Select one of the following pairs of important features distinguishing Gnetum from Cycas and Pinus and showing affinities with angiosperms
the absence of resin duct and leaf venation
the presence of vessel elements and absence of archegonia
perianth and two integuments
perianth and two integuments
B.
the presence of vessel elements and absence of archegonia
Gnetum resembles angiosperms in many aspects.
i) The leaves in Gnetum have reticulate venation that is an angiosperm character.
ii) The presence of vessels in the xylem is also an angiosperm character and also found n Gnetum.
iii) In Gnetum female gametophyte is only partly cellular before fertilisation and becomes completely cellular only after fertilisation. Some of the free nuclei act as an egg as there is no archegonium.
The short apices in Gnetum and angiosperms show a distinct tunical and corps configuration.
The cortex of stem of Pinus is traversed by large resin ducts or canals. Each duct or canal is linked by a layer of thin -walled parenchymatous glandular secretory cells constituting epithelium. The epithelial cells secrete resin into the canal. The resin is the chief source of turpentine.
Earthworms have no skeleton but during burrowing, the anterior end becomes turgid and acts as a hydraulic skeleton. It is due to
Coelomic fluid
blood
gut peristalsis
gut peristalsis
Cornea transplant in humans is almost never rejected. This is because
its cells are least penetrable by bacteria
It has no blood supply
It is composed of enucleated cells
It is composed of enucleated cells
The energy -releasing process in which the substrate is oxidised without an external electron acceptor called
fermentation
photorespiration
aerobic respiration
aerobic respiration
Thorn of Bougainvillea and tendril of Cucurbita are examples of
analogous organs
homologous organs
vestigial organs
vestigial organs
In the light of recent classification of living organisms into three domains of life (bacteria, archaea and eukarya), which one of the following statement is true about archaea?
Archaea resemble eukarya in all respects
Archaea have some novel features that are absent in other prokaryotes and eukaryotes
Archaea completely differ from both prokaryotes and eukaryotes
Archaea completely differ from both prokaryotes and eukaryotes
Thermococcus, Methanococcus and Methanobacterium emplify
archaebacteria that contain protein homologous to eukaryotic core histones
archaebacteria that lack any histones resembling those found in eukaryotes but DNA is negatively supercoiled
bacteria whose DNA is relaxed or positively supercoiled but which have cytoskeleton as well as mitochondria
bacteria whose DNA is relaxed or positively supercoiled but which have cytoskeleton as well as mitochondria
A competitive inhibitor of succinic dehydrogenase is
malonate
oxaloacetate
alpha-ketoglutarate
alpha-ketoglutarate
Vacuole in a plant cell
is membrane-bound and contains storage
is membrane-bound and contains water and excretory substances
lacks membrane and contains air
lacks membrane and contains air
Which one of the following items gives its correct total number?
Floating ribs in humans - 4
Amino acids found in proteins - 16
Types of diabetes - 3
Types of diabetes - 3
