Biol-1009 Major Lab Quiz #1 Review

Biol-1009 Major Lab Quiz #1 UMN Twin Cities Spring 2024

Scientific Method

Scientific Method

• Process in which scientists utilize in order to explain and gain knowledge about the physical and natural world.

Steps of the scientific method:

1. Observations

2. Hypothesis

3. Prediction

4. Test

5. Results

   • Results can support or not support hypothesis and can be revised/remade

6. Conclusions

   • Can lead to refinement of an existing hypothesis

Comprehensive model of Scientific Processes:
Exploration and Discovery: Aims to fill a knowledge gap in the field

• How the scientific method aims to explore causation in activities and processes in the natural world

• Conducted via making observations, asking ?’s, or being inspired to meet medical needs, or inspiration from other literature

Comprehensive model of Scientific Processes:

Forming and Testing Hypotheses

• Determines if there’s support or not for a hypothesis

• Hypotheses = tentative answer to tentative question that explains natural processes in the world

  • May be revised if not supported

Comprehensive model of Scientific Processes:

Community Analysis and Feedback

• Allows for testing and review of studies to determine validity

• Was the study conducted fairly? Reasonable conclusions based on evidence?

• Society’s input = important 

  • Because everyone can contribute ideas to science to strengthen knowledge and conclusions

Comprehensive model of Scientific Processes:

Societal Benefits and Outcomes

• Studies conducted for solving problems or meet needs in society

• Via: Finding new info, developing technology, or furthering knowledge

• Science answers questions for society w/empirical backing 

Hypothesis

• Tentative answer to tentative question in which it explains natural processes and activities

• Must be testable, predictable, and empirically supported w/given info

• Can NEVER BE PROVEN, only supported or not supported

Independent and Dependent Variable

• 1. Variable manipulated by experimenter

• 2. Variable of interest that is measured by experimenter. Measured to determine causation due to IV

Control Group

• Individuals who are not exposed to treatment and may go undergo placebo

Placebo

• A “false” treatment is given to see if the idea of having an effect will make it happen

Control

• Variables that remain the same throughout

Positive and Negative Control

• Positive control = Expect an effect ex: Bleach in CURE

• Negative control = No effect ex: Water in CURE

Dissecting Microscope

• Low magnification microscope

• Can see 3D object with higher detail using light from above

Compound Microscope AKA (Light Microscope)

• Lenses let you see enlarged image of species

• Magnification improves resolution, making the image sharper

Eyepiece

• Contains ocular lens

Pointer

• Located in ocular lens

• Indicates location of object

Sliding interpupillary distance adjustment scale

• Adjusts distance between ocular lenses so it coincides w/distances between pupils

• Ensures you only see one view when you look through eyepieces

Mechanical stage and stage clip:

• Holds the slide in place

X & Y Stage Controls

• Knobs that control horizontal and vertical movement of mechanical stage

• Y is on top of the X

Coarse and Fine Adjustment Knobs:

• Sharpen image of specimen

• Coarse= Big one

• Fine = Small one

Diopter Adjustment Ring

• Compensates for differences in your eye strength

•  Located on left eye piece

Illuminator

• Light Source

Illumination intensity knob:

• Regulates amount of light transmitted from illuminator

Iris diaphragm lever

Regulates amount of light that reaches specimen

• Right under condenser

Condenser

• Focuses light through specimen

• Located under microscope slide typically

• Better to focus the edges of FOV

• May need to be rotated slightly downward

Objective and ocular lenses to total magnification

Objective x ocular = total magnification

AKA: (Obj.) Magnification strength x (Ocul.) 10 = total magnification 

Ex: Objective lens 40x * 10 = 400x total magnif.

Diameter of field: Field of View

• Circular illuminated area seen when you look through eyepiece of microscope

• Negative relationship w/magnification 

Center of Field

• Objective lenses region where objects are in sharp focus

• Fixed at each magnification

Depth of field

• Vertical zone of center of focus

• Not sharp in focus, but is still visible

• Negative relationship w/magnification

Division per field, mm per field, and μm  per field relationship

10:1:1000 ratio

Ex:  Div.OF: 45.  mm: 4.5  μm 4500

Enzymes

• Organic catalyst that speeds rate of reaction

• Via: Enzyme substrate complex

  • Enzyme and substrates are available

  • Substrate binds to enzyme’s active site

  • Substrate converted to products

  • Product released, and enzyme is unchanged and can be used again

Temperature on enzymatic activity

• There is an optimum temperature for each enzyme’s optimum activity

• Going above it = chemical bonds of enzyme becomes denatured hence reaction is quickly reduced

• Going below = reactants moving w/less kinetic energy hence not enough energy for reaction and rate of reaction is reduced

  • Decreasing temperature more gradual, increasing past optimum is a sudden drop

pH on enzymatic activity

• Optimum pH where enzyme has optimal activity

• Reduced and excess pH = disrupted chemical bonds in enzyme

• Rate of reaction is inhibited and enzyme is less efficient

  • Bell curve

Substrate concentration on enzymatic activity

• Substrate concentration increases enzymatic activity as more active sites get filled,

  • However all active sites will eventually be filled

  • Enzyme will be the limiting reactant at that point hence rate of reaction does not change after that point

• Graph will top up at that point

Enzyme concentration on enzymatic activity

• Enzyme concentration increase enzymatic activity because more active sites are available for catalysis UNTIL

  • Substrate concentration will be limiting because there will be too many active sites to fill

  • Substrate = Limiting reactant

• Graph tops up at that point as well 

Starch Hydrolysis Reaction

• Addition of water to break down starch

• Catalyzed by amylase enzyme

Forms products: Glucose and maltose

Spectrophotometer

• Detects amount of light absorbed by amber compound formed by reduction agents glucose and maltose

• Displays absorbance value proportional to concentration of colored product

  • Is also proportional to concentration of glucose/maltose

Use of blanks

• Ensures absorbance value in spectrometer is only tied to the sample material and not components of solution

• Accuracy and reduces contamination for experiment

Detection Reagent

• Glucose and maltose reduce it to 3-amino 5-nitrosalyicylic acid

• An amber color compound, and intensity of color is directly proportional to quantity of glucose and maltose

  • Darker = higher concentration