Q5. Which gymnosperm does NCERT name as one of the tallest tree species?
The giant redwood tree, Sequoia (NCERT page 32).
Q6. What are microsporangiate strobili?
Strobili that bear microsporophylls and microsporangia, also called male strobili (NCERT page 33).
Q7. Give the ploidy, in a gymnosperm, of the pollen grain, nucellus, megaspore, female gametophyte and zygote.
n, 2n (sporophyte tissue), n, n, 2n (NCERT page 33).
Q8. Where does the pollen tube discharge the male gametes in a gymnosperm?
Near the mouth of the archegonia in the ovule (NCERT page 33).
Q9. Which gymnosperm has unbranched stems, and which have branched stems?
Cycas has an unbranched stem; Pinus and Cedrus have branched stems (NCERT page 32).
Q10. Assertion: gymnosperms do not need external water for fertilisation. Reason: their male gametes are carried to the archegonia by a pollen tube. Are both true, and does the reason explain the assertion?
Both are true, and the reason explains the assertion: the pollen tube brings the male gametes to the archegonia inside the ovule (NCERT page 33), so they need no film of water outside the plant, unlike the antherozoids of bryophytes and pteridophytes (pages 29 and 32). The assertion itself is beyond the NCERT text.
Q11. Is the pollen grain haploid or diploid, and why?
Haploid: it develops from a haploid microspore and is the reduced male gametophyte (NCERT page 33).
Q12. Which of these is not a gymnosperm: Pinus, Cycas, Selaginella, Ginkgo?
Selaginella, a pteridophyte (NCERT page 32); Ginkgo appears with Cycas and Pinus in NCERT Figure 3.4 (page 33).