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Descriptions of  four biological samples (I - IV) are given below

1. Can be viewed using a light microscope with a total magnification of 1000X; possesses cell wall and does not possess mitochondria.

2. Can be seen using a light microscope with a total magnification of 100X; possesses cell wall and has a nucleus.

3. Needs electron microscope for viewing ; can be found attached to the membrane system in the cytoplasm.

4. Needs electron microscope for viewing; cannot replicate on its own, needs other specific cells for replication.

I, II, III, and IV respectively represent:

(A) virus; plant cell; ribosome; bacteria

(B)  plant cell; bacteria; vacuole; virus

(C) bacteria; plant cell; ribosome; virus

(D) bacteria; protist; plant cell vacuole; mitochondria

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I) Bacteria – At 1000x magnification we will be able to see 0.180mm, or 180 microns. Bacteria are too small to see without the aid of a microscope. While some eukaryotes, such as protozoa, algae and yeast, can be seen at magnifications of 200X-400X, most bacteria can only be seen with 1000X magnification.

Bacteria cells have ribosomes and a cell wall, but they don't have organelles such as nuclei, mitochondria or chloroplasts. Bacteria cells do have a cytoplasm and cell membrane. One of the key structures of a bacteria cell is the plasmid.

II) Plant cell – Using a light microscope of 100X magnification power, we can view cell walls, vacuoles, cytoplasm, chloroplasts, nucleus and cell membrane of plant cell.

Plant cells have a cytoplasm, cell membrane, mitochondria and nucleus which all perform the same functions as animal cells.

III) Ribosome - A ribosome is a cell organelle which can be seen only through electron microscope and cannot be seen with a light microscope. It functions as a micro-machine for making proteins. Ribosomes are found ‘free’ in the cytoplasm or bound to the membrane system i.e., the endoplasmic reticulum (ER) to form rough ER.

IV) Virus – Viruses are very small and most of them can be seen only by electron microscopy. A virus is a small collection of genetic code, either DNA or RNA, surrounded by a protein coat. A virus cannot replicate alone. Viruses must infect cells and use components of the host cell to make copies of themselves. Often, they kill the host cell in the process and cause damage to the host organism.

Hence, option (c) is correct.

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