A membrane that only lets certain molecules in while keeping other molecules out is
1:flexible
2:bilipid layers
3:slectively permeable

Natural resources are any materials that humans obtain from the earth to meet our wants and needs.

Number and variety of living organism; includes genetic, species, and ecological types

In a population that is in hardy-weinberg equilibrium, there are two possible alleles for a certain gene, a and a. if the frequency of allele a is 0.4, what fraction of the population is heterozygous? a. 0.40 b. 0.60 c. 0.16 d. 0.48