Question

Griffith's experiments showe some chemical compound in cells must be responsible for bacterial ____________?

Answer 1

It's talking about bacterial "transformation."

In biology, TRANSFORMATION is where an organism takes foreign DNA into itself,
and expresses the gene.

I've posted a neat picture of an example of transformation.

It's a picture of a tobacco plant,
with a gene that belonged to a firefly.

What scientists did was they took genetic material from a firefly,
and they put it into the tobacco plant.

You know how fireflies normally glow?
Well, the firefly gene cause the tobacco plant to glow too. Just like a firefly.

So you see here,
the tobacco plant took foreign DNA, from the firefly into itself.
And it expresses the gene, by glowing.

Again, we call this an example of TRANSFORMATION.