instruction:
Given a scientific passage and an answer, generate a question for the given answer.
question:
Passage: Although most of a cell's DNA is contained in the cell nucleus, mitochondria have their own DNA. Mitochondria also have the machinery to manufacture their own RNAs and proteins. The human mitochondrial DNA sequence has 16,569 base pairs encoding 37 total genes: 22 tRNA genes, 2 rRNA genes, and 13 peptide genes. The 13 mitochondrial peptides in humans are integrated into the inner mitochondrial membrane, along with proteins encoded by nuclear genes. Answer: nucleus
answer:
Where is most of the cell's dna contained?

question:
Passage: Pharyngeal slits : Pharyngeal slits are located in the pharynx. The pharynx is the tube that joins the mouth to the digestive and respiratory tracts. Answer: pharynx
answer:
What is the name of the tube that joins the mouth to the digestive and respiratory tracts?

question:
Passage: Mountain streams may erode waterfalls. As shown in Figure below , a waterfall forms where a stream flows from an area of harder to softer rock. The water erodes the softer rock faster than the harder rock. This causes the stream bed to drop down, like a step, creating a waterfall. As erosion continues, the waterfall gradually moves upstream. Answer: a waterfall
answer:
When a stream flows from a hard to soft rock area, what is often formed?