Lab midterm practice

What organism is this?

Elodea

What organism is this a picture of?

E Coli

What variable is plotted on the X-axis

Independent

What variable is plotted on the Y-axis

Dependent

What graph type should be used for continuous data?

Line

What graph type should be used for discrete data?

Bar

Where is the title of a table placed?

Above table

Where is the title of a graph placed?

Below figure and numbered

Part 1 of cell theory

The cell is the basic unit of life

Part 2 of cell theory

All living things contain one or more cells

Part 3 of cell theory

All cells come from pre-existing cells and share a common origin

All cells have what structures in common?

-Plasma membrane

-DNA

-Ribosomes

-Cytoplasm

What is this cell?

Potato

What is this cell?

Avocado

What stains were used to stain lipid inclusions?

Sudan IV

What stains were used to stain starch granules?

IKI

This organelle contains ___

Starch (amyloplast/chloroplasts)

This organelle contains ___

Lipids

What color should a starch containing organelle be when stained with IKI?

Dark blue, variant of blue

What color should a lipid containing organelle be when stained with Sudan IV?

Red, orange, brown, etc.

What type of cell is this? What part is the nucleus?

Cheek cell, dark blue spot in the middle of the cell

What is shown here?

Plant cell wall

What is shown here?

Chloroplast

What are four main types of organic molecules?

-Carbohydrates

-Lipids

-Proteins

-Nucleic acids

Carbohydrates and most lipids contain only…

Carbon, hydrogen, oxygen

Proteins and nucleic acids can contain…

Nitrogen, phosphorous

What is used to test for glucose? How do you determine a positive result?

Benedicts Solution. There is glucose present if Benedicts Solution is added, and the substance turns another color like green/orange brown. If no glucose is detected, the color remains its initial blue.

What is used to test for starch? How do you determine a positive result?

IKI. If the solution turns blue, there is starch present. If it remains red, orange, yellow…

What is used to test for proteins? How do you determine a positive result?

Buret reagent. If proteins are present, the solution will turn from clear blue to violet.

What are used to test for lipids? How would you determine the result to be positive?

Sudan IV. If the powder dissolves and stains the solution a deep reddish color, then a lipid is present. If the powder clumps, no lipids are present.

What determines solubility?

Polarity, molecular structure, charge, and in some cases temperature.

What substances are more soluble in water? Give an example

Polar molecules. Sugar dissolving in water.

How is pH determined?

By the concentration of hydrogen ions and hydroxyl ions

If a solution has a pH of 4, what is the concentration of H+ and OH-?

H+ = 10^-4

OH- = 10^-10

If a solution has an OH^- concentration of 10^-13, what is the pH of this solution?

pH = 1

Identify the phenomena illustrated in the carmine powder experiement

The carmine powder demonstrates Brownian movement, as the particles moved in a zigzag motion

Identify the phenomena illustrated in the dialysis tubing experiment

The diffusion and osmosis of water across a selectively permeable membrane

Describe the dialysis tubing experiment. Explain the results. What molecules were able to pass through the pores of the dialysis tubing?  How was it determined? 

What happens to a plant cell if placed in a hypertonic solution?

Membrane pulls away from cell wall and becomes plasmolyzed

What happens when elodea cells are placed into hypertonic solutions?

Water moves out of the cell via osmosis. Plasmolysis ensues.

What type of organic molecules is an enzyme?

Catalyst

Why are they sensitive to temperature and pH?

Changes in temperature and pH can alter the shapes of their active sites, which alters their ability to bind with substrates. They can become denatured and no longer function at an efficient rate, if at all.

What would be the correct name of the enzyme that catalyzes the oxidation of lactose?

Lactose oxidase

How do you determine the optimum condition for an enzyme?

Test and observe how the enzymes behave when exposed changes in temp/ph

What is the substrate associated with catalase?

Hydrogen peroxide

How is catalase enzyme activity detected?

Bubbling from H2O2

What substrate is associated with catechol oxidase?

Benzoquinone

How is catechol oxidase enzyme activity detected?

Visual color change, such as turning brown in color

What was the effect of PTU on catechol oxidase activity?

Inhibits reactions

What substrate is associated with bromelain?

Proteins

How is bromelain detected?

Putting it with proteins such as gelatin and observing if it breaks down the protein or not

Dialysis tubing experiment

Made of cellulose fibers formed into a hollow tube. The pores allow for small solutes to pass through the tubing, but the larger solutes cannot.hW

What was able to pass through the dialysis tube? How was this determined?

-Glucose, water, IKI solution

-By observing the colors in the bags and in the beakers after a period of time

Explain role of polarity and molecular weight on movement of substances through a membrane

Heavier molecules diffuse slower, and affinity (charge) may also affect movement via attraction to the matrix.

Can sucrose molecules pass through dialysis bags?

No, they are too large to pass

What was the effects of higher sucrose concentrations on the weight of the bags?

Increase in weight due to osmosis moving water into the dialysis bag to dilute the sugar. Less water outside of bag at end of experiment

What was the effects of lower sucrose concentrations on the weight of the bags?

Less weight gained, water was higher outside of bag

What carbohydrates show optimal gas production? Why?

The glucose showed the most optimal gas production because glycolysis rapidly breaks down glucose (which has 6 carbons). Most of the tubes containing the glucose and yeast mixture lost their corks towards the end of the experiment because the buildup of all the CO2

How did exercise affect the time needed for the solution to change color? Explain why the color change occurred (How does BTB work?)

Exercising and then blowing into the straw made the solution change colors quicker than when we all blew into it at a resting heart rate. The BTB changes color when rising amounts of CO2 are added. Exercising results in higher CO2 emissions being expelled from the body.

What can you conclude about the effect of exercise on the amount of carbon dioxide that is present in your exhaled breath? Why is this so?

We inhale O2 and exhale CO2, so during exercise, the body needs to take in more O2 alongside needing more energy to function. When the body generates more energy, it subsequently releases more CO2 because it’s a waste product of aerobic respiration.

What can you conclude about the effect of exercise on breathing rate? Why is this so?

Exercise increases breathing rate because more oxygen must be taken in during strenuous physical activity.

What can you conclude about the effect of exercise on heart rate? Why is this so? What do your muscles need during exercise that the blood brings?

Heart rate increases because it needs to pump more blood to the heart so it can receive the oxygen it needs to continue aerobic respiration.

Which step of aerobic respiration are we examining?  In other words, during which step is the most CO₂produced?

The citric acid cycle

What is used to test seed viability?

Tetrazolium

What color is tetrazolium when oxidized?

Clear

What color is tetrazolium when reduced?

Red

When tetrazolium is applied to seeds, what color will they turn if they are germinating (alive)?

Pink/red

When tetrazolium is applied to seeds, what color will they turn if they are dead?

It remains clear

What kernels were viable? Raw or boiled?

Raw

What part of the seed shows the highest respiration?

The embryo

In the fermentation of yeast experiment, what gas fills the tubes?

CO2