Q1.
Study the given diagrams of a bacterial cell, a plant cell, and an animal cell (Fig. 2.10a, b and c). Observe the different structures present in each of them. Record your observations in Table 2.1.
Answer
Here is Table 2.1 completed from Fig. 2.10.
| S. No. | Cell structures | Bacterial cell | Plant cell | Animal cell |
|---|---|---|---|---|
| 1. | Cell membrane | Present | Present | Present |
| 2. | Cell wall | Present | Present | Absent |
| 3. | Cytoplasm | Present | Present | Present |
| 4. | Well-defined nucleus (genetic material enclosed by a membrane) | Absent | Present | Present |
| 5. | Primitive nucleus or nucleoid (genetic material without membrane around it) | Present | Absent | Absent |
| 6. | Membrane-bound organelles | Absent | Present | Present |
Two more structures are visible in Fig. 2.10 and worth noting: the bacterial cell has an appendage for locomotion and free ribosomes; the plant cell alone has chloroplasts and a large central vacuole.
Why it happens: the pattern in the table is not a list of random differences — it splits cells into two kinds. Rows 4, 5 and 6 all move together: a cell either encloses its DNA in a nuclear membrane and has membrane-bound organelles, or it does neither. That is because both features depend on the same ability, namely to build internal membranes. Bacteria lack it, so their DNA lies free in the cytoplasm as a nucleoid and all their chemistry happens in one open compartment. Rows 1 and 3 are in every column because no cell can exist without a boundary and a fluid interior.
Tip: row 2 is the row that separates plants from animals, and rows 4–6 are the rows that separate bacteria from both. Read the table by rows, not by columns, and the logic appears.