Biology Investigation Skills

define a variable

define a variable

anything that can change or be changed

independent variabke

the variable that is being manipulated

dependent variable

the variable that is being measured

control variable

what are control variables

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Control Variables are factors in an experiment that are kept constant to ensure that the only thing affecting the dependent variable is the independent variable being tested.

why do we need control variables?

to ensure that the only thing affecting the dependent variable is the independent variable being tested.

why is there a control group and an experimental group

the control group lacks the independent variable to serve as a baseline for comparison

experimental group includes the independent variable to observe its effects.

This setup helps isolate and identify the impact of the independent variable.

Why must an experiment be repeated many times, use replicates or use a large number of individuals (i.e. sample size)? 2 reasons

• To reduce variability: we can minimize the impact of random variation in the results.

• To increase reliability: Multiple trials help ensure that the findings are consistent and reliable, also enhancing the validity of the conclusions.

validity

refers to the degree to which an investigation design provides data that assesses what is intended to measure

what is reliability

refers to the degree to which an investigation yields the same results under repeated conditions

how do we make an experiment reliable?

1) consistent conditions

2) appropriate sample sizes

3)randomize samples

4)control variables

5)replicate the experiment.

how do we make an experiment valid

1. Control extraneous variables.

2. Use random sampling.

3. Ensure measurement tools are accurate.

4. Use appropriate research design.

5. Conduct pilot studies.

hypothesis

a testable statement that links the indepedent variable between the dependent variable

uncontrolled variables

Factors that are not kept the same for both control and experimental group. They may have been overlooked or impossible to control.

repetition

doing the same experiment multiple times

replication

Having a number of identical experiments running together

performing the experiment on a large number of subjects at the same time

other ways to ensure reliability

have one person doing each thing, having someone oversee the experiment

concentration of reactants

chemical reactions occur faster if reactant particles are kept close together and have a greater chance of hitting each other. increase number of colosions bby keeping concentration as high as possible

state of subdivision reactants

dividing reactants into smaller pieces will increase their surface area and the number of reactant collisions.

temperature

higher the temperature, the more energy the particles will have to react together to form the products. warming up chemical reaction container speeds up chemical reaction

catlysts

special substances used to speed up chemical reaction without themselves being used in the chemical reaction.

enzymes → catalysts in naturally occuring chemical reactions

inhibitors are the opposite, that slow a chemical reaction down