Cell structure

Question 1

What is the function of a ribosome?

Answer 1

The function of a ribosome is in protein synthesis. Photosynthesis takes place in chloroplasts.

Question 2

A type of white blood cell called a macrophage measures 5 x 10-5m. What does it measure in micrometres?

Answer 2

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

Question 3

If the actual size of a cell is 100 μm, and 10 cm in a book, what is the magnification of the image in the book?

Answer 3

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

Question 4

How have microscopes developed over the years?

Answer 4

Increased magnification, increased resolution

Question 5

If a cell called a megakaryocyte measures 1 x 10-4m, and a neutrophil measures 1 x 10-5m, what is the difference in order of magnitude?

Answer 5

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.

Question 6

an advantage of the transmission electron microscope compared with the light microscope?

Answer 6

Higher magnifications are possible with the transmission electron microscope. Higher resolutions are possible also.

Question 7

Which of the following is the correct sequence for setting up a microscope on high power?

Answer 7

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. A specimen should always be examined on low power first - it would be difficult to locate it using low power as the field of view is very narrow.

Question 8

an adaptation to the transport of substances in the xylem?

Answer 8

Xylem vessels are adapted to transport by having no end walls, and their side walls are thickened. It is the sieve tubes of the phloem that are perforated.

Question 9

How is a muscle adapted to its function

Answer 9

Muscle is adapted to bringing about movement as it contains protein filaments that slide over each other and cause contraction. Muscular tissue has many nuclei because at some time during evolution, muscle cells must have merged to make contraction more efficient.

Question 10

a feature of eukaryotic cells not present in prokaryotic cells?

Answer 10

Mitochondria are present in eukaryotic cells but not in prokaryotic cells. Plasmids are found in bacteria, but very rarely in eukaryotic cells.