Tag: the life of a butterfly

• Complete metamorphosis consists of four stages i.e. egg, larva, pupa and adult. 
• Incomplete metamorphosis consists of three stages i.e. egg, nymph and adult.
• Complete metamorphosis occurs in wasps, ants and butterflies while incomplete metamorphosis occurs in termites, praying mantis and cockroaches.

Moulting is the process of casting off the dead rigid outer covering or the exoskeleton or skin of the animal body during its growth. The young larvae casts off its skin in order to allow the growth of the larvae to from the adult. This process is also known as ecdysis.

Extraembryonic membranes are formed outside the embryo from the trophoblast only in amniotes (reptiles, birds and mammals) and perform specific functions.

Periblastula is the blastula of a centrolecithal egg, which is formed by superficial segmentation. This kind blastula occurs in insects.
Centrolecithal eggs develop to superficial blastula, which consists of a single layer of epithelial cells surrounding the centrally placed yolk and there is no blastocoele.
Thus, the correct answer is option (B).

• Metamorphosis refers to the way that organisms develop, grow, and change form.
  
• Metamorphosis majorly occurs in insects.
• metamorphosis has four stages i.e egg, larva, pupa and adult. The female lays eggs then the larva hatch from the eggs. Then the larva makes cocoons around themselves this stage is called a pupa. Inside the cocoon, the larvae change into the adult.
• Hence Changes that convert larva into adult constitute metamorphosis

Tadpole is one of the developmental stages in the life cycle of frogs. The larvae are free-swimming forms which are found in the water. The larvae get metamorphosed to form the adult frog. The thyroid hormones are required for the control and regulation of the events which take place during metamorphosis. 

Thyroxine, the principal hormone, of thyroid gland, is required for tissue differentiation and metamorphosis (the rapid transformation from the larval to the adult form) in amphibians. So in the presence of antithyroid substance, (that inhibits the synthesis of thyroid hormone) e.g., thiourea, tadpoles remain in the larval stage indefinitely. Thiourea is an organic compound of carbon, nitrogen, sulphur and hydrogen. It is similar to urea, except that oxygen atom is replaced by a sulphur atom. 

The remarkable axolotl or Ambystoma mexicanum is part of the family of 'mole salamanders', but exhibits an unusual and extreme trait known as neoteny, or paedomorphosis. This is the retention of larval stage characteristics throughout life, so axolotls usually never fully resemble an adult salamander. It is a urochordate.

So, the correct option is ‘i and ii correct’.

• Morphogenesis is the process of the development of shape and structure of an organism when they get mature.
  
• Epimorphosis is the development of the cells and tissues through the dedifferentiation of adult or pre-existing cells. Here the tissues and organs that are lost are replaced by the existing ones. The new organs are originated according to the shape and size required and are also dependent upon surrounding factors.
• Morphallaxis is the formation of tissues and organ due to loss or transformation of an existing organ.
  

A. Cell necrosis - is a form of cell injury which results in the premature death of cells in living tissue by autolysis.

 B. Pinocytic activity - is a mode of endocytosis in which small particles suspended in extracellular fluid are brought into the cell through an invagination of the cell membrane, resulting in a suspension of the particles within a small vesicle

C. Programmed cell death is the death of a cell in any form, mediated by an intracellular program. PCD is carried out in a biological process, which usually confers advantage during an organism's life-cycle.

D. Cell senescence- is a phenomenon by which normal cells cease to divide

So, the correct option is ‘Programmed cell death’.