What causes down syndrome? a deletion antibiotics a substitution nondisjunction

Nondisjunction.

Explanation:

Down Syndrome is a condition caused by trisomy 21, in which the person has 47 chromosomes instead of 46. The error in cell division called nondisjunction    (causes trisomy 21).

Nondisjunction Is the failure of paired chromosomes to divide during cell division, so in this division both chromosome go to one daughter cell. This cause errors in chromosomes number such as Down Syndrome (Trisomy 21) and turner syndrome (Monosomy X).

a time line cause it goes from 685 to 978

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.