Answer:
C. 3, 2, 1
Explanation:
During a single PCR cycle, the very first step is the heat separation of the double stranded DNA. Primer binds only single stranded DNA/RNA because it has complimentary bases which match single strand of DNA/RNA that is why it is necessary to unwind both the strands of DNA by providing temperature.
As soon as the DNA strands have separated by increasing the temperature to ~ 95 °C, in the next step the primer binds the portion of DNA which is complimentary to the bases of the primer. In order for primer to bind DNA, the temperature is lowered to ~ 72 °C and the process is called as annealing.
Once primer has bound to the DNA, the next step is polymerization i.e. nucleotides which are the monomer units of DNA are added one by one with the help of enzyme named as Taq polymerase. This is how the strand extends ahead of primer and exact copies of the given DNA are produced.
Note: PCR may be considered as in vitro DNA synthesis or replication.
Question 1 the answer is cats
2 is round worm
Answer:
is one in which blood flows through two capillary beds before being sent back to the heart.
Explanation:
A portal system can be defined as a system of blood vessels having a capillary network at each end, meaning that the blood vessel starts and ends in capillaries, before finding its way back to the heart. The blood draining through the capillary bed flows via the larger vessel to supply the blood to the another structure's capillary bed.
