基础生物实验 1 - 实验一简介：Experimental Design
新坑！这一部分实验的内容将放在生物基础与进阶文集的基础部分之后。这一部分的内容旨在介绍生物实验的基本方法，并提供线上虚拟实验的独特体验。本期是第一期，内容是实验设计的理论基础。下一期将是实验一的实验手册、下下期则是实验模拟（中文）。
本部分内容来自 University of California, Berkeley - UC Berkeley Extension, 虚拟实验的内容来自 Labster. 本部分内容均不会标记为为原创，但由于是UP主购买的课程，因此不接受非授权的转载，谢谢您的理解。
每一个生物基础实验均会分为三部分：第一部分为实验的生物理论；第二部分为实验的指导手册；第三部分为 Labster 的虚拟实验模拟。第一部分的基本信息由 Ying Liu, Ph.D. 提供，第二部分的实验手册来自 Labster, 第三部分的实验模拟过程由UP主操作。
Lab 1 - Experimental Design: Basic Information:
[1] Lab Safety & Housekeeping
Lab safety
- Wear closed-toe shoes
- Long hair tie back
Locate safety items
Lab cleanup pROCedures
- Wipe the bench clean before and after work
- Glassware
- Equipments
- Different (biohazard) wastes
[2] Metric System
- Official system of measurement in almost every country in the world
- Developed by the English in 1600s
- First adopted by the French after the Revolution
- US is the only industrialized country that has not adopted it!
Base units for measurements: meter, liter, gram
Units are related by factors of 10, and denoted by standard prefixs (e.g. milliliter (ml), kilometer (km), microgram (μm)
Universally used in sciences
Metrix vs. English System
Conversion in Metric System
Move the decimal point: The right direction & The right number of places
Example: 100 µL = ? mL - µL=10^-6 L, mL=10^-3 L
[3] Experimental Design / Scientific Method
Elements of a Scientific Approach
Observations lead to a question
Hypothesis is the tentative answer or explanation
- Must be testable and falsifiable
- Cannot be proved
Prediction is made based on hypothesis and experiments designed to test it (think: if…then…)
Bad vs. Good Questions
- Good questions are: Well defined, Measurable (testable), Reasonable, Consistent with existing bodies of knowledge, and Falsifiable
- Bad questions are broad or do not have a clear answer, example: "Is nicotine bad for you?"
- A good scientific question has a narrow, unambiguous answer: "Does nicotine cause lung cancer?"
Science as a Way of Knowing
- Observation: my neighbor’s lawn looks more healthy than mine. Hmmmm…
- Question: Does the amount of water we each put on our lawns account for the difference?
- Hypothesis: My neighbor’s lawn is more healthy because it gets more water than mine
Design an Experiment
VARIABLES:
Independent: factor being manipulated for effect on dependent variable (experimental condition)
Dependent: the response being studied
Controlled (confounding): other factors that experimenter holds constant
PROCEDURE:
Level of treatment-- value or range of the independent variable
Control-- parallel pROCedure in which the independent variable is set or omitted
Replication-- one comparison not enough!
Performing the Experiment
- Prediction: IF a lawn gets more water, THEN it will be greener and grow faster than a lawn with less water (you have determined how you will measure ‘healthy’)
- Do the experiment
- Collect and analyze data
- Repeat the experiment
- Publish / communicate with the scientific community
Hypothesis vs. Theory
Hypothesis: tentative answer to a rather narrow question
Theory: well-supported, broad explanation
A scientific theory is much broader and better supported than a hypothesis.
A scientific theory is:
- Broad in scope – a big idea!
- General enough to generate new hypotheses
- Supported by a large body of evidence
Some well-known theories in biology: Cell theory, Germ theory of disease, Theory of evolution by natural selection, etc.
Graphing Results
- Independent variable plotted on x-axis
- Result (dependent variable) plotted on y-axis
- Statistics (standard error) tells us how uncertain a particular value is
Line vs. Bar Graphs
- Line graph: used to show changes that occur in related variables, and trends over time
- Bar graph: compare data (measurements) from different groups, can show large changes over time
Experimental Design
Learning objectives:
Explain and apply the scientific method
Design an experiment and test your hypothesis
Correctly use experimental controls
感谢阅读！下一期为实验手册 & 下下期将进行 Labster 实验！
