Answer:
a. is the answer
Explanation:
The correct answer is scanning electron microscope and scanning tunneling microscope.
The SEM refers to a kind of electron microscope, which generates three-dimensional images of a specimen by scanning the surface with a focused beam of electrons. The electrons associated with the atoms in the specimen, generating different signals, which comprise data regarding the composition of the specimen and the surface topography.
An STM refers to an apparatus for imaging three-dimensional image surfaces at the atomic level. In this, good resolution is regarded to be 0.01 nm depth resolution and 0.1 nm lateral resolution.
The STM can be utilized not only in a high-ultra vacuum but also in water, air, and numerous other gas or liquid ambient, and the temperatures spanning from 1000 degree Celsius to zero Kelvin.
Answer:
Different combinations between these four set of chemicals
Explanation:
There can be billions of combinations between the four chemicals of DNA. The four set of chemicals i.e nucleotide (generally referred to as bases) namely -
A- Adenine
T- Thymine
C - Cytosine
G - Guanine
These nucleotide form codon i.e set of three nucleotide and form chain structure which can be long up to any extent.
Codon example - ATC TGA
Thus, variation in combination of four nucleotide and ability to form long chain of codon allows DNA to have several forms and variations