In bone, 

1,25-dihydroxycholecalciferol acts synergistically with PTH to stimulate osteoclast activity and bone resorption.

TLS Online TPP Program

#Id: 98

#Unit 5. Developmental Biology

In conditional specification the array of interactions it has with its neighbors, which may include: 

cell-to-cell contacts (juxtacrine factors)

secreted signals (paracrine factors)

physical properties of its local environment (mechanical stress)

TLS Online TPP Program

#Id: 1201

#Unit 7. System Physiology – Animal

Theca cells synthesize and secrete progesterone.

TLS Online TPP Program

#Id: 554

#Unit 2. Cellular Organization

Vegetative cells begin sporulation when a key nutrient- carbon or nitrogen source becomes scarce.

TLS Online TPP Program

#Id: 2880

#Unit 13. Methods in Biology

The denser a biological structure is, the faster it sediments in a centrifugal field.

TLS Online TPP Program

#Id: 5509

#Unit 10. Ecological Principles

Different kinds of metapopulations