Question

(3:40 - 4:30) gametes, which are sex cells, carry the alleles. why must a gamete carry one allele (represented by a letter) from each gene? meaning, why cant a gamete carry an \hh\ instead of an \hs\ or an \hh\ instead of a \hs?\ (hint: think about where the gametes come from!) a. because everyone has two copies (alleles) of every gene, one copy from mom and one copy from dad b. because different letters are confusing c. because alleles have to match exactly from both parents for them to work

Explanation:

Gametes are formed through meiosis. During meiosis, diploid cells (with two sets of chromosomes, one from each parent) divide to form haploid gametes. Each gamete gets one allele from each gene. This is because the offspring will receive one gamete from each parent. If gametes had two alleles (like "hh" or "Hh" as wrongly suggested in the question), when two gametes fuse during fertilization, the offspring would have four alleles for each gene instead of the normal two (one from each parent). Option A correctly explains that humans (and many organisms) are diploid - having two copies of each gene (alleles), one from mom and one from dad. Gametes (haploid) carry one allele per gene so that when fertilization occurs, the diploid number (two alleles per gene) is restored. Option B is incorrect as letter confusion is not a biological reason. Option C is wrong because alleles do not need to "match exactly" from both parents for them to work; there can be dominant - recessive relationships etc.

Answer:

A. Because everyone has two copies (alleles) of every gene, one copy from mom and one copy from dad