Test: Cell Structure - Grade 10 MCQ

Mitochondria are present in eukaryotic cells but not in prokaryotic cells. These are absent in prokaryotic cells. Mitochondria are thought to be the result of prokaryotic cells entering other cells way back in evolutionary history.

Xylem vessels are adapted to transport by having no end walls, and their side walls are thickened. The thickening is of a chemical called lignin. Xylem vessels thickened with lignin are called wood.

Higher magnifications are possible with the transmission electron microscope owing to the shorter wavelengths of the electron compared with visible light.

Microscopes have developed over the years to give increased magnification and increased resolution. These have increased markedly since the invention of the electron microscope.

A macrophage measures 50 μm. One micrometre equals 10^-6 m, so a macrophage measuring 5 x 10^-5 m would be fifty times this.

Muscle is adapted to bringing about movement as it contains protein filaments that slide over each other and cause contraction. In skeletal muscle, these filaments create the bands that we see when examining muscle with the light microscope.

A microscope should be focused on low power using the coarse adjustment, the high power objective moved in line with the specimen, and then the image refocused with the fine adjustment. If the final step is not successful, return to low power and refocus.

The difference in the order of magnitude between a megakaryocyte and a neutrophil is one. Orders of magnitude are to the base 10, so the calculation is 5-4.

The magnification of the book image is 1000 times the actual size. The calculation is 100 000 μm ÷ 100 μm = 1000.

The function of a ribosome is in protein synthesis.