Select one of the following pairs of important features distinguishing Gnetum from Cycas and Pinus and showing affinities with angiosperms.
Perianth and two integuments
Embryo development and apical meristem
Absence of resin duct and leaf venation
Presence of vessel elements and absence of archegonia
D.
Presence of vessel elements and absence of archegonia
Unlike Cycas and Pinus, Gnetum shows the occurrence of vessel elements and the absence of archegonia. Archegonia are altogether absent in the female gametophyte and vessels occur in the xylem along with the tracheids in the secondary wood. Thus Gnetum shows affinities with angiosperms. Besides it resembles angiosperms in several other aspects like presence oftetrasporic embryo sac, free nuclear divisions in the embryo sac, two cotyledonous embryo etc.
Bacteria, fungi, lower plants survive in adverse conditions by
diapause
suspended growth
migration
formation of thick walled spores.
seed plants showing abnormal forms of growth and development
plants described only in fossil state
plants described in the literature but which Bentham and Hooker did not see in original
a few orders which could not be placed satisfactorily in the classification.
Which of the following statements about Spirogyra is correct?
Lateral conjugation takes place in homothallic species
Scalariform conjugation takes place in homothallic species.
Lateral conjugation takes place in heterothallic species
The type of conjugation is unrelated to homothallic and heterothallic species
Which statement is correct regarding mosses
They have dominant and independent sporophyte.
Their antherozoids require water for fertilization.
Their archegonia produce many eggs.
Their antherozoids are multiflagellated
Which one of the following is correct matching of a plant, its habit and the forest type where it normally occurs?
Prosopis, tree, scrub
Saccharum, grass, forest
Shorea robusta, herb, tropical rain forest
Acacia catechu, tree, coniferous forest
How many genome types are present in a typical green plants cell
More than five
More than ten
Two
Three
Assertion : Conifer trees produce a large quantity of wind borne pollen grains.
Reason : The pollen grains have wings.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
Which one of the following categories of organisms do not evolve oxygen during photosynthesis
Red algae
Photosynthetic bacteria
C4 plants with Kranz anatomy
Blue green algae
Assertion : Algae and fungi are classified as thallophytes.
Reason : They both are autotrophs.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
