Answer:
Polymerase chain reaction (PCR) test is used to duplicate traces of DNA from any living form, for identification purposes. The correct sequence is 1, 3, 2; based on the options given.
Explanation:
The steps to be followed for the PCR procedure are:
<em>Denaturation</em>
Option 1. Involves incubation at 94°C to denature DNA strands into single strands by breaking of weak hydrogen links
<em>Annealing</em>
Option 3. Temperature is lowered to 60°C to allow primers joining their similar DNA sequences.
<em>Elongation</em>
Option 2. Incubate at 72°C to promote the extension of the DNA strands, actually extending them.
Answer: The correct answer is D. the central nervous system and the peripheral nervous system.
The nervous system is a complex system that is made up of nerves and nerve centers in different organisms that carries messages to and from the brain and the spinal cord to send them into various parts of the body.
It is primarily divided into-
1) CNS that is central nervous system ( made up of brain and spinal cord). The CNS is responsible for the voluntary functions of the body.
2) PNS that is peripheral nervous system ( possess cranial and spinal nerves arising from brain and spinal cord respectively). It controls the involuntary functions of the body.
Answer:
There is a great difference between light and scanning electron microscope. The source of illumination is light rays in light microscope while in scanning electron microscope electrons are the source of illumination.
The resolving and magnification power of scanning electron microscope is much greater than that of a light microscope. The magnifying power of a light microscope is 1000X and of electron microscope is 10,00,000X.
In light microscope image is seen through the eyepiece while in scanning electron microscope it is seen on a fluorescent screen. Even small specimens up to 0.1 micrometers can be seen by scanning electron microscope which is not possible to see by light microscope.
The answers are A, B, & C. Steroid hormones have a
longer half-life than peptide hormones because steroid hormones ride on carrier
proteins in the blood. In other words, they
are bound to protein carriers that transport molecules across the membrane. They can also be stored temporarily in the adipose
tissue. And also, steroid hormones are sent to the nucleus where it regulates transcription
while peptides don’t require this process. This is the reason why the effects of
steroid hormones are exerted more slowly than peptides.
