Biology: Science of Life

Ch.1

(1-1) Characteristics of Life

1. Organization & Cells

2. Response to Stimuli

3. Homeostasis

4. Metabolism

5. Growth & Development

6. Reproduction

7. Change thru Time

Organization

• Cells: basic unit of life• Tissues: groups of cells w/ similar functions

– Muscle tissue

• Organs: tissues carry out specialized jobs– Lung

• Organ Systems: organs that work

together to perform a task– Respiratory system

Figure 41.2

Stomach as an Organ Within Digestive System

Cell Structure & Function

• Unicellular: 1 cell– Bacteria

• Multicellular: many cells– Humans

• Differentiation: cells become specialized

Why cells specialize:"A jack of all trades is master of none"

Doing it all means not doing any one thing really well.

Example of tradeoff

Fully-f eatured Swiss Army knif e does many jobs, but each tool can be awkward to use.

Response to Stimuli

• Stimulus: change in the internal or external environment– Dilating pupils

Homeostasis

• Stable internal conditions

• Ex: – Temperature

• Ex: Thermostat

– Water intake– Food intake– pH

Metabolism

• Sum of all chemical rxns that take in & transform E & materials from the environment

• Photosynthesis: converts light E into chemical E

• Cellular Respiration: converts organic cmpds into usable E (ATP)

Growth & Development

• Cell division: formation of 2 cells from an existing cell

• Development: process by which an organism grows – Repeated cell divisions & differentiation

Reproduction

• DNA (deoxyribonucleic acid): large molecule of hereditary info

• Gene: segment of DNA that contains instructions for development of a single trait

• Sexual (2 1) vs. Asexual (1 2) reproduction

Change Thru Time

• Evolution

(1-2) Themes of Biology

• 3 major themes1. Diversity & Unity of Life

2. Interdependence of Organisms

3. Evolution of Life

Diversity & Unity of Life

• All living things have in common:– Genetic code– Tree of Life (lineages)

• 3 domains• 6 kingdoms

Interdependence of Organisms

• Ecology: study of the relationship b/w organisms & their environment

• Ecosystem: all the biotic & abiotic (nonliving) components of an environment

Evolution of Life

• Adaptations: traits that improve ability to survive & reproduce

• Natural selection: organisms w/ favorable traits reproduce at higher rates than those w/out such traits– “Survival of the fittest”

(1-3) Scientific Method

1. Observe2. Hypothesize

• Explains observations & data & can be tested (“if, then”)

3. Predict4. Experiment

• Qualitative vs. quantitative (#’s) data

5. Communicate– Theorize: well-tested explanation of observations

Experiment Variables

• Control group: standard– Hunts in light

• Experimental group: identical to control except 1 factor– Hunts in dark

• Independent variable: manipulated variable– Amount of light

• Dependent variable: responding variable– Distance of owl’s strike

(1-4) Microscopes

• Instrument that produces an enlarged image of an object

• Ex:– Light (living)– Electron (nonliving)

Measurement

• SI: standard system of measurement used by scientists

• Base units: 7 fundamental SI units– Length: m– Mass: kg– Time: second