NEET Biology Solved Question Paper 2008

The basic parts of cell cycle are interphase and M-phase or dividing phase. The interphase is metabolically the most active stage and divided into G₁, S and G₂ phases. The correct sequence of phases in cell cycle is

G₁ $\to$S $\to$G₂ $\to$M $\to$G₁

In an epigynous flower, the innermost whorl, ie, gynoecium is covered by the elongated margins of thalamus thus, their position is inferior in regard to other floral whorls, which arise above the ovary and thus superior, eg, sunflower, Cucurbita, coriander.

The cell wall contains a porous matrix of cellulose consisting of vary fine coalesced fibrils the microfibrils and an interfibrillar system of microcapillaries containing various non-cellulosic wall constituents.

Colchicine is an alkaloid obtained from the plant. Colchicum autumnale and is found to prevent the formation and organization of spindle fibres. It induces polyploidy in many plant and animal cells.

Bentham and Hooker published natural system of classification in their Genera Plantarum. This system was based on arrangement of leaves and venation pattern, number of members in floral whorls, cohesion of various floral organs, number of cotyledons and presence or absence of cover around the seeds.

In floral formula, (K) denotes polysepalous condition. When the sepals of a flower are free from each other the condition is called polysepalous and if they are fused with each other, the condition is known as gamosepalous.

Polypetalous is a flower in which the corolla consists of seperate petals.

Gametopetalous is a flower in which the petals are fused to form a corolla tube.

Photosynthesis is the synthesis of organic compounds (primarily sugars) from carbon dioxide (CO₂) and water using light energy. The green cells of the plant convert the solar energy into chemical energy through this process. It's importance lies in the transformation of low energy compounds ie, CO₂ and H₂O into high energy compounds such as carbohydrates.

Wilting is the loss of turgidity of leaves and other soft aerial parts of a plant causing their drooping, folding and rolling. It is caused by blocking of xylem.

Photophosphorylation is the synthesis of ATP from ADP during light reaction of photosynthesis. It was discovered by Amon et al, in 1954.

The cells of sclerenchyma are long or short, narrow, thick walled and lignified. These are dead cells and do not perform any metabolic function. Tracheids (tracheary element) are elongated cells with tapering ends. The wall of tracheids is moderatly thick and usually lignified.