Introduction to Life on Earth - General Biology | BIOL 1001, Study notes of Biology

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CHAPTER 1:

An Introduction to Life On Earth

Defining Life

• (^) Dictionary definition of life is:
  • (^) the quality that distinguishes a vital and functioning being from a dead body
• (^) Living things are more than the sum of their parts  life is difficult to define
• (^) Certain characteristics define what is technically “alive”

Characteristics defining LIFE

1. Structure is complex
2. Acquire materials & energy from the environment
3. Maintain internal conditions
4. Growth
5. Respond to stimuli
6. Reproduce
7. Capacity to evolve

Living Things Are Both Complex and

Organized

• (^) Salt: Organized but simple (non-living)

Living Things Are Both Complex and

Organized

• (^) Oceans: complex but unorganized (non-living)

Living Things Are Both Organized

and Complex

• (^) Water flea: complex and organized (living)

• (^) Each level of complexity or structure is based on the one below it
• (^) Levels of biological organization, in order of least to most complex illustrated in Fig. 1-

Living Things Are Both Organized

and Complex

Least complex Most complex LEVELS OF BIOLOGICAL ORGANIZATION

AtomAtom Molecule Molecule Cell Cell Tissue Tissue LEVELS OF BIOLOGICAL ORGANIZATION Organ Organ Organ Organ System System Least complex Most complex

Multicell.Multicell. Organism Organism Population Population Species Species Community Community Least complex Most complex LEVELS OF BIOLOGICAL ORGANIZATION Ecosystem Ecosystem Biosphere Biosphere This is a good exam question!

The CELL: Smallest unit of LIFE

Living Things Respond to Stimuli

• (^) Organisms sense and respond to internal and external environmental stimuli - (^) Sensory organs detect and respond to external stimuli - (^) light - (^) sound - (^) chemicals - (^) Plants and bacteria respond to stimuli as well - (^) light - (^) attraction towards nutrients

Living Things Maintain Internal

Conditions

• (^) Homeostasis : maintenance of relatively constant internal conditions - (^) body temperature - (^) pH of blood - (^) water concentration
• (^) Automatic mechanisms maintain homeostasis
  • (^) sweating during hot weather or during exercise
  • (^) metabolizing more food
  • (^) basking in the sun to raise body temperature
• (^) Organisms still grow and change while maintaining homeostasis

Living Things Acquire and Use

Materials and Energy

• (^) Materials & Energy required to maintain organization, grow, and reproduce
• (^) Important materials (nutrients) acquired from air, water, soil, or other living things
• (^) Metabolism is the sum total of all the chemical reactions needed to sustain life
• (^) Organisms obtain energy in two ways
  • (^) autotrophs (make own food)
  • (^) heterotrophs (eat others)
• (^) All energy that sustains life comes directly or indirectly from the sun

Living Things Acquire and Use

Materials and Energy

Fig. 1-

Living Things Grow

• (^) Every organism becomes larger over time
  • (^) Organisms grow by producing more cells to increase their mass
  • (^) Bacteria grow by enlarging their cells and divide to make more individuals
• (^) Growth involves the conversion of acquired materials to molecules of the organism’s body

Living Things Reproduce Themselves

• (^) Organisms give rise to offspring of the same type (reproduction)
• (^) The parent’s genetic material (DNA) is passed on to the offspring, creating continuity of life
• (^) Diversity of life occurs because offspring may be genetically different from their parents

DNA is the Molecule of Heredity

• (^) Deoxyribonucleic acid (DNA) contains segments called genes

DNA is the Molecule of Heredity

• (^) An organism’s DNA is the molecular instruction manual for operating its body
• (^) A copy of the parent’s DNA is made abd passed to its offspring in a highly accurate copying process
• (^) Occasional errors in copying (mutations) produce variety
• (^) Mutation, and therefore variation, is essential for living things to evolve

Living Things As a Whole Have the

Capacity to Evolve

• (^) The genetic composition of a whole species changes over many generations
• (^) Mutations and variable offspring allow a species to evolve
• (^) Evolution states that modern organisms descended with modification from pre-existing life- forms
• (^) Natural selection is a process where organisms with certain adaptations survive and reproduce more successfully than others - (^) “survival of the fittest”: adaptation

Scientific Principles Underlie All

Scientific Inquiry

• (^) Biology is a scientific discipline
• (^) All scientific inquiry is based on a small set of assumptions or principles - (^) natural causality (cause and effect) - (^) uniformity in space and time - (^) common perception

Principle I: Natural Causality

• (^) Historical approaches to studying life
  1. Belief that some events happen through supernatural forces (ex: Greek gods)
  2. Belief that all events can be traced to natural causes
• (^) Evidence gathered from nature has not been deliberately distorted to fool us

• (^) Natural laws are uniform in space and time
• (^) This principle is key to the understanding of biological events (ex: evolution) that occurred before humans recorded them
• (^) Creationism is contrary to the principle of uniformity-in-time and natural causality - (^) Creationists hold that different species were created one at a time by the direct intervention of a supernatural being, contrary to events we see happening today

Principle II: Uniformity in space and time

• (^) All human beings perceive natural events in fundamentally the same way
• (^) Common perception allows us to accept observations of other humans as reliable
• (^) Common perception is usually not found in appreciation of art, poetry, and music, nor between cultures or religious beliefs - (^) value systems are subjective - (^) science requires objectively gathered data

Principle III: Common Perception

The Scientific Method Is the Basis for

Scientific Inquiry

1. Observation of a specific phenomenon 2.The observation, in turn, leads to a question 3.The question leads to formulation of a hypothesis, that is offered as an answer to the question (nole/alternative) 4.The hypothesis leads to a prediction, typically expressed in “if…then…” language 5.The prediction is tested by carefully controlled manipulations called experiments 6.The experiments produce results that either support or refute the hypothesis, allowing the development of a conclusion