Lab Exam

Question 1

What is natural selection?

Answer 1

Mechanism of evolution caused by differential survival and reproduction of individuals in a population in response to some selective pressure in the environment

Question 2

What did Darwin believe about nat selec? Why was it not fully correct?

Answer 2

In many organisms the process was too slow to observe during a persons lifespan -> thousands of generations but it can occur more rapidly in organisms with short generation times like bacteria -> first antibiotic resistance bacteria found in 1940

Question 3

What’s the longest running expirement on evolution?

Answer 3

Richard lenski of Michigan state uni growing E. coli in liquid cultures insect 1988, started with a single cell that was than split into 12 population and since 1988 daily he’s taken small samples and replanted them for 50000+ generations. Every 500 generations he freezes to preserve and compare to og -> shown they evolve bc grow 75% faster now

Question 4

What are the results of the lenski expirement?

Answer 4

After 30000 (15 yrs) developed ability to metabolize citrate another component of liquid medium which is unexpected bc ecoli cannot transport citrate into cells-> can’t use for energy but a mutations in membrane transport protein allowed uptake -> cells can still use glucose but less successful than ancestors -> split into two lineages that coexist in same flask using diff resources (glucose vs citrate)

Question 5

What’s the set up of the lenski experiment?

Answer 5

Time only factor inflicting evolution, grew in flask of glucose (only sugar) constant temp, no predator and replated daily

Question 6

What list of factors could be introduced to an expirement like lenski to accelerate evolution process?

Answer 6

Selective pressure- antibiotics, predators, uv radiation, chemical irritants, competing populations/species
Changes to envo conditions- temp, humidity, light availability, comp/pred/birus
Anyimicrobial additives- antibiotics, heavy metals, bleach, alcohol
Changed to growth media, sugar, ph , nutrients or salt
“Natural” agents- garlic, honey, turmeric

Question 7

What’s a bacterial lawn?

Answer 7

Term used to describe pattern of bacterial culture growth on agar plates when all indv colonies merge to form a uniform field of bacteria across the surface of the plate

Question 8

What is preferred bacterial lawns or indv colonies in assays to screen for antibiotics?

Answer 8

Indv-desirable bc represent coronal growth from a single bacterium (all cells in colony identical)
Lawn-used extensively to screen for antibiotic resistance or bacteriophage infection bc shows ZOI

Question 9

What’s the aseptic technique?

Answer 9

Clean lab coat completely buttoned with sleeves rolled down, no bare legs, no open toed shoes, long hair tied back, bench space free of extraneous material and disinfected before and after each lab,hands washed before and after, turn on Bunsen burner at blue colour and played should be ardound sterilization area on the Bench

Question 10

What’s the proper handwashing technique?

Answer 10

Plenty of soap, all surfaces of hand for min 15 sec, always keep hands up (don’t let drop down), rinse hands throughly with running water, dry with paper towels that then goes in garbage

Question 11

What’s in the sharp wastes?

Answer 11

Clean broken class

Question 12

What’s in biohazard out waste?

Answer 12

Contaminated broken glass-bacteria or other microbes, materials contaminated with other body fluids

Question 13

What goes in the autoclave waste?

Answer 13

Bacterial/microbial waste including used agar plates, puppets tips, tubes

Question 14

What goes in the garbage?

Answer 14

Gloves and paper towels

Question 15

Evolution by natural selection is inevitable if?

Answer 15

Natural variation of traits in a population, selective pressures that favour some traits over others (better repro chances), traits can be inherited by offspring , enough time for traits to be fixed in the population

Question 16

What is the point of the disk diffusion experiment?

Answer 16

Infusing paper disks with anti microbial agent to create a zone of growth inhibition which can be measured as an indication of anti microbial strength

Question 17

What’s the disc diffusion assay?

Answer 17

Aka agar diffusion test- comply used in drug discovery research to test the antimicrobial properties of chemicals and drugs such as antibiotics, in lab directly used w bacteria isolated from patient infections to decide the best course of treatment by determining susceptibility of bacteria to different clinically approved antibiotics

Question 18

How does the disc diffusion assay work?

Answer 18

Placing filter paper disks that has been infused with anti microbial agent onto agar plate that has been uniformly inoculated with bacterial culture -disc content diffused into agar such that conc of agent wil be highest next to the disc and decrease as the distance from the disk increases

Question 19

What’s the PICO question framework?

Answer 19

Population being studied, intervention being tested, comparison with an indentified control and outcome that will be measured

Question 20

Available antimicrobials?

Answer 20

Antibiotics-kanamycin, streptomycin, gentamicin,
Heavy metal salts- copper sulphate, zinc sulphate, silver nitrate, aluminum sulphate,
Household agents- dettol, chloroxylenol

Question 21

The higher the ZOI what does that mean for the agent?

Answer 21

Greater antimicrobial activity

Question 22

What other factors can affect ZOI?

Answer 22

solubility of agent (how week it can diffuse into agar from infused disc in a conc dependent manner, higher viscosity solutions (oil or alc) don’t diffuse as well and can be difficult to assesses)
Molecular size of agent-( molecular weight is inversely proportional to rate of diffusion larger moles won’t diffuse as far from disc in given incubation time and have smaller ZOI)
Stability of agent (some compounds good at killing short term but not stable enough to maintain constant efficacy over 12-16 hour incubation time or high temp, volatile agents can quickly kill bacteria but evaporate rapidly and no longer effective after only a few min)

Question 23

What are we comparing in the cure project?

Answer 23

Not efficacy of different agents to eachother but the effects of long term exposure to these agents and observing whether the agents retain their antimicrobial activity over the duration of the expirement or whether the bacteria develop resistance and adapt to the agent

Question 24

What’s an example of interactions between aquatic and terrestrial ecosystems?

Answer 24

Eutrophication of water bldies

Question 25

What are oligotrophic aquatic ecosystems?

Answer 25

Healthy = relatively low in dissolved nutrient (oligo- few tropic-nutrients)

Question 26

What are eutrophic aquatic ecosystems?

Answer 26

High nutrient levels and tend to be dominated by algae or/and other aquatic surface plants which is generally not a dished state

Question 27

What’s eutrophication?

Answer 27

Process by which a body of water becomes enriched in nutrients from terrestrial ecosystems and can happen by natural processes (ex. Banks of river erroded) but human activities (ex. Cultural eutrophication) such as addition of fertilizer to aquatic systems are often the cause of or at least speed up the process - can cause anoxic dead zones that take years to recover bc photosynthetic organisms under algae mats die than get decomposed by bacteria which consume all o2

Question 28

What are the primary nutrients needed by plants and algae?

Answer 28

Nitrogen, phosphorus snd potassium which are major constants of fertilizer (N-P-K numbers on fertilizer)

Question 29

Why do plants and algae need large quantities of N and. Phosphorus? Potassium?

Answer 29

Major constituents of proteins and DNA, potassium essential bc important role in maintaining turnout pressure in plant cells and in activation of many enzymes

Question 30

Green algae vs Cyanobacteria?

Answer 30

Cyanobacteria can fix gaseous nitrogen into a form used by cells so can survive in nitrogen poor envo unlike green algae

Question 31

What’s the major limiting factor for plant (and algae) growth in many ecosystems (including agroecosystems made by humans for crop growth)

Answer 31

Avalibolgu of N, P, K mostly N

Question 32

Why did we set up microcosms?

Answer 32

Investigate the effects of increasing fertilizer application on terrestrial plants and on aquatic ecosystem over a few weeks

Question 33

How can eutrophication due to human activities occur?

Answer 33

Add fertilize in quantities higher than plants use immediately so excess are carried into water bodies as topsoil is eroded via runoff, nutrients are also introduced via Effluent from sewage treatment plants, causes eutrophication

Question 34

How to increase amount of N,P and K in ecosystems?

Answer 34

Add fertilizer and/or animal waste to cropland to enhance naturally occurring forms of these nutrients - unfortunately added in quantities higher than plants use immediately

Question 35

What are in/ components of our microcosms?

Answer 35

Upper chamber-terrestrial ecosystem/field, contains soils which drains into a lower chamber, has terrestrial plants, air holes for gas exchange Lower chamber-aquatic ecosystem/pond , air holes for gas exchange, phytoplankton

Question 36

What are phytoplankton?

Answer 36

Foundation for most aquatic food webs, tend to be short lived, responding to increased nutrient availability with rapid increases in population growth,

Question 37

Why do we have zooplankton in our pond?

Answer 37

To feed on phytoplankton and stimulate the ecosystem that exists naturally

Question 38

What’s the amount conc of each part of fertilizer we were given?

Answer 38

N-P-k 15%-30%-15% and trace of others, measured by weight

Question 39

What are the microcosm treatments?

Answer 39

Q00 ml of tap water 3x a week for 3 weeks (900ml tot v if fertilizer/water provided), water in 2-6 is replaced w 100 ml of fertilizer solution at specific intervals 1-tap water 2- 0.78 g/L fertilizer conc- water replaced w 100 ml of fert 1 per 14 days- 0.156 g total added 3- 1.56 - 1/14 -0.312 4- 3.12- 1/14 -0.624 5- 3.12- 1/7 -0.936 6- 3.12- 3/7 -2.808

Question 40

How to quantify the zooplankton added to the pond?

Answer 40

Add 500 ņl of the culture to a 1.5 mL microcenterfuge tube Add 500 ņl of lugols iodine to the micro centrifuge tube, close the lid and invert to mix Obtain Palmer-Maloney counting slide and place coverslip over and add 0.1 ML aliquot of the culture-iodine into the side parts of the slide Use a light microscope to count the number of cells at 10x objective over 5 fields of view Calculate

Question 41

Wh do you add lugols iodine to your microcentrifuge tube?

Answer 41

Kills the cells enabling u to count the number of cells in each v of liquid accurately

Question 42

How to calculate # of cells p ml of pond water?

Answer 42

1. Num of cells per slide= # cells counted x (100/(o.02 x 0.4 x 5)) (vol of culture + iodine mix added /(a of field of view at 10x x depth of slide reservoir x # of fields counted)) 2. # cells per 500 ņL of culture = # of cells p slide x2 x5 3. # cells/mL =(# of cells per 500ņL)/ V of pond (mL)

Question 43

What are the parts of a microscope?

Answer 43

Ocular lens is what u look through, revolving nose piece is where the objective lens’ are, objective lens- mag u can change, stage clips- metallic clip used to secure specimen, stage- platform where specimen is, power switch, light intensity control knobs, stage control knobs- movement of stage control, coarse and fine focus knob

Question 44

What are categorical variables?

Answer 44

Variables describing group membership or categories Discrete Participant ID- unique identifier for each participant Sex- bio sex Diet type- primary dietary pattern (omni, veg, vegan) Sun ecposure- self reported level of sun exposure of the participant

Question 45

What are binary variables?

Answer 45

Variables take values of 0 or 1, indicates presence of condition or symptom Yes/no data Has fatigue Has bone pain Anemia diagnosis-whether participant meets criteria for anemia Night blindness diagnosis-whether participant meets criteria for night blindness

Question 46

What are continuous variables?

Answer 46

Numerical measurements Across a range of Age BMI-body mass index vitamin a percent RCA- vitamin a intake as a percentage of recommended daily allowance vitamin D percent RCA- vitamin D intake as a percentage of recommended daily allowance vitamin B12 percent RCA- vitamin B12 intake as a percentage of recommended daily allowance Iron perceny percent RCA- Iron intake intake as a percentage of recommended daily allowance

Question 47

What lizard population were we tracking of lizards?

Answer 47

Small ground dwelling lizards across 3 ecosystems over 6 years, vary in dorsal colouration which is a trait largely influenced by a single gene w 2 alleles (A darker a lighter, A/a intermediate) bc predators hunt visually camouflage affects survival allows us to investigate nat selec and genetic drift influence on allele freq over time

Question 48

What does data visualization allow us to do?

Answer 48

Summarize large amounts of info quickly to detect patterns and trends, allows us to compare groups, identify variability and communicate result clearly

Question 49

What are histograms?

Answer 49

Used to visualize the distribution of a continuous variable, show how frequently diff Eng values of continuous variables occur rather than displaying indv data points -> use data ranges called bins, show whether data is normally distributed, skewed and how varied it is

Question 50

When do you use histograms?

Answer 50

Starting point of data exploration mostly rather than final visual, allows u to see if data distributed normally or values skewed, if outliers and how variable a population is->critical in ego bio where nat selec act in variance and histograms help us see how much variation exists

Question 51

What are column charts/bar graphs?

Answer 51

Used to compare summary stats (mean or median) across categories. Allow u to compare diff groups, plotting one categorical variable (the groups) against one continuous variable , discrete categories of summery values of continuous data

Question 52

When do u use bar graphs?

Answer 52

Communicate summery stats quickly and simply and often enhanced using error bars which can additionally convey stand dev or stand error

Question 53

What’s stand deviation?

Answer 53

Amount of variation or dispersion of a set of data from their mean value

Question 54

What’s SEM?

Answer 54

standard error of the mean, measure of the variability in the data used to calculate the sample mean and can be used to indicate how well your sample represents the population

Question 55

What are scatter plots?

Answer 55

Used to examine relationships (trends) b/w 2 continuous variables, show how 2 cont variables relate to one another w each point representing one observation

Question 56

When do you use scatter plots?

Answer 56

Allows us to detect pos or neg relationships b/w 2 continuous variables and w the addition of trendlines help us visualize correlation (or lack of)

Question 57

In the wide ranging species of small ground dwelling lizards living in three different ecosystems what was measured and for how long?

Answer 57

Over six years, each year Mean local temp Whether predators present Pop size # of lizards w each of 3 genotypes at a single locus (A/a A/A a/a) measured

Question 58

What predators do the lizards face and what do they favour colouration wise?

Answer 58

Mainly birds. Hunt mostly by sight, more camouflage more survivable and repro, in forests and grasslands- darker better (A), in wetlands lighter (a)

Question 59

What are the three catagories of predators in the data set?

Answer 59

No pred Pred Y1-Y6 pop sustained predation by specific species throughout study Pred Y4-Y6 in wetland a bird species appears partway through study and begins preying on lizards, predation sustained during year 4-6 where previously none

Question 60

When do u use line graphs?

Answer 60

Visualize data that exists on a continuum that is being sampled at regular intervals (usually time) to see change in the same sample set

Question 61

Types of variables in the lizard colouration dataset?

Answer 61

Categorial (group membership and discrete)- ecosystem, predator orescenese Continuous-temp, pop size, phenotype counts

Question 62

What is the question, hypothesis and way to test for the lizard population?

Answer 62

I lizard colouration under slelective pressure in these ecosystems? Hypo-colouration patterns will change based on prescience of predators in the ecosystem, colouration patterns will change based on mean temperatures Test- dye remind allele frequencies in pop to look for changes

Question 63

How to measure total chlorophyll content of terrestrial plant leaves?

Answer 63

Choose greenest lead and cut circular disc avoiding midline being, grind it w 2ml of ethanol until dissolved that put into centre fudge w ethanol up to 4 ml, centerfuge 3000 rpm for 5 min, measure using spectrophotometer at 649 nm-

Question 64

How does a spectrophotometer work?

Answer 64

Determine conc of pigment molecule by measuring how much light of a specific wavelength is absorbs White light source-light dispersion decide-slit-cuvette-photocell-reach out

Question 65

Wii do u use a blank for spectrophotometer?

Answer 65

To account for any background absorbency of solvent

Question 66

What does size and overlap of SEM error bars tell you?

Answer 66

No SEM overlap, means are different therefor these groups/categories are likely different

Question 67

What does a figure caption need?

Answer 67

Descriptive title, explanation of content, relevant methods, scale and units, abbreviations and symbols, provides additional context or background information necessary for understanding the figure