7. The is a collection of buried, long-dead organisms and can tell us information about prior ancestors - the a fossil is, the it is in age and the related it is to modern organisms.

Fossil.

Explanation:

Fossil is a collection of buried, long-dead organisms that can tell us information about ancestors of an organism. The physical features of fossil provides information about its relationship with modern organisms. The fossil which is present in very deep in the soil are more older than the fossil that is present in less depth. We can find age of the fossil by using radiometric dating methods which tells us about the existence of fossil on the earth.

advantage of using stem cells in medical research:

1.       it provides medical benefits in the fields of therapeutic cloning and regenerative medicine.

2. it provides great potential for discovering treatments and cures to a variety of diseases including parkinson disease, spinal cord injuries, diabetes, alzheimer’s disease and many more.

3. limbs and organ could be grown in lab from stem cells and then used in transplant or treat illness.