What is the mechanism by which binding of testosterone to the testosterone receptor leads to upregulated gene transcription

This binding causes a conformational change in the receptor which enters into the nucleus and binds DNA to activate transcription

Explanation:

Testosterone is a steroid hormone responsible for inducing protein synthesis and growth of tissues with androgen receptors. Testosterone receptors, also known as androgen receptors, are a class of nuclear receptors activated by binding androgenic hormones (e.g. testosterone) in the cytoplasm, whose binding induces a conformational change of the receptors that are subsequently translocated to the nucleus. Within the cell nucleus, these activated receptors form homodimers that bind DNA in order to promote the transcription of target genes capable of regulating cell growth, cell cycle progression and survival.

answer: that would be cheating

explanation:

any abiotic or biotic factor in an ecosystem that causes a population's size to slow or decrease is a limiting factor.