What happened during the cambrian explosion ?

a. groups of dinosaurs began to evolve into the ancestors of modern birds.

b. animals evolved a variety of complex body parts.

c. early chordates began toj appear.

d. many groups of vertebrate animals became extinct.

Plz genetic engineering can be applied to many fields including medicine and agriculture. which of the following is a medical application of genetic engineering? a. giving crop plants recombinant dna so that they would be resistant to herbicides. b. examining a persons pedigree to determine whether they can carry a gene for a genetic disease. c. analyzing a persons dna to see how closely they are related to another person. d. certain genes into bacteria so that they will produce a needed medicine.

Which of the following is the source of energy for photosynthesis? a.) glucose b.) chlorophyll c.) carbon dioxide d.) sunlight

What drives an advertising campaign?