Question

which of the following is a characteristic that luca is believed to have shared with all modern life?
the presence of chloroplasts for photosynthesis.
a complex brain and nervous system.
ribosomes and a universal genetic code.
the ability to breathe oxygen through lungs.

Explanation:

• Chloroplasts for photosynthesis are present in some modern organisms (like plants) but not all (e.g., animals, fungi), so LUCA (Last Universal Common Ancestor) wouldn't have this as a shared trait with all modern life.
• A complex brain and nervous system is a feature of more advanced organisms (like vertebrates) and not present in all modern life (e.g., bacteria, plants), so LUCA didn't have this.
• Ribosomes are involved in protein synthesis, and the universal genetic code is shared by all modern life (all organisms use DNA/RNA with the same basic code for translating genes to proteins). LUCA is believed to have had these, as they are fundamental to life's processes and conserved across all life forms.
• The ability to breathe oxygen through lungs is a trait of specific complex organisms (like mammals, reptiles) and not present in all modern life (e.g., bacteria, plants, fungi), so LUCA didn't have this.

Answer:

Ribosomes and a universal genetic code.