Billy is sitting in a chair in class. if the action force is the downward push of his weight on the chair, what is the reaction force?
a. there is no reaction force
b. the upward force of the chair pushing on billy
c. the downward force of billy's weight on the earth
d. the upward force of the earth on billy

Agene with the original sequence of atgtt—tact underwent substitution mutation to form atatt—tact after a few generations. tact is a part of a muscle protein encoding region, and atgtt codes for a digestive enzyme. what will be the effect of this mutation? a. the production of muscle protein will be affected. b. the production of digestive enzymes will be affected. c. the production of both the protein and the enzyme will be affected. d. the production of neither the protein nor the enzyme will be affected.

Which statements best describe the differences or similarities between a comparative investigation and an experimental investigation? check all that apply. experimental investigations are best for showing cause-and-effect relationships, while comparative investigations do not necessarily show this type of relationship. comparative investigations are often impractical and unrealistic, while experimental investigations are the most practical and realistic kinds of investigations. comparative investigations allow for the use of a wide range of variables but do not have a control group, while experimental investigations involve variables that can be controlled. both experimental investigations and comparative investigations are designed to answer scientific questions. both experimental investigations and comparative investigations focus on making observations rather than collecting new data.

Ivan is looking at a cross section of a stem taken from a vascular plant. he sees two different types of vascular tissue: the xylem, which is closer to the center of the stem, and the phloem, located around the xylem, closer to the outside of the stem. how do these two structures work together in a living plant?