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goats,etc.) including human beings. After Similarly the different stages of the life cycle of
attaining a certain stage of growth the young a frog are:
ones are delivered out of the body of the Eggs® early tadpole ® late tadpole ® adult
female organism. The chances of survival of frog
young ones are quite high in these animals In the above cases the features that are
because the mother provides proper present in the adults are not seen in the young
embryonic care and protection to the
ones. This transformation of the larva into an
developing embryo.
adult through drastic changes is called
Oviparous: External fertilization takes place in metamorphosis.
these animals. They produce eggs that hatch PUBERTY
outside the body of the mother .e.g.
Amphibians, birds, and most insects, fish, and Definition : It is the process of physical changes
reptiles etc. The eggs are covered by hard shell by which a child's body get matured to the
adult body.
made up of calcium carbonate and are laid in
safe place in environment to protect the young Changes associated with puberty in males :
ones from the predators. After a period of ! Growth of muscles of body.
incubation young ones hatch out. ! Broader shoulders are developed.
Ovoviviparous: These animals possess ! Increase in secretion of sweat and oil glands.
qualities of both the types. The female ! Development of secondary sexual
ovoviviparous organism lays eggs that stay characters occurs like development of
inside its body. The eggs hatch inside the body beard.
of the female and the young ones are born ! Testis start to produce sperms and the male
alive. Internal fertilization takes place but sex hormone testosterone.
there is no placental connection. The baby ! Voice box or larynx is bigger in boys already,
inside the body is nourished by the egg yolk. voice of boys becomes deep.
This type of reproduction is peculiar to certain Changes associated with puberty in females :
aquatic animals such as sharks and some
species of reptiles and insects. ! Voice becomes high pitched.
! Increase in secretion of oil and sweat glands.
METAMORPHOSIS
! Development of secondary sexual
Most of the new individuals which are born or
hatched from eggs look very much similar to characters like breast development.
their parents. In other cases the young ones as ! Ovaries begin to produce ova and the female
they are born look very much different from sex hormone called estrogen.
the adults. For example you can recall life cycle ENDOCRINE GLANDS
of a silkworm or life cycle of a frog. The life Testis and ovaries are endocrine glands. Their
cycle of a silkworm goes through the following activity is controlled by another endocrine
stages: gland called as pituitary or master gland.
Egg ® Larva Endocrine glands are the ductless glands and
or caterpillar® pupa ® adult their secretion is poured directly into the
blood.
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