He majority of animals are invertebrates. This means that they have this characteristic. lack a backbone

have a backbone

lack cell walls

have cell walls

lack a backbone

Explanation:

"Vertebrae" means backbone. Invertebrate means no backbone.

the right answer is a. skin cells forming from sunlight.

the liver is an organ endowed with a fantastic ability to regenerate

. thus, if a hepatectomy (ablation) of 70% of the hepatic mass is performed in the rat, there is complete recovery in 7 to 10 days.

prokaryotes are beings that have existed since the existence of life on earth, and do not come from another realm.

ribosomes are organelles that exist naturally in eukaryotes, either in free form or attached to the endoplasmic reticulum.

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