Question

Write any four characters of gymnosperms with examples.

Answer 1

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¤¤¤ They have naked seeds as the ovules are not enclosed by any ovary wall and remain closed.

¤¤¤ They includes Shrubs and Trees [ medium and tall sized].

¤¤¤ They have generally tap roots, stem may be unbranched [ Cycas] or branched [ Pinus, Cedrus ], leaves needle like [ Pinus] and Pinnate [ Cycas].


¤¤¤ Roots of Pinus have fungal association in the form of mycorriza.

¤¤¤ Cycas have small specialised roots called coralloid root which are associated with N2 fixing cyanobacteria.

¤¤¤ They are heterosporous -- Produce haploid microspores and megaspores.

¤¤¤ Male cone has microsporophylls which bear microsporangia having microspores which develop into reduced gametopyte called Pollengrain.


¤¤¤ Female cone has megasporophylls which bear megasporangia having megaspores which are enclosed within the megasporangium [ Nucellus ] . One megaspore develops into female gametopyte bearing two or more archegonia.


¤¤¤ Pollen Grains carried in air currents reach ovules, from pollen tube which reach archegonia and release male gametes which fertilise egg cell and form zygote which produces Embryos. Ovules develop into seeds which are not covered.

Answer 2

Answer-

Gymnospermae-

• They are most primitive and simple seed plants.

• The seeds produced by these plants are naked and are not enclosed within fruits.

• Usually perennial, evergreen and woody plants.

• Sporophylls are aggregated to form cones. There are separate male and female cones.

• Xylem lacks vessels the phloem lacks companion cells.

• The microspores and megaspores are produced by male and female cones .

• Endosperm cells are haploid.

• In the place of flower they have cone.

• In it male sex organ known as (Antheredia) and female sex organ known as (Achegonia).

Example - Cycas, Ginkgo, Pinus etc.

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