Studying Life

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Biology

• Means study of life

• Science that seeks to understand the living world

• In order to be considered alive, organisms must meet 8 criteria

1. Made up of cells

• Cells - smallest unit of life

• Unicellular - made of 1 cell

• Multicellular - made of several cells

2. Reproduction

• Produce new organisms through a process called reproduction

• Asexual - single parent, divides in 2, creates identical offspring

• Sexual - 2 parents, genetically different offspring

3. Based on a Genetic Code

• Offspring inherit traits from parents

• Directions for inheritance carried in DNA - genetic code

4. Growth and Development

• All living things grow during at least part of their lives

• Some, like bacteria, just grow in size

• Multicellular organisms go through stages of development

5. Need for Material & Energy

• Organisms need materials and energy to grow, develop, and reproduce

• Get energy from photosynthesis or consuming energy stored from photosynthesis

• Metabolism

6. Response to Environment

• Organisms detect and respond to stimuli from environment

• External stimuli - light & temp.

• Internal stimuli - blood sugar level

7. Maintaining Internal Balance

• Organisms must keep internal temp. and water content fairly constant to survive

• Homeostasis - maintaining internal balance– Shiver, sweat

8. Evolution

• As a group, organisms evolve, or change over time

• Ex. - fish bony plates to scales

Levels of Organization

BiosphereEcosystem

CommunityPopulation

OrganismGroups of cells Cells

Molecules