Answer:
The presence of an additional chromosome
Explanation:
Look at "pair" 21. See how there are THREE chromosomes instead of TWO? Normally, there would only be two chromosomes in each pair but this karyotype shows a trisomy (see def. below) of the 21st pair. This was caused by a nondisjunction mutation of the 21st pair. The is also the karyotype of a person with Down's Syndrome.
Definition of Trisomy:
A condition of the presence of three chromosomes in a pair instead of two. This normally causes developmental irregularity.
Answer:
The troposphere is the lowest layer
Explanation:
hope this helps!! there could be more that are right I'm just not sure so
Well the excretory system produces waste.
It is a mode of natural selection where an extreme phenotype is favored by the other phenotypes causing the allele frequency to shift over time in the direction of that phenotype
