Answer:
producers
Explanation:
producers are plant which are at the base of an ecosystem.
Answer:
birds
Explanation:
<em>Archaeopteryx</em> is an iconic fossil bird that lived during the Late Jurassic, approximately 150 million years ago. <em>Archaeopteryx</em> is iconic because it is a transitional fossil between non-avian dinosaurs (reptiles) and birds. The osteology of <em>Archaeopteryx</em> indicates that it was similar to that of nonavian theropod dinosaurs, i.e., dinosaurs characterized by hollow bones and three-toed limbs. Unlike modern birds, <em>Archaeopteryx</em> had a full set of teeth, a long tail, three fingers with claws and hyperextensible second toes commonly known as 'killing claws'.
The Precambrian eon is separated from the Phanerozoic eon in the fossil record because of the sudden appearance of organisms.
Explanation:
Precambrian eon is the initial existence on earth that can be predicted by the study of rocks and remaining of fossils. It has been seen as the existence of skeleton in this era, before this era no such things has been observed, even the development of sexual reproduction.
The Phanerozoic era comes after the Precambrian era, more advanced kinds of fossils of animals had been observed in this era. Phanerozoic era period of life on earth. Large organisms sudden appearance are seen in the Phanerozoic era i.e. First dinosaurs, mammals, fishes, angiosperms,first vertebrates etc.
Discovery of structure of DNA by Franklin and Watson and Crick.
Explanation:
Rosalind Franklin was researching about DNA structure at the King’s College at London based on x-ray diffraction studies; while, Crick and Watson were researching on the same at the Cambridge University based on Linus Pauling discovery of proteins.
Once when Watson happen to listen to Franklin’s lecture upon DNA structure and how it depends on relative humidity of the air and other facts relating to DNA; he along with Crick made physical DNA models which became a big failure.
Later, Franklin found that a wet form of DNA with high humidity had a helix like structure. This point became the base of later discovery of Watson and Crick’s double helix model of DNA along with the discovery of DNA molecules being made up of double chain of nucleotides.
