LS23L Final Review

A p-value is:

a) a measure of how much evidence there is against the hypothesis

b) a parameter in the null hypothesis

c) always greater than the significance level

d) calculated from the significance level

e) a probability with a value ranging from 0 to 1

e) a probability value with a value ranging from 0 to 1

What is the difference between a p-value and a t-value?

The p-value tells you the probability that the null hypothesis is correct while the t-value is the first step to finding the p-value.

In order to reject the null hypothesis in the Memory Interference Test lab:

The p-value must be less than 0.05.

A t-test resulted in a p-value of 0.04, which means that there is a ____% probability that the difference in the sample groups occur by chance. ___% certain that accepting the alternative hypothesis is correct, and __% chance that the two sample groups are significantly different.

a) 96, 4, 96

b)4, 96, 4

c) 4, 96, 96

d) 96, 4, 4

e) 4, 4, 96

c) 4, 96, 96

In a recent study, scientists proposed the following hypothesis: "Consumption of Omega-3 fatty acid can reduce the size of cancerous tumors." The following hypothesis was tested. A sample of 500 rats with tumors was collected. Within this sample size, 250 rats were feed with omega-3 (Group 1) while the remaining 250 rats were not (Group 2). After one month of periodically feeding Group 1 with Omega-3 fatty acid, rat autopsies were taken for both groups. The average changes of tumor size were measure and recorded.

Average Change of Tumor Size

Group 1: -0.124 g

Group 2: -0.112 g

Degrees of Freedom: 498

T-test: 1.75

P-value: 0.08

Based on the results from the experiment, which of the following is the best conclusion?

Consumption of Omega-3 fatty acid has no statistical effect on decreasing the size of previous cancerous tumors.

What is a null hypothesis?

It predicts no effect or no difference between two or more tested samples.

What is a population?

The entire collection of measurements on which the researcher intends to draw conclusions.

What is a sample?

The set of measurements actually made

Which of the following is critical in designing a scientific experiment to test memory in chimpanzees?

The experimenter should control for lurking variables by specifying standard conditions (i.e. room temperature)

What is the mean?

One of the statistics that measures the central tendency of a variable; commonly known as the average

-sum of all measurements in the sample divided by the sample size

What is the median?

Measurement located at the middle of the ordered set of data

What is the mode?

The mode is defined as the measurement of relatively great concentrations in a set of data.

In a bimodal distribution of data, you would have:

Two modes, one mean, one median

What is standard deviation?

Measure of variation around the mean

What is a t-test?

Useful tool that determines the difference between two samples by comparing their means while taking into account their variances

What is the statistical test that will be used in this week's lab (Memory Interference Test)?

Student's t-test

T or F: Part of the MIT is taken using pen and paper.

False

T or F: According to the Research Information Sheet, you are required to participate in the Memory Interference Test in order to satisfactorily complete this course.

False

According to the Research Information Sheet, possible risks you assume while participating in the Memory Interference Test include:

fatigue and tiredness

T or F: After you have finished the MIT, you shouldn't close the window until you get the message that the MIT has successfully concluded

True

T or F: According to the research information sheet, you will be paid for participating in this study.

False

A null hypothesis states that the difference between 8 hours of sleep and 3 hours of sleep has no effect on the number of pictures a student will remember during a Picture Memory Interface Test (PMIT). Examining the MIT database, an extremely small t-value of 0.1611 is found. This t-value is much smaller than the smallest t-value on the chart for p-value reference. From this information we can:

Accept the null hypothesis because the p-value obtained shows that the difference between the two groups being tested is not statistically significant.

What is epidemiology?

The study of diseases and populations at risk

___________ is the rapid spread of disease to a large population over a short period of time, and _________ is when _________ strikes at a global scale.

Epidemic, pandemic, epidemic

Which of the following factors is mentioned as contributing to the spread of a disease?

a) All of these factors

b) Natural environment of a region

c) Infrastructure present in a nation

d) Cultural and social practices

e) Genetic background of a population

a) All of these factors

Why is CCR5 important in HIV?

-Individuals naturally immune to HIV have a mutated form of CCR5, rendering the HIV virus unable to enter the cells and replicate.

-If the CCR5 gene were to be artificially mutated in the blood stem cells of a person with HIV, all progeny of those stem cells would be HIV-resistant and the person's viral load would decrease.

-Mutating CCR5 could also be used as a preventative treatment in regions where HIV is extremely incident.

What is the function of SDS-PAGE?

commonly used to separate proteins based on size and conformations

What is the function of a spectrophotometer?

It may be used to accurately determine the concentration of DNA, RNA, or protein in a sample.

According to the lab safety sheet, which of the following is a potential hazard that will be present in the lab room during the lab (Epidemiology)?

Bacterial cultures

Which of the following pieces of information does not need to be included when you label your plate for the epidemiology exercise?

Your age

How many rounds of handshaking will the epidemiology exercise have?

4

T or F: According to the lab safety sheet, cotton swabs, gloves, sponges and petri dishes contaminated with bacteria must be placed in the autoclave waste container.

True

T or F: According to the lab safety sheet, the bacteria used in the epidemiology activity is considered a BSL Risk Group 1 agent and is not associated with disease in healthy adult humans.

True

According to the lab safety sheet, during the epidemiology lab activity you must wear: (Epidemiology)

a) Standard lab attire

b) Safety goggles

c) Lab coat

d) Glove on our non-dominant hand only

e) All of the above

e) All of the above

1 microgram (μg) is equal to how many milligrams (mg)?

0.001 mg

What is a pipettor?

volumetric instrument designed to measure and dispense liquids precisely and safely

Why is it most important to learn to use pipettes correctly?

Pipettes are an important and omnipresent piece of equipment in biology laboratories.

What is the range of the p1000 pipettor?

100-1000 ul

What is the range of the p200 pipettor?

20-200 ul

What is the range of the p20 pipettor?

2-20 ul

How is the volume read on the p1000?

-Number in red represents thousands of microliters

-Middle digit is hundreds of microliters

-Lowest digit is tens of microliters

How is the volume read on the p200?

-Top number indicates hundreds of microliters

-Middle digit is tens of microliters

-Lower digit is individual microliters

How is the volume read on the p20?

-Top digit indicates tens of microliters

-The middle is individual microliters

-The red digit is tenths of microliters

What is the proper pipetting technique?

1) 1st stop

2) Fully released with aspirated sample

3) 1st stop, expel sample

4) 2nd stop, complete expulsion

5) Remove from vessel, fully release

6) Eject tip

What part of the pipettor changes the volume the pipettor can transport?

The volume adjustment ring

T or F: The maximum volume for a pipetter can be found on the pushbutton.

True

What is the maximum volume you can safely and accurately pipet with a p200 pipetter?

200 ul

What is the minimum volume you can safely and accurately pipet with a p1000 pipetted?

100 ul

What is the minimum volume you can safely and accurately pipet with a p20 pipetter?

2 ul

In a P1000 pipetter, the numbers read 094 from the top down. How many microliters is this?

940 microliters

A volume of liquid measuring ____ is most accurately measured and dispensed using a ____ pipetted.

a. 1.2ml, p200

b. 0.12ml, p200

c. 0.012ml, p2000

d. 0.012ml, p200

e. 0.12 ml, p2000

b) 0.12 ml, p200

If you are asked to pipet 590 microliters of colored water, which pipetter would you use and what is the proper setting in each volumeter window? (top, middle, bottom)

p1000, (0,5,9)

The picture below shows the volumeter window for a p20 pipetter. What volume will be pipetted with these settings?

0,9,7

9.7 ul

Which of the following techniques for handling a pipetter is INCORRECT:

a) When drawing up the sample liquid into the pipet tip make sure that you slowly release the pushbutton so as to prevent any air bubbles from forming.

b) A different disposable polyprolene tip should be used when pipetting different solutions so as to ensure no cross contamination between samples.

c) When releasing the liquid, you must first press the pushbutton to the first stop, then to the second stop so as to expel any remaining liquid.

d) You must be sure to press the pushbutton to the first positive stop before placing the tip of the pipet into the sample liquid.

e) All of these techniques are CORRECT

e) All of these techniques are CORRECT

What does the enzyme B-galactosidase do?

The enzyme B-galactosidase catalyzes the hydrolysis of lactose to galactose and glucose.

What is the natural substrate of beta-galactosidase?

lactose

In the presence of glucose, Beta-galactosidase:

does not have to be produced because there is no need for it

What does the I gene of the lac operon code for?

Always active; codes for repressor that is constantly being made

What happens when lactose is present and binds to the repressor?

A conformational change occurs in the repressor and makes it fall off of the operator region, allowing for the transcription of B-galactosidase.

The lac operon is a/an:

inducible system because lactose, the inducer, is required to turn the operator on

Why is ONPG an ideal substrate to assay for B-Gal activity?

because it is cleaved by B-Gal into galactose and o-nitrophenol, a yellow compound

Tamique tested E. Coli B-Galactosidase activity but the buffer solution she used for the B-Gal assay was 4 pH units higher than the optimal pH. What problem did Tamique observe?

The pH of the solution was too basic for B-Galactosidase to bind to ONPG.

What type of blank should be used for the b-galactosidase enzyme activity assay?

"b-gal blank" made by your group

According to the Lab Safety Sheet provided for this week, when working with E. coli cells you must wear: (check all that apply)

-Safety goggles

-Gloves

-Lab coat

-Standard lab attire

How should chloroform be handled?

Only in the fume hood

What are the potential risks associated with using chloroform?

-May be fatal if swallowed, inhaled, or absorbed through skin

-Causes irritation to skin, eyes, and respiratory tract

-May affect central nervous system, cardiovascular system, liver, and kidneys

SUSPECT CANCER HAZARD

Chemicals/materials you will use in the b-galactosidase assay include:

a) All of these

b) Chloroform

c) ONPG

d) Z-buffer mix

e) E. coli cells

a) All of these

Microcentrifuge tubes with chloroform in the bottom must be:

Capped and placed in the labeled hazardous waste bin in the hood

What is the purpose of Luria broth in this lab?

provides nutrients for bacteria growth

What is the purpose of chloroform in this lab?

added to partially disrupt the cell membrane, allowing cellular proteins to diffuse out of the cell

What is the purpose of Z buffer?

promotes the reaction between B-galactosidase and ONPG by optimizing the pH of the sample

What is the purpose of Na2CO3?

stops the reaction of B-galactosidase and ONPG by changing the pH from 7 to 11

Is the level of B-galactosidase activity influenced by the carbon (sugar) source in the media? Explain using your results.

Yes.

-In the sample with lactose, the absorbance was much higher than the control which did not contain sugar.

-In the sample with glucose, the absorbance should be lower than the control because there is a lower transcription rate.

Did you observe a difference in B-galactosidase activity between your 20-minute time point and your 70-minute time point among the three cultures? Why is there difference/no difference in the activity levels at the different times? Explain using your results.

Yes.

-There is a difference because after incubating an additional 50 minutes, there is more cell growth and therefore more enzymatic activity occurring which leads to a higher absorbance reading at the 70-minute time point for lactose.

-In the sample with glucose, B-galactosidase activity decreases over time because it slows down the enzymatic activity.

Why did you need to measure cell density at the 20-minute point as well as at the 70-minute time point?

We need to measure cell density at both time points in order to determine if the induction of B-galactosidase synthesis in E. coli is time-dependent.

An assay of which of the following solutions will theoretically have the highest amount of b-galactosidase enzyme activity?

Luria Broth and lactose, at 70 mins of incubation

In the absence of lactose, what gene(s) on the lac operon is/are transcribed?

I gene

What does the Z gene on the Lac operon code for?

B-galactosidase

What does the Y gene on the Lac operon code for?

Permease

What does the A gene on the Lac operon code for?

Thiogalactoside transacetylase

What is metabolism?

the sum of all anabolic and catabolic reactions

What are poikilothermic organisms?

organisms whose body temperature changes when the environmental temperature changes, thus making the organism's metabolic rate easier to manipulate

What makes goldfish a good model organism for the metabolism lab?

a) They are homeothermic.

b) All of these

c) Their body temperature varies with the environment temperature change.

d) Two of these

e) Their metabolism is easy to manipulate

d) Two of these

In measuring metabolic rates of goldfish, which of the following is a good indicator?

oxygen consumption

T or F: Because the rate of gas consumption will be measured, taking into account the mass of the organism will not have an effect on the interpretation of the data.

False

One of the objectives of this lab is to formulate a hypothesis that is (Goldfish Lab):

testable

Which of these is not a variable that is mentioned as one that can be tested in this lab?

a) pH

b) light/darkness

c) caffeine

d) nicotine

e) salinity

a) pH

T or F: According to the lab safety sheet, if you get treated "fish water" in your eyes you don't have to rinse them because the water used for fish is non-toxic.

False

What are the potential hazards in the goldfish metabolism lab?

The fish water is treated with sodium bicarbonate and Ammo-lock which contains alphatic amine salts and a trace amount of sodium thiosulfate pentahydrate.

-can cause skin and eye irritation

When working with the goldfish you must wear:

-standard lab attire

-goggles

-lab coat

T or F: Since we will be measuring the rate of metabolism, it will be unnecessary to monitor the behavior of the organism.

False

What is the trend for animals regarding the ratio between body volume and body surface area?

The volume to surface area ratio increases as volume is increased.

What is the relationship between mass-specific metabolism and body size?

As body size increases, M-S metabolism decreases

In the goldfish metabolism lab, there was a probe attached to the chamber. What was it used for?

The probe was measuring the dissolved oxygen concentration in the water.

An ectotherm is:

An animal that obtains its body heat from the environment therefore its body temperature varies with outside temperature

In a series of experiments on the effect of caffeine on goldfish metabolic rates, a p-value of 0.28 is found. The conclusion that should be drawn from these experiments is:

Caffeine did not have a significant effect on metabolic rate and the null hypothesis cannot be rejected.

What is mitochondrial DNA?

-small circular molecules that are remnants of endocytosed bacteria

-inherited strictly from the mother

What is a haplotype?

the nucleotide sequence of your mitochondrial genome

What is a haplogroup?

consists of all individuals with the same haplotype as you, along with other haplotypes that are very similar

Mitochondrial DNA is used to follow maternal inheritance and sequences on the Y chromosome are used to follow paternal inheritance. Why is it not practical to analyze paternal inheritance in this class?

Because only men have a Y chromosome, the women in the class wouldn't be able to participate.