What type of reaction takes place when using this enzyme (endergonic or exergonic)? lactase is the enzyme

Which substances have the lowest melting points: ionic covalent, or metallic

Explanation for basic character?

What will most likely happen in the absence of a cell membrane? a) photosynthesis will not take place. b) the cell will not store food, water, nutrients, and waste. c) energy will not be released during cellular respiration. d) substances will pass in and out of the cell in an uncontrolled manner.