxide makes water more acidic
- perform a first-hand investigation using the light microscope and prepard
slides to gather information to estimate the size of red and white blood cells
and draw scaled diagrams of each
white cells are much larger than red cells
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2.4
this is because they need to engulf foreign materials
red need to fit through small capillaries
there is also a lot more red than white cells in our bodies
white:red = 1:1000 to 1:2000
size- white:red = 2:1
- describe the main changes in the chemical composition of the blood as it
moves around the body and identify tissues in which these changes occur
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inorganic ions (sodium, potassium, calcium etc), concentrations remain stable
plasma proteins- depends on if proteins are needed
red blood cells- heart- if more oxygen is needed in certain parts of the body
white blood cells- if an infection occurs or bacteria becomes present
2.S.3
- analyse information from secondary sources to identify current technologies
that allow measurement of oxygen saturation and carbon dioxide
concentration in blood and describe and explain the conditions under which
these technologies are used
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pulse oximeter- oxygen saturation of haemoglobin, pulse rate and blood flow.
Gives no information about carbon dioxide levels
non-invasive probe with sensor attached to finger/ear lobe measures percentage
of haemoglobin that is saturated with oxygen, together with heart rate
used in intensive care units, anaesthesia, recovery after surgery and during
hypoxia
arterial blood gas analyser- oxygen, carbon dioxide and pH levels of the blood
invasive technology, which requires a blood sample or an arterial probe to be
inserted into artery in wrist, groin or arm
used in intensive care units, baby care units, labour wards
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2.S.4
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- analyse information from secondary sources to identify the products
extracted from donated blood and discuss the uses of these products
whole blood- to replace blood after large loss (>20%)
red blood cells- where oxygen carrying capacity is required to increase
(anaemia, severe bleeding)
white blood cells- low white cell count or when serious infections are present
plasma- to increase blood volume after transplants or surgery, to increase blood
proteins and dissolved minerals for clotting factors
platelets- help clottingfor severe haemorrhaging and bleeding due to diseases
such as leukaemia or haemophilia
cryoprecipitate- blood clotting factors for severe bleeding, haemophilia etc
anti-D- prevents haemolytic disease in newborn babies of Rh negative mothers
(rhesus disease)
intagram- boost immune system, reducing susceptibility to infections
hyper-immune globulins- treats/prevents specific infections (chickenpox, Hep B,
tetanus, cytomegalovirus)
2.S.5
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2.5
- analyse and present information from secondary sources to report on
progress in the production of artificial blood and use available evidence to
propose resons why such research is needed
scientific breakthroughs in recent years have led to successful synthesis of
certain blood components, however artificial blood is not used as a complete
replacement for real blood
one in 3 people will require the use of donated blood in their life but there aren’t
enough people donating
this means that artificial blood is often required, but the technology to fully
replicate and use it safely is not avilable yet
- outline the need for oxygen in living cells and explain why removal of
carbon dioxide from cells is essential
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2.6
removal of carbon dioxide is essential as too much carbon dioxide raises the
acidity of the blood
this is an issue as it will cause the enzymes used in our metabolism to denature
and the organism will suffer
oxygen is required in blood for respiration to occur
this allows our cells to reproduce and repair in our body
- describe current theories about processes responsible for the movement of
materials through plants in xylem and phloem tissue
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2.7
xylem pulls water and minerals up the plant, from the roots to the leaves
this is called transpirational pull
phloem moves organic material up and down the plant
- choose equipment or resources to perform a first-hand investigation to gather
first-hand data to draw transverse and longitudinal sections of phloem and
xylem tissue
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diagrams are in last years study notes
3.1
- explain why the concentration of water in cells should be maintained within
a narrow range for optimal function
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3.2
cells require an amount of water to function, providing them with nutrients and
removing wastes
too much water will effectively drown the cell
too little will dehydrate it, the lack of nutrients and build up of wastes killing it
- explain why the removal of wastes is essential for continued metabolic
activity
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3.3
wastes in the body take the form of uric acid, ammonia or urea, depending on
the organism
these chemicals are extremely toxic and harmful to the body
if they are not removed, they will poison the cells, halting the metabolic activity
by denaturing the enzymes and killing the cells
- identify the role of the kidney in the excretory system of fish and mammals
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3.4
the role of the kidney in mammals and fish is to filter out waste
blood enters the kidneys and all of the nutrients it carries are moved into the
Bowman’s capsules
the usable nutrients are filtered back into the blood while the useless ones and
wastes are expelled through urination
- explain why the processes of diffusion and osmosis are inadequate in
removing nitrogenous wastes in some organisms
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3.5
this is only possible for fish to do as the ammonia taken from the blood in its
purist form is instantly washed away, impossible on land
this means terrestrial organisms must convert the pure waste into less toxic
forms before expulsion
- distinguish between active and passive transport and relate these to processes
occurring in the mammalian kidney
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3.6
active transport requires energy and is the movement of a substance from a low
concentration to a high concentration
an example of this is an ion pump, like the sodium-potassium pump
passive transport requires no energy and is the movement of water from an area
of high concentration to low concentration
an example of this is diluting wastes for expulsion via urination
- explain how the processes of filtration and reabsorption in the mammalian
nephron regulate body fluid composition
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the nephron acts as a regulator in the kidney for minerals and other nutrients
the nephron tubules take in any excess substance and delivers it into an area of
lower concentration
3.7
- outline the role of the hormones, aldosterone and ADH (anti-diuretic
hormone) in the regulation of water and salt levels in the blood
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3.8
ADH is released when the receptor cells in the kidney detect low water
concentration
it acts on the collecting ducts, making their membrane more permeable to water
low salt levels in the blood are picked up by receptor cells in the adrenal cortex
of the kidney and aldosterone is released
it increases permeability of the membrane of the nephron tubules to sodium
- 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
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3.9
3.S.7
enantiostasis is the maintenance of metabolic and physiological functions in
response to variations in the environment
some organisms alter their behaviour, by burrowing into the sand or hiding in a
shell
some swim quickly away from the changing conditions
some change their internal state to match that of the extaernal change, called
osmoconformers
plants can discard excess salt through their leaves or store it and shed the leaves
- describe adaptations of a range of terrestrial Australian plants that assist in
minimising water loss
AND
- performa first-hand investigation to gather information about structures in
plants that assist in the conservation of water
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waxy cuticles on the leaves prevent losing water through the pores on them
some leaves are curled to avoid water falling from them
some leaves have small hairs on them, allowing them to catch water
large root systems, spreading over as much distance as possible
mangroves have root structures prtruding from the ground, so as they can gather
rainwater and avoid too much salt water
3.S.1
- 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
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3.S.2
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we identified cortex, medulla, pelvis, renal artery, renal vein and ureter
diagram in prac book
- gather, process and analyse information from secondary sources to compare
the process of renal dialysis with the function of the kidney
dialysis works with the same crucial effect as the kidney: to filter nitrogenous
wastes from the blood and remove them from the body
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3.S.3
in haemodialysis blood is circulated outside of the body into a machine that
cleans it before returning it to the patient
this is done by diffusion, emulating the kidney
in peritoneal dialysis the peritoneal membrane of the patient is used
waste is passed into the dialysate (which is pumped through a machine) and then
removed from the body
- present information to outline the general use of hormone replacement
therapy in people who cannot secrete aldosterone
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aldosterone replacement can be taken as a tablet
this is a synthetic steroid called fludrocortisone (sold as Florinef)
if severe insufficiency occurs patients may experience lower back pain,
diarrhoea, vomiting, low blood pressure and loss of consciousness, followed by
death
3.S.4
- analyse information from secondary sources to compare and explain the
differences in urine concentration of terrestrial mammals, marine fish and
freshwater fish
AND
- use available evidence to explain the relationship between the conservation
of water and the production and excretion of concentrated nitrogenous wastes
in a range of Australian insects and terrestrial mammals
3.S.5
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mammals have dilute urine, as their cells cannot tolerate the high toxicity of
ammonia that is the purest form of nitrogenous waste
this means they have to expend water to dilute it, but as most mammals have
sources of water readily available to them, this is no concern
insects and birds do not have the water conservation structures that most
mammals do, so they must excrete the waste using as little water as possible
this involves converting it into pellets or a dry paste, any unused water leftover
from this conversion process being reabsorbed
fish have the option of excreting said waste in its most toxic form, as it can be
instantly diluted and washed away upon contact with the water
marine fish, that is those residing in saline environments, can afford to keep less
toxic wastes in their system as they are constantly taking water and salts in
freshwater fish have more concentrated water levels in their body than in the
surrounding environment so they are constantly expelling water anyway as it
would flood their cells otherwise
this allows them to expel their wastes easily