What is a dominant allele?

question 6 options:

an allele that can never be expressed

an allele that is only expressed when no dominant allele is present

an allele that is acquired after birth

an allele that is always expressed when the allele is present

1. Dominance (complete dominance) would be a case in which 1 allele is always dominant over the other(s).

Example: we could see this clearly when breeding to homozygous dominant organisms (offspring are always dominant).

Conclusion:

Option 4 (d) is correct.

Hope it helped,

BiologiaMagister