Section 1.1

Characteristics of Life

1. Cells & Organization

» Cell- basic unit of All life

˃ Unicellular: organism made up of 1 cell

˃ Multicellular: organism made up of many cells

» Differentiation:

˃ Cells in multicellular organisms become specialized in shape, size & function

Nerve cell Epithelial (skin) cell

» All life is organized (even if unicellular)

organism organ system organ tissue

atom molecule organelle cell

2. Response to Stimuli

» Stimulus- anything that causes reaction such as light, temp, odor sound ˃ ex: eyes (pupils) respond to light

˃ Living things respond to stimuli to survive

3. Homeostasis

» Ability to maintain constant or stable conditions necessary for life

ex: sweating to cool off » Cells expend energy to maintain homeostasis

4. Metabolism

» Energy is used to power all life functions

» Metabolism: sum of all enrgy reactions in body

» If you have a “fast metabolism” you burn more energy (calories) than you store.

» If you have a “slow metabolism” you store more energy (calories) than you burn.

5. Growth & Development

» ALL life grows:

˃ Unicellular: cell gets larger

˃ Multicellular: grow by cell division and

differentiation

» Development: cycles of change- physical, emotional, intellectual

ex: puberty

6. Reproduction

» DNA (genetic code) is passed from parent to offspring

» 2 types:

a. Sexual – involves 2 parents & exchange of DNA offspring different from parents

b. Asexual- 1 parent only, no exchange of DNA offspring identical to parent

6. Change through Time

» Populations evolve (slowly change) over time

» Important for survival in a changing world

» Explains diversity of life on Earth

» No!

» Noncellular infectious particles

» No life functions outside of living host

» 2 parts: protein coat

nucleic acid core

ebola

Section 1.2

Scientific Method

Controlled Experiment- tests one variable at a time

» Variable – factor being studied

1. Independent Variable (IV) – manipulated or changed during experiment

2. Dependent Variable (DV) – factor affected by the IV

- DV is measured or observed

- D = “data” (results in experiment)

» To observe the affect of IV, scientists set up 2 experiments:

1. Control Group:

» Nothing is tested here – IV unchanged

» Used for comparison

2. Experimental Group:

» This is the test group – IV is changed

Does the addition of fertilizer (IV) increase plant height (DV)?

A B

experimental gp. control gp.

+ fertilizer no fertilizer

» In the example, the addition of fertilizer is the ONLY difference.

Constant – variables in experiment that remain the same

- ex: water, sunlight, soil all remain constant

- sometimes called “Controls” (poor terminology)

Section 1.3

Microscopes

» Uses light for viewing

» Specimen thin – so light can pass

» Magnify up to 1000x

» Focus – uses glass lenses

» Total magnification – total power of all lenses

˃ (ocular x objective)

» Limit of resolution – limit of scope to magnify

clearly at high power

1. Coarse Focus/Adjustment: initial focus

2. Fine Focus/Adjustment: crisp focus

3. Arm: used to carry scope

4. Stage clips: holds slide in place

5. Base: supports scope

6. Ocular lens/Eye Piece: allows viewer to “see”

specimen, magnification

7. Body Tube: transmits image to ocular lens

8. Revolving Nose Piece: changes magnification

9. Objective Lenses: magnification

10. Stage: supports slide

11. Diaphragm: Controls amount of light

12. Light Source: illuminates specimen

13. Aperture: allows light to pass through stage

» Uses beam of electrons

» Focus – uses magnets to bend e- beam

» Requires vacuum chamber – so air does not interfere w/ e- beam

» Magnifies up to 10,000x