Tag: flowers and fruits

 Phloem is the vascular tissue responsible for transport of sugars and other liquid materials. Phloem is composed of several cell types including sclerenchyma, parenchyma, sieve elements and companion cells. The function of companion cells is uncertain though it appears to regulate the activity of the adjacent sieve elements. Albuminous cells have a similar role to companion cells, but are associated with sieve cells only and are hence found in gymnosperms.

Gymnosperms are archegoniate spermatophytes. Spermatophyte is another term from phanerograms which are the seeded plants- gymnosperms and angiosperms. Archegonia is the female sex organ which is present in bryophytes, pteridophytes and gymnosperms. So, the gymnosperms are the only one which are both spermtophyte and archegoniate.

Gymnosperm undergo double fertilization, therefore in haploid stage of the gynosperm life cycle the plants have only one set of chromosome, thus haploid microspores are released into air as pollen and in gymnosperm endosperm is formed before fertilization from the female gametophyte(n). Hence it is haploid.

Gymnosperms lack typical companion cells and instead possess albuminous cells (or transfer cells) associated with sieve cells. The metabolic activity and functional control of the sieve elements in gymnosperms are regulated by the nucleus of these albuminous cells.

A male cone contains microsporophylls where male gametophytes ( pollen ) are produced and are later carried by wind to female gametophytes. The megaspore mother cell in the female cone divides by meiosis to produce four haploid megaspores; one of the megaspores divides to form the female gametophyte. So the correct option is 'Male and female gametophytes are independent of the sporophyte'.

Gymnosperms are vascular seed plants that include trees, shrubs, and lianas, but they do not form true herbaceous plants in the botanical sense of true herbs. Thus, herbs are the correct answer as they lack the woody persistent stems typical of gymnosperms.

The Gymnosperms originated during the late paleozoic era but floursihed very well during mesozoic era. Hence, the mesozoic period is called as 'Age of Gymnosperms'.

Gymnosperms are naked seed plants. The ovules are freely exposed before and after fertilisation.

The derivation of the word "gymnosperm" means naked seeds and is from the Greek words 'gymno' meaning naked or bare and 'sperm' meaning seed. 

The order Gnetales is considered to have several features that resemble angiosperms, such as the presence of vessels in the xylem and the structure of their reproductive organs.