1. If a new form of carbon fi xation was discovered that was not biased toward carbon-12, would this affect our analysis of the earliest evidence for life? 2. Soil-based nitrogen-fi xing bacteria...

1. If a new form of carbon fi xation was discovered that was not biased toward carbon-12, would this affect our analysis of the earliest evidence for life?

2. Soil-based nitrogen-fi xing bacteria appear to be highly vulnerable to exposure to UV radiation. Suppose that the ozone level continues to be depleted, what are the long-term effects on the planet?