Why did the dinosaurs become extinct?

A. A meteorite or comet crashed into the Earth, causing smoke and ash that blocked the sun and caused death of the plants that were food for herbivorous dinosaurs.
B. Cycads and other gymnosperms upon which herbivorous dinosaurs fed declined, and the dinosaurs were unable to digest the angiosperms that arose in their place.
C. Increasing carbon dioxide levels produced climates too hot for the incubation of their eggs.
D. The changing climate caused the evolution of most dinosaur species into the existing bird, mammal, and reptile species that exist today.
E. The pollen produced by the rise in flowering plants produced allergenic responses in dinosaurs and interfered with their ability to communicate with potential mates.


A. A meteorite or comet crashed into the Earth, causing smoke and ash that blocked the sun and caused death of the plants that were food for herbivorous dinosaurs.

Biology & Microbiology

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A) the dideoxynucleotide analogs have no 3'-OH group to continue DNA synthesis. B) the dideoxynucleotide analogs have no 5'-OH group to continue DNA synthesis. C) the dideoxynucleotide analogs have no 2'-OH group to continue DNA synthesis. D) the mixture is heated to 92°C to stop DNA synthesis at specific time intervals. E) the dideoxynucleotide analogs are in greater concentration than the actual nucleotides.

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The polysaccharide that helps strengthen cell walls in transport tissues of hornworts is called ____

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Archaea do not have the typical peptidoglycan structure found in bacterial cell walls.

Answer the following statement true (T) or false (F)

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