Transcript 1.1 The Study of Life

1.1 The Study of Life
Earth is home to an incredible diversity of life.
• Diversity – differences
• The Biosphere includes all living things and all the places
they are found.
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The biosphere includes many environments.
– land
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– saltwater and freshwater environments
– portions of the atmosphere
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• Biodiversity is the variety of life.
– Biodiversity generally increases from the poles to the
equator.
– Biodiversity is greater in areas with consistently warm
temperatures.
Biodiversity is
greater closer to
the equator.
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• A species is one particular type of living thing.
– Members of a species can interbreed to reproduce.
– There are about 2 million different living species that
have been identified.
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An organism is any individual living thing.
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All organisms share certain characteristics.
•Characteristics of Life:
1. All are made of one or more cells.
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2. All need energy for metabolism.
- Sum of all chemical processes in a body
3. All respond to their environment.
– Stimuli  Environmental Factors (light, temperature,
touch)
– Response  Reaction of the organism to the stimulus
4. All Reproduce and Develop
– All have DNA that they pass on to offspring.
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All levels of life have systems of related parts.
• A system is an organized group of parts that interact to
form a whole.
– A cell is a system of chemicals and processes.
– A body system includes organs that interact.
• An ecosystem includes living and nonliving things that
interact in a physical environment.
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• Biologists study many different systems.
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Structure and function are related in biology.
• Structure determines function.
– Proteins with different structures perform different
functions.
– Different species have different anatomical structures
with different functions.
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Organisms must maintain homeostasis to survive in
diverse environments.
• Homeostasis is the maintenance of constant internal
conditions in an organism.
• Cells function best in limited conditions
– Temperature, blood sugar, acidity, etc.
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• Homeostasis is usually maintained through negative
feedback.
– Negative feedback system – a change in a system
causes a response that returns the system to its
original state.
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• Behaviors and adaptations can help maintain
homeostasis.
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Evolution explains the unity and diversity of life.
• Evolution is the change in living things over time.
– The genetic makeup of a population of a species
changes.
– Evolution can occur through natural selection of
adaptations.
– Adaptations are beneficial inherited traits that are
passed to future generations.
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• Natural selection of genetic traits can lead to genetic
diversity which is responsible for the diversity of life.
• Organisms have similar cell structure and similar
chemical processes
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Maintaining safety
• Safety Symbol – a symbol that warns you about a danger
that may exist from chemicals, electricity, heat, or
procedures you will use
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Like all science, biology is a process of inquiry.
Scientists make careful and systematic observations.
• Observation – using our senses to study the world.
Scientists record observations as data.
1. Qualitative Data – descriptions
2. Quantitative Data – measurements
• (mass, volume, Temperature)
Scientists form a hypothesis as a possible answer to a
question.
•hypothesis must be specific and testable
Scientists test their hypotheses and analyze their data.
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Independent variable condition that is changed by
scientists
Dependent variable are observed and measured during
an experiment.
– Only 1 independent variable is tested in an
experiment
– Constants are conditions that are kept the same.
Control Group – Everything is kept constant (normal conditions)
Experimental Group – Independent variable is changed
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Analyzing Data
• Statistics and Mathematics
• 2 possible outcomes
• Nonsignificant – data shows no effect or so small of an
effect it could of happened by chance
•Hypothesis is rejected  often leads to a new
hypothesis
• Statistically significant – effect is likely not due to chance
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• A theory is supported by a wide range of scientific
evidence.
• Theories can change based on new evidence.
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Imaging technologies provide new views of life.
• A microscope provides an enlarged image of an object.
– light microscopes (LM) – light passes through specimen
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Imaging technologies provide new views of life.
• A microscope provides an enlarged image of an object.
– light microscopes (LM)
– scanning electron microscopes (SEM) – 3 D image of the
surface
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Imaging technologies provide new views of life.
• A microscope provides an enlarged image of an object.
– light microscopes (LM)
– scanning electron microscopes (SEM)
– transmission electron microscopes (TEM)
Electron microscopes
• higher magnification
•Cannot be used to study living organisms
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• Imaging technology is used in medicine.
– X-ray images Xray images – look
at skeleton
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• Imaging technology is used in medicine.
– X-ray images
– magnetic
resonance
imaging (MRI) –
strong magnetic
field
- Can view soft
tissue
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• Imaging technology is used in medicine.
– X-ray images
– magnetic
resonance
imaging (MRI)
– functional MRI (fMRI)
- Shows where activity is
taking place
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• Computer models are used to
study systems that cannot be
studied directly.
– heart attacks
– effect of medicines on the
human body
– movement of water molecules
into and out of a cell
– spread of a disease through a
population
• Computer models are used when
experiments are not safe, ethical,
or practical.
Normal heartbeat
Heart attack
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The tools of molecular genetics give rise to new
biological studies.
• A gene is a segment of DNA that stores genetic
information.
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• Through our understanding of DNA, we can study
genetics on a molecular level.
– molecular
genetics – study
and manipulation
of DNA
– Genomics –
study and
comparison of
genomes both
within a species
and across
species
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Your health and the health of the environment depend
on your knowledge of biology.
• food allergies
• potential effects of obesity
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• Knowledge of biology helps you understand: your health
– cancer
– effects of alcohol, tobacco, and other drugs
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• Knowledge of biology can help you understand:
environmental issues
– interactions in ecosystems
– pollution
– Animal deformities
– chemicals in water,
radiation, infection
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Biotechnology is the use and application of living things
and biological processes.
– Medicine, agriculture, forensics
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• Transgenic – altered copies of an organisms own genes
– crops - (genetically modified) increase nutrients, yield of
plants and resistance to insects
– bacteria – make human insulin (diabetes)
– sheep/cows – human antibodies and proteins
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• Questions are raised about the use of biotechnology.
– long term effects
– spread of undesirable genes
– decrease in biodiversity
– ethical considerations
– Who should have access? (insurance companies?)
– How should information be used? (reveal child might
have genetic disorder or choose characteristics of
children?)
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• There are still many questions to answer in biology.
– How are memories stored in the brain?
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– How are memories stored in the brain?
– How do viruses mutate?
– Does life exist on planets other than Earth?