I need help I don’t know where to start on this worksheet

What does it mean for a cell membrane to be selectively permable

Flock x flock y flock z total pieces of food eaten (from previous page) 147 93 60 food percentage* % % % simulated number of birds in flock for 3rd generation** * divide each flock's total pieces of food by 300, the total number of pieces of food eaten. ** multiply the food percentage for each flock by the total number of birds (30).

When a gasoline engine burns gasoline, what type of chemical reaction is occurring?