Question \( 3.2[4 \) marks] A biologist is examining a micrograph of a cross-section of a plant cell taken with a light microscope. The magnification of the micrograph is \( 200 x \), and the diameter of the chloroplast in the micrograph is measured to be 0.25 cm . Calculate the actual size of the chloroplast in micrometres \( (\mu \mathrm{m}) \). TOTAL: 8 GRAND TOTAL: 30

To find the actual size of the chloroplast, we can use the formula: \[ \text{Actual size} = \frac{\text{Measured size}}{\text{Magnification}} \] Substituting in the values: \[ \text{Actual size} = \frac{0.25 \text{ cm}}{200} = 0.00125 \text{ cm} \] Now, converting centimeters to micrometres: \[ 0.00125 \text{ cm} = 0.00125 \times 10^4 \text{ µm} = 12.5 \text{ µm} \] Therefore, the actual size of the chloroplast is \( 12.5 \, \mu m \). --- Did you know that the term "chloroplast" comes from the Greek words "chloros," meaning green, and "plastos," meaning formed or molded? These tiny powerhouses of photosynthesis allow plants to convert sunlight into energy! Talk about green innovation! Furthermore, if you're measuring microscopic objects frequently, try keeping a conversion chart handy! Common mistakes occur when switching between centimeters and micrometers. Remember: \( 1 \text{ cm} = 10,000 \, \mu m \). It’s a big leap in numbers!