Given a scientific passage and an answer, generate a question for the given answer.

[Q]: Passage: Figure 7.22 Osteoporosis Osteoporosis is an age-related disorder that causes the gradual loss of bone density and strength. When the thoracic vertebrae are affected, there can be a gradual collapse of the vertebrae. This results in kyphosis, an excessive curvature of the thoracic region. Answer: osteoporosis
[A]: What is the age-related disorder that causes the gradual loss of bone density and strength?

[Q]: Passage: Most fungi get organic compounds from dead organisms. Fungi use their hyphae to penetrate deep into decaying organic matter. They produce enzymes at the tips of their hyphae. The enzymes digest the organic matter so the fungal cells can absorb it. Fungi are the main decomposers in forests. They are the only decomposers that can break down cellulose and wood. They have special enzymes for this purpose. Answer: hyphae
[A]: What do fungi use to penetrate deep into decaying matter?

[Q]: Passage: Figure 36.20 When light strikes rhodopsin, the G-protein transducin is activated, which in turn activates phosphodiesterase. Phosphodiesterase converts cGMP to GMP, thereby closing sodium channels. As a result, the membrane becomes hyperpolarized. The hyperpolarized membrane does not release glutamate to the bipolar cell. Answer: phosphodiesterase
[A]:
When light strikes rhodopsin, the g-protein transducin is activated, which in turn activates what?