Q5. Classify each as tuber, rhizome or corm: potato, ginger, zaminkand.
Potato, tuber; ginger, rhizome; zaminkand, corm (beyond the 2026–27 NCERT text).
Q6. Which one is not a modified stem: potato, ginger, sweet potato, Colocasia?
The sweet potato, which is a root; the others are underground stems (beyond the 2026–27 NCERT text; NCERT page 68 calls the potato an underground stem).
Q7. Name the propagating stems of jasmine, Eichhornia and pineapple.
Jasmine, stolon; Eichhornia, offset; pineapple, sucker (beyond the 2026–27 NCERT text).
Q8. Which plant of arid regions has a fleshy cylindrical green stem?
Euphorbia (beyond the 2026–27 NCERT text).
Q9. Assertion: the eyes of a potato show that it is a stem. Reason: the eyes are nodes bearing buds. Are both true, and does the reason explain the assertion?
Both are true, and the reason explains the assertion: nodes with buds are a mark of the stem (NCERT pages 59 and 69; the potato’s eyes are beyond the 2026–27 NCERT text).
Q10. The thorn of Bougainvillea and the tendril of a gourd do different jobs. Are they homologous or analogous?
Homologous: both are modified axillary buds, one origin put to different uses. NCERT Class 12 Biology says the thorn and tendrils of Bougainvillea and Cucurbita represent homology (Section 6.3, page 115).
Q11. In grass, what happens when the older parts of a runner die?
The parts that have rooted at the nodes live on as new plants (beyond the 2026–27 NCERT text).
Q12. Is the corm of Colocasia a root or a stem? Give a reason.
A stem: it bears nodes with scale leaves and buds, which a root never has. Storing food does not decide it, since storage roots store food too (beyond the 2026–27 NCERT text).