NEET biology

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Question
CBSEENBI11002405

Which one of the following structures between two adjacent cells is an effective transport pathway?

  • Plasmodesmata

  • Plastoquinones

  • Endoplasmic reticulum

  • Plasmalemma

Solution

A.

Plasmodesmata

The primary cell wall contains many small openings or pores situated in the primary pit fields.The cytoplasm of adjacent cells communicates through the pores by means of cytoplasmic bridges called plasmodesmata. The plasmodesmata permit circulations of fluid and passage of solutes between cells.

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Question
CBSEENBI11002406

Single -celled eukaryotes are included in 

  • Protista

  • Fungi 

  • Archaea

  • Monera

Solution

A.

Protista

Kingdom - Protista includes all unicellular eukaryotic organisms like flagellates, diatoms, dinoflagellate, slime mould, Sarcodina, etc.
Fungi represent a group of eukaryotic achlorophyllous, non - photosynthetic heterotrophic organisms of diverse forms, sizes, physiology and mode of reproduction. The members of Archaea (Archaebacteria) are prokaryotes and include the extreme halophiles, the thermoacidophiles and the methanogens.
Monera is the kingdome, that in older classifications contain all prokaryotes.

Question
CBSEENBI11002407

In unilocular ovary with a single ovule, the placentation is 

  • marginal

  • basal

  • free central 

  • axile

Solution

B.

basal

In basal placentation, the ovary is bicarpellary, syncarpous and unilocular and a single ovule is borne at the base of ovary, eg, marigold. 
In marginal placentation, the ovary is simple unilocular and the ovules are arranged along the margin of ovary eg, pea. 

In free central placentation, the ovary is unilocular and the placenta bearing ovules arise from the central axis, e,g Stellaria. 
In axile placentation, the ovary is two or more chambered usually as many as the number of carpels, eg, Petunia. 

Question
CBSEENBI11002408

An element playing important role in nitrogen fixation is 

  • Molybdenum

  • copper

  • manganese

  • zinc

Solution

A.

Molybdenum

Molybdenum is absorbed as molybdate by plants. It is involved in nitrogen metabolism including nitrogen fixation. It is a component of enzyme nitrogenase and acts as an enzyme activator. Its deficiency cause chlorosis and necrosis, whiptail of cauliflower and premature leaf fall. 
Copper is absorbed by the plant in ionic form. Its deficiency causes necrosis, die back in Citrus, reclamation in legumes.
Manganese is absorbed by the plants as a bivalent ion. It acts as the enzyme activator. Its deficiency causes interveinal chlorosis as well as yellowing of starch and their subsequent degenerate. 
Zinc is needed for biosynthesis of IAA and also acts as the enzyme activator. Its deficiency causes chlorosis, little leaf, rosette, the white bud of maize and mottling of leaves.

Question
CBSEENBI11002409

One example of animals having a single opening to the outside that serves both as mouth as well as anus is 

  • Octopus

  • Asterias

  • Ascidia

  • Fasciola

Solution

D.

Fasciola

Fasciola hepatica (sheep liver fluke) belongs to phylum - Platyhelminthes. These worms have an incomplete alimentary canal, there is a single opening for both ingestion and egestion. This is also called as blind sac body pain.