HUMAN TRISOMIES

Trisomy 18 - Edward syndrome

Trisomy 13 - Patau syndrome. 

TLS Online TPP Program

#Id: 4962

#Unit 6. System Physiology – Plant

Induction-Reversion Responses or, Low Fluence (LF) Responses

Examples include:

Light-sensitive seed germination;

Many seeds require light for germination (like lettuce), whereas others are inhibited by light (wild oats, Phacelia, Royal Paulownia). Phytochrome presumably stimulates GA synthesis/release which in turn, stimulates the mobilization of stored reserves

TLS Online TPP Program

#Id: 4963

#Unit 6. System Physiology – Plant

Light-sensitive seed germination;

This provides energy for the germinating seed and also decreases the solute potential for water uptake necessary for providing the force for the radicle to push its way through the seed.

TLS Online TPP Program

#Id: 4965

#Unit 6. System Physiology – Plant

Reversal of etiolation

Etiolated plants are those that have been grown in the dark, light stimulates increased [cytokinin] which stimulates cell division and greening.

increases [GA] which presumably stimulates IAA oxidase production to get rid of excess IAA that causes the long spindly growth.

IAA stimulates ethylene synthesis which maintains the apical hook, treating the apical hook with red light + ethylene maintains the hook.

TLS Online TPP Program

#Id: 4966

#Unit 6. System Physiology – Plant

Change surface charge

Red light-treated barley root tips adhered to the sides of a beaker (with a negatively charged surface) but released after far red treatment, caused the surface to become positively charged and far red light negatively charged.

TLS Online TPP Program

#Id: 4967

#Unit 6. System Physiology – Plant

Change surface charge

Red light causes a depolarization of membranes and far-red reverses or even causes a slight hyperpolarization.

TLS Online TPP Program

#Id: 4968

#Unit 6. System Physiology – Plant

Very Low Fluence (VLF) Responses

It sensitive to low levels of light (0.1 nmol m -2 . Less than 0.02% is Pfr). These are not photo-reversible and saturate at 50 nmol m -2 . Some examples include;

a) mesocotyl elongation in cereals; and 

b) Arabidopsis seed germination