What is the only way in which viruses are similar to cells

Each trait of a plant is determined a. an allele b. one gene c. a pair of genes d. one dominant gene

Milk production during breastfeeding is increased by the suckling of a newborn from his mother's nipple. this type of feedback mechanism best describes a positive or negative

Which is an example of a vestigial structure? a. tail of a monkey b. fin of a fish c. flower of a plant d. tailbone of a human