Cell Membrane And Tonicity Worksheet is an amount of pointers ... - Free Printable

Let's solve this Cell Membrane & Tonicity Worksheet step by step. I'll fill in the blanks, explain each answer, and help you match the diagram labels correctly.

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Part 1: Composition of the Cell Membrane & Functions

> The cell membrane is also called the ________ membrane and is made of a phospholipid ________.

- Answer:
The cell membrane is also called the plasma membrane and is made of a phospholipid bilayer.

> The phospholipids have a hydrophilic (water attracting) ________ and two hydrophobic (water repelling) ________.

- Answer:
Hydrophilic heads, hydrophobic tails.

> The head of a phospholipid is made of an alcohol and ________ group, while the tails are chains of ________.

- Answer:
Head: alcohol and phosphate group
Tails: chains of fatty acids (or hydrocarbon chains)

> Phospholipids can move ________ and allow water and other ________ molecules to pass through into or out of the cell. This is known as simple diffusion because it does not require ________ and the water or molecules are moving ________ the concentration gradient.

- Answer:
Phospholipids can move freely
Allow small, nonpolar molecules to pass (but actually, small polar like water *can* pass slowly; however, the key here is simple diffusion — so we focus on small, uncharged molecules). But since it says "water and other", and water is polar, let’s be accurate:

→ Allow small molecules to pass
→ This is known as simple diffusion because it does not require energy
→ Moving down the concentration gradient

So:
- freely
- small (or nonpolar/polar depending on context; but best fit: small)
- energy
- down

> Another type of lipid in the cell membrane is ________ that makes the membrane more fluid.

- Answer: Cholesterol

> Embedded in the phospholipid bilayer are ________ that also aid in diffusion and in cell recognition.

- Answer: Proteins

> Proteins called ________ proteins go all the way through the bilayer. Large molecules like ________ or carbohydrates use proteins to help move across cell membranes. Some of the membrane proteins have carbohydrate ________ attached to help cells recognize each other and certain molecules.

- Answer:
- Transport proteins
- Glucose (or amino acids, but glucose is common)
- chains

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✔ Completed Fill-in-the-Blanks:

> The cell membrane is also called the plasma membrane and is made of a phospholipid bilayer. The phospholipids have a hydrophilic (water attracting) heads and two hydrophobic (water repelling) tails. The head of a phospholipid is made of an alcohol and phosphate group, while the tails are chains of fatty acids. Phospholipids can move freely and allow water and other small molecules to pass through into or out of the cell. This is known as simple diffusion because it does not require energy and the water or molecules are moving down the concentration gradient.
>
> Another type of lipid in the cell membrane is cholesterol that makes the membrane more fluid. Embedded in the phospholipid bilayer are proteins that also aid in diffusion and in cell recognition. Proteins called transport proteins go all the way through the bilayer. Large molecules like glucose or carbohydrates use proteins to help move across cell membranes. Some of the membrane proteins have carbohydrate chains attached to help cells recognize each other and certain molecules.

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List 2 functions of the cell or plasma membrane:

a. Regulates what enters and exits the cell
b. Provides protection and structural support
(Other valid answers: cell recognition, communication, enzyme attachment, etc.)

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Sketch and Label Instruction:

> SKETCH AND LABEL a phospholipid coloring the heads red and the tails blue.

✔ Instructions for sketch:
- Draw a single phospholipid molecule.
- Two blue tails (hydrophobic fatty acid chains) pointing downward.
- One red head (phosphate group) at the top (hydrophilic).
- Label: "Head" (red), "Tails" (blue).

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Match the cell membrane structure or its function with the correct letter from the diagram.

Let’s analyze the labeled diagram:

Looking at the typical structure of a cell membrane:

- A: Entire thickness of membrane → Bilayer (phospholipid bilayer)
- B: Protein spanning the membrane → Transport protein (transmembrane protein)
- C: Glycoprotein (carbohydrate chain attached to protein) → Involved in cell-to-cell recognition
- D: Cholesterol molecule → Helps maintain flexibility
- E: Carbohydrate chain → Glycoprotein, involved in recognition
- F: Phospholipid tail → Repels water (hydrophobic)
- G: Phospholipid head → Attracts water (hydrophilic)
- H: Cholesterol → helps with fluidity
- I: Phospholipid bilayer → Make up the bilayer

Now match:

| Structure/Function | Letter |
|--------------------|--------|
| Attracts water | G (phospholipid head) |
| Helps maintain flexibility of membrane | D or H (cholesterol) |
| Involved in cell-to-cell recognition | C or E (glycoproteins) |
| Repels water | F (phospholipid tail) |
| Make up the bilayer | A (entire bilayer) |
| Help transport certain materials across the cell membrane | B (transport protein) |

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✔ Final Matching Table:

| Letter | Structure/Function |
|--------|---------------------|
| G | Attracts water |
| D or H | Helps maintain flexibility of membrane |
| C or E | Involved in cell-to-cell recognition |
| F | Repels water |
| A | Make up the bilayer |
| B | Help transport certain materials across the cell membrane |

> Note: Since both D and H are cholesterol, either is acceptable. C and E are both glycoproteins; choose based on labeling. In most diagrams:
> - C = carbohydrate chain
> - E = glycoprotein (protein + sugar)
> So likely C is the carbohydrate chain, which is involved in recognition.

Thus, best matches:

| Letter | Structure/Function |
|--------|---------------------|
| G | Attracts water |
| D or H | Helps maintain flexibility |
| C | Involved in cell-to-cell recognition |
| F | Repels water |
| A | Make up the bilayer |
| B | Help transport certain materials |

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✔ Summary of Answers:

#### Fill-in-the-blanks:
1. plasma
2. bilayer
3. heads
4. tails
5. phosphate
6. fatty acids
7. freely
8. small
9. diffusion
10. energy
11. down
12. cholesterol
13. proteins
14. transport
15. glucose
16. chains

#### Two functions of the plasma membrane:
a. Regulates movement of substances in and out of the cell
b. Facilitates cell signaling and recognition

#### Matching:
- Attracts water → G
- Helps maintain flexibility → D or H
- Involved in cell-to-cell recognition → C
- Repels water → F
- Make up the bilayer → A
- Help transport materials → B

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