An investigation was designed to determine the effect of ultraviolet light on mold spore growth. two groups of mold spores were grown under identical conditions, except one group was exposed only to ultraviolet light, while the other group was grown in total darkness. in this investigation, what would you name the group of mold spores grown without receiving any ultraviolet light? (1) control
(2) hypothesis
(3) dependent variable
(4) limiting factor

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

Two students are working together on an experiment that measures the effect of different liquid fertilizers on the thickness of plants’ stems. which is most likely to result in the greatest amount of error in their scientific experiment? a.one student measures the plant stem widths by using calipers. the other student measures the widths of the same plant stems again by using a different pair of calipers. b.one student measures the plant stem widths by using calipers. the other student types the measurements as they are taken into a computer spreadsheet. c.one student weighs liquids for the experiment by using a calibrated scale. the other student weighs liquids for the experiment by using a different calibrated scale.

How does the human body lever work?