Magnification - Introductory Biology 0FHH0022 Lesson 1 worksheet 2 ... - Free Printable

Let's solve each part of this worksheet step by step.

---

1) Complete the diagram to show: names of the units of measurement, unit symbols, mathematical operations for converting between units.

We are given a vertical chain of metric units related to length, starting from centimetre down to nanometre, with conversion factors.

#### Step 1: Identify the missing units and their symbols

From top to bottom:

- Centimetre (cm) → already given
- Millimetre (mm) → symbol is mm
- Next is Micrometre → symbol is μm (already shown)
- Then Nanometre → symbol is nm

So we fill in:
- Millimetre → (mm)
- Micrometre → (μm) → already labeled
- Nanometre → (nm)

Now, we need to determine the conversion factors between these units.

#### Conversion relationships:

We know:
- 1 cm = 10 mm → so going down from cm to mm: ×10
Going up: ÷10
- 1 mm = 1000 μm → so from mm to μm: ×1000
From μm to mm: ÷1000
- 1 μm = 1000 nm → so from μm to nm: ×1000
From nm to μm: ÷1000

But the diagram shows only × or ÷ with numbers. Let’s analyze the arrows.

The green arrows go up (larger to smaller), so they represent division.
Red arrows go down (smaller to larger), so they represent multiplication.

So:

- From cm → mm: ×10 (red arrow) → correct
- From mm → μm: ×1000 (red arrow) → missing number
- From μm → nm: ×1000 (red arrow) → missing number

And for the green arrows (going up):
- From mm → cm: ÷10 → already shown
- From μm → mm: ÷1000
- From nm → μm: ÷1000

Now fill in the blanks:

```
Centimetre
(cm)
↑÷10 ↓×10
Millimetre
(mm)
↑÷1000 ↓×1000
Micrometre
(μm)
↑÷1000 ↓×1000
Nanometre
(nm)
```

✔ So complete diagram:

- Millimetre → (mm)
- Micrometre → (μm) → already there
- Nanometre → (nm)

Green arrows (up):
- Between mm and μm: ÷1000
- Between μm and nm: ÷1000

Red arrows (down):
- Between mm and μm: ×1000
- Between μm and nm: ×1000

---

✔ Final Answer for Question 1:

```
Centimetre
(cm)
↑÷10 ↓×10
Millimetre
(mm)
↑÷1000 ↓×1000
Micrometre
(μm)
↑÷1000 ↓×1000
Nanometre
(nm)
```

---

2) Complete the table to show corresponding values in nanometres, micrometres, and millimetres.

We use the following conversions:

- 1 μm = 1000 nm
- 1 mm = 1000 μm = 1,000,000 nm

So:
- To convert nm → μm: divide by 1000
- To convert μm → nm: multiply by 1000
- To convert μm → mm: divide by 1000
- To convert mm → μm: multiply by 1000
- To convert mm → nm: multiply by 1,000,000

Let’s fill in row by row.

| Nanometre | Micrometre | Millimetre |
|----------|------------|------------|
| 5 | 0.005 | 0.000005 | ← Given
| 1 | | |
| | 1 | |
| | | 1 |
| | 3 | |
| 7 | | |
| | | 0.5 |

---

#### Row 2: Nanometre = 1

- 1 nm = 1/1000 μm = 0.001 μm
- 1 nm = 1/1,000,000 mm = 0.000001 mm

→ Fill: 0.001, 0.000001

---

#### Row 3: Micrometre = 1

- 1 μm = 1000 nm
- 1 μm = 0.001 mm

→ Fill: 1000, 0.001

---

#### Row 4: Millimetre = 1

- 1 mm = 1000 μm
- 1 mm = 1,000,000 nm

→ Fill: 1,000,000, 1000

---

#### Row 5: Micrometre = 3

- 3 μm = 3 × 1000 = 3000 nm
- 3 μm = 3 / 1000 = 0.003 mm

→ Fill: 3000, 0.003

---

#### Row 6: Nanometre = 7

- 7 nm = 7 / 1000 = 0.007 μm
- 7 nm = 7 / 1,000,000 = 0.000007 mm

→ Fill: 0.007, 0.000007

---

#### Row 7: Millimetre = 0.5

- 0.5 mm = 0.5 × 1000 = 500 μm
- 0.5 mm = 0.5 × 1,000,000 = 500,000 nm

→ Fill: 500,000, 500

---

✔ Completed Table:

| Nanometre | Micrometre | Millimetre |
|---------------|--------------|----------------|
| 5 | 0.005 | 0.000005 |
| 1 | 0.001 | 0.000001 |
| 1000 | 1 | 0.001 |
| 1,000,000 | 1000 | 1 |
| 3000 | 3 | 0.003 |
| 7 | 0.007 | 0.000007 |
| 500,000 | 500 | 0.5 |

---

3) When studying cell structure using a microscope, the smallest unit of measurement commonly used to describe findings is the nanometre. Explain why.

#### ✔ Explanation:

Cells and their internal structures (like organelles, membranes, proteins, and DNA) are extremely small. While many parts of a cell can be seen in micrometres (e.g., a typical human cell is about 10–100 μm), subcellular components such as:

- Ribosomes (~20–30 nm)
- DNA helix (~2 nm wide)
- Cell membrane thickness (~7–10 nm)
- Viruses (often 20–300 nm)

are best measured in nanometres (nm) because they are too small to be accurately described in micrometres.

Using nanometres allows scientists to precisely measure and describe ultrastructural details visible under electron microscopes, which have much higher resolution than light microscopes.

Thus, nanometres are essential for describing the fine details of cellular structure at the molecular level.

---

✔ Final Answer for Question 3:

> The nanometre is used because many cellular structures, such as ribosomes, membranes, and DNA, are extremely small—typically ranging from 1 to 100 nanometres. These features are too small to be accurately measured in micrometres, so nanometres provide the necessary precision for describing subcellular details observed under high-resolution microscopes like electron microscopes.

---

✔ Summary of Answers:

#### 1) Diagram Completion:

```
Centimetre
(cm)
↑÷10 ↓×10
Millimetre
(mm)
↑÷1000 ↓×1000
Micrometre
(μm)
↑÷1000 ↓×1000
Nanometre
(nm)
```

#### 2) Completed Table:

| Nanometre | Micrometre | Millimetre |
|---------------|--------------|----------------|
| 5 | 0.005 | 0.000005 |
| 1 | 0.001 | 0.000001 |
| 1000 | 1 | 0.001 |
| 1,000,000 | 1000 | 1 |
| 3000 | 3 | 0.003 |
| 7 | 0.007 | 0.000007 |
| 500,000 | 500 | 0.5 |

#### 3) Explanation:

> The nanometre is used because it provides the precision needed to measure very small structures within cells, such as membranes, ribosomes, and DNA, which are typically less than 1 micrometre in size. These structures are often only a few nanometres across, making nanometres the most appropriate unit for detailed microscopic analysis.

Let me know if you'd like this formatted as a printable PDF or image!