Answer:
i believe its A because i studied this
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Answer:
The answer should be C: mostly in the 20th century
Explanation:
Explanation:
In the majority of cases, the extra copy of chromosome 21 comes from the mother in the egg.
In a small percentage (less than 5%) of cases, the extra copy of chromosome 21 comes from the father through the sperm.
In the remaining cases, the error occurs after fertilization, as the embryo grows.
The answer is <span>the number of DNA mutations in an organism is measured over time to determine how long it will take for a new species to evolve.</span>
Answer:
Where is the question bro!!!
Explanation:
