Biology Flashcards
Identify the role of enzymes in metabolism, describe their chemical composition and use a simple model to describe their specificity on substrates
CHEMICAL COMPOSITION:
Globular proteins; increase reaction rate (catalyse)
Unchanged at end of reaction
Bind to substrate (active site)
Protein molecules (amino acid chain) fold in specific shape
Act on reactant molecule (substrate) fit with at specific location on enzyme molecule surface (active site)
ROLE IN METABOLISM:
Acceleration of chemical reactions
Lowers activation energy needed for reaction; reaction starts quickly without temp change
Lowering of activation energy
Brings specific molecules together (instead of relying on random collisions)
Action on specific substrates
Only one particular enzyme works on one particular substrate molecules
Active site is reciprocally shaped to bind with that molecule
CHARACTERISTICS:
Temperature sensitive
Function best at body temp (above 60℃→ stop working)
Heat breaks hydrogen bonds→ alters active site (not reciprocally shaped)
Temp too high or low→ will denature
pH sensitive
Narrow pH range functions efficiently; levels outside optimum; alters shape
Substrate specific
Each enzyme catalyses one particular reaction; act on one substrate
MODELS:
Induced fit
Enzyme changes shape as substrate approaches (molecules flexible)
Reaction occurs, substrate changes, product released (enzyme returns to original form)
E.g. Gloved hand changes to catch ball; active site is palm, closes around ball when it draws near
Lock and key
Simply fits into active site to form immediate reaction (not considered accurate)
Depends on unlikely random collisions between enzyme and substrate
E.g. Like trying to get key in lock by throwing key at lock with eyes closed
Identify data sources, plan, choose equipment or resources and perform a first hand investigation to test the effect of:
- Increased temperature
- Change in pH
INCREASED TEMP:
Milk with rennin; curdled quickly (temp approx 370C)
Temps higher or lower than optimum→ milk with rennin doesn’t curdle (doesn’t react)
CHANGE IN pH:
pH affects activity of catalase in potato tissue (has optimum pH)
Height of foam measured when catalase put in hydrogen peroxide
pH of 9 is optimum for catalase (average bubble height was higher)
Identify the pH as a way of describing the acidity of a substance
pH scale→ indicates acidity
Lower value; acidic, Higher value ;alkaline
Explain why the maintenance of a constant internal environment is important for optimal metabolic efficiency
Stable for enzyme functioning→ maintain metabolism (enzymes sensitive to change)
Small variations from narrow range→ small decreases in activity
Larger variation from narrow range → reduced metabolic efficiency
Gather, process and analyse information from secondary sources and use available evidence to develop a model of a feedback mechanism
Stimuli→ increased or decreased body temp (E.g. hot/cold surroundings, exercise)
Co-ordinating centre→ Hypothalamus detects change; activates cooling or warming mechanism
Effectors:
- High temp; Skin vessels dilate (blood carries heat to skin surface) Sweat glands (evaporate)
- Low temp; Skin vessel constrict (reduce heat loss from skin surface) Skeletal muscles (shiver)
Negative feedback loop→ body temp increases or decreases, hypothalamus shuts off warming or cooling mechanism
Describe homeostasis, as the process by which organisms maintain a relatively stable internal environment
Maintenance of constant (or almost) internal state, regardless of external environmental change
Body regulates respiratory gas, protects against pathogens, maintain salt/fluid balance, constant temp
Regardless of environmental change→ body temp, blood pH, water/salt balance, blood pressure, oxygen, carbon dioxide concentration; kept constant.
Explain that homoeostasis consists of 2 stages:
- Detecting changes from the stable state
- Counteracting changes from the stable stage
Any internal deviation must be quickly corrected. Counteract; use corrective mechanism
Stage 1: Detect change from stable state: Receptors detect change. E.g. Thermoreceptors in skin
Stage 2: Counteract change: Effector (muscle or gland) receives message to counteract change. Response initiated to reverse change, restore body to stable. E.g. Muscles shiver to generate heat
If variation exceeds normal; NEGATIVE FEEDBACK counteracts, returns body to homeostasis
Analyse information from secondary sources to describe adaptations and responses that have occurred in Australian organisms to assist temperature regulation
GENERATE HEAT:
Shivering: Rapid muscle contractions
Increased metabolism; Activity of thyroid gland stimulated, speeds up metabolism
RETAIN HEAT:
Raised hair: traps warm air, reduces heat loss by convection. Muscles contract
Vasoconstriction: Blood vessels construct so heat carried in blood is redirected to core of body, prevents heat loss from body surface
RELEASE HEAT:
Vasodilation: Arterioles expand, blood directed to body surface, heat lost by radiation, convection
Sweating: liquid secreted onto skin, heat removed to evaporate liquid
GENERATE LESS HEAT:
Decreased metabolism: Thyroid gland lowers metabolism, generates less heat
Flattened hairs: Laid flat, increases heat loss
Outline the role of the nervous system in detecting and responding to environmental changes
Function of nervous system→ coordination
Receptors; Thermoreceptors, hypothalamus detects change → converts to message, travels along nerves in CNS (brain, spinal cord)
Control centre: CNS processes info about change in specific parts of brain
Motor nerves; Carry info as nerve impulses from CNS to effectors
Effectors: Muscle or gland receives impulses, instruct effectors to respond
Response; Counteracts original change; ensures homeostasis
Identify the broad range of temperatures over which life is found compared with the narrow limits for individual species
Living creatures can survive temps of -70℃ (poles), high as 56℃ (deserts), 350℃ ( hot vents in sea)
Individual species need much narrower range of temp (have optimum temp they function at)
Tolerance range; temp range species can survive, usually few degrees outside of optimum
Compare responses of named Australian ectothermic and endothermic organisms to changes in the ambient temperature and explain how these responses assist temperature regulation
Endothermic; maintain constant internal temp; using internal metabolism to generate heat (mammals)
Ectothermic: Body temp governed by external heat sources, environment regulates temp (reptiles)
ENDOTHERMIC: RED KANGAROO
Hottest part of day→ seek shade; tail, hind legs shade by body (reduces surface are exposed to sun)
Lowers body temp
ECTOTHERMIC: BLUE TONGUE LIZARD
Cold weather→ remain inactive (buried in shelter) lowers metabolic rate→ conserve energy
Sunny days→ emerge to bask→ raises temp
Identify some responses of plants to temperature change
LEAF FALL:
Hot conditions→ plants drop leaves (reduces surface area to sun, reduces water loss through transpiration)
SHINY LEAVES:
Reflect solar radiation→ reduces heat absorbed
ORIENTATION:
Vertical orientation→ reduces surface area to sun, reduces amount of heat exposed to)
ICE FORMATION BETWEEN CELLS:
Temps below freezing→ ice form in cells, forms in gaps between plant cells; cell walls protects cytoplasm being pierced by ice crystal→ cell survives
PLANTS AND ANIMALS TRANSPORT DISSOLVED NUTRIENTS AND GASES IN A FLUID MEDIUM
Transport system; distributes food/oxygen to cells, removes carbon dioxide and waste
Blood; fluid transport medium; contains 3 types of cells
RBC: Carry oxygen, maintain pH of blood
WBC: Part of immune system, protects against invading organism
Platelets: Clotting of blood, stops blood loss
Plasma; Makes up most blood volume; carries nutrients, gases etc
Identify the form(s) in which each of the following is carried in mammalian blood:
- Carbon dioxide
- Oxygen - Water
- Salts - Lipids
- Nitrogenous wastes
- Other products of digestion
OXYGEN
Carried from lungs to heart, body tissues
98.5% as hemoglobin in RBC, 1.5% dissolved in plasma
CARBON DIOXIDE:
Cellular respiration product carried to lungs
70% as hydrogen carbonate ions, 7% as plasma, 23% combined with haemoglobin
Travels in RBC, plasma
WATER:
Reabsorbed from nephron to body cells
Travels in plasma as water molecules
SALTS:
Reabsorbed from nephrons to all body cells.
Dissolved in plasma as ions
LIPIDS:
Absorbed across villi wall of small intestine to veins in shoulder,
As fatty acids, glycerol dissolved in plasma
NITROGENOUS WASTES :
Urea processed in liver → moves into blood
Transported dissolved in plasma to kidneys (removed across nephrons)
OTHER PRODUCTS OF DIGESTION (AMINO ACIDS, GLUCOSE) :
Proteins broken down into amino acids, transported across small intestine wall.
Dissolved in plasma to be absorbed into cells for making proteins
Perform a first- hand investigation to demonstrate the effect of dissolved carbon dioxide on the pH of water
Water in beaker (add universal indicator)
Blow bubbles with straw (carbon dioxide) for 2 mins
Colour will change→ estimate pH using colour chart (makes more acidic)
Perform a first hand investigation using the light microscope and prepared slides to gather information to estimate the size of red and white blood cells and draw scaled diagrams of each
Known diameter of RBC= 7.5um
Calculate field of view (mini grid) → on slide estimate number of RBC that fit across diameter of fov
Estimate number of WBC, repeat and compare with known
Explain the adaptive advantage of haemoglobin
Haemoglobin: Oxygen carrying molecule (carries 4 oxygen molecules)
Each RBC carried 200-300 million haemoglobin molecules→ so 800-1200 million oxygen molecules
Protein of 4 polypeptide chains (globins) bonded to iron containing group (haem)
INCREASES OXYGEN-CARRYING CAPACITY OF BLOOD:
1 haemoglobin molecule binds with 4 oxygen molecules
More oxygen can be carried in blood cells
INCREASES BINDING OF OXYGEN ONCE FIRST OXYGEN MOLECULE BINDS:
Bonding causes haemoglobin to change slightly, easier for subsequent oxygen molecules to bind
Increases rate and efficiency of oxygen intake
RELEASE OF OXYGEN INCREASED WHEN CARBON DIOXIDE IS PRESENT
Has to release oxygen from blood to where it’s needed
Metabolising cells release carbon dioxide (lowers pH)
Haemoglobin at lower pH has lowered attraction to oxygen (can release)
ENCLOSED IN RBC
If it were just dissolved in plasma, oxygen would upset osmotic plasma balance
Compare the structure of arteries, capillaries and veins in relation to their function
Arteries; Carry blood under pressure away from heart to other organs
Capillaries; Tiny blood vessels carry blood close to cells; link arteries and veins
Veins: Carry blood towards heart from other organs
ARTERIES:
Carry blood from heart to other body parts
Thick walls (withstand high pressure of pumped blood)
No valves→ pressure is high (not needed to stop backflow)
Elastic wall fibres→ increases elasticity, expand for increased blood volume pumped in each heartbeat
CAPILLARIES:
Brings blood into contact with tissue (chemical exchange in cells and bloodstream)
Large network to spread blood (no cell far away from blood supply)
Walls only 1 cell layer thick (efficient diffusion)
Small lumen→ Forces RBC to pass in single file (slows flow, increases exposed surface area for gaseous exchange)
VEINS:
Carry blood from tissues back to heart
Thinner walls→ blood flows in, not pumped
Wider lumen (easy blood flow)
Valves (small pocket folds→ lines lumen) → prevents backflow
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 see technologies are used.
Levels of chemical in blood→ indicate state of health
Changes in level→ ineffective metabolic functioning (results in poor health)
Carbon dioxide/oxygen concentrations in blood→ how well lungs function, blood circulates
PULSE OXIMETER
Clip with sensor placed on finger→ shows pulse rate and oxygen saturation level
Check blood oxygen levels; people with heart attacks, cancer etc (non-invasive)
ARTERIAL BLOOD GAS ANALYSIS (ABG)
Invasive→ blood removed from artery, blood analysed in sample
Used to discover is patient has lung/kidney disorder, lung disease
Details about level of chemicals in blood (pH, bicarbonate ions, oxygen levels)
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.
Circulatory system; transport of substances to and away from parts (gases, nutrients, wastes, hormones)
Metabolism→ relies in correct chemical balance brought to cells, removal of wastes
Function of organ→ determines difference in chemical concentration of blood entering or leaving
All organs→ Internal gae exchange (cellular respiration) lungs→ external
Deoxygenated blood→ arrives at lungs, releases CO2 and picks up oxygen→ Haemoglobin carries
CO2→ cells release,diffuses into capillaries→ carried in haemoglobin→ travels back via veins
BLOOD PASSING THROUGH LUNGS:
Increase Oxygen, & Decrease CO2
BLOOD PASSING THROUGH ANY ORGAN NOT LUNGS:
Decrease Oxygen & Increase CO2
BLOOD PASSING THROUGH ANY ORGAN INVOLVING ABSORBING DIGESTED FOOD:
Increase in digestive end products (glucose)
BLOOD PASSING THROUGH LIVER:
Decrease in digestive end products (E.g. Glucose, fatty acids, amino acids)
Increase nitrogenous wastes (Urea)
BLOOD PASSING THROUGH KIDNEY:
Decrease nitrogenous wastes (filter and excrete)
BLOOD PASSING THROUGH GLANDS:
Increase in hormones (secreted and travel to where needed)
Outline the need for oxygen in living cells and explain why removal of carbon dioxide from cells is essential
Oxygen→ necessary for cellular respiration (combines with glucose during CR to release energy ATP)
CO2→ Must be removed to prevent pH changes in cells and bloodstream
CO2 reacts with water (in cytoplasm or plasma) → forms carbonic acid (build up is toxic) lowers pH
Lowered pH→ prevents enzyme functioning (reduces metabolic efficiency)
Analyse information from secondary sources to identify the products extracted from donated blood and discuss the uses of these products
First transfusions (most killed) 120 years ago → discover specific blood types (incompatible groups= fatal)
Before blood donations→ cross matching of blood groups needed
RBC→ helps patients carry more oxygen (helps replace lost cells after bleeding)
Platelet→ treats bleeding from diseases where platelets don’t function properly
Frozen plasma→ patients who need immediate clotting (E.g. After large transfusions
LIABLE PRODUCTS:
Perishable→ short shelf life
Need to be transported in refrigerated conditions
E.g. RBC, platelets, plasma
STABLE PRODUCTS:
Longer shelf life
Produced by- separating different protein components from plasma
E.g. Blood clotting factors, immunoglobulins
Describe current theories about processes responsible for the movement of materials through plants in xylem and phloem
XYLEM:
Carries water ions from roots to leaves
Made of vessels, tracheids, fibres, parenchyma cells
Transpiration stream theory
Water sucked up stem; evaporative pull of transpiration
Water drawn up tubes; replace water loss from evaporation in leaves
Evidence:
Vessels are hollow→ offer little resistance to water
Concentration gradient; leaf surface (high), centre of leaf (low) creates tension as moves across gradient→ doesn’t break due to cohesion/adhesion of molecules
PHLOEM:
Carries nutrients (sugars, amino acids) to all parts of plant, moves both ways
Made of fibres, parenchyma, sieve cells and companion cells
Pressure flow theory
Active process (needs energy) driven by osmotic pressure gradients (generated by differences in sugar water concentration)
Sugar loaded into phloem at source then uploads into surrounding tissue (sink)
Loading attracts water flow (osmotic pressure)
Offloading at sink→ water moves out
Analyse and present information from secondary sources to report on progress in the production of artificial blood and use available evidence to propose reasons why such research is needed
Past→ attempts to treat bleeding in WW1 & WW2→ failed. Encouraged modern artificial blood
Blood transfusions work (Problems; need cross matching and short storage life)
1980’s→ urgent research; response to sudden appearence of HIV in blood transfusion patients
AIDS crisis in South Africa- driving force in becoming one of the first countries to clear artificial blood for limited use in patients
IDEAL CHARACTERISTICS:
Can be stored for long periods of time and easily transported
Doesn’t need to be cross matched for different blood types
Continues to circulate (doesn’t settle) and has no toxic effects on body
When patient’s own blood is restored→ can be safely excreted
Oxygen carriers being developed: Perfluorocarbons, haemoglobin based oxygen carriers and microcapsules
PERFLUROCARBONS:
Carry oxygen in dissolved forms
Carry up to 50x more dissolved oxygen than plasma
HAEMOGLOBIN BASED OXYGEN CARRIERS:
Extract haemoglobin from outdated human blood; modify for use in artificial blood
MICROCAPSULES:
Artificial red cell currently being developed as microcapsules
Phospholipid- haemoglobin can be placed inside
Explain why the concentration of water in cells should be maintained within a narrow range for optimal function
Changes in water concentration lead to corresponding changes in solute concentration in cells
Water in cells→ determines osmotic pressure of cells
Water moves by osmosis→ water movement into/ out of cells depends on solute concentration inside/ out of cells
Water provides necessary medium in which all chemical reactions of metabolism occur:
Chemical reactions occur→ only if reactants are dissolved in water; levels must be constant
Water concentration; Too much→ cells may burst. Too little→ cell contents shrink
Too little water→ increase in solute concentration→ lowers pH (must be maintained→ enzymes)
Water accumulates→ may dilute reactants and slow down metabolism
Explain why the removal of wastes is essential for continued metabolic activity
Accumulation of wastes is toxic→ must be removed to maintain homeostasis
If build up→ alters conditions→ stops enzyme functioning. Can change pH→ stops enzymes
Accumulation that doesn’t alter pH→ alters reaction rates, osmotic imbalance→ affects membrane functioning
E.g. Accumulation of Carbon Dioxide→ internal environment becomes too acidic
Gather, process and analyse information from secondary sources to compare the process of renal dialysis with the function of the kidney
KIDNEY:
Filters blood, remove waste/excess fluids→ turn into urine (excreted)
Passive: Glomerular capillaries diffuse wastes through membrane
Active: Reabsorption in nephrons, wastes reused into bloodstream
180 L blood filters everyday (entire blood volume filtered 20-25 x per day)
Maintains chemical balance in blood
RENAL DIALYSIS:
Carries out function of failed kidneys (cleans blood)
Haemodialysis→ transfers blood to machine to be filtered before returned to body
Glucose levels same in fluid (so doesn’t diffuse)
Passive transport; diffusion of substances in dialysis membrane between blood and fluid
Blood filtered for 3-4 hours (2-3 times a week)
Removes wastes to stop accumulating; maintains chemical balance in blood
Identify the role of the kidney in the excretory systems of fish and mammals
Water accumulates in body→ by eating/drinking, metabolism. Nitrogenous wastes→ metabolism
Water potential: Tendency of a solution to lose water by osmosis (typical; high water concentration)
Water concentration in environment; Determines organism’s need to conserve or lose water
FRESHWATER FISH:
Live in rivers/lakes (high water potential) water freely available (few salts)
Urinate frequently; water accumulates (osmosis→ high concentration surroundings to low in fish)
Too much water in bodies→ Kidneys excrete excess and wastes. Conserve salt
MARINE FISH:
Live in sea- urinate less (lose body water across gills to surroundings)
Salt diffuses into bodies→ main kidney function (remove excess)
Kidneys conserve water rather than extract
TERRESTRIAL MAMMAL:
Water and salt loss from body;respiration ,excretion (sweat, urine)
Control mechanism; ensure balance maintained of amount excreted
Urine; dilute or concentrated (adjusted depending on body needs)
Large amount of salt lost by sweat→ needs replacing for stable osmotic pressure in body
Explain why the process of diffusion and osmosis are inadequate in removing dissolved nitrogenous wastes in some organisms.
Both are slow (rely on concentration gradient difference; slows as difference is smaller, stops; equal)
Solution; combine active transport and osmosis (quick; removes waste even against gradient)
Used to pump salts from urine back into kidney (draws water with them by osmosis)
PROBLEMS WITH DIFFUSION:
Rate of movement is slow
Wastes must be dissolved with water when removed→ Concentrations equalise movement slows and stops
Not all wastes can be removed by diffusion
If concentrations equalise and no further wastes removed→ pH would be altered
PROBLEMS WITH OSMOSIS:
Too much water may be lost in urine
Contains too much nitrogenous wastes, water will be drawn into urine to dilute waste (equalise concentration) → dilute urine (loses too much)
Movement of water may make wastes too dilute for excretion by diffusion
Slows down excretion by diffusion (lowers concentration gradient)
Present information to outline the general use of hormone replacement therapy in people who cannot secrete aldosterone
Adrenocortical insufficiency (Addison’s disease) some immune systems cause inflammation in own glands, other causes are tuberculosis and cancer Decreased secretion of aldosterone→ increased sodium loss Clinically; Person is weak, thin, have salt-cravings, faintness, feel light-headed, low blood-sugar Most patients → require treatment with fludrocortisone plus cortisone as a replacement glucocorticoid
Distinguish between active and passive transport and relate these to processes occurring in the mammalian kidney
Passive→ diffusion, osmosis (molecules move along concentration gradient) no energy input
Active→ needs cellular energy to move molecules against concentration gradient
Diffusion; Particles from region of high concentration to low until equilibrium is reached
Osmosis; water molecules from high water concentration to low,through semi permeable membrane
PASSIVE TRANSPORT IN KIDNEY:
Limitations; relies on difference in concentration gradient (slow)
Tubules→ wastes from bloodstream to be excreted as urine
Substances needed→ removed from urine and returned to bloodstream
Passive moves water (osmosis), some wastes (ammonia, urea) into kidney
ACTIVE TRANSPORT IN KIDNEY:
Sometimes have to move against gradient
Carrier proteins spans membrane and carrier molecule actively move chemicals from low to high concentration using cellular energy
Mainly sodium ions, glucose, amino acids across wall of nephron (reabsorbed)
Sodium pump in tubules→ transports salts from urine back into kidney (conserve salt and water→ salt draws water)
Analyse information from secondary sources to compare and explain the differences in urine concentration of terrestrial mammals, marine fish and freshwater fish.
Urine concentration; depends on need to conserve water.
High solute; concentrated. Low solute; dilute
FRESHWATER FISH:
Only dilute
Sources; drinks, osmosis into fish
MARINE FISH:
Only concentrated
Sources; Drinks,osmosis out of fish
TERRESTRIAL MAMMAL:
Conserve water (concentrated)
Consumes water (dilute
Source; Drinking, eating
Explain how the processes of filtration and reabsorption in the mammalian nephron regulate body fluid composition
FILTRATION:
Occurs between glomerulus, lining of Bowman’s capsule
High pressure; blood flowing through glomerulus (small substances squeeze through capillary wall under pressure→ pass through cell layer in Bowman’s capsule→ move into lumen)
Pass through; blood cells, proteins, water→ carry dissolved amino acids, glucose, salts, wastes (fluid; glomerular filtrate)
Substances body needs; reabsorbed into bloodstream (so not lost with urine)
REABSORPTION:
Filtrate with molecules needed; amino acids, glucose→ actively reabsorbed into proximal tubule
Passed to interstitial fluid, capillaries surrounding nephron→ to renal vein; carried back to general circulation
99% water reabsorbed by osmosis, only 1% excreted as urine
Ascending loop→ salts actively pumped into interstitial fluid in medulla (draw water out by osmosis)
SECRETION:
Toxic substances removed from capillaries, tissues
Drugs secreted in proximal tubule, urea in descending loop of Henle
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
Limited water availability→ must conserve water and excrete waste
High water availability→ water conservation not necessary (waste may be dilute)
Moth, blowfly→ uric acid as paste (low toxic) high energy needed, but conserve water
Spinifex hopping mouse→ concentrated urea; conserve water (moderate toxic)
Humans, moth, blowfly→ water not freely available (must be sourced)
Outline the role of the hormones, aldosterone and ADH (anti- diuretic hormone) in the regulation of water and salt levels in blood
ADH
Dehydration, blood volume drops→ detected by hypothalamus in brain; stimulates pituitary gland to release ADH→ acts on nephrons to increase reabsorption of water
Increases permeability of membranes lining distal, collecting tubule; water reabsorbed (conserved)
ALDOSTERONE
Decrease in sodium ion concentration in blood→ secreted from adrenal gland cortex (above kidney)
Aldosterone via bloodstream reaches kidney; increase permeability of nephron to sodium→ reabsorption into surrounding kidney tissue (less lost by urine)
Process and analyse information from secondary sources and use available evidence to discuss processes used by different plants for salt regulation in saline environments.
MANGROVE:
Concentrate salt accumulation to certain parts (leaf) → fall off, salt leaves mangrove.
Leaves; salt glands secrete salt entering; can be blown or washed away
Roots; first line of defense→ filter out incoming salt
BLADDER SALTBUSH:
alt enters roots, travels to leaves. Stored in vacuole and moves to bladder cell
Bladder cell ruptures→ salt released
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 concentration
Enantiostasis:
Survival mechanism; organisms cope with extreme fluctuations in environmental conditions
Estuary:
Water/salt concentrations fluctuate daily→ high tide; salt in river. Low tide; freshwater in
Organisms need to maintain normal metabolic functioning (despite fluctuations)
OSMOCONFORMERS:
Tolerate change; alter internal solute concentration to match external environment
E.g. Fiddler crab accumulates additional solutes in high salt, then pumps out excess when low salt
OSMOREGULATORS:
Avoid change in internal environment; keep solutes at optimal level regardless of environment
E.g. Mussels in rock pools close valves when tide it out (keeps salt concentrate same as seawater)
Perform a first-hand investigation to gather information about structures in plants that assist in the conservation of water.
SHEOAKS:
Needle like leaves→ reduces surface area, reduces water loss
EUCALYPTUS:
Waxy cuticle→ reflects sun, reduces water loss by evaporation
Leaves hang vertically→ reduces exposure to sun
GREVILLEA:
Small curled leaves→ Retain more water
Hairy leaves→ hair returns water, increases humidity
WATTLE:
Grey colour→ Light colour to reflect sunlight, reduces evaporation
Hair on undersurface→ retains water
Describe adaptations of a range of terrestrial Australian plants that assist in minimising water loss.
Needle-like leaves→ reduces surface area, water loss. E.g.She-oakes
Woody fruits→ Less water loss that in fleshy fruits. E.g She-oakes
Leaf curling→ Reduce surface area. Traps humid layer of air→ reduced water loss.
Hanging leaves→ reduce exposure to sun
Hairy/shiny leaves→ hairy undersurface→ reduces air movement, increase humidity→ less water loss. Upper surface, reflects radiation from sun (reduced heat gain)
Water directing leaves/stems→ shaped so water runs down to roots. E.g. Acacia
EVIDENCE OF EVOLUTION SUGGESTS THAT THE MECHANISMS OF INHERITANCE, ACCOMPANIED BY SELECTION, ALLOW CHANGE OVER MANY GENERATIONS
Macro evolution→ Millions of years, arising new species. E.g wolf and dog from common ancestor
Micro evolution→Shorter time periods, pop changes but no new species. E.g. Different dog breeds
Outline the impact on the evolution of plants and animals of
- Changes in physical conditions in environment
- Changes in chemical conditions in environment
- Competition for resources
- Changes in physical conditions in environment
Early organisms; water to land habitat→ reduced UV radiation (ozone forming)
Aus climate; cool/wet→ hot/dry, rain forests to woodland,
Lakes dry up→ evolution to conserve water
Ice age→ change in sea levels, temp. Dinosaurs→ meteorite; reduced light, plant life→ no food - Changes in chemical conditions in environment
First life; anoxic environment; some produced CO2; led to photosynthetic organisms
Increased oxygen levels; evolution of organisms using oxygen (complex-diverse animals today)
E.g. Peppered moth; industrial revolution. Black moth protected from soot; white stand out and killed - Competition for resources
Comp for light, soil, nutrients, water, shelter, mates, territory
Organisms compete; most successful survive and reproduce; pass on genes
Plan, choose equipment or resources and perform a first-hand investigation to model natural selection
Pop begins with 30 moths (10 black, grey, white) → chart works out offspring colours.
Spin for predator (colour removed) shuffle cards; repeat until trend recognisable; dominant species?
Analyse information from secondary sources to prepare a case study to show how an environmental change can lead to changes in species (SNOW GUM)
HIGH ALTITUDE: Cold, shallow soil, exposed to snow Small and twisted to bend away from elements. Short leaves Large fruit Thin bark More resistance to frost Short trees
LOW ALTITUDE: Warm, high precipitation, Tall and straight to receive nutrients and rainfall Long leaves Small fruit Thick bark Less resistance to frost Tall trees
Describe, using specific examples, how the theory of evolution is supported by the following areas of study:
- Palaeontology, including fossils that have been considered as transitional forms,
- Biogeography,
- Comparative embryology,
- Comparative anatomy,
- Biochemistry
PALAEONTOLOGY:
Scientific study of fossils and extinct life
Fossils→ evidence of past life forms; evolutionary transitions to modern living forms
Undisturbed rock fossils; show sequence living things arose; have common features (change over time)
E.g. Lobe- finned fish; bones in fin→ dragging from water to land (amphibians evolved from fish)
Limitations; fossil record incomplete, bias to fossils with body/environment better suited to fossilisation
BIOGEOGRAPHY:
Study of geographical distribution of organisms
Darwin/Wallace theory; new species; group isolated from rest→ thought species close; similar, far apart; different
E.g. Flightless birds/continental drift→ common Gondwana ancestor; different pop evolved on continents. E.g. Emu in Aus, Kiwi in NZ→ share similar features; flat breastbone
COMPARATIVE EMBRYOLOGY:
Comparison of similarities in vertebrate early embryos
Embryos of closely related organisms have homologous parts→ support common ancestor
E.g. Fish, bird, mammal, reptile embryos; gill slits, tails (later internal gills in fish)
COMPARATIVE ANATOMY:
Similarities in organisms structure (similarities; common ancestor, differences; modification) evolution
Limitations; fossils often incomplete→ hard to compare with extinct life form
E.g. Pentadactyl limb; (homologous structure) same basic sequence of bones in dog, human, bird;
BIOCHEMISTRY:
DNA hybridisation:
Compare DNA sequence of 2 organisms; unzip, zip codes to match
E.g. Heat applied to chimpanzee, human DNA→ high temp means more closely related; 83℃
Amino acid sequencing
Similarities in protein sequencing→ Similarities; shared ancestor. Differences; evolved over time
E.g. Humans. chimps→ identical sequence in haemoglobin. More related than gibbons,humans (3 differences)
Use available evidence to analyse using a named example, how advances in technology have changed scientific thinking about evolutionary relationships (CLASSIFICATION OF PRIMATES CHANGED)
DNA in amino acid sequencing, DNA hybridisation→ new biochemical evidence
Historically; orangutans, gorillas, chimps→ 1 family, humans another (based on structure of leg, teeth)
60’s→ Chimps, humans→ identical haemoglobin, cytochrome c sequence→ different to gorilla
Humans, chimps small DNA difference, (more closely related than orangutans→ diverged earlier)
New genetic tree→ humans, chimps diverged more recently from common ancestor
Explain how Darwin/Wallace’s theory of evolution by natural selection and isolation accounts for divergent evolution and convergent evolution
Proposed; variations within species and more offspring produced than can survive and reproduce
Some individuals have adaptive characteristics; enable survival better→ passed on to next generation
Over time; natural selection→ pop with adaptations most suited to environment
Source of variation; gene mutation; phenotypic advantage
Isolation; if species pop geographically isolated, interbreeding stops; separate species develop
Divergent; one species forms other with adaptations suited to variety of environments
E.g. Aus marsupials; evolved from common possum like ancestor; common structure, but dominant differences
Convergent; Organisms come to resemble each other; share similar environment, perform same function. E.g. Streamline dolphin/shark body for swimming in sea. Similar but dolphin; mammal, shark; fish
Analyse information from secondary sources on the historical development of theories of evolution and use available evidence to assess social and political influences on these developments
England 1858→ Darwin/Wallace published theory
Invention of machinery, people flocked to cities (disease) social changes in class, French revolution
New discoveries; people looked to science.
Outline the experiments carried out by Gregor Mendel
Heredity in garden peas; pure bred (consistent characteristics) Deliberately crossed one variety with another→ observed next generation Removed stamens (so no self pollination) repeated experiments, kept records Monohybrid cross; Offspring of cross (F1) Crossbred tall x short (all offspring tall) Tall then grew (F2) F2 most tall, some short (3:1) Law of segregation; 2 genes that control each characteristic; segregate during reproduction; 1 factor each in a gamete→ factors recombine at fertilisation (match together) Law of Independent assortment; Pairs segregate independently of other pairsof factors Reproductive cells combine at fertilisation; offspring had one factor for tallness and one for shortness→ only tallness observed (dominated shortness)
Describe the aspects of the experimental techniques used by Mendel that led to his success
Cross pollinated by hand, studied large number of characteristics
Used quantitative data, studied characteristics one at a time
By chance→ characteristics he studied carried out on different chromosome
Studied separately characterises occurring in pairs (tall or short) previously; whole plant studied
Solve problems involving monohybrid crosses using Punnett squares or other appropriate techniques
Check for dominance and assign symbols
Write down parents phenotype and genotype
Write down parents gametes gametes, noting only one allele for characteristic in gamete
Make punnett square and write down all possible crosses underneath
Describe outcomes of monohybrid crosses involving simple dominance using Mendel’s explanations
2 different parents→ F1 generation only has dominant trait
F1 crossed→ F2 generation has dominant trait, recessive trait in (3:1)
Process information from secondary sources to describe an example of hybridisation within a species and explain the purpose of this hybridisation
Hybridisation; Crossbreeding two genetically non-identical individuals
Parents with desirable traits selected; offspring reflecting desired traits further breed; hybrid offspring
E.g. Hybridisation within species: Labradoodle (Labrador x Poodle) → successful hybridisation leads to hybrid vigour (increased strength, better health, greater fertility)
ADVANTAGES:
Increases genetic variety
Combine best features of each parent→ hybrid vigour
DISADVANTAGES:
May combine weaker features of parents→ offspring have less stamina, resistance to disease etc
Very expensive (especially if no hybrid vigour)
Sometimes offspring are infertile or reduced fertility
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
Homozygous→ Identical alleles of a particular gene for a characteristic.
E.g. TT, tt, HH, hh
Heterozygous→ Two different alleles of a particular gene for a characteristic.
E.g. Aa, Bb, Ee
