If most animals without a backbone have a more complex nervous system, then animals that tend to have complex nervous systems are missing what? Answer choices: - Energy - Energy. - nervous system - Chlorophyll - backbone - alleles - abdomen - brain
backbone
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If puberty leads to sexual changes that travel throughout the body in the blood, then puberty leads to sexual changes that travel throughout the body in what? Answer choices: - blood - A drug. - hair - sleep - painful - years - eyes - chest
blood
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If adrenaline is a response to threats, then what is adrenaline a response to? Answer choices: - earthquakes - water - magnetism - threats - Heart rate - hormones - threatened - heat
threats
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If trees grow for paper to be made, then what needs to grow for paper to be made? Answer choices: - paper - books - trees - birds - grass - flowers - fibers - plants
trees
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