A mutation is a change in the DNA of an organism. The change may or may not result in a change to the physical characteristics (or phenotype) of the organism. Mutations that occur in a gamete (sperm or eggs) can be passed to the next generation, whereas mutations that occur in body (or 'somatic') cells may be harmless or may result in a disease such as cancer. Mutations can result in DNA being copied incorrectly. Mutagens can also cause mutations.
A point mutation is a change in one base in the genetic code. The change of one base to a different base (often caused by the DNA being copied incorrectly)-this is called a substitution mutation.
Autosomal mutations may result in:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Disease in an individual
The passage says mutations in body (somatic) cells may be harmless or may result in a disease such as cancer.
Option (1) Disease in an individual — Correct. A mutation in a gene on an autosome may change a protein of the body and so cause a disease in the individual, such as sickle-cell anaemia.
Option (2) Predictable change in an individual — Incorrect. Mutations are random and directionless, so the change they cause in an individual cannot be predicted in advance.
Option (3) Always beneficial change for evolution — Incorrect. Many mutations are harmful or neutral; only some are useful. So mutations are not always beneficial, though the useful ones can be selected in evolution.
Option (4) Affecting the cell division at metaphase — Incorrect. The passage links autosomal mutations to disease in an individual, as in sickle-cell anaemia or phenylketonuria. It does not say that they affect cell division at metaphase.