The first successfully cloned mammal, Dolly the sheep, was produced using:
A. Somatic cell nuclear transfer
B. Recombinant DNA technology
C. Artificial insemination
D. Gene therapy
Answer: Option A
Solution (By JKSSB Mock Tests)
Dolly (1996) was created by somatic cell nuclear transfer (SCNT), where the nucleus from an adult somatic cell (udder) was transferred into an enucleated egg cell, which was then implanted in a surrogate. This proved that differentiated somatic cells can be reprogrammed to totipotency. She was the first mammal cloned from an adult cell.
Explanation:
The pollen grain contains the male gametophyte, which produces two sperm cells. The ovule contains the female gametophyte (embryo sac). Endosperm is the triploid nutritive tissue formed after double fertilization.
Consider statements about microorganisms: 1. Bacteria reproduce asexually by binary fission. 2. Fungi reproduce by spore formation. 3. Viruses can reproduce independently. Which are correct?
Explanation:
Bacteria are prokaryotes that primarily reproduce asexually through binary fission, a process where a single cell divides into two identical daughter cells. Fungi reproduce both sexually and asexually, but asexual reproduction commonly occurs through the formation and dispersal of spores (like conidia or sporangiospores). Viruses are obligate intracellular parasites; they lack the metabolic machinery for independent reproduction and must hijack a host cell's machinery to replicate. Thus, statements 1 and 2 are correct.
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