Answer: The correct answer is 3) A segment of a DNA molecule that contains the instructions for producing a trait in an organism.
Gene is a segment of DNA molecule that contains instructions ( in the form of nucleotide sequences), which are required for producing a specific trait ( characteristic) of an organism.
For this, gene is first transcribed into mRNA ( messenger RNA), which is then translated to produce a particular protein. The protein thus formed gives a specific characteristic to the organism.
Thus, option 3) is the best description for a gene.
starch into glucose
proteins into amino acids
lipids into fatty acids
There are many more examples of chemical digestion which takes place in the body. Chemical digestion is the breaking of larger more complex molecules into smaller, simpler ones that can be taken up by the cells more easily and readily by the use of chemical agents.. Chemical digestion is carried out primarily using biological molecules called enzymes. For example, the breakdown of starch is done by an enzyme known as amylase, which is present in the saliva.