Solution: First, choose 3 crew roles from 7: $\dbinom73$. Then, select 2 biome systems from 5: $\dbinom52$. Since each system needs a unique role, multiply by the number of ways to assign roles to biomes: $\dbinom73 \times \dbinom52 \times 3! = 35 \times 10 \times 6 = 2100$. However, if roles are independent of biomes, the answer simplifies to $\dbinom73 \times \dbinom52 = 35 \times 10 = 350$. Clarifying the problem's constraints, the most logical interpretation is $\boxed350$. - Groen Casting