Differentiate between the following pairs of terms based on the clues given in parentheses:
Cell membrane and cell wall (permeability)
(i) The cell membrane is selectively permeable, which means it allows only specific molecules to pass through it. In contrast, the cell wall is fully permeable, which means it allows all substances to pass through it freely.
RER and SER (structure)
(ii) The RER (Rough Endoplasmic Reticulum) has ribosomes attached to its surface, which gives it a rough structure. In contrast, the SER (Smooth Endoplasmic Reticulum) lacks ribosomes on its surface, which gives it a smooth structure.
Chloroplasts and chromoplasts (pigments)
(iii) Chloroplasts contain the green pigment chlorophyll, which is essential for photosynthesis. Chromoplasts contain coloured pigments (other than green), such as yellow, orange, or red pigments.
Explanation
The question requires differentiating between three pairs of cellular components based on specific clues. For permeability, the cell membrane acts as a selective barrier, whereas the cell wall allows free passage. Structurally, the presence or absence of ribosomes distinguishes RER from SER. Based on pigments, chloroplasts are identified by chlorophyll, while chromoplasts contain other coloured pigments.