Chapter 1 An Introduction to Life on Earth

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Chapter 1 An Introduction to Life on Earth

• What are the characteristics of living things?
• How do scientists categorize the diversity of
  life?
• What is the science of biology?
• Evolution The unifying theory of biology

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Characteristics of Living Things

• Living things have a complex, organized structure
  made up of organic (carbon based) molecules

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Characteristics of Living Things
Element of Earths Crust of Human Body
Carbon 0.19 9.5
Hydrogen 0.22 63.0
Oxygen 47.0 25.5
Silicon 28.0 lt0.01
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Characteristics of Living Things

• The cell is the basic unit of life

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Characteristics of Living Things
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Characteristics of Living Things

• Living things respond to stimuli from their
  internal and external environment
• A stimulus is a change that brings about a
  response

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Characteristics of Living Things

• Living things maintain their complex structure
  and internal environment in a process called
  homeostasis

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Characteristics of Living Things

• This occurrence is known as physiological
  homeostasis and it is essentially a corrective
  mechanism. Consider the following scenario in a
  person
• The level of glucose in the bloodstream drops 
• The person requires glucose in cells to meet the
  demand for ATP 
• The body detects this with a particular receptor
  designed for this function 
• These receptors release hormones, chemical
  messages that initiate the start of the feedback
  mechanism 
• The hormones travel to their target tissue and
  initiate a corrective response 
• In this case, the corrective response is the
  secretion of more glucose into the bloodstream

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Characteristics of Living Things

• Living things acquire and use materials and
  energy from their environment in a process called
  metabolism
• Catabolism lt-gt Anabolism
• Cellular Respiration lt-gt Photosynthesis
• C6H12O6 6O2 6H2O lt-gt 12H2O 6 CO2

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Characteristics of Living Things

• Living things grow
• Materials acquired from the environment are
  converted into the specific molecules of the
  organisms body

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Characteristics of Living Things

• Continuity of life occurs because organisms
  reproduce offspring of the same type (species)
• Diversity of life occurs because offspring are
  slightly different from their parents due to
  sexual reproduction and mutation

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Characteristics of Living Things

• Living things reproduce themselves using a
  molecular blueprint called deoxyribonucleic acid
  (DNA)

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Characteristics of Living Things

• Living things, as a whole, have the capacity to
  evolve
• The theory of evolution states that modern
  organisms arose, with modification, from
  preexisting life forms

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Diversity of Life
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Diversity of Life
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Diversity of Life
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Diversity of Life (Student Completion)
Domain Kingdom Cell Type Cell Number Mode of Nutrition
Bacteria
Archaea
Eukarya Protista
Fungi
Plantae
Animalia
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Scientific Method

• The scientific method is the experimental testing
  of a hypothesis formulated after the systematic,
  objective collection of data.

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Scientific Method

• The scientific method is often divided into
  steps. This is helpful for putting the method
  into context, but keep in mind that the key
  element of the scientific method is testing the
  hypothesis. In other words, can you prove that
  you are wrong?

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Steps of the Scientific Method

• Observe the situation
• Ask a question
• Turn that question into a testable hypothesis
• Predict the outcome of your experiment
• Perform your experiment
• Analyze the results
• Evaluate your hypothesis

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Evolution

• Evolution is the unifying theory that explains
  the origin of diverse forms of life as a result
  of changes in their genetic makeup.
• Modern organisms descended, with modification,
  from preexisting life-forms.

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Evolution

• Darwin and Wallace formulated a theory of
  evolution in the 1800s based on three natural
  processes
• Genetic variation within a population
• Inheritance of variation by offspring of parents
  who carry the variation
• Natural selection the survival and enhanced
  reproduction of organisms with favourable
  variations

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Evolution

• Darwin's finches. The finches numbered 1-7 are
  ground finches. They seek their food on the
  ground or in low shrubs. Those numbered 8-13 are
  tree finches. They live primarily on insects.
• Since Darwin's time, these birds have provided a
  case study of how a single species reaching the
  Galapagos from Central or South America could -
  over a few million years - give rise to the 13
  species that live there today.

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Evolution

• Structures or behaviours that aid survival and
  reproduction in a particular environment are
  called adaptations