Question

The first successfully cloned mammal that gained worldwide publicity was
A. Molly, a sheep
B. Polly, a sheep
C. Chance, a bull
D. Dolly, a sheep

Answer 1

Hint: Clones refers to organisms that are genetically identical to each other. Using somatic nuclear transfer offspring is created identical to their parents. Other than somatic nuclear transfer, other techniques used for cloning are Rosalin and Honolulu techniques.

Complete answer:
Dolly was the first cloned mammal by Ian Wilmut in Scotland. Clones are organisms that are genetically identical to each other. Unfertilized eggs of female Scottish blackface sheep were taken without a nucleus and were fused with a mammary cell of Finn Dorset sheep. This fused egg cell was implanted into the uterus of another female Black Scottish sheep and this led to the birth of the clone Dolly. Dolly was the clone of adult Finn Dorset sheep and was genetically identical to it. Dolly was a healthy and fertile sheep that gave birth to 4 lambs. This technique is called somatic nuclear transfer
Three main cloning techniques are performed in labs to produce clones:
i. Somatic nuclear transfer: Clone embryos are created using somatic nuclei. This is mainly used as an initial step in human reproductive cloning.
ii. Roslin technique which is slightly different from somatic nuclear transfer.
iii. Honolulu technique: This technique uses an adult cell and nucleus. Adult cell's nuclei are removed and the donor nucleus is inserted in the cell. The cell is then cultured in the lab and new cells are grown.
Main limitations of these techniques are
a. They are applicable and useful for a short duration of time.
b. Cloned offspring have a short life span and are also prone to diseases.
Hence, the correct answer is option D.

Note: The term clone was coined by Herbert J. Webber. Cloning in biotechnology refers to the process of creating clones of organisms or copies of cells or DNA fragments. It is a method of reproduction used by plants, fungi and bacteria. Examples of species that have been cloned are Zebrafish, mice, water buffalo, pig, rhesus monkey, etc.