Duckweed consists of tiny, free-floating green plants. duckweed typically consists of a leaf or cluster of leaves with small roots that hang down into the water; leaves and stem are not distinguishable from each other. it occurs on the surface of ponds, inlet creeks, and ditches. it and can exist as floating mats on the water's surface. which of these accurately describes the likely effect that duckweed has on the submerged plant populations in the lakes where duckweed is found?

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation:

answer; i believe its echoic memory,it is believed to last three to four seconds; good luck

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.

paper covers rock.

explanation:

rock only smashes scissors.