<h3><u>
Answer:</u></h3>
<u>(a) Reason for the heart beating fast:</u>
- When we exercise/run the muscles work hard and need more oxygen.
- So, when Ravi's heart beats faster more blood can be pumped to the muscles thus giving the oxygen required.
<u>(b) Organs involved along with the heart to help Ravi complete his race:</u>
- The main organs involved along with the heart are quadriceps, hip flexors, hamstring, glutes and calf muscles.
- The nervous system, muscular system, skeletal system, respiratory system and circulatory system function effectively when a person runs.
The correct answer is: segmentation.
Segmentation is the fact that some animals and plants have parts of the body that are divided into segments, which typically have a similar structure (they are then called repetitive segments).
Humans also have a segmentation, for example in their spine.
Out of the following give choices;
a. All DNA strands
contained only the heavy nitrogen isotope.
b. Half of the DNA strands contained only the light nitrogen
isotope.
c. All DNA strands contained both heavy and light nitrogen
isotopes.
d. All DNA strands contained only the lighter nitrogen
isotope.
The answer is b. Meselson–Stahl experiment demonstrated the semi-conservative model of DNA replication.
When DNA is replicated, one strand of the new double
helix strand is the parent's strand while the other is the newly synthesized
one. This made the semiconservative model stand out over the other two, dispersive
and conservative models.
<span>Fossil
fuels represent carbon storage areas. Carbon that is locked in these
fossil fuels does not cycle through the Earth. When humans burn fossil
fuels, the stored carbon is released into the atmosphere as carbon
dioxide. The carbon is then free to cycle through the Earth and can
upset the natural balance of the carbon available, changing the way that
processes occur on Earth.</span>
