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In dna, only the_ varies from one nucleotide to another. base phosphate sugar amino acid

Plz ! for many generations farmers in north america have been choosing to cross corn plants with large ears of corn each year this results in the new generation of plants also growing large ears of corn. what is the technique called? a. selective breeding. b. natural selection. c. mitosis. d. asexual budding.

Describe two recent or ongoing space missions.