Eddie’s assignment is to prepare a dichotomous key for several objects. His first task was to arrange the objects. The objects are a lightning bug, a butterfly, a ladybug, and a canary. While organizing the objects, Eddie considered several options and found that the most general categories should be listed first. Which criteria should Eddie use first to divide the organisms into two groups?

A) is living or is not living
B) has legs or does not have legs
C) has wings or does not have wings
D) has feathers or does not have feathers

I’m doing some practice exam questions for biology, and i’m not sure how to do these 3 parts to the question.

The fruit of a certain plant is sweet and fleshy. the seeds of this plant have a seed coat that is fairly tough. the seeds germinate better if they are exposed to acid, or scarification. what is the most likely type of dispersal for this seed? water animal wind

The kidney filters potentially toxic substances in the blood, and thus “clears” the blood of those substances. this clearance function is dependent upon and proportional to the diffusion gradient of the substance across filtering capillaries, i.e. if the concentration of the substance is doubled, twice as much will be cleared from each ml of blood that is filtered. suppose that the body produces a constant amount of a substance x per unit of time. the kidneys eliminate substance x at a rate directly proportional to the concentration of the substance and the volume of blood cleared each minute (c): elimination = c × [x], where [x] is the steady-state concentration of substance x. imagine an individual with an initial concentration of x equal to [x]0 who develops kidney disease. her baseline clearance c0 drops to one half of the original (½c0). what is the new steady state concentration of x? (for simplicity, assume that substance x is 100% filtered by the kidney).