Q.7. Explain the life cycle of pinus with the help of labelled diagrams only. (1997)
Ans.
Q.8. Describe the structure of mature ovule of Pinus. (2012)
Ans. Structure of ovule: -
A mature ovule bears central parenchymous multicellular nucellus. The ovule is enclosed by a two-lipped protective covering known as the integument. Integument is united with the nucellus except at the micropylar end where it becomes prolonged to form a short tube beyond the nucellus. The opening forms the micropyle. A further prolongation of the integument results in the formation of an arm on either side of the microphyle. A small space is left in the upper region of the nucellus below the integument.
Q.9. Describe the structure of pollen grain of pinus. (2013)
Ans. The microspore (pollen grain) is the basic unit of male gametophyte. It is a uninucleate structure with two assymetrically placed air-bladders. The air bladder is also known as wing or saccus and arises on the lateral sides of microspores. Each pollen grain has a cuticularised outer layer called exine and an inner thin layer called intine. The outer wall of the wing has a reticulate sculpture. Male gametophyte develops partially in the microsporangium and partially in the ovule.
Q.10. Give a comparative account of Pinus and Cyca mature ovules. Draw labelled diagrams. (2007)
Related Questions -
Q. Draw longitudinal diagram of ovule of Cycas. (2005)
Ans. Camparison of Pinus and Cycas Mature Ovule
Q. 11. Compare male and female gametophyte of Cycas and Pinus. (1996)
Ans. Male Gametophyte: -
