Pioneering work in the field of genetics began prior to the 20th century. However, much of the early work relied only upon simple observation Select the genetics concepts below that were discovered before the year 1900.
a. preservation of beneficial traits
b. the location of genes on chromosomes
c. calculation of Mendelian inheritance
d. the molecular structure of DNA

Use this dichotomous key for insect identification to identify the insect shown. 1. a. insect has one pair of wings. order diptera b. insect has two pairs of wings. go to #2 2. a. front wings thicker in texture than hind wings go to #3. b. front and hind wings are same texture throughout. go to #4 3. a. front wings are short order dermaptera b. front wings cover entire abdomen order coleoptera 4. a. wings with scale on all parts of their area. order lepidoptera b. wings without scales go to #5. 5. a. hind wings smaller than front wings. order ephemeroptera b. front and hind wings nearly equal in size. order odonata the insect pictured is in the order diptera. ephemeroptera. coleoptera. odonata.