Biology Chapter 1: The Basis of Life

Chapter 1: The Basis of Life

• Artificial life is a scientific field exploring minimal requirements for life.
• In 2010, a team successfully replaced a bacterium's DNA with a synthetic form.
• Biology studies life and living organisms (Bio + Logy).
• Life exists almost everywhere on Earth.
• Earth has a vast array of diverse life forms.
• All living things share common characteristics.

Characteristics of Life

• Organized: Living things are organized into a hierarchy of levels (cells, tissues, organs, organ systems, organism, population, community, ecosystem, biosphere).
  • A cell is the smallest unit of life.
  • Tissues are groups of similar cells.
  • Organs are groups of tissues.
  • Organ systems are groups of organs.
  • Populations are organisms of the same species.
  • Communities are interacting populations.
  • Ecosystems are communities and their physical environment.
  • Biosphere encompasses all regions of Earth inhabited by living things.
• Acquire materials and energy: Organisms need outside sources of materials and energy, including building blocks and capacity to do work.
• Reproduce: Reproduction is creating a new organism like itself. Methods vary among organisms.
• Respond to stimuli: Organisms respond to their environment by moving toward (or away from) a stimulus. This can be voluntary or involuntary.
• Homeostatic: Maintains a consistent internal environment. Dynamic equilibrium is maintained.
• Grow and develop: Growth is an increase in size or number of cells. Development is changes during an organism's life, from conception to death.
• Adapt: Organisms adapt to changing environments.

Additional Notes

• The sun is the ultimate source of energy for most ecosystems.
• A variety of food sources can influence beak types, as a characteristic example.
• Adaptations aren't always linked to evolution. Adaptations and choosing proper clothing for different weather conditions or using protective gear are examples of adaptation not related to evolution.