Which of the following is monoecious?

Coralloid roots of $Cycas$ are useful in

In $Pinus$,male gametes are produced in the pollen tube by the division of which of the following cells?

Plants in which seeds develop on sporophylls and are not enclosed by fruits are classified as -

What is the biological importance of the following structures in gymnosperms?
$(i)$ Mycorrhiza in roots
$(ii)$ Coralloid roots

In which plant group are the sporophylls arranged on a central axis to form distinct compact structures called strobili or cones?