Question

how does an allele cause a trait in an organism?
a. the allele is used during transcription to make dna.
b. the allele causes a certain type of protein to form.
c. the allele is a code to form a type of gene.
d. the allele is used by proteins to create chromosomes.

Explanation:

An allele is a variant form of a gene. Genes code for proteins through transcription and translation processes. Proteins determine the traits of an organism. So an allele causes a certain type of protein to form which in turn leads to a trait. Transcription makes RNA from DNA, not the other - way - around as stated in option A. Alleles are variants of genes, not codes to form genes as in option C. Proteins do not use alleles to create chromosomes as in option D.

Answer:

B. The allele causes a certain type of protein to form.