lecture 3: studying life

Question 1

What is a biological specimen and what can it be?

Answer 1

Your subject/unit of study

- Can be an organism, cell population, biomolecule preparation, ecological group/population

Question 2

What are some characteristics of model organisms?

Answer 2

1. Convenient to study: small size, simple feeding
2. Large number of offspring (rapid development)
3. Genetics understood and controlled through breeding
4. Have attributes that make them useful to study

Question 3

What are the 2 approaches to studying life?

Answer 3

1. Reductionist
2. Holistic

• Need to use both

Question 4

What is reductionism?

Answer 4

Reduces a system into components

• Starts with this first
• Easier
• But miss emergent properties and understanding of a system

Question 5

What is holism?

Answer 5

• Tries to understand how components work together
• More informative to understand life
• Harder

Question 6

What are the 2 types of biological studies?

Answer 6

1. Discovery studies: DESCRIBES nature using INDUCTIVE reasoning
2. Hypothesis testing: EXPLAINS nature using DEDUCTIVE reasoning

Question 7

What are the 2 types of reasoning?

Answer 7

1. Inductive reasoning (new discovery): Oberservation —> Generalizations —> Hypothesis
2. Deductive reasoning —> Hypothesis —> Predictions —> Experiment

Question 8

What is “describing nature”?

Answer 8

• Based on observations
• Leads to generalizations
• Leads to hypothesis testing

Question 9

What are the steps in “explaining nature”?

Answer 9

1. Ask a question: from observations
2. Form a hypothesis: propose possible answers to questions; based on solid rationale
3. Hypotheses lead to predictions: lead to predictions that are testable
4. Testing predictions: experiments designed to test predictions made by hypotheses

Question 10

What are the 2 possible results of experiment?

Answer 10

1. POSITIVE RESULT: supports hypothesis
2. NEGATIVE RESULT: falsify hypothesis
   - The null (no effect) hypothesis is supported

Results cannot PROVE a hypothesis, it SUPPORTS/FALSIFIES it

Question 11

Types of variables?

Answer 11

1. Qualitative: non-numerical and descriptive
2. Ranked: data listen in order of magnitude
3. Quantitative: numbers, continuous/discontinuous

Question 12

What is a causal experiment?

Answer 12

To determine whether one variable (x) has an EFFECT on another (y) to support the hypothesis

Question 13

What is a controlled experiment?

Answer 13

Experiment conducted in an environment where only the variable to be tested has an effect on the result
- To control for unwanted variables not by eliminating them through environmental regulation,. but by CANCELLING their effect using a CONTROL TREATMENT

Question 14

What is a control treatment?

Answer 14

Subject is treated under a condition where all variables are held constant BUT independent variable is CHANGED & set to a REFERENCE CONDITION

Question 15

What does a control treatment tell you?

Answer 15

Allows experimenter to measure the BASELINE (initial condition) measurement of dependent variable

Question 16

Why is a control treatment important?

Answer 16

Allow experimenter to determine whether a change observed in the experimental treatment is due to independent variable or not

Question 17

What is a controlled variable?

Answer 17

Variable held constant between treatments (one varibale that should change is the independent variable)

Question 18

What are replicates?

Answer 18

Multiple independent subjects (units of study) for each treatment to form a group

Question 19

What do replicates tell you?

Answer 19

The VARIABILITY in the response of your subjects WITHIN the same treatment group (BIOLOGICAL VARIABILITY)

Question 20

Why are replicates important?

Answer 20

Must know variability in the response WITHIN a treatment group to know wheter a DIFFERENCE BETWEEN TREATMENT GROUPS IS REAL (to know that results aren’t just caused by biological reasons)

Question 21

What are the 2 reasons why replicates are important?

Answer 21

1. Must know how variable a response is between replicates treated the same way to know if A DIFFERENCE OBSERVED FOR A SUBJECT TREATED DIFFERENTLY IS REAL (statistical test to verify)
2. Larger samples = better estimates of the characteristics of the population under study
   - The more replicates, the better
   - Reduces sampling error

Question 22

What is the difference between a scientific theory vs Hypothesis?

Answer 22

• Theory is:
  1. Much broader
  2. General
  3. Supported by much greater body of evidence