Q: Changes in the number of what can lead to disorders like down syndrome? Choices: - prokaryotes - dna - genes - chromosomes A:
chromosomes

Q: What is the source of most electricity? Choices: - methane - the Sun - air - coal A:
coal

Q: Not surprisingly, what is the function of the most developed part of a bird's brain? Choices: - controlling digestion - controlling breeding - controlling thought - controlling flight A:
controlling flight