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

Smooth muscles are plain, non- striated, involuntary or unstriped muscles due to the absence of striations. These occur in the walls of hollow internal organs, in capsules of lymph glands, spleen etc, in iris and ciliary body of eyes, skin dermis, penis and other accessory genitalia etc. 

Vessel or tracheae are made up of a row of cells, placed one above the other, with their intervening walls absent or variously pored. The walls of vessels are lignified and hard, but not very thick. The cell cavity or the lumen is wide. The thickening may be annuler, spiral, scalariform, reticulate and pitted. 

The vascular bundles in Hordeum vulgare (barley) plant are scattered in ground tissue, many in number and vary in size-smaller towards the periphery and bigger towards the centre of the ground tissue, oval or rounded in outline, conjoint, collateral and closed.

severe combined immunodeficiency (SCID) caused by adenosine deaminase deficiency (AIDA) is the first genetic disorder to be treated with gene therapy. T-cell-directed gene transfer was useful in the treatment of ADA-SCID, whereas the retroviral-mediated gene transfer to haematopoietic stem cells was insufficient for the achievement of clinical benefits.

Oscillatoria is a photosynthetic cyanobacterium. In this, during photosynthesis water is electron donor and oxygen is a by -product, ie oxygenic photosynthesis occurs. Rhodospirillum and Chlorobium are non- oxygenic photosynthetic, purple non- sulphur and green sulphur bacteria. chromatium is a purple sulphur bacterium, also a non- oxygenic photosynthetic.

In ECG, P-wave indicates impulse of contraction generated by SA-node and it spreads in atria causing atrial depolarization.

T-wave is the most constant and conspicuous wave having the tallest amplitude. It is the first positive deflection during ventricular depolarization.

S - wave is the next downward deflection constant but often inconspicuous.

T- wave is repolarisation wave of ventricular relaxation.

The body cavity of an earthworm is true coelom (schizocoelous) as it is formed by the division of mesoderm. The coelom fluid, which contains different types of corpuscles. Thus, if the alive earthworm is prickled with a needle on its outer surface, the coelomic fluid will come out.

The middle lamella is cementing layer between the cells. It is made up of Ca and Mg pectates. The basic chemical unit of pectin is galacturonic acid, which has the capability of salt formation with calcium and magnesium (an acid-base reaction).

In the human brain, the hypothalamus is a centre for hunger, thirst sweating, sleep. fatigue, temperature, anger, pleasure, love, hate and satisfaction.

Medulla oblongata contains centre for a heart beat, respiration, digestion, BP, involuntary functions, urination, etc.

Cerebellum regulates posture and balance.

The cerebrum is the centre for intelligence, emotion, will- power, memory consciousness, imagination, etc.