Transcript Bio_principles of biology

An introduction to HKDSE Biology
•Syllabus Basics and Important Notes
HKDSE Biology curriculum framework:
About SBA
School-Based Assessment (SBA) is a component of the HKDSE
examination, for both the Biology and Combined Science (Biology). It refers
to assessments administered in schools and marked by the students’ own
teachers.
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How much does SBA account for?
(a) Biology
The SBA mark accounts for 20% of the final subject mark. The SBA
comprises the assessment of:
(1)
practical related tasks which refer to students’ laboratory work and
field work, and
(2)
non-practical related tasks (assignments).
The examination and weightings
Component of HKDSE
Outline
Paper 1 Compulsory Part
Weighting
Duration
60%
2.5 hours
20%
1 hour
20%
S5–S6
Public examination
Paper 2 Elective Part
School-based
(SBA)
assessment
Practical related tasks and non-practical
related tasks (assignments)
Starting from the 2014 HKDSE, students will be assessed on both the
practical and non-practical related tasks in the SBA. The marks for
practical related tasks will constitute 14% and those for non-practical related
tasks will constitute 6% of the final subject mark.
Practical related tasks
Ability area
A
B
Weighting
8%
12%
S5
1
1
S6
1
1
Minimum
number of
assessments
Moderation
Assignments_non-practical related tasks
u
information searching
u
report writing
u
survey studies
u
field-studies
u
site-visit reports
u
pages
designing posters/pamphlets/web
u
writing articles
u
building models
u
developing multimedia artefacts
Curriculum emphasis and Generic skills to be
demonstrated and assessed in assignment :
Chapter 1
Biology: Exploring Life
• Biology
• Is the scientific study of life
• Biology’s Most Exciting Era
• The phenomenon we call life
• Defies a simple, one-sentence definition
Figure 1.1
• We recognize life
• By what living things do…..???
• Some properties of life
(a) Order
(b) Evolutionary
adaptation
(c) Response to the
environment
(d) Regulation
(e) Energy
processing
(f) Growth and
development
Figure 1.2
(g) Reproduction
• Concept 1.1: Biologists explore life from the
microscopic to the global scale
• The study of life
• Extends from the microscope scale of
molecules and cells to the global scale of the
entire living planet
A Hierarchy of Biological Organization
• The hierarchy of life
• Extends through many levels of biological
organization
• From the biosphere to organisms
1 The biosphere
Figure 1.3
• From cells to molecules
9 Organelles
1 µm
Cell
8 Cells
Atoms
10 µm
7 Tissues
50 µm
6 Organs and organ systems
Figure 1.3
10 Molecules
• An ecosystem consists of all the organisms
living in a particular area
– As well as the nonliving environmental
components
• All the living organisms in an ecosystem
– Make up a community
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• A population
– Consists of a localized group of
individuals of a species
• An individual living entity
– Is an organism
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• The hierarchy continues downward with
 Organ systems
 Organs
 Tissues
 Cells
 Organelles
 Molecules
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1.2 Living organisms and their environments
form interconnecting webs
• Ecosystems are characterized by the cycling
of chemical nutrients from the atmosphere and
soil
– To producers to consumers to
decomposers and back to the
environment which contains both living
and nonliving components
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ENVIRONMENT natural world:
•
the natural world affects an organism survival
•
An organism have an impact
environment – especially human
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on
the
1.2 Living organisms and their environments
form interconnecting webs
•
Two major processes are at work in an
ecosystem:
1. The recycling of chemical nutrients
2. The flow of energy
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Energy Conversion
• Activities of life require organisms to perform
work, which depends on an energy source
• The exchange of energy between an organism
and its surroundings
• Often involves the transformation of one form of
energy to another
Question
• Explain how the
photosynthesis
of plants
functions in both
1. the cycling of
chemical nutrients
2. the flow of
energy in an
ecosystem.
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• Photosynthesis use light energy to
convert carbon dioxide and water to make
energy rich compounds/food,
• making it the pathway for nutrients and
energy for most organisms. It is the basis
of the entire food chain for all living
organisms.
• Energy flows one-way through an ecosystem
– From the sun to producers to consumers
and exits as heat
Sun
Air
Inflow
of
light
energy
O2
CO2
CO2
Chemical
energy
Producers
Cycling
of
Chemical
nutrients
Decomposers
H2O
Soil
Figure 1.2
Ecosystem
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Consumers
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Loss
of
heat
energy
Question
• Explain why cells are considered the basic
unit of life
They are the lowest level in hierarchy of
biological organization at which properties of life
actually appear.
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A Closer Look at Cells
• The cell
– Is the lowest level of organization that can perform
all activities required for life
Figure 1.5
25 µm
The Cell’s Heritable Information
• Cells contain chromosomes made partly of DNA, the
substance of genes
• Which program the cells’ production of proteins and
transmit information from parents to offspring
Sperm cell
Nuclei
containing
DNA
Egg cell
Figure 1.6
Fertilized egg
with DNA from
both parents
Embyro’s cells
with copies of
inherited DNA
Offspring with traits
inherited from
both parents
1.3 Cells are the structural and functional units of life
•
A cell
 Is the basic unit of life that can perform all
functions necessary for life including:
1. Regulate its internal environment
2. Take in and use energy
3. Respond to its local environment
4. Develop and maintain its complex organization
5. Divide to form new cells
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Two types of cells
• Eukaryotic cells
Contain membrane-enclosed organelles,
including a DNA-containing nucleus
• Prokaryotic cells
Nucleus
(contains DNA)
Prokaryotic cell
Eukaryotic
cell
Lack such organelles
DNA
(no nucleus)
25,000 
Organelles
Figure 1.3
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Question
• What is the chemical basis of all life’s
kinship / family relationship ?
DNA / RNA is the genetic material for all
living things
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UNITY AND DIVERSITY in Biological world
1.4 The unity of life: All forms of life have
common features
• DNA is the genetic information
– For constructing the molecules that make
up cells and organisms
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• Each species’ genetic instructions
–
Are coded in the sequences of the four building
blocks making up DNA’s two helically coiled chains
A
C
T
A
T
A
C
C
G
T
A
G
T
Figure 1.4A
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A
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DNA /RNA is the genetic code for ALL living things
Genetic
instructions are
coded in the
sequences of the
four building
blocks making up
DNA.
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All organisms share a common set of features
1. Ordered structures
2. Regulation of internal conditions
Figure 1.4B
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Figure 1.4C
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3. Growth and development
4. Energy use –nutrition and respiration
5. Response to environmental stimuli
6. The ability to reproduce and evolve
Figure 1.4D
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Figure 1.4E
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1.5 The diversity of life can be arranged into
three domains / superkingdom
• Organisms are grouped (classified) into:
– the prokaryotic 2 domains:
•
Bacteria and Archaea
– the eukaryotic domain
•
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Eukarya
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SEM 3,250
• Domains Bacteria and Archaea
SEM 25,000
Figure 1.5A
Figure 1.5B
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• Domain Eukarya includes
–
Protists (protozoans and algae, falling into
multiple kingdoms)
–
The kingdoms Fungi, Plantae, and Animalia
275
Kingdom Fungi
Kingdom Animalia
Protists
(multiple kingdoms)
Kingdom
Plantae
Figure 1.5C
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The three Domains of living
things on Earth
1.6 Evolution explains the unity and diversity of life
• Charles Darwin
– Synthesized the theory of evolution by
natural selection
Figure 1.6A
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Fossils and Comparative Anatomy
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unity and diversity in biological structures
Concept Check
Darwin proposed the theory of
natural selection.
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 Natural selection is an editing mechanism:
 That occurs when populations or organisms,
having inherited variations, are exposed to
environmental factors that favor the reproductive
success of some individuals over others
1 Populations with varied inherited traits
2 Elimination of individuals with certain traits
Figure 1.6B
3 Reproduction of survivors
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• All organisms have adaptations
–
That have evolved by means of natural
selection
Killer whale
Pangolin
Figure 1.6C
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Post-Darwin Evolution Evidence
Molecular Evidence
- Our increased
understanding of DNA
and protein structures
has led to the
development of more
accurate
evolutionary trees.
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Did human descend
from apes?
Did human
descend from
apes?
NO! according
to to evolutionary
theory, we are
closed related
and have a
distant common
ancestor
Did human descend from
apes?
NO! according to
to evolutionary
theory, we are
closed related
and have a
distant
common
ancestor
The evolutionary
tree of life
The concept of evolution
unites all living things and
suggest that all living
things might have
a common
ancestor
Question
• How does natural selection allow a
population to adapt to its environment?
On average, those organisms with heritable traits
best suited for their local environment produce the
largest number of offspring that survive and
reproduce.
This increases the frequency of these traits in the
population.
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THE PROCESS OF SCIENCE
1.7 Scientists use two main approaches to learn
about nature
• Science
– Is a way of knowing
– Seeks natural causes for natural
phenomena
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1. Discovery Science
• In discovery science
 Scientists describe some aspect of the
world and use inductive reasoning to
draw general conclusions
 Inductive:
LOGIC
reaching
a
conclusion based on observation:
generalizing to produce a universal claim
or principle from observed instances
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2. Hypothesis-Based Science
• In hypothesis-based science
 Scientists attempt to explain
observations by testing hypotheses
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1.8 With hypothesis-based science, we pose and
test hypotheses
• Hypothesis-based science involves:
 Observations, questions, hypotheses as
tentative answers to questions and
 Deductions leading to predictions, and
then tests of predictions to see if a
hypothesis is falsifiable
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Question
• What is the difference between discovery
science and hypothesis-based science?
In the first, scientists make observations and describe
objects and phenomena (inductive reasoning);
in the second, they propose hypotheses, make deductions,
and test predictions.
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Hypothesis
Theory needing investigation: a tentative
explanation for a phenomenon, used as a basis
for further investigation
The hypothesis of the big bang is one way to
explain the beginning of the universe.
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Deduction
•Drawing a conclusion: the process of drawing
a conclusion from available information.
•LOGIC reasoning: the forming of conclusions
by applying the rules of logic to a premise
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A Case Study from Everyday Life
• Deductive reasoning is used in testing hypotheses as
follows
–
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If a hypothesis is correct, and we test it, then we
can expect a particular outcome
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Figure 1.8A The hypothesis-driven scientific method (layer 1)
Observations
Question
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Hypothesis # 1:
Dead batteries
Hypothesis # 2:
Burnt-out bulb
Prediction:
Replacing batteries
will fix problem
Prediction:
Replacing bulb
will fix problem
Test prediction
Test prediction
Test falsifies hypothesis
Test does not falsify hypothesis
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Figure 1.8A The hypothesis-driven scientific method (layer 2)
Observations
Question
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Hypothesis # 1:
Dead batteries
Hypothesis # 2:
Burnt-out bulb
Prediction:
Replacing batteries
will fix problem
Prediction:
Replacing bulb
will fix problem
Test prediction
Test prediction
Test falsifies hypothesis
Test does not falsify hypothesis
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Figure 1.8A The hypothesis-driven scientific method (layer 3)
Observations
Question
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Hypothesis # 1:
Dead batteries
Hypothesis # 2:
Burnt-out bulb
Prediction:
Replacing batteries
will fix problem
Prediction:
Replacing bulb
will fix problem
Test prediction
Test prediction
Test falsifies hypothesis
Test does not falsify hypothesis
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Five Steps of the scientific method
1. Observation come from others or results of earlier
tests
2. Questions are asked about unclear aspects of the
observations: How? Why? When?
3. Hypotheses are tentative explanation of a
phenomenon phrased in such a way as to be
testable.
4. Predictions are logical, testable outcomes of the
hypotheses developed by the use of deductive
reasoning. Predictions take the form of if (statement
of hypotheses) is true, then (predictions).
5. Tests of prediction are performed to determine if the
predictions are supported (fail to falsify) or falsified.
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On important quality of the hypotheses-based science
A hypothesis must be testable.
A hypothesis becomes credible when
repeated attempts to disprove it fail.
Hypothesis
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---- theory ----- law
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Controlled experiment -- one that is designed to
compare an experimental group with a control group.
• Ideally, the experimental and control groups differ
only in the one factor the experiment is designed to
test.
• Without the control group, one could not rule out
certain test areas as the cause of the difference.
• This experimental design should leave only one
factor to account for the difference in the two
groups.
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Question
• What are the required features of an
hypothesis?
It must be testable
•It must be falsifiable
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Question
• Why is it difficult to draw a conclusion from
an experiment that is not controlled?
Without a control you don’t know if the experimental
outcome is due to the variable you are trying to test or due
to some other variables.
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BIOLOGY AND EVERYDAY LIFE CONNECTION
1.8 Biology is connected to our lives in many ways:
 Biology in the news has an enormous impact on our
every day lives. Some examples of biology in the news
are endangered species, genetically modified crops,
global warming, pollution, cloning, nutrition, emerging
diseases, and medical advances.
 Technology is the practical application of scientific
knowledge and discovery. Scientists speak of discovery
while engineers speak of inventions. Scientists and
engineers benefit from the work and success of each
other.
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•
Biology is connected to many important issues in
our lives
1. Environmental problems and solutions
2. Genetic engineering
3. Medicine
Figure 1.9
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Biology is Beautiful, Wonderful and Fun!
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