Answer:
1/4
Explanation:
Given that the F2 cross produces offspring according to the expected 9:3:3:1 ratio.
YyRr X YyRr:
Let us break the dihybrid cross into individual monohybrid crosses.
Yy X Yy :
Y y
Y YY Yy
y Yy yy
2/4 or 1/2 of the offspring are heterozygous for the trait.
Similarly, in Rr X Rr cross, 1/2 of the offspring are heterozygous for the trait.
Together, 1/2 * 1/2 = 1/4 of F2 plants are expected to be heterozygous for both traits.
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Answer:
The fish did not yet exist when the old layers of rocks were deposited. In fact, animals with hard parts did not evolve until about 600 million years ago, which is only about 13% of the 4.5 billion year age of the Earth. Multicellular animals without hard parts left tracks in older sediments, but had no fossilize-able body parts.
Explanation:
Sickle cell trait is not a disease; it is an inherited red blood cell condition that can affect athletes at all levels. While sickle cell trait is not a barrier to playing competitive sports, athletes with sickle cell trait have experienced significant physical distress, including collapse and death during intense exercise. Heat, dehydration, inadequate acclimatization, altitude and asthma can increase the risk for medical complications in athletes with sickle cell trait Through awareness, education and proper physical conditioning under the supervision of a primary athletics health care provider, athletes with sickle cell trait may safely achieve outstanding athletic performance
The right answer is B.
The answer B is the only proposition which specified at which stage the event must occur, in fact, the meiosis.
Meiosis is a characteristic division of reproductive cells that can generate gametes to form new species (desendence). So if a mutation occurs at this time (such as recombinations) it will inevitably be inherited.