Outcomes
· Conducts investigations to collect valid and reliable primary and
secondary data information
· Selects and processes appropriate qualitative and quantitative
data and information using a range of appropriate media
· Describes single cells as the basis for all life by analysing and
explaining cells ultrastructure and biochemical processes
Content Focus
Cells are the basis of life. They coordinate activities to form
colonial and multicellular organisms. Students examine the
structure and function of organisms at both the cellular and tissue
levels in order to describe how they facilitate the efficient
provision and removal of materials to and from all cells in
organisms. They are introduced to and investigate biochemical
processes through the application of working scientifically skills
processes.
These tools will be used throughout the course to assist in making
predictions and solving problems of a multidisciplinary
nature.
Content
· Investigate different cellular structures, including but not
limited to;
· Examining a variety of prokaryotic and eukaryotic cells
Prokaryote
Similarities
Eukaryote
· May contain plasmids
· Can be multi or unicellular
· DNA is arranged in linear chromosomes
· Located in nucleus
· Plant cells
· Many plant cells have a large vacuole
· Many plant cells contain chloroplasts
· Note: not ALL plant cells have a chloroplast
· Example; cells in the underground roots cannot photosynthesise,
so do not contain any chloroplasts
· Describe a range of technologies used to determine a cell’s
structure and function
Light microscope:
Energy Source
Treatment
Stains can be applied to highlight different components of the
cell
Image
Transmission electron microscope:
Treatment
Process
Image
Can display inside the cell or whole organism, multiple images can
create a 3D image
Electron microscope:
· Highly detailed
· Higher resolution
Scanning electron microscope:
Treatment
Stained, dehydrated, fixed specimen, coated in a thin layer of
metal atoms
Process
Image
· Investigate a variety of prokaryotic and eukaryotic cell
structures, including but not limited to;
· Drawing scaled diagrams of a variety of cells
Estimating cell size:
Cell structure and function:
Cytoplasm:
· A watery, gel-like substance
· Place where chemical reactions, food storage and other “cellular
activity” takes place
Nucleus:
· Control centre
· Explains how the cell should act
· When the cell makes a new cell it copies the DNA found here
Vacuoles:
· May store food or nutrients for the cell
Mitochondria:
· The powerhouse of the cell which releases energy from food
Endoplasmic reticulum:
· Forms a pathway to allow materials to move through the cell
Ribosomes:
· Found in animal cells
· Packs chemicals into small membrane vesicles for storage or
secretion
· Example of this is the lysosome
· Lysosomes: Garbage disposal units which remove waste
· Modelling the structure and function of the fluid mosaic model of
the cell membrane
Fluid mosaic structure:
· Selectively permeable membrane
· Can allow some substances to move into the cell while preventing
others from entering
· These membranes are dynamic structures that can form, change and
reform
· They are made from 2 thin sheets of phospholipid bilayer
sandwiched together and contain many types of embedded molecules
throughout its structure
· Phospholipid bilayers:
· Most important aspect of this layer is the structure of the
individual phospholipid
· Made of;
Cell Function
Inquiry Question: How do cells coordinate activities within their
internal environment and their external environment?
· Investigate the way in which materials can move into and out of
cells, including but not limited to;
· Conducting a practical investigation modelling diffusion and
osmosis
Diffusion:
· Passive movement of ANY particles in a solution from areas of
high to a low concentration until equilibrium is reached
· Passive as molecules are moving along the concentration
gradient
· Example; food dye in water
· Factors affecting the rate of diffusion:
· Concentration → greater difference in concentration = faster
diffusion
· Temperature → higher temp = faster diffusion occurs
· Particle size → smaller particles = faster rate
Facilitated diffusion:
· Some larger particles do not readily pass through the
phospholipid bilayer
· They require protein channels and carrier proteins to assist
them
Osmosis:
· Occurs when the concentration gradient involves dissolved
molecules or ions which CANNOT get through the membrane
· Refers to the net movement of water molecules across the
semipermeable membrane
Practical: Diffusion and Osmosis
Aim → to observe and describe an example of diffusion and osmosis
using a selectively permeable membrane
OBSERVATIONS
· Clear starch in tubing turned into a muggy, purple colour
· Colour suggests that yellow iodine from the water moved through
the tubing and reacted with the starch
· The initial appearance of the tubing was clear, therefore meaning
there was no obvious change
· Once the water mixed with solution and was heating, it turned a
solid orange colour suggesting the glucose had moved from the
tubing to the outside
Part A: Diffusion
Using 20ml of starch solution, pour into dialysis tubing and note
weight and colour, place this tubing in a 200ml beaker of water and
enough iodine that the water turns yellow. Leave for 20
minutes.
Part B: Osmosis
Using 20ml of 10% glucose solution, pour into dialysis tubing and
note weight and colour, place the tubing into water and leave for
20 minutes. Collect 5ml of the water from the beaker and place into
a test tube with 2ml of Benedict’s reagent added. Heat and note
colour changes. (NOTE: Benedict's turns from Blue to Orange in the
presence of glucose)
· Examining the roles of active transport, endocytosis and
exocytosis
Passive and active transport:
· Diffusion and osmosis happen automatically and not with the cell
having to use any energy → this is a passive transport
process
· Many other proteins, carbohydrates and other molecules regularly
move in and out of cells
· Cells have to deliberately move substances across the membrane
using ways other than diffusion and osmosis
· These ways require the cell to use the energy (ATP from cellular
respiration) to move substances → this is an active transport
process
· Active transport process: Sodium-Potassium Pump
Endocytosis:
· Membrane pinching outwards to surround the desired substance and
envelop it
· Membrane rejoins itself to seal the cell, leaving the targeted
substance inside
· Phagocytosis: (phago = eating, cyto = cell)
· Cell engulf a solid material to form a food vacuole
· Pinocytosis: (pino = drink)
· Receptor-mediated endocytosis:
Exocytosis
· Specialised cells need to remove wastes to distribute them to
other parts of the organism
· Exocytosis is the process by which cells are transported to the
external environment of the cell
· Membrane-bound vesicle moves to the cell membrane, fuses with it
and then releases its contents to the exterior of the cell
· Relating to the exchange of materials across membranes to the
surface-area-to-volume ratio, concentration gradients and
characteristics of the materials being exchanged
SA: V ratio:
· The surface-area-to-volume ratio gets smaller as the cell gets
larger
· If the cell grows past a certain point, not enough material will
be able to cross the membrane fast enough
· The amount of food, oxygen and other substances a cell needs
depends on its volume
SA divided by the V
SA → Total area of the cell membrane
V → space taken up by the total contents of the cell
Concentration gradients:
· The relative concentration of the substance on either side of the
membrane affects the rate of diffusion of that substance
· If the concentration gradient is high, then the substance will
diffuse rapidly
· In order to maintain a rapid rate of diffusion, cells need to
maintain a high concentration gradient
· As the concentration gradient decreases, the rate of diffusion
will be slower
· Once the concentration reaches equilibrium, there will be no net
movement across the cell membrane
· Investigate cell requirements, including but not limited
to:
Cell requirements:
· Exchange gases
· Obtain energy
· Remove waste
· Have suitable forms of energy, including light and chemical
energy in complex molecules
· Suitable forms of energy, including light energy and chemical
energy in complex molecules
Energy (ATP):
· All cells use glucose as the main source of energy
· When glucose is broken down, it’s energy is released
· It is trapped and stored in high energy molecules called
adenosine triphosphate
· Matter, including gases, simple nutrients and ions
Inorganic compounds:
· Compounds without carbon atoms or simple molecules with only 1 or
2 carbon atoms
· Water: makes up 70-90% of most organisms
· Oxygen: required for cellular respiration
· Carbon Dioxide: required for photosynthesis
· Nitrogen: key atom for 20 types of amino acids → proteins
· Minerals: important for building enzymes and vitamins
Organic Compounds:
· Complex chemicals: containing carbon and hydrogen atoms which are
found in living things:
· Carbohydrates: important energy source
· Proteins: composed of amino acids
· Nucleic Acid: composed of nucleotides
· Carry genetic information
· Removal of wastes
· These MUST be removed
· Excretion is the removal of any waste from an organism
· Accumulation of these waste products can prevent the normal
functioning of cells
· the cell membrane regulates the exit of waste products depending
on size and concentration
Waste removal from autotrophs:
· Plants produce no true waste
· Aquatic plants release waste into the water
Waste removal from heterotrophs:
Photosynthesis:
· The process by which plants utilise energy, typically from the
sun, which is trapped by chlorophyll
· It uses this energy to break apart water and carbon dioxide
molecules, build them up to oxygen, energy-storing glucose
molecules and water molecules
Cellular Respiration:
· All organisms break down glucose as a form of energy
· Glucose can be broken down either in the;
· Presence of oxygen (aerobic cellular respiration)
· Absence of oxygen (anaerobic cellular respiration)
· Conduct a practical investigation to model the action of enzymes
in cells
Enzyme notes:
· All organisms are adapted to a characteristic temperature
range
· This temp range allows the organism’s enzymes to control its
metabolism by operating at their optimum efficiency within this
range
· High temperatures → (80-100°C) → Thermophiles
· Extremely low temperatures → (0-4°C) → Psychrophiles
· Most mammals → (30-45°C)
· Most average around 37°C
Enzymes are biological catalysts. This means they lower the energy
required to start a chemical reaction within a cell but do not get
used up by the reaction.
Factors affecting enzymes:
· Lock-and-Key Model
· On the surface of the enzyme molecule is the “active site”
· According to the Lock-and-Key Model, the shape of an enzyme’s
active site is a perfect fit for the substrate
· Induced Fit Model
· A modified version of the Lock-and-Key Model
· According to the Induced Fit Model, the active site is somewhat
flexible and can change its shape in order to bond with the
substrate
Practicals on Enzyme Activity:
2. Substrate concentration: Hydrogen peroxide concentration
3. pH
· Investigate the effects of the environment on enzyme activity
through the collection of primary or secondary data
· Body temperature and pH are critical to survival because the
vital enzymes can only perform efficiently in a narrow range of
temperature and/or pH
BIOLOGY PRELIMINARY NOTES
Outcomes
· Solves scientific problems using primary and secondary data,
critical thinking skills and scientific processes
· Communicates scientific understanding using suitable language and
terminology for a specific audience or purpose
· Explains the structure and function of multicellular organisms
and describes how the coordinated activities of the cells, tissues
and organs contribute to macroscopic processes in organisms
Content Focus
Multicellular organisms typically consist of a number of
interdependent transport systems that range in complexity and allow
the organism to exchange nutrients, gases and wastes between the
internal and external environments. Students examine the
relationship between these transport systems and compare nutrient
and gas requirements.
Models of transport systems and structures have been developed over
time, based on evidence gathered from a variety of disciplines. The
interrelatedness of these transport systems is crucial in
maintaining health and in solving problems related to
sustainability in agriculture and ecology.
Content
Inquiry Question: How are cells arranged in a multicellular
organism?
· Compare the differences between unicellular, colonial and
multicellular organisms by:
· Investigating structures at the level of the cell and
organelle
Prac investigation: Comparing different types of cells
· Unicellular, colonial and multicellular organisms differ in their
cell size, cell functions and cell specialisation
Page 9 of Module 2 Notes
Name of Specimen
Type of Cell
Eukaryotes
Eukaryotes
One cell carries out all the functions to sustain life
Individual animals,
Cells are specialised to perform specific functions by the
organism
Cellular function
· Obtaining nutrients
· Exchanging gases
· Removing wastes
Functions are carried out with the cell
Functions are carried out by individuals with specific roles in the
colony
Functions are carried out at cellular, tissue, organ and system
level
Microscopic & Macroscopic
Usually macroscopic
Macroscopic
Increasing the number of cells allows for an increase in body
size
Life Span
Short lifespan:
Long lifespan
Long lifespan
Usually, specific zooids are responsible for reproduction
Only cells specialised for reproduction (gametes) will
reproduce
· Relating the structure of cells and cell specialisation to
function
Structural organisation of multicellular organisms:
Organelles
· Membrane-bound compartment or structure in a cell that performs a
special function
· Example: Mitochondria, vacuole
· Example: Root hair cell, lead guard cell
Tissues
· A group of similar cells working together to carry out a specific
function in multicellular organisms
· Example: Muscle tissue, root tissue
Organs
· Two or more tissues that work together to perform one or more
specialised tasks
· Example: Heart, liver, kidneys, flowers, leaves
Systems
· A group of organs that work together to perform a vital
task
Cell specialisation and differentiation:
· Specialisation: a specialised function for a cell
· Differentiation: the process where a cell changes from one type
to another, typically an unspecialised cell becoming
specialised
Structure relating to function:
· Thin outer membrane allows oxygen to diffuse easily
· Shape increases SA: V which allows oxygen to be absorbed more
efficiently
· No nucleus leaving room for haemoglobin
· Shape allows it to squeeze through vesicles and thin
capillaries
Epidermal cell
· Has 2 layers to keep external and internal environments
separate
Xylem cell
· Transports water and nutrients from the soil to stems and
leaves
· Provides mechanical support and storage
· Internal hydrophobic surface facilitating water transport
· Tracheids are hollow and connect to each other to improve
transport efficiency
· Think lignin coated cell walls provide shape and structure
Phloem cell
· Next to xylem for osmosis of water
· Has a source and sink as transport for substance
Guard cell
· Multiple chloroplasts for photosynthesis
· One thicker wall for stability and a thinner wall for
differentiation
· Close stomata when they lose potassium ions
Palisade mesophyll cells
· The main function is light absorption
· Multiple chloroplasts for photosynthesis
Root hair cell
· Extremely narrow tubes
· Have thin hairs which protrude outwards, allowing an increase in
SA: V for osmosis
· Long and thin to penetrate between soil particles and prevent
harmful organisms from entering the plant
Cohesion: water molecules stick together because they are attracted
to each other due to their charges
Adhesion: water molecules stick to surfaces
Capillarity: water molecules move up thin tubes (xylem)
· Investigate the structure and function of tissues, organs and
systems and relate those functions to cell differentiation and
specialisation
Circulatory system
· Equalises body temperature
· Delivers oxygen to the blood
Excretory system
· Performs the breakdown and discharge of wastes in the body
Digestive system
· Removes waste from undigested food
· Justify the hierarchical structural organisation of organelles,
cells, tissues, organs, systems and organisms
For multicellular organisms to function effectively and live
successfully in order to reproduce, there needs to be a high level
of organisation in the arrangement of their specialised
cells.
Atoms → Molecules → Organelles → Cells → Tissues → Organ Systems →
Organisms
Level of Organisation
Atomic level
Atoms are the smallest unit of an element that still maintains the
property of that element
Carbon, Hydrogen, Oxygen
Molecular level
Atoms form to combine into molecules which can have entirely
different properties than the atoms they contain
Water, DNA, Carbohydrates
Cells are the smallest unit of life.
Cells are enclosed by membrane or cell wall and often perform
specific functions
Muscle cell, Skin cell, Neutron
Tissue level
Muscle, Connective
Organ level
Organs are 2 types of tissue that work together to complete a
task
Heart, Liver, Stomach
Organ system level
Group of organs that carry out a more generalised set of
functions
Digestive system, Circulatory system
Human
· Allows the intake and expel of oxygen and carbon dioxide
Muscular System
· Speech
· Eating
· Removes waste from undigested food
Urinary System
· Removes waste from the blood and excretes them
Endocrine System
· Pituitary gland
· Thyroid gland
· Equalises body temp
Male Reproductive System
Female Reproductive System
· Supports embryo and gametes until birth
· Produces milk for infant
Nutrient and Gas Requirements
Inquiry Question: What is the difference in nutrient and gas
requirements between autotrophs and heterotrophs?
Distinguishment between autotrophs and heterotrophs:
Autotrophs can produce their own organic compounds from inorganic
compounds surrounding them whereas heterotrophs must consume other
organisms for organic substances for energy.
Autotroph: Can produce its own food using photosynthesis
→ Producers
Heterotroph: Cannot make its own food, therefore derives its food
nutrition from other sources
→ Consumers
· Investigate the structure of autotrophs through the examination
of a variety of materials, for example:
· Dissected plant materials
· Using a range of imaging technologies to determine plant
structure
· Investigate the function of structures in a plant, including but
not limited to:
· Tracing the development and movement of products of
photosynthesis
Photosynthesis is the process by which energy from light converts
water and carbon dioxide molecules into glucose and oxygen. The
oxygen is released from the leaves while the energy contained by
the glucose molecules is used for the plant's growth.
· Investigate the gas exchange structures in animals and plants
through the collection of primary and secondary data and
information, for example:
· Microscopic structures: alveoli in mammals and leaf structure in
plants
Plants:
· Forms a divide between the plant and external environment
Stomata:
· The leaf epidermis is covered with tiny pores, called
stomata
· Each stomata has a guard cell on each side
· The stomata allow gases to move into and out of the leaf
· Water vapour escapes through the stomata into the surrounding
air
· Stomata and water loss:
· The plant has to balance the need for carbon dioxide (open
stomata)
· Against the need to reduce water loss (closed stomata)
· How stomata open and close:
· Guard cells control the diameter of the pore by changing
shape
· When guard cells take up water (via osmosis) they swell and
become tight
· This makes the pore wider
· Gain → wider
· When the guard cells lose water they shrink and become
flaccid
· Pores become smaller
· Lose → smaller
Stomata are open in the light and close in the dark
Mammals:
· Gaseous exchange occurs in all animals and involves the movement
of gases between the internal and external environments by
diffusion across cell membranes
· Oxygen is essential for all cells to carry out cellular
respiration to release energy from the nutrients they have
consumed
· The respiratory system enables the exchange of gases between an
organism and it's environment
· Macroscopic structures: respiratory systems in a range of
animals
Fish:
· Need to obtain oxygen in order to remove carbon dioxide
· Water flowing over them ensures maximum oxygen uptake
· As the water is only flowing in one direction the water can enter
and flow over the gills and then leave via the gill slit
Insects:
· Spiracles → breathing pores
· Tracheal tubes
· Interpret a range of secondary-sourced information to evaluate
processes, Claims and conclusions that have led scientists to
develop hypotheses, theories and models about the structure and
function of plants, including but not limited to:
· Photosynthesis
· An incorrect conclusion that water makes plants grow, not
water
· John Priestly
· Jan Ingenhousz
· Jean Senebier
· Transpiration-cohesion-tension theory
· Creates negative pressure: tension
· Tension extends from leaves to roots
· Transpiration’s effect on water = straw
· Trace the digestion of foods in a mammalian digestive system,
including:
· Physical digestion
· Begins in the mouth when teeth break food by cutting or tearing
food
· Chemical digestion
· Process of using digestive enzymes to chemically break down the
larger, complex molecules in food
· Absorption of nutrients, minerals and water
· Mainly occurs in the jejunum section of the small intestine
· Products diffuse or use active transport through villi, which
lines the intestinal wall
· Glucose and amino acids are absorbed into the capillaries
· Elimination of solid waste
· Faeces are formed and stored in the rectum before being passed
out of the body through the anus.
· Compare the nutrient and gas requirements of autotrophs and
heterotrophs
Nutrient/ Gas Requirement
Diffuses through the respiratory surface
Carbon dioxide gas
Glucose
Produced by photosynthesis
Ingested into the digestive system as either simple or complex
carbohydrates, and absorbed into the bloodstream
Lipids/ proteins
Produced by the plant from glucose and mineral ions
Ingested into the digestive system and absorbed into the
bloodstream as amino acids, fatty acids or glycerol
Mineral ions
Move into the plant through the roots by diffusion and active
transport
Ingested into the digestive system and absorbed into the
bloodstream
Transport
Inquiry Question: How does the composition of the transport medium
change as it moves around an organism?
· Investigate transport systems in animals and plants by comparing
structures and components using physical and digital models,
including but not limited to:
· Macroscopic structures in plants and animals
· Microscopic samples of blood, the cardiovascular system and
plants vascular system
Xylem:
· It is made of specialised xylem tissue
· Water enters the root system via osmosis
Phloem:
· Phloem is the vessel that transports products of photosynthesis
via active transport
· Phloem consists of two types of living cells;
Companion cells
· Smaller cells found along the side of the sieve tube cells
· Contain nucleus, mitochondria, vacuoles and other cell
organelles
· Control the activities of sieve tube cells
Sieve tube cells
· Long and thin with large pores through the cell wall at either
end
· No nuclei, mitochondria or vacuole
· Arranged end to end in sieve tubes
· Investigate the exchange of gases between the internal and
external environments of plants and animals
· Compare the structure and function of Transport systems in
animals and plants, including but not limited to:
· Vascular systems in plants and animals
· Opened and closed transport systems in animals
Comparing the roles of respiratory, circulatory and excretory
systems:
Similarities
· Controlled systems (all act to maintain homeostasis)
· Homeostasis → the ability to maintain internal stability in
organisms
· This includes; the control of body temperature, carbon dioxide,
oxygen hormones and blood pressure
· All regulate against external changes
· Water/ salt concentrations
· Involves pump
· Sweat
MODULE 3: BIOLOGICAL DIVERSITY
· Develops and evaluates questions and hypotheses for scientific
investigation
· designs and evaluates investigations in order to obtain primary
and secondary data and information
· Communicates scientific understanding using suitable language and
terminology for a specific audience or purpose
· Describes biological diversity by explaining the relationships
between a range of organisms in terms of specialisation for
selected habitats and evolution of species
Content Focus
Biodiversity is important to balance the earth's ecosystems.
biodiversity can be effected slowly or quickly over time by natural
selective pressures. human impact can also affect biodiversity over
a shorter time period. in this module, students learn about the
theory of evolution by natural selection and the effect of various
selective pressures.
Monitoring biodiversity is key to being able to predict future
change. Monitoring, including the monitoring abiotic factors in the
environment, enables ecologists to design strategies to reduce the
effects of adverse biological change. Students investigate the
adaptations of organisms that increase the organisms ability to
survive in their environment.
Content
Effects of the Environment on Organisms
Inquiry Question: How do environmental pressures promote a change
in species diversity and abundance?
· Predict the effects of selection pressures on organisms in
ecosystems, including:
Selection pressures:
Biotic and abiotic factors in an organism’s environment can affect
behaviour, survival and reproduction
· Population changes:
· Emigration: organisms moving out of a population
Abundance: the number of individuals per unit area. Can be measured
through quadrats
Distribution: the spread of a population over space
· Biotic factors
Non-living components of an environment such as; temperature, light
and chemical components
· Abiotic factors
Living components of an environment such as; bacteria, fungi,
plants and animals
· Dynamic → tide, water, wind
· Chemical → salinity, nutrients, pH
In ecosystems, organisms interact and depend on one another for
survival. Individual: a single organism such as one animal, plant,
fungus or unicellular organism
Species: a group of organisms that can reproduce and produce
fertile offspring Population: a group of individuals of the same
species that live together
Community: an ecological group of different species living together
and interacting with each other Biomes: a group of communities that
have similar structures and habitats extending over a large area
system formed by communities of organisms interacting with one
another and their surroundings Biosphere: largest and most complex
ecosystem, a sum of all ecosystems on Earth
· Investigate changes in a population of organisms due to selection
pressures over time, for example:
· Cane toads in Australia
· Quickly spread;
· No known predators
· Prickly pear distribution in Australia
· Introduced from Spain for the dye industry
· Whenever its branches come into contact with soil it grows
· Allowed the plant to grow rapidly
· Introduction of a moth to reduce numbers
Adaptations
Inquiry Question: How do adaptations increase the organism’s
ability to survive?
· Conduct practical investigations, individually or in teams, or
use secondary sources to examine the adaptations of organisms that
increase their ability to survive in their environment,
including:
Adaptations: characteristic that an organism inherits that makes
them more suited to their environment. This occurs as a result of
selection pressures or environmental factors to increase the
chances of survival and reproduction
· Structural adaptations
Modifications of specific structures that give an organism an
advantage in a particular environment
· SA: V
Affect functioning at different levels. Can affect biochemical
reactions in organelles or physiological functions at a whole
organism level
· Camoflague
· Evaporative cooling
· Behavioural adaptations
Actions that only an organism takes to improve survival or
reproduction
· Burrowing
· Migration
· Investigate, through secondary sources, the observations and
collection of data that were obtained by Charles Darwin to support
the theory of evolution by natural selection, for example:
Natural selection:
The process by which organisms that are best suited to their
environment reproduce, passing on their favourable traits,
characteristics include;
· Organisms produce more offspring that can survive
· Variation occurs amongst species
· Some variations help individuals survive
· Over time, favourable traits cause a population to change
· Finches of the Galapagos Islands
· Darwin observed small ground finches on the Galapagos Islands and
collected the specimens that were living on each of the
islands
· Notes that the finches had naturally occurring variation in, for
example; beak size, colour and leg length
· The descendants of these birds gradually populated other islands,
each of which had different environmental conditions
· The finches which were not adapted to the environmental
conditions died out
· Australian flora and fauna
Darwin’s Observations
How Darwin's observation related to his theory of evolution by
natural selection
Magpies and crows are similar to the jackdaws in England, but
obviously belonging to different species
The potoroo (rat-kangaroo) is similar to the rabbit in
England
The potoroo is a miniature kangaroo the size of a European rabbit,
behaving somewhat like a rabbit, darting about in the
undergrowth
The platypus is similar to water rats
Darwin's observations of birds, marsupials and monotreme mammals in
Australia revealed the similarities with European mammals that
lived in similar environments.
This led to the idea that organisms could evolve to become
similar
· (convergent evolution)
If organisms live in similar habitats, similar variations that they
process would be favoured by natural selection to enable them to
survive and breed in those conditions.
· These favourable variations would then be passed onto the next
generation
Vegetation: Darwin describes eucalyptus, “ the nearly level country
is covered with thin scrubby trees, bespeaking the curse of
sterility”.
In Darwin's observations of plant life in Sydney, he made the link
between the harsh environment and the adaptations observed in the
vegetation. he also mentions that many of the trees in Australia
and other Southern continents are Evergreen as opposed to those in
the Northern Hemisphere
Theory of evolution by natural selection
Inquiry Question: What is the relationship between Evolution and
biodiversity?
· Explain biological diversity in terms of the theory of evolution
by natural selection by examining the changes in and
biodiversification of life since it first appeared on the
Earth
Biological diversity and the Theory of Evolution by Natural
Selection:
· Biological diversity refers to the variety of all forms of life
on earth
· Diversity within a population is what allows it to adapt to
changes within the environment
Biodiversity type
Genetic Diversity
Total number of genetic characteristics in the genetic make-up of a
species
Species Diversity
Measure of the diversity of different species in an ecological
community
Ecological Diversity
Population change and allele frequencies:
Cause of population change
description of the Factor
Exchange of alleles between populations
When migrating animals or dispersed seeds reproduce in a new
location
Blue-eyed people from Sweden migrate to a small town in
Mexico
Genetic drift
Can change the distribution and proportion of alleles
American bison
Founder effect
When a population of individuals are isolated and for new
population
Amish people in Pennsylvania have high incidences of
polydactyly
Genetic bottleneck
When a large population is dramatically reduced in size thereby
reducing its genetic variation
Hunting and poaching of many of the African elephants
· Analyse how an accumulation of microevolutionary changes can
drive evolutionary changes and speciation over time, for
example:
Microevolution:
Macroevolution:
· The evolution of groups larger than species
· What is observed when looking at the history of life on
Earth
· Evolution of the horse
· Over 50 million years ago the horse evolved from a dog-sized,
forest-dwelling animal
· Fossils show changes in body size, number of teeth and foot
shape
· The first horses were 25-50m tall with a long tail, short legs,
snout and back
· Ate fruits and soft plants
· Evolved due to drier climate, shrinking forests and growth of
more grass
· Evolution of the platypus
· Has many genes in common with both reptiles and birds
· Explain, using examples, how Darwin and Wallace's theory of
evolution by natural selection accounts for:
· Convergent evolution
Evolution through natural selection of similar features in
unrelated organisms
· Example; dolphins and sharks
· Divergent evolution
Separated populations diverge, whether that be by random factors
such as genetic drift or natural selection
· Explain how punctuated equilibrium is different from the gradual
process of natural selection
· Punctuated equilibrium → evolution occurs in spurts of rapid
change with long periods of no change
· Gradual process → slow, gradual change, occurring in small
periodic changes in the gene pool
Evolution - the Evidence
Inquiry Question: What is the evidence that supports the theory of
evolution by natural selection?
· Investigate, using secondary sources, evidence in support of
Darwin and Wallace's Theory of Evolution by natural selection,
including but not limited to:
· Biochemical evidence, comparative anatomy, comparative embryology
and biogeography
Evidence type
Humans and chimps
Palaeontology
· Palaeontology is the study of fossils
· Provides direct evidence
Fossil evidence:
Relative dating:
· Relies on the assumption that that fossils found higher up in
rock strata are younger than the lower fossils
Absolute dating/radiometric dating:
· The actual age of the specimen is determined by using the
radioactive elements which are presented in the specimen
· Explain modern-day examples that demonstrate evolutionary change,
for example:
· The cane toad
· Antibiotic-resistant strains of bacteria
· Some strands of bacteria randomly become resistant to modern
antibiotics
· These strands then reproduce and become more resistant