What is a protein that recognizes and responds to a signal

How can antibodies "remember" a particular bacterial invader or "antigen" on that invader?

Which of the following describes a difference when gram-positive bacteria are compared to gram-negative bacteria?

Diego conducted an experiment to find out what kind of ball bounces the highest when dropped from a five-foot platform. he used a golf ball, a tennis ball, and a soccer ball. he dropped each ball from the balcony once. diego recorded his observations after each drop. what can diego do to best improve the reliability of his results? a) drop each ball from the platform three more times b) record his observations in more than one unit c) write at least two scientific questions after the experiment is complete d) share his results with other people who have done similar experiments you for the !