Question

during sexual reproduction, each parent contributes
choose one option
a a double helix of chromosomes.
b one strand of chromosomes, or half of the new organism’s dna.
c a dominant gene and a recessive gene.
d multiple mutated cells.

Explanation:

• Option A: Chromosomes are made of DNA (double helix), but during sexual reproduction, parents contribute haploid cells (not a double helix of chromosomes in the way described here—gametes have half the chromosome number, not a double - helix - structured set of chromosomes as a contribution unit).
• Option B: In sexual reproduction, each parent (through gametes: sperm and egg) contributes half of the offspring's DNA. Gametes are haploid, meaning they have one set of chromosomes (one "strand" in terms of the chromosome complement, relative to the diploid somatic cells), so this option is correct.
• Option C: Parents don't specifically contribute one dominant and one recessive gene. They contribute alleles, and whether an allele is dominant or recessive is about its expression relative to other alleles, not a fixed contribution of one dominant and one recessive per parent.
• Option D: Mutated cells are not a normal contribution during sexual reproduction. Sexual reproduction involves the contribution of gametes with normal genetic material (barring rare mutations, but this is not the normal process).

Answer:

B. one strand of chromosomes, or half of the new organism’s DNA.