Question

a) All human beings have cellular oncogenes but only a few suffer from cancer disease Give reason b) How is malignant tumour different from a Benign tumour?

Answer 1

All humans contains inactivated oncogenes known as proto-oncogenes which are not harmful. But sometimes due to some chemical, mutation, ultraviolet rays these inactive genes are converted into cancer causing oncogenes. So cancer occurs only in those individuals in which proto-oncogenes are converted into oncogenes.
Benign tumour remains confined to its original position and do not spread throughout the body. They are considered non-cancerous.
Malignant tumour invade or spread throughout the body that is they exhibit metastasis. These tumours are actually considered as true cancers.