NEET

  Development in frog   (i) Breeding

• Frog breeds in the rainy season, June to September.
• Male frogs produce crocking sound (mating call) by their vocal sacs.
• The sexual embrace of the male and female frogs is called am plexus (false copulation).

  (ii) Ovulation

• Ovulation is the release of eggs from ovary in the body cavity.
• The eggs in the stage of secondary oocytes are released into the body cavity by rupture of ovary during ovulation.

  (iii) Spawning

• Spawning is the act of laying of eggs by the female frog stimulated by the male during am plexus.
• Spawn is a cluster or mass of eggs laid by a female.
• a spawn of Rana Tigrinya contains about 3000-4000 eggs.
• The diameter of frog’s egg more...

  Growth   Introduction An embryo and off springs body gradually enlarges and assumes the form and size characterstic for the adult of its species (growth). The animals carries on the various vital processes to maintain health and keep alive. In its body, the cell organelles are constantly renewed worn out cells are healed up (repair). In certain animals, even the lost organs of the body are regrown (regeneration). Since the animals have limited life span, their body starts undergoing degenerative changes showing sign of old age (ageing). The last events of which is death.   (i) Meaning and definition of growth: Growth is an important properties of all living organisms. All organisms grow from a young stage to an adult stage. Growth is more...

  Repair and Regeneration   (i) Definition: It is that post-embryonic morphogenetic phenomenon which when temporarily stimulated brings about repair of the damaged cells, Tissues, or replacement or redevelopment of severed body parts or reconstruction of whole body from a small body fragment.   (ii) Capacity for regeneration: Among animals, power of regeneration was first discovered in Hydra by Tremble, in 1740. The capacity of repeated regeneration, though, present throughout the animal kingdom, but to varying degree. It is more marked in the lower animal than in the higher animals. Among invertebrates, protozoans, sponges and coelenterates, the regeneration capacity is very high. In higher animals, regenerative ability is much greater in the embryonic and larval stages than in the adult. In man, it is more...

  Ageing   (i) Definition: Ageing is the show deterioration in the structure and function of body cells tissues and organs of an animal and starts after the adulthood.   (ii) Gerontology: The field of developmental biology that deal with the process and problems of ageing is known as gerontology - (Gr. geron = old man; logos = discourse). The scientists involved in the science of ageing are called gerontologist.   (iii) Life cycle and life span: In all metazoan animals, the life cycle includes two developmental period; embryonic period (pre-natal developmental period) which extends from zygote to offspring till hatching or birth, and post embryonic period (post-natal developmental period), which includes growth, adulthood, reproduction, ageing. Thus, the life cycle comprises five main events: more...

Inflorescence     Inflorescence : Raceme, umbel or a solitary flower.       Flower : Bracteate or ebracteate, pedicellate, hermaphrodite, complete, zygomorphic, hypogynous. Calyx : Sepals 5, polysepalous, imbricate aestivation. Corolla : Petals 5, polypetalous, ascending imbricate aestivation. Androecium : 10 stamens, or staminodes are found as in Cassia, free filaments of unequal size, anther lobes bilocular, introrse, versatile. Gynoecium : Monocarpellary, unilocular, ovary superior, marginal placentation, stigma capitate. Fruit : Legume. Floral formula : \[%\,\,\,\,\,\,{{K}_{5}}\,{{C}_{5}}\,{{A}_{1+2+2+2+3\,\left( \text{staminodes} \right)}}\,\text{or}{{\,}_{7+3\,\left( \text{staminodes} \right)}}\,{{G}_{1}}\]   Subfamily – Mimosoideae   Inflorescence : Head or capitulum or spike, flowers arranged in acropetal succession. Flower : Bracteate or ebracteate, sessile, hermaphrodite, complete actinomorphic, hypogynous, pentamerous. Calyx : 5 sepals (4 in Mimosa) gamosepalous, connate at the base, valvate aestivation, rarely imbricate (e.g., Parkia). Corolla : 5 petals (4 in Mimosa) gamopetalous or more...