This combination of two positive feedback loops:

one that activates a CDK1 activator (Cdc25C)

one that inhibits a CDK1 inhibitor (Wee1)

results in the abrupt and irreversible transition from G2 into mitosis.

TLS Online TPP Program

#Id: 4992

#Unit 6. System Physiology – Plant

For a “sun plant” or “shade-avoiding plant” there is a clear adaptive value in allocating its resources toward more rapid extension growth when it is shaded by another plant.

TLS Online TPP Program

#Id: 4993

#Unit 6. System Physiology – Plant

It can enhance its chances of growing above the canopy and acquiring a greater share of unfiltered, photosynthetically active light.

TLS Online TPP Program

#Id: 4994

#Unit 6. System Physiology – Plant

To favoring internode elongation is usually reduced leaf area and reduced branching, but at least in the short run this adaptation to canopy shade seems to work.

TLS Online TPP Program

#Id: 4997

#Unit 6. System Physiology – Plant

To favoring internode elongation is usually reduced leaf area and reduced branching, but at least in the short run this adaptation to canopy shade seems to work.

TLS Online TPP Program

#Id: 4998

#Unit 6. System Physiology – Plant

To favoring internode elongation is usually reduced leaf area and reduced branching, but at least in the short run this adaptation to canopy shade seems to work.

TLS Online TPP Program

#Id: 4999

#Unit 6. System Physiology – Plant

R:FR ratio and seed germination,

large-seeded species, with ample food reserves to sustain prolonged seedling growth in darkness (e.g., underground), do not require light for germination.