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Packet #5 – Cells: Internal Environment, part 1 Summer 2014

This Activity Packet belongs to: __________________________

You should expect a variety of quizzes: announced, unannounced, open-notes and closed-notes.

If this packet is LOST, please: drop it off at the BHS Science Dept. (rm 365) OR

drop it off in Ms. Brunson’s classroom (rm 350) OR call the Science Dept. at (617) 713-5365.

Packet page Activity Points

Earned Avail. The wacky history of the cell theory 5

Living vs. Nonliving Sorting Activity --- ---

Notes: Cell Structures and Types (and Venn Diagram) 2

Animal vs. Plant Microscope Lab 6+

Why are cells so small? 7

Can you stand the heat? 5

Notes: Transport and Diffusion --- ---

The Eggs-periment 20

Bubble Membranes 10

Diffusion Practice Problem Set 10

Review Guide for Part 1 20

Total 85

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The wacky history of the cell theory http://ed.ted.com/lessons/the-wacky-history-of-cell-theory 1. What are the three parts to the cell theory?

a.

b.

c.

2. What was like the iPad of the early 1600s (for naturalists)?

3. Anton van Leeuwenhoek discovered bacteria by looking at what?

4. What did van Leeuwenhoek call bacteria?

5. Robert Hooke was the first to use the term “cell.” What was he looking at when he came up with that term?

6. Matthias Schleiden was a botanist, meaning he studied what kinds of organisms?

7. What was Schleiden’s main discovery?

8. What kind of cells did Theodore Schwann study?

9. What did Rudolf Virchow contribute to the cell theory?

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Living vs. Nonliving Sorting Activity In this activity, you will sort through a series of wods and identify them as living, never living, and once living. Use your knowledge from other science classes and your own ideas about what makes something living to help you sort through the items. It’s okay to be wrong, and it’s okay to disagree with your group members – but please listen and be respectful and think carefully. Procedure: 1. Divide your desk into four quadrants (sections) using a piece of chalk. Give each section one of

these four labels: Living Never living Once living (but not living now) Unsure

2. Get the word slips from your teacher and place each word in the quadrant where you think it belongs. When you are finished, let the teacher know.

3. As a class, we’ll go through the list of word and organize a group poster of which categories each word falls into. We’ll figure out where we are unsure, and then try to learn more about what characteristics something must have to be considered living and then go back to our list of unsure words.

For your records, here are the words: Dog

Fire

Earthworm

Cactus

Butterfly

Bacteria

Pencil

Glass

Lichen

Potato

Roasted Peanut

Coral

Algae

Mildew

Yeast

A radish seed

Sand

Salmon

Penguin

Human

Pine tree

Rock

Plastic

Jellyfish

Rose bush

Telephone

Clock

Cloud

Sun

One oak leaf

A blade of grass

Water

Sea sponge

Crab

Wood

Fern

Mold

Paper

Air

Ant

An ear of corn

A dead mouse

Dirt

Virus

Mushroom

Pollen

Frog

Snake

Moss

Chair

Milk

Yogurt

Blood

Fire

Sea anemone

A fingernail

clipping

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Cell Types and Structures Organization of Living Things: Prokaryotes (see diagram sheet) Eukaryotes (see diagram sheet) Examples of things made of cells Examples of things NOT made of cells

Organelle In plant or

animal cells? In both?

Function? Good to know?

Nucleus

Mitochondria

Lysosome

ER (rough)

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Organelle In plant or animal cells? In both?

Function? Good to know?

ER (smooth)

Golgi Apparatus

Cytoskeleton

Cilia/flagella

Chloroplast

Vacuole (large central)

Cell Wall (plant, not bacteria)

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How do prokaryotic, animal, and plant cells compare? Place each of the following into the Venn Diagram:

Cell membrane Cellulose cell wall Non-cellulose cell wall Flagellum Smooth ER Rough ER Free ribosomes Golgi apparatus Lysosome

Large central vacuole Nucleus DNA Cytoplasm Centriole Chloroplast Mitochondria Eukaryotic

               

ALL  Cells:                                                                    

Bacteria  

Animal  Plant  

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Animal vs Plant Microscope Lab Purpose: This lab will introduce you to the light microscope, as you will use the microscope to look at live cells from plants and animals. You will learn the parts of the microscope, how to make a wet-mount slide, and how to use a microscope to look at living tissue. Materials: slides, cover slips, water, iodine, red onion, elodea, tape, tweezers, and microscope PART I: Learning about the microscope 1. One member of your lab group should obtain a microscope. Always carry

the microscope in an upright position (not tilted) using two hands. One hand should hold the microscope’s arm and the other hand should support the base, as shown in Figure 1. Set it down away from the edge of the table. Always remember that a microscope is an expensive, precision instrument that should be handled carefully. Do not push the microscope around on the table, but instead swivel the ocular lens or reposition your body.

2. Plug the microscope in at your lab desk. Turn it on and make sure that the light comes on.

3. The ocular lens is marked with its magnification power. (This is how much larger the lens makes objects appear.) What is the magnification power of the ocular lens of your microscope? _____________

4. The three objective lenses are marked with their magnification power. The first number marked on each lens is the magnification power of that lens.

a. What is the magnification of the lowest power lens of your microscope? _______ b. What is the magnification of the high power lens? _______

5. To find the total magnification of the microscope as you are using it, multiply the ocular lens power times the power of the objective lens that you are using. For example, if the ocular lens of a microscope has a power of 5x and you use an objective that is 10x, then the total magnification of the microscope at that time is 50x (5x10 = 50).

a. What is the total magnification of your microscope when using low power? ____ What is the total magnification of your microscope when using high power? ____

PART II: THE LETTER “e” (Practice)

1. From the newspaper, find a lower case letter “e.” 2. Cut out the letter. 3. Place 1-2 drops of water on the slide, then place the letter on a slide (so that it looks like an e,

upright). 4. Lower a cover slide. Use a 45-degree angle to minimize air bubbles. 5. Start with lowest power, and then move up to medium power. 6. Using 100X total magnification, sketch everything that you see (not what you THINK you should

see). Use pencil, and include as much detail as possible. Don’t forget to label your diagram with the total magnification used.

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PART III: ANIMAL CELL OBSERVATIONS (Human Skin Cells) 1. Using soap and water, wash the underside of your wrist. Dry your wrist. 2. Stick a clean piece of clear tape on the underside of your washed wrist. 3. Gently remove the piece of tape from the wrist being careful to avoid getting fingerprints on the

tape. Use tweezers to be sure to avoid fingerprint contact. 4. Place the tape, sticky-side up on a clean microscope slide. 5. Stain the top, sticky side of the tape with 2 or 3 drops of Iodine solution to stain the cells and make

them visible. 6. Gently place a cover slip over the sticky tape. Lower the cover slip down onto the tape. Keep your

fingers out of the way. 7. Examine the slide under a microscope. Look for the cells with low power first, and then switch to

higher power for details. 8. Using pencil, sketch your observations. Label your drawing with the magnification used.

PART IV: PLANT CELL OBSERVATIONS (Elodea cells and onion) Part A: Elodea

1. Obtain a piece of Elodea leaf, and place it on a slide with 1-2 drops of water (you do NOT need iodine for this sample).

2. Using a 45-degree angle, lower a cover slip onto the slide. 3. Begin on lower power, and then move up to higher power. Using detail and pencil, sketch what

you see below. Don’t forget to record the total magnification used. Part B: Onion

1. Remove one layer from the onion wedge that has been submerged in pure water. 2. Use forceps to separate a piece of the transparent, paper-thin layer from the outside of the original

layer. 3. Lay the piece flat on a clean microscope slide. 4. Use the pipette to add 1 drop of distilled water to the slide. Add one drop of iodine to the slide,

then place a cover slip over the piece of onion skin. (Note: if using red onion, you may not need to add iodine).

5. Observe the slide under the microscope. Remember to begin at low power, then go up to higher power.

6. Using at least 100X magnification, draw your observations on the data sheet. The drawing should be in pencil, and should be detailed. Draw everything that you see in the field. Then, pick one cell in your drawing, darken its outer boundary (cell membrane and cell wall), and label its nucleus (if you can see it).

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DISCUSSION QUESTIONS: (1 point per question) 1. Was there anything unusual about the way the “e” looked under the microscope and the way it

looked to your naked eye?

2. Why does the specimen placed under the microscope have to be thin (rather than putting your whole arm, we used a thin layer of the skin)?

3. Why did we have to add iodine to the skin cells (and not to the elodea)?

4. Are the cells that you observed eukaryotic or prokaryotic? Explain why (remember what makes something eukaryotic and prokaryotic).

5. What are three characteristics that plant and animal cells have in common?

6. What are two differences between plant and animal cells?

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Why Are Cells So Small? Pre-Lab Directions: Read the entire lab. As you read the lab, make notations as follows: * = relates to main idea; ?? = confusing; ! = interesting point; ? = question to ask in group discussion. Background Information: Most cells are between 2 micrometers and 200 micrometers – too small to be seen with the naked eye. A micrometer is 1 millionth of a meter! Why can’t cells ever become larger than that? Why don’t we regularly find one-celled organisms the size of small multicellular animals, like frogs or even flies? When cells grow to a certain size, their rate of growth slows down until they stop growing entirely. They have reached their limit.

In order for cells to survive, they must constantly exchange ions, gases, nutrients, and wastes with their environment. These exchanges take place at the cell’s surface – across the cell membrane. The movement of these materials is accomplished mostly by diffusion (flow of solutes from high to low concentration) across the cell membrane. Surface area is the amount of cell membrane available for diffusion. So for a cell, surface area actually represents how much diffusion can happen at one time. It would seem reasonable, then, that cells with plenty of surface area (meaning membrane area) would survive better than those with less surface area.

Volume is the amount of cytoplasm (the thick aqueous solution inside the cell) contained within the cell membrane. So for a cell, volume represents how long it takes needed materials to get from the membrane to the center of the cell by diffusion. Therefore, in a large cell those materials would take longer to reach the center of the cell and in a smaller cell those materials would take less time. In this lab activity, you will use agar cubes as cell models. You will investigate how increasing a cell’s size affects the time for diffusion to move material across the cell. The agar for the cubes has been dyed with bromothymol blue (BTB) – a pH indicator that turns from blue to yellow in the presence of acid. When the agar cubes are placed in vinegar (a source of acid), they will begin to turn yellow as the vinegar diffuses into the agar. You will time this diffusion process for 3 different sized cells and compare them. Diffusion will be considered complete when the blue color completely disappears from the center of the cell. Materials: 3 cubes of 3% agar-bromothymol blue: 0.5x0.5x0.5 cm, 1x1x1 cm, and 1.5x1.5x1.5 cm, 3 beakers with vinegar, timer Procedure Part 1: Complete the table below while following this procedure.

1. Put the three cubes in separate beakers of vinegar at the same time (start the timers when they are placed in the vinegar.

2. Record the amount of time it takes for the blue color to completely disappear from each cube in the data table below.

3. While you are waiting, complete the calculations in the table below for surface area, volume, and surface area to volume ratio (SA:V ratio).

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Data (3 pt)

Cube (cm) Surface Area (SA) Volume (V) SA:V ratio

Time for complete diffusion (seconds)

0.5 x 0.5 x0.5

1 x 1 x 1

0.5x0.5x4

Surface area= length x width x number of sides Volume= length x width x height For SA:V ratio, divide surface area by volume Analysis: 1. What evidence tells you that the vinegar diffused into the 3% agar-bromothymol blue cubes? (1)

2. As the cubes increase in size, what happens to the surface area to volume ratio? (1)

3. According to your data from the lab, which cell was most efficient at receiving the needed “nutrient” (vinegar)? Use data from your table to back up your conclusion. (1)

4. In general, what is the relationship between the SA:V ratio and diffusion time? (1)

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Part 2: “How Big is a…” URL: http://learn.genetics.utah.edu/content/begin/cells/scale/ Navigating the site: There is a bar under the picture that allows you to zoom in and out. Here you will look at objects on a virtual piece of paper. Your job is to find them and estimate the length of each (in picometers, nanometers, micrometers, or millimeters). (Note: 1 m = 1,000 mm = 1,000,000 micrometers = 1,000,000,000 nanometers)

Object Eukaryotic or Prokaryotic

Size in picometers (pm), nanometers (nm), micrometers

(mm), or millimeters (mm)

Class notes

Grain of rice

Amoeba proteus

Skin Cell

Red Blood Cells

Baker’s Yeast

Mitochondrion N/A (organelle)

E. coli

HIV N/A (virus)

Rhinovirus N/A (virus)

Hemoglobin N/A (protein)

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Can you stand the heat? Internal Environment Maintaining a Balance Digestive system (Review) Absorption the Small Intestine (Review + a little more)

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Can you stand the heat? Read the story A Pause That Refreshes? on the next page. 1. After reading the scenario, work with your partner to develop an explanation for Josh’s condition.

Consider the evidence you have and what inferences you can make about how Josh’s body responded to external stress.

2. What stresses from the external environment was Josh’s body (internal environment) having to

balance? 3. How did the choices Josh made affect the stresses placed on his body? 4. What symptoms did Maggie show that were evidence that her body (her internal environment)

was under stress from the conditions outdoors (her external environment)? 5. Develop a list of four terms and concepts that relate to homeostasis. 6. What were some of the class terms we came up with?

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Notes: Membranes and Diffusion Cell Membrane Structure Cell Membrane Function (What does each component do?) The Problem: Imagine the plastic bag is a cell and the candy is the food. You must get the candy into the bag, using the following rules:

• The candy must enter through a solid part of the bag • The inside of the bag may not be directly open to the external environment • The candies entering the bag must remain clustered together • You may work with your hands inside the bag to act as the inside of the cell • The candy may only be eaten if it enters the bag “cell” under these conditions

Describe your final solution: What is diffusion

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Types of diffusion Osmosis

Active Transport

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Let’s Do an Eggs-periment!

Background: In this demo, we will observe osmosis and/or diffusion of materials into and out of an egg. Eggs normally have a hard outer shell that is impermeable to most materials, but we can remove the shell to expose the cell membrane by soaking the eggs in vinegar for ~72 hours. Procedure: 1. Three shell-less eggs will be massed to determine their starting masses. 2. One egg will be placed into a beaker full of corn syrup. Another will be placed in a beaker full of

water. Another will be placed in a beaker full of control substance (the vinegar) 3. The eggs will stay submerged for 24 hrs. 4. The next day, we will take the masses of each the eggs and record them in the “Ending Mass” column.

We will then calculate the % change in mass in each of our three eggs. Predictions: (3 pt) What do you predict will happen to the masses of each of the eggs? If it helps, draw pictures of the eggs in the solutions and think about what materials might move in and out of the eggs based on your knowledge of passive diffusion and osmosis. Write your predictions below: Egg 1: Submerge in water What will happen to the mass? Bigger Smaller Stay same Why? Egg 2: Submerge in vinegar (Control) What will happen to the mass? Bigger Smaller Stay same Why? Egg 3: Submerge in corn syrup What will happen to the mass? Bigger Smaller Stay same Why?

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DATA (3 pt)

Starting mass

Ending mass

Change in mass

(end-start)

% change in mass (change in

mass/start mass) x 100%

Did water move IN or OUT of the

egg?

Egg 1: submerge in water

Egg 2: submerge in vinegar (control)

Egg 3: submerge in corn syrup

Starch/ Iodine Demonstration In this demonstration you will observe the diffusion of a substance across a semi-permeable membrane. A semi-permeable membrane only allows some things to pass through, based on size or charge. Iodine is a known indicator for starch. An indicator is a substance that changes color in the presence of the substance it indicates. Recall that iodine is amber and turns blue-black when in contact with starch. Make some predictions: (4 pt) 1. If the bag were permeable to starch (allowed starch to move through it), which way would the starch

move – into or out of the bag (remember – molecules move from high concentration to low concentration)? ____________________

2. a. If the bag were permeable to starch, what color would you expect the solution in the baggie to turn?

__________________ b. What about the solution in the beaker? __________________

3. If the bag were permeable to iodine, which way would the iodine move – into or out of the bag?

_________________ 4. a. If the bag were permeable to iodine, what color would you expect the solution in the baggie to turn?

__________________ b. What about the solution in the beaker? __________________

starch

iodine

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Observations (2) Starting Color Ending Color

Baggie (starch/water) White/clear

Beaker (Iodine/water) amber

Questions – Discuss the following with a partner and fill in the blanks: (8 pt) 1. Permeability is __________________________________________________

2. The plastic bag is permeable to _______ (starch or iodine) – I know this because I observed ___________________________________________________________________________

3. The iodine entered the bag because it was _________________________________________ 4. The starch could not enter the beaker because ______________________________________

5. The plastic bag is like the cell membrane because __________________________________ ___________________________________________________________________________

6. In the Eggsperiment, the water moved into the egg when the surrounding solution had __________ sugar.

7. In the Eggsperiment, the water moved out of the egg when the surrounding solution had __________ sugar.

8. Water moved _______________________ the egg when it was in a solution that was the same as the egg.

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Bubble Membranes Intro: Soap bubbles are bilayers very similar to cell membrane bilayers, so they can be used to display some of the properties of the cell membrane.

Purpose: What are the characteristics of a cell membrane? Procedure: Immerse the membrane holder into the pan of soap solution. Demonstrate the following characteristics of a lipid bilayer and RECORD ALL OBSERVATIONS in the table below. Observations Fluidity: Form a layer in the membrane holder. Let the light shine off of its surface and look at the movement you see within the film.

Flexibility: Twist the two straws in opposite directions, and bend it into different types of configurations.

Self-sealing: Stick the following objects through the bubble membrane and observe what happens when you try to remove them as well: a. Wooden flint stick b. Soap-coated flint stick c. Your finger d. Your soap-coated finger

Transport proteins: Form a film in your membrane holder. Dip the thread (or elastic band) in the soap solution and carefully place it onto the membrane. The thread should float in the membrane. Pop the inside of the circle. Stick your dry finger (or another dry object, like your pencil) through the pore created by the circular thread and gently move it around the membrane. Try to carefully remove the thread from the membrane and see if the membrane is able to self-seal.

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Analysis Questions 1. Describe what you observed about the bubble membrane’s “fluidity” and explain how this relates to the

structure of the cell membrane.

2. What are the three major components of the cell membrane and how are they organized? (A diagram would work well here.)

3. Explain how the “self-sealing” bubble membrane show how a membrane is selectively permeable.

4. What happened when you placed a circular thread into the bubble film? Explain why this thread represents a transport protein and describe how transport proteins work.

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Diffusion Practice Problem Set 1. The best definition of Homeostasis is:

a. Keeping a constant temperature inside a cell or organism despite external changes. b. Keeping constant conditions within a cell or organism despite external changes. c. Keeping a constant pH inside a cell or organism despite external changes. d. Keeping constant conditions outside a cell or organism despite internal changes.

2. The three most abundant molecules in the plasma membrane are:

a. b. c.

3. This is true of the structure of the plasma membrane:

a. It is a double layer of protein molecules with phospholipid molecules randomly dotted along it b. It is single layer of phospholipid molecules c. It is a double layer of phospholipid molecules with protein molecules dotted along it. d. It is single layer of protein molecules with phospholipids dotted along it.

4. Explain each of the following mechanisms that molecules use to pass through the membrane.

Mechanism Description (P)assive or (A)ctive?

Simple Diffusion

Facilitated Diffusion

Osmosis

Active Transport through a pump

Endocytosis/Exocytosis

5. A semi-permeable membrane is a membrane that:

a. allows some molecules to go through but not others b. allows all molecules to go through c. is different on each side d. is partly made from permeable compounds

6. Active transport: (select all that apply)

a. uses energy b. uses no energy c. occurs from a lower concentration of molecules to a higher concentration d. occurs from a higher concentration of molecules to a lower one e. results in an even distribution of molecules

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7. Circle the correct answer. a. When red blood cells are placed in an isotonic solution they: swell / stay the same / shrink.

b. Red blood cells placed in a high salt solution would: swell / stay the same / shrink. c. Red blood cells placed in distilled water (100% water) would: swell / stay the same / shrink.

d. When red blood cells are placed in distilled water: the water enters the cells / the water leaves the cells / the water does not move / the salts in the cells leave the cells

e. A dialysis bag (made of an artificial semi-permeable membrane) filled with 0.5% salt solution and placed in a beaker containing 3.0% salt solution will: swell / stay the same / shrink.

8. Three bottles are filled with three different solutions. One with distilled water, one with 0.9% salt

solution and the third with 9.0% salt solution. A few dried apricots are placed in the three bottles and left in the solutions for an hour. (Hint – drawing the arrows on the picture helps!)

a. The apricots in bottle A stay the same. b. The apricots in bottle B shrink c. The apricots in bottle C swell.

Now answer the following questions:

1. Which bottle contains the high salt solution? A B C 2. Which bottle contains pure water? A B C 3. Which bottle contains the isotonic salt solution? A B C

9. The cell membrane is made of a ___________________ ______________________.

10. The cell membrane is _________________permeable. This means that ____________ ______________________________________________________________________.

11. Diffusion always causes particles to move from a region of _______________ concentration to a region of ______________ concentration.

12. Does a cell use energy when molecules diffuse in or out of the cell? 13. Consider the solution in the drawing below, with the two sides divided by a perforated membrane. In

the blank drawing on the right, show how the solution would look once it has reached equilibrium.

A   B   C  

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14. A semi - permeable membrane (dialysis) bag, containing 4% salt, 4% glucose and 4% albumin is suspended in distilled water. Assume the bag is permeable to all substances except albumin.

Circle the correct answer in the statements below. (See above for information about permeability.)

a. The salt: moves into the bag / moves out of the bag / does not move

b. The water: moves into the bag / moves out of the bag / does not move c. The albumin: moves into the bag / moves out of the bag / does not move

d. The glucose : moves into the bag / moves out of the bag / does not move e. The salt moves by: diffusion / osmosis / active transport / it does not move because the

molecules are too large. f. The water moves by: diffusion / osmosis / active transport / it does not move because the

molecules are too large. g. The albumin moves by: diffusion / osmosis / active transport / it does not move because the

molecules are too large. h. The glucose moves by: diffusion / osmosis / active transport / it does not move because the

molecules are too large. 15. Suppose that a cell membrane is permeable to water but impermeable to glucose (sugar). The inside of

the cell has a higher glucose concentration compared to the outside of the cell. Using the diagram below, (1) draw what the concentrations of water and glucose would look like at the beginning of the experiment (NOTE the symbols for each molecule shown below), and (2) indicate the direction of movement that would occur during osmosis. Which molecule would move?

Inside  cell  

Outside  environment  • = water Δ = glucose

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16. What are three examples of molecules that a cell would want to be able to move effectively across its cell membrane? (Be more specific than “food.”)

17. What general type of organic molecule is a phospholipid? What is an example of this general type of

molecule that you could find at home (in your kitchen maybe??). 18. Use arrows to indicate the direction of diffusion in each case: is a molecule that can pass through

the cell membrane. is a cell membrane. A) B) 19. For each of the situations below use an arrow to indicate the net movement of sugar into or out of the

cell. (Assume that the sugar molecules can pass through the cell membrane in each case.) 20. When you take a bath, the cells in the skin of your fingers are immersed in water.

a. Assuming the bath is pure water, which is the stronger solution (more solute): the solution inside your skin cells or the bath water?

b. Your skin cells have a semi-permeable membrane. Does osmosis cause water to pass from the cells of your fingers into the bath, or from the bath into the cells of your finger?

c. What will happen to the size of the skin cells in your fingers?

21. Honey is a very strong solution of sugar. By contrast the cytoplasm in a bacterium cell is a much weaker solution. The cell wall of a bacterium is made up of a semi-permeable membrane.

a. Would water flow from the bacterium to the jam, or from the jam to the bacterium by osmosis?

b. Suggest a reason why microbes find it difficult to survive in honey.

1%  sugar  

5%  sugar  

3%  sugar  

1%  sugar  

1%  sugar  

1%  sugar  

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Study Sheet for Cell Quest All students must make a 3 x 5” index card, front and back, for use during the exam. Everyone is required to make one; you will turn this in on the day of the exam. It must be hand-written unless you have an accommodation (see me ahead of time). I suggest that as you study, you identify concepts that give you the most difficulty and use the index card for those concepts. Making your own study sheet – Please type your work (exceptions can be made for those who have very neat, easily readable handwriting). Do not attempt to cram everything into one page; expect it to be multiple pages. You do not need to write in complete sentences, but your answers should be thorough and clear. Please number your questions and do your best to answer them in order. You should incorporate the question into your answer OR download this document from the class website and place your answers after the questions and bring in a hard copy. Your study sheet should be made so that it will be useful to you for the final exam, so explain things such that when you are reviewing this sheet in six weeks, it will be clear to you in the future. Wacky history of cell theory and cell notes 1. What are the three parts of the cell theory? 2. What is the difference between prokaryotes and eukaryotes? What do they have in common? 3. What are the internal compartments (organelles) in a cell? What are the functions of each of the

organelles of the cell? Be able to identify these on a diagram. 4. Which of the following is made of cells?

oak tree butterfly paper chair desk snickers bar onion monkey

Animal vs. Plant Cell Microscope Lab 5. What do plant cells have in common? What do animal cells have in common? Compare and contrast

plant and animal cells. Why are cells so small? 6. Explain why cells MUST be small. Use the concept of surface area to volume ratio in your answer. Can you stand the Heat? 7. Define homeostasis. 8. Explain how the human body, its organs, and its cells can be considered ‘compartments’. Eggsperiment, Notes: Transport and Diffusion, and Diffusion Practice Problems 9. What are diffusion and osmosis? Give examples of these. What causes diffusion to occur? 10. Define isotonic, hypertonic, and hypotonic. Explain what happens to blood cells and onion cells when

placed in isotonic, hypertonic, and hypotonic solutions. Explain why these changes occur. 11. Distinguish between the following terms: permeable, impermeable, & selectively permeable. 12. What are the differences and similarities between simple diffusion and facilitated diffusion? 13. What is the difference among passive transport and active transport? 14. Describe the types of active transport: membrane-associated pumps, endocytosis, and exocytosis. Bubble Membranes 15. Explain how molecular size influences whether or not a substance can pass through a membrane. 16. What is the chemical make-up of the cell membrane? Explain what is meant by “lipid bilayer.” 17. Why is the membrane called a fluid-mosaic model?