Introduction to Life Science: Evolution and Adaptation

Study Notes

Evolution and Adaptation:
- All biological beings must adapt to their environment to survive
- Adaptation: any structure, behavior, or internal process that allows response to a stimulus, giving a better chance of survival
- Evolution: gradual accumulation of adaptations over time
- Examples of adaptations in polar bears:
  - White fur for camouflage
  - Thick layer of fat for thermoregulation
  - Long stiff hair for protection from cold and slipping on ice
  - Strong swimming ability for catching prey
  - Hollow fur for buoyancy and insulation
  - Small rounded ears to prevent water from entering and freezing eardrums
Charles Darwin's contributions:
- Natural selection: process by which individuals better suited to their environment survive and reproduce most successfully (survival of the fittest)
- Descent with modification: each living species has descended, with changes, from other species over time due to natural selection

All organisms can respond to their environment
Stimulus: any condition in the environment that requires an organism to adjust
Response: reaction to stimulus
Homeostasis: stable level of internal conditions (e.g. body temperature, water content)

All living things are organized into cells and made of the same organized matter
Types of organism organization:
- Unicellular: organism is made up of one cell
- Multicellular: organism is made up of more than one cell
Cells can be differentiated: different cells in one organism have different functions (e.g. heart cells and lung cells)

All organisms use energy to grow, respond, maintain homeostasis, and adapt
Metabolism: the chemical process by which a plant or animal uses food, water, etc. to grow and heal and make energy
Categories of living things according to food source:
- Autotrophic: organism uses energy from the sun for photosynthesis to make its own food (e.g. plants)
- Heterotrophic: organism ingests food to receive energy (e.g. animals, fungi)

All organisms reproduce new organisms like themselves by transmitting hereditary material to their offspring
DNA (Deoxyribonucleic acid): contains the hereditary material of a cell; the blueprint of reproduction, growth, and development
Growth: an increase in the amount of living material
Development: all changes that an organism undergoes in its lifetime

Ecology: the study of the interaction of organisms with their environment
Energy from the sun is passed from one organism to another: producers (plants) to herbivores (plant eaters) to carnivores (meat eaters) to decomposers (breakdown dead organisms)
Factors that determine interdependence, survival, and growth of an organism in an environment:
- Abiotic factors: non-living factors (e.g. air, water, energy, soil, temperature, minerals)
- Biotic factors: all living things on earth

Theories about the origin of life:
- Special Creation: life-forms may have been put on earth by supernatural or divine forces
- Extraterrestrial Origin: life may have originated from another planet
- Spontaneous Origin: living organisms can originate from inanimate objects
Hypotheses about where life started:
- At the ocean's edge under a reducing atmosphere
- Under frozen oceans
- Deep in the earth's crust
- Within clay
- At deep-sea vents
The Miller-Urey experiment: an early attempt to see what kinds of organic molecules might have been produced on the early earth