4. Which of the following would be an organ system:* O heart, stomach and intestines
O stomach, intestines, mouth
O skin, brain, liver
5. Which are the 6 most common elements in living things?
carbon
helium
oxygen
hydrogen
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nitrogen
phosphorus
sulfur

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.

because they are eaten by the frog and the frog getseaten by the snake and the snake by the eagle

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

answers are:

lysogenic     viral dna merges with host cell dna

lysogenic     no symptoms

lytic               viral dna takes over

lysogenic     virus does not destroy host cell

lytic               virus destroys host cell

lytic               induces symptoms of viral infection

lysogenic       cell reproduces and spreads provirus