Spraying juvenile conifers with gibberellins hastens their maturity period, thus leading to early seed production. Auxin controls xylem differentiation. Abscisic acid (ABA) increases the tolerance ofplants to various kinds ofstresses therefore, is also known as stress hormone.

Cornea is a tranparent layer of tissue continuous with sclerotic that forms the front part of vertebrae eye over the iris and lens. It refracts light waves entering the eye onto lens. Cornea is avascular (ie, it has no blood supply). It is one of the first organs to be successfully transplanted because it lacks blood vessels.

Pseudostratified columnar ciliated epithelium occurs in the trachea and large bronchi. It is a type of epithelium that comprises only a single layer of cells.

Genera like Selaginella and Salvinia which produce two kinds of spores, macro (large) and micro (small) spores, are known as heterosporous pteridophytes. Lycopodium and Equisetum are homosporous pteridophytes i.e. they produce only one type of spores.

Anatomical Dead Space is the total volume of the conducting airways from the nose or mouth down to the level of the terminal bronchioles and is about 150 mL on the average in humans.

In retrogressive metamorphosis, degeneration is shown by larva to form less developed adult. It is a type of metamorphosis seen in Herdmania (Urochordate). It involves transformation of an active, free swimming larva with advanced characters into sedentary and simple adult.

Each muscle fibre has many parallely arranged myofibrils. Each myofibril contains many serially arranged units called sarcomere which are the functiorial units. Each sarcomere has a central 'A' band made of thick myosin filaments, and two half 'T' bands made of thin actin filaments on either side of it marked by Z' lines. In a resting state, the edges of thin filaments on either side of the thick filaments partially overlap the free ends of the thick filaments leaving the central part of the thick filaments. This central part of thick filament, not overlapped by thin filaments is called the 'H' zone.

In the given figure:

1. A is pulmonary vein which brings pure blood from lungs to left atrium.

2. B is dorsal aorta which carries blood from heart to body parts.

3. C is vena cava which carries impure blood from body parts to right atrium.

4. D is pulmonary artery which takes impure blood from heart to lungs.

Mammals have heterodont type of dentition i.e, teeth are of different types.

Uracil is one of the four nucleobases in the nucleic acid of RNA. It binds to adenine via two hydrogen bonds in RNA. It is replaced by thymine in case of DNA.