Define following terms:-1) monozygotic twins2)fossils3)radial symmetry
Answers
Twins are two offspring produced by the same pregnancy. Twins can be either monozygotic ("identical"), meaning that they develop from one zygote, which splits and forms two embryos, or dizygotic ("fraternal"), meaning that each twin develops from a separate egg and each egg is fertilized by its own sperm cell.
FOSSILS
the remains or impression of a prehistoric plant or animal embedded in rock and preserved in petrified form.
"sites rich in fossils"
RADIAL SYMMETRY
symmetry about a central axis, as in a starfish or a tulip flower.
"starfish have a fivefold radial symmetry"
1)Monozygotic twins-during early period of embryonic development ,cells of embryo divide into two groups.Those two groups develop as two separate embryos and thus monozygotic twins are form.Such twins are genetically similar in their appearance and their gender is also same
2)A fossil is the naturally preserved remains or traces of animals or plants that lived in the geologic past. There are two main types of fossils; body and trace. Body fossils include the remains of organisms that were once living and trace fossils are the signs that organisms were present (i.e. footprints, tracks, trails, and burrows).
3) The arrangement of parts in an organ or organism such that cutting through the centre of the structure in any direction produces two halves that are mirror images of each other. The stems and roots of plants usually show radial symmetry, while all animals belonging to the Cnidaria