| ANTIOXIDANT | In biology, a substance such as vitamin C, vitamin E or beta carotene |
| FDA | D.C. vitamin monitors |
| CLASS | In biology, a division above an order and below a phylum; a number of schoolchildren taught together; or, in a sporting cliche, "permanent" quality as opposed to "temporary" form (5) |
| MEDIUM | Channel or means by which something is communicated; or, a substance such as oil or water in which pigments are mixed (6) |
| LACUNA | In biology, a cavity or depression, such as any of the spaces in the matrix of bone |
| STERIGMA | In biology, a minute stalk bearing a spore or chain of spores in certain fungi (8) |
| STIMULANT | A substance such as caffeine that raises levels of nervous or physiological activity in the body (9) |
| DENSITY | Word for the compactness of a substance, such as bone; mass per unit volume; the opacity of a photograph; or, obtuseness/stupidity (7) |
| REDBRICK | Rosy wants first in biology - a strain at such a university? |
| KNEAD | To work and press a substance, such as dough, into a uniform mixture with the hands (5) |
| ORDER | In biology, a taxonomic group ranking below a class and above a family (5) |
| SHEET | A thin piece of a substance such as paper, glass, etc, usually rectangular (5) |
| SOFTENER | General word for a substance such as zeolite for hard water or fabric conditioner for laundry (8) |
| KNEADS | Works and presses a substance such as dough he into a uniform mixture with the hands (6) |
| METAL | A substance such as iron or gold (5) |
| PHOSPHOR | General term for a substance, such as the coating on a cathode-ray tube, that emits light when irradiated with particles of electromagnetic radiation (8) |
| ASSAY | Test(ing) of a substance, such as precious metal (5) |
| CLADE | In biology, a group of organisms considered to have evolved from a common ancestor (5) |
| ASCORBIC | Which acid is commonly known as Vitamin C. (8) |
| ACID | Organic chemical compound better known as vitamin C (8,4) |
