Final answer:
The correct designation for a human aneuploidy condition is b) 46, XX, +21, which indicates Down Syndrome. This is because Down Syndrome is caused by having an extra third copy of chromosome 21. Overall, trisomy is more compatible with life than monosomy, as seen with the survivability of individuals with trisomy 21 versus other trisomies.
Step-by-step explanation:
Aneuploid Designations in Humans
Based on the karyotypes provided in the questions, aneuploidy refers to a condition in humans where the number of chromosomes differs from the normal diploid number of 46. This might include an extra chromosome (trisomy) or a missing chromosome (monosomy). The most well-known example of trisomy is chromosome 21, which causes Down Syndrome.
The correct aneuploid designation from the options provided would be b) 46, XX, +21. This indicates a typical female (46, XX) with an extra copy of chromosome 21, which is consistent with Down Syndrome. None of the other options correctly represent a viable human aneuploidy condition.
The increased survivability of individuals with trisomy 21 over other trisomies, like trisomy 18, suggests that chromosome 21 is smaller and has fewer genes impacted by the 'gene dosage' effect, thereby allowing for more individuals with this condition to survive into adulthood.
In terms of surviving offspring, those with 2n+1 chromosomes are more likely to survive than offspring with 2n-1 chromosomes, as generally, the loss of genetic material is more critical than the gain of an extra chromosome.