If vertebrates have a backbone, then what do vertebrates have? Answer choices: - tails - strength - eardrum - heart - brain - Chlorophyll - back bone - stamina
back bone

If amutation in the sex cells of a parent can cause children to look very different from their parents, then amutation in what of a parent can cause children to look very different from their parents? Answer choices: - chromosomes - sex cells - fur and fat - coded genes - hormones - sperm - epidermal - Enzymes
sex cells

If bucks display less aggression when there are fewer older bucks, then what displays less aggression when there are fewer older members? Answer choices: - bacteria - rocks - bucks - bamboo - toads - cats - dogs - the Sun
bucks

If tuna have a circulatory system with a two-chambered heart, then what has a circulatory system with a two-chambered heart? Answer choices: - salmon - Man - Toyota - Birds - koalas - tuna - sharks - toads
tuna