Question

Which of the following is a naturally totipotent cell?

• A. Ovule
• B. Egg cell
• C. Zygote
• D. Sperm cell

Hint:

Remember the hierarchy:
Totipotent (Zygote) $>$ Pluripotent (Embryonic stem cells) $>$ Multipotent (Adult stem cells).
In plants, the unique feature is that many differentiated somatic cells can regain totipotency, which is the basis for micropropagation.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks to identify which cell type naturally possesses "totipotency." Totipotency is the ability of a single cell to divide and produce all the differentiated cells in an organism, including extra-embryonic tissues.
Detailed Explanation:

• Concept of Totipotency:
A totipotent cell has the highest differentiation potential.
It can give rise to an entire, functional organism.
In plants, most somatic cells can be induced to become totipotent under specific hormonal conditions in tissue culture (Gottlieb Haberlandt's concept).

• The Zygote:
The zygote is the cell formed by the fusion of male and female gametes.
In nature, it is the quintessential totipotent cell.
It undergoes cleavage and differentiation to form the embryo, the endosperm (in many plants), and all vegetative and reproductive organs of the mature plant.

• Analysis of other options:
Ovule: A complex structure containing several types of cells (integuments, nucellus, embryo sac). It is not a single totipotent cell.
Egg cell and Sperm cell: These are gametes. They are haploid and highly specialized. While the egg cell provides the cytoplasm for the zygote, it is not totipotent on its own; it must be fertilized or induced (parthenogenesis) to develop further.

Step 3: Final Answer:
The zygote is the naturally occurring totipotent cell that gives rise to a complete organism.