A student was observing slides of cell division. In one of the slides, he noticed loosely coiled chromatin depicting DNA duplication. Which phase of the cell cycle could it be?

A.
S phase
B.
Metaphase
C.
M phase

A. S phase

Explanation:

The cell cycle involves all the series of division events that occurs to an organism. Cell division, which can be meiosis or mitosis, involves two main stages viz: Interphase and M phase.

Interphase describes the resting stage of the cell i.e. when the cell is not dividing. The cell uses this time to prepare itself for the next round of division. Interphase stage further consists of three main phases viz: G1, S and G2 phases.

In the S phase or synthesis phase of Interphase, the cell duplicates its genetic material (DNA). Hence, an onion cell observed by a student to have loosely coiled chromatin depicting DNA duplication is in the S-PHASE.

tsd is temerature dependent sex determination.

tsd: it is a type of environmental sex determination in which the temperature experienced during embryonic/ larval development (ambient temperature for development) determine the sex of the offspring.

crocodile displays the tsd where the ambient temperature of the developing egg determines the individual's sex. for example in the american alligator's eggs, incubation at 33 ºc produces mostly males, while incubation at 30 ºc produces mostly females. so if the american alligator's egg will get the ambient temperature (33 degree celcius)during embryonic development from egg, the offspring will be male and same for the female sex determination.