In plant cells, during metaphase chromosomes line up around the equator of the spindle and attached by their centromere to the spindle fibres (microtubules). In animal cells, during metaphase, smaller chromosomes are usually central in position with larger ones peripheral in position.

The 3-D structure of DNA is represented by a double helix, in which each turn has a diameter of 34 Å and contains 10 base pairs at a distance of 3.4 Å. The width of DNA molecule is 20 Å.

After fertilization, the mature, ripened ovary develops into fruit. The ovary wall forms the covering of the fruit called fruit wall or pericarp. Some other post fertilization changes also occur like nucellus develops into perisperm, ovules develop into seeds, outer integument forms testa, inner integument forms tegmen, etc.

Prothallus is a small, flattened, multicellular structure that represents the independent gametophyte generation of a fern. The prothalli bear antheridia (male sex organs) and archegonia (female sex organs) which produce male and female gametes, respectively.

Parthenogenesis (virgin origin) is the development of an embryo from an unfertilized egg or if a spermatozoan does penetrate the egg, there is no union of male and female pronuclei. It is found in many plants (dandelions and hawk weeds) and (aphids and honey bees).

The female cone of Pinus is formed by the aggregation of megasporophylls, which bear ovules. Each megasporophyll consists of a lower bract scale and a larger upper ovuliterous scale.

Fern (pteridophyte) differs from a moss s(bryophyte) in having independent gametophyte, while in moss the sporophyte is simpler than the gametophyte and remains attached to the parent gametophyte throughout its life. This sporophyte is dependent upon gametophyte partially or wholly for its nutrition.