Bamboo flowered once in its life time after 50-100 years. Therefore he could not see any flower on bamboo trees

1. Gemmules are the internal buds found in coelenterates and sponges.
2. Gemmae are the external buds found in bryophytes

In unisexual or cross pollinating plants, the pollination helps in transfer of pollen grains to the stigma. Pollen grains germinate on the stigma and produce the pollen tubes. The latter carry the male gametes and reach the ovule and discharge male gametes near the egg.

Differences between binary fission and multiple fission.

(i) both angiosperms and vertebrates have a more complex structural organisation.
(ii) They have evolved very efficient mechanism of sexual reproduction.
(iii) Since asexual reproduction does not create new genetic pools in the offspring and consequently hampers their adaptability to external conditions, these groups have resorted to reproduction by the sexual method which introduces variations. 

(i) Protandry: (maturation of anthers before stigma) or protogyny (maturation of stigma before anther) i.e. Dichogamy may take place.
(ii) To bear styles of different lengths.
(iii) Heterostyly: To bear lever mechanism e.g. Salvia.

(i) Both male and female gametes are non-motile, eg. certain algae and few fungi.
(ii) In seed plants, the male gametes are non-motile and are carried in the pollen tube to the egg.

1. Pre-fertilisation events are those events of sexual reproduction that occur prior to fusion of gametes (syngamy).
2. Gametogenesis and gamete transfer are the two major pre-fertilisation events.

(a) Those mammals which are reproductively active throughout their reproductive phase, are called continuous breeders.
(b) Those mammals which are living in natural/wild conditions and exhibit the reproductive cycles only under favourable seasons during their reproductive phase, are called seasonal breeders.

Offset.  The plants propagate vegetatively at such a phenomenal rate that it is very difficult to get rid of them; it drains oxygen from the water and causes mortality of aquatic organisms.

1. In haploid organisms, showing haplontic life cycle, gamete formation involves only mitosis; the diploid zygote formed by the fusion of two haploid gametes, undergoes meiosis (zygotic meiosis).
2. In diploid organisms, showing diplontic or haplodiplontic life cycle, gamete formation involues meiosis (gametic meiosis) and haploid gametes are formedl; the diploid zygote undergoes mitosis to form diploid individuals.

(a) 60 years      
(b) 15 years      
(c) 140 years      
(d) 1-2 weeks