D) The AV valves are supported by chordae tendineae so that they do not blow back up into the atria during ventricular contraction.
<em>A</em><em>n</em><em>s</em><em>w</em><em>e</em><em>r</em><em>:</em>
YY
<em>E</em><em>x</em><em>p</em><em>l</em><em>a</em><em>n</em><em>a</em><em>t</em><em>i</em><em>o</em><em>n</em><em>:</em>
Y-purple while y-white
YY is the genotype of a pure breed purple flowered pea plant
Yy is the genotype of a heterozygous pea plant flower (purple is dominant over white)
yy is the genotype of a white flowered pea plant that is generally called as recessive
Because of underdeveloped lungs the frog has to breathe through moist skin. Therefore for exchange of gases the skin is thin and moist
The answer is 2 because its the outside number and not in the parentheses
