list one key similarity and one key difference between a vaccine and the pathogen it protects against

Living cells cannot use heat to provide the activation energy for biochemical reactions because which choice(s) complete the sentence correctly? a) answer choice ii. eliminate b) answer choices ii and iv. c) answer choice iii and iv. d) all answers can complete the sentence.

Each pair of clay balls represents two planetesimals. if each planetesimal is composed of the same material and is separated he the same distance, which pair experiences the frayed gravitational attraction?

What are the two causes of density in deep current waters? a. salinity (how much salt) of the water and high temperaturesb. salinity (how much salt) of the water and low temperatures c. oxygen content of the water and high temperatures. d. oxygen content of the water and low temperatures