Chapter 2

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Chapter 2Biology as a Science

• Charles Page High School
• Stephen L. Cotton

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Section 2.1Characteristics of Living Things

• Objectives
• List and describe the characteristics of living
  things.

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Section 2.1Characteristics of Living Things

• Objectives
• Define homeostasis.

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Section 2.1Characteristics of Living Things

• Think of making a list of characteristics
• the line between life and nonlife
• there are certain accepted traits
• 1. Made of cells 2. Reproduce
• 3. Grow, develop 4. Obtain/use energy
• 5. Respond to the environment

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Section 2.1Characteristics of Living Things

• 1. Made up of CELLS
• small, self-contained units
• separated from its surroundings
• can make an entire organism - called unicellular
  Fig 2-2, page 28
• multicellular is made of many cells
• Cells are never formed by non-living things

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Section 2.1Characteristics of Living Things

• 2. Living things REPRODUCE
• This means they produce new organisms of the same
  type
• individuals will die thus they must reproduce if
  the group of similar organisms (species) will
  survive

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Section 2.1Characteristics of Living Things

• Two basic kinds of reproduction
• 1. Sexual reproduction- requires 2 cells from
  different individuals unite
• 2. Asexual reproduction- a single organism can
  reproduce without the aid of another
• some single-cell organisms will simply divide
  into two new cells

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Section 2.1Characteristics of Living Things

• 3. Grow and Develop
• at some stage, living things are capable of
  growth taking in materials from the surroundings
  and transforming it into living tissue
• different from a snowball growing
• development- a cycle of change
• Fig. 2-4, page 29

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Section 2.1Characteristics of Living Things

• As development continues, a process called aging
  occurs
• processes become less efficient
• ability to reproduce ceases
• death is the end result
• life span Fig 2-5, page 29
• Death is then also a process of change that
  separates living and nonliving

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Section 2.1Characteristics of Living Things

• 4. Obtain and Use Energy
• energy comes from the surroundings, or
  environment
• energy used to grow, develop, reproduce
• Anabolism- process of putting together simpler
  materials into more complex materials (a building
  process)

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Section 2.1Characteristics of Living Things

• Plants- obtain energy from sunlight in a process
  called photosynthesis
• photo- means light
• synthesis- means put together
• Animals cannot perform photosynthesis they must
  take in energy in the form of food

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Section 2.1Characteristics of Living Things

• Catabolism- breakdown of complex materials into
  simpler items
• Living things have both anabolism and catabolism
• Sum total of both is metabolism - the balance of
  all chemical reactions in the body

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Section 2.1Characteristics of Living Things

• 5. Respond to the environment
• some can be rapid, some are slow
• they react to a stimulus
• light, temperature, odor, sound, gravity, heat,
  water, pressure, etc.
• Irritability - ability to react to stimulus
• Homeostasis a balance of conditions

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Section 2.2Biology The Study of Life

• Objectives
• Compare the different branches of biology.

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Section 2.2Biology The Study of Life

• Objectives
• Describe the different types of microscopes and
  their limits of resolution.

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Section 2.2Biology The Study of Life

• Objectives
• Discuss the advantages and disadvantages of
  different types of microscopes.

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Section 2.2Biology The Study of Life

• Biology means the study of life.
• Bio- means life
• -logy means study of
• A biologist is anyone who uses the scientific
  method to study living things.

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Section 2.2Biology The Study of Life

• Some branches of Biology include
• Zoologists- study animals
• Botanists- study plants
• Microbiologists- study microorganisms (small
  organisms)
• Paleontologists- extinct organisms
• Ethologists- animal behavior

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Section 2.2Biology The Study of Life

• Biology at the molecular level
• may study the basic chemical units of life
• the workings of DNA and genetics
• the effect of drugs on molecules in cells, to
  better understand why entire organisms react as
  they do

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Section 2.2Biology The Study of Life

• Biology at the cellular level
• how normal cells become cancerous
• how a single cell divides and changes to form the
  variety of types in an adult
• how cells communicate with nearby cells

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Section 2.2Biology The Study of Life

• Biology at the multicellular level
• the study of multicellular organisms
• zoologists interested in what tells animals when
  to sleep, eat, or even mate
• paleontologists explain how certain animals
  changed over a period of time
• ethologists explain why certain males are more
  brightly colored than females

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Section 2.2Biology The Study of Life

• Biology at the population level
• interested in groups of organisms
• how populations interact with their environment
• how construction of roads or dams might affect
  nearby plants and animals
• effects of pesticides or industrial waste

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Section 2.2Biology The Study of Life

• Biology at the global level
• the effects on the Earths climate due to burning
  of coal and oil
• why fishing is excellent one year, and poor the
  next

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Section 2.2Biology The Study of Life

• Qualifications for a Biologist?
• Hard work, curiosity, and energy!
• Curious about life, and have the energy to ask
  questions in a scientific way
• Many famous biologists were amateurs
• Charles Darwin theory of evolution
• Gregor Mendel basic unit of heredity

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Section 2.2Biology The Study of Life

• Tools of a biologist? There are many, such as
• standard laboratory tools
• pipettes and graduated cylinders to measure and
  transfer small amounts of liquid
• electronic balances to measure solids
• fume hoods, computers

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Section 2.2Biology The Study of Life

• What one tool comes to mind?
• The MICROSCOPE
• used to study small organisms- produces larger
  than life images, pictures, or even videotapes
• there are several different types

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Section 2.2Biology The Study of Life

• Compound Light Microscope (Fig 2-12, p. 34)
• very common in high school labs
• specimen placed on glass slide covered
• 2 lenses (thus the word compound)
• top lens is the ocular- look through this
• bottom lens is the objective
• may magnify up to 1000 times

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Section 2.2Biology The Study of Life

• Magnification important, but so is the
  resolution how well we can see detail
• There is a limit of resolution- beyond this,
  items get blurry and detail is lost
• For most light microscopes, the limit of
  resolution is about 0.2 micrometers
• a typical cell is about 10 micrometers across

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Section 2.2Biology The Study of Life

• Using the compound light microscope
• many specimens must be stained because they are
  so thin
• some stains color everything others color only
  certain parts of the cell
• Since some stains kill cells, other types of
  light microscopes can be used to observe living
  specimens

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Section 2.2Biology The Study of Life

• Some different types of light microscopes such
  as
  a) phase contrast microscope
  b) dark field microscope c)
  Nomarski microscope
• Fig. 2-14, page 35
• each uses a different property of light rays to
  improve the contrast (clarity)

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Section 2.2Biology The Study of Life

• Light microscopes have their limit of resolution
  that restricts usefulness
• Electron microscopes use electromagnets to bend
  streams of electrons, much like glass lenses bend
  light
• these have a limit of resolution 1000 times
  greater than light microscopes!

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Section 2.2Biology The Study of Life

• Types of electron microscopes
• 1. Transmission electron microscope (TEMs)- shine
  a beam of electrons, and then magnify on screen
• 2. Scanning electron microscopes (SEMs)- scans
  back and forth across the surface of the specimen

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Section 2.2Biology The Study of Life

• Limitations of electron microscopes
• specimen must be placed in a vacuum
• TEM must have special stains, then cut into very
  thin slices
• SEM do not need sliced, but still need to be in a
  vacuum
• thus, living cells must be killed first

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Section 2.2Biology The Study of Life

• Which is better Light, TEM, or SEM?
• All types do different things
• Light microscope - can see living things
• TEM reveals innermost details, but only after
  killed, sectioned, and stained
• SEM allows surface study in 3-D
• Thus, each have their own purpose!

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Section 2.2Biology The Study of Life

• Laboratory Techniques of a Biologist
• Staining - allows more visibility
• Centrifugation - while spinning, parts separate
  (heaviest to the bottom)
• Micro dissection - remove specific parts of cells
• Cell cultures a single cell placed in nutrients
  to grow many additional cells