Chapter 1 : The Science of Life pg. 4 Section 1 : The World of Biology

Biology- the study of life How is biology important to a person’s daily life and to human society?

Knowledge of biology allows us to make informed decisions and know about our health, technology, the food we eat, pollution, diseases, and the environment.

Characteristics of Life 1. Organization and Cells 2. Response to Stimuli 3. Homeostasis 4. Metabolism 5. Growth and Development 6. Reproduction 7. Change Through Time

1. Organization and Cells Organization- the high degree of order within an organism’s internal and external parts and in its interactions with the living world

Organs- structures that carry out specialized jobs within an organ system; made of tissues Tissues- groups of cells that have similar abilities Cell-the smallest unit that can perform all life’s processes

Organelles- tiny structures that carry out functions necessary for the cell to stay alive Examples: mitochondria & Golgi Apparatus Biological molecules- the chemical compounds that provide physical structure and enable other cellular functions and biological molecules are made of ATOMS

Organization also includes: Unicellularity- Multicellularity- Single-celled More than one cell

2. Response to Stimuli An organism’s response to a stimulus (a physical or chemical change in the environment) Examples: pupil dilation in response to bright light What are some other examples of an organism responding to a stimulus?

3. Homeostasis Homeostasis- the maintenance of a stable level of internal conditions even though environmental conditions are constantly changing. Examples: burning calories to stay warm :Birds fluffing up feathers to keep warm

4. Metabolism Metabolism- the sum of all the chemical reactions that take in and transform energy and materials from the environment; getting energy from the food we eat Or………………. photosynthesis

5. Growth and Development *All living things grow and increase in size. Growth in living things occurs by cell division and not accumulation of matter such as occurs in crystals (nonliving) Development- the process by which an organism becomes a mature adult

6. Reproduction Producing offspring *NOT essential to the survival of an individual DNA transmits heredity information from parent to offspring

Why is reproduction an important characteristic of life? Gene- a short segment of DNA that contains the instructions for a single trait of an organism Why is reproduction an important characteristic of life? *Reproduction is essential to the continuation of a species*

Types of Reproduction Asexual Sexual One parent; produces identical offspring Ex. bacteria 2 parents produce offspring that contain genetic material from both parents; a different individual

7. Change Through Time Evolution- changes in a population over time The ability of populations of organisms to change over time is important for survival in a changing world. Also, it explains the diversity of life-forms found on earth today. Evolution- changes in a population over time