I think the correct answer would be A. The yolk sac becomes the placenta. It is membranous sac that is attached to the embryo. It provides all the nutrition and the blood cells needed by the embryo. It is also called the umbilical vesicle.
The correct answer is B.
The cell membrane is a two-layer lipid membrane that surrounds and protects the cell. It allows only certain molecules to enter and leave the cell, that's why we call it semi-permeable. The membrane is permeable only for small,uncharged molecules which enter and leave in the process of osmosis. All other types of molecules require a special transport protein or a channel in order to be transported trough the cell membrane.
If it displays the dominant genotype, we can assume that this plant would have a heterozygous (hybrid) genotype, i.e.
With a purebred recessive plant, the geneotypes would be 50% Bb and 50% bb.
With a purebred dominant plant, the genetpyes would be 50% BB and 50% Bb.
With a <span>heterozygous (hybrid) plant, the genotypes would be 25% BB, 50% Bb and 25% bb.</span>
After the 1st half-life 250 g of the radioactive material will be left.
<span>After the 2nd half-life 125 g of the radioactive material will be left. </span>
<span>After the 3rd half-life 62.5 g of the radioactive material will be left. </span>
<span>Therefore after 60 minutes, 3 half lives would have occurred. </span>
<span>Therefore the half-life = 60 / 3 = 20 minutes when 250 grams of the original material would have remained radioactive. </span>
<span>Therefore the answer is A) About 250 gram of the material decayed in 20 minutes.</span>
The Flatirons are part of a rock unit known as the Fountain Formation. These rocks are sedimentary—that is, rocks that have been formed by broken fragments of older rock. The Fountain Formation was deposited approximately 280 million years ago, during a time geologists refer to as the Pennsylvanian Period.
Hope this helps!
