Close inbreeding is harmful because it increases the proportion of homozygotes and thereby boosts the probability that deleterious and lethal recessive alleles.

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.

TLS Online TPP Program

#Id: 5000

#Unit 6. System Physiology – Plant

In all photoperiodic plants,

In the winter when days are short, [P_R] > [P_FR]

In the summer when days are long, [P_R] < [P_FR]

TLS Online TPP Program

#Id: 5001

#Unit 6. System Physiology – Plant

The critical difference is that,

In short-day (i.e., winter flowering) plant species, P_FR inhibits flowering.

In long-day (i.e., summer-flowering) plant species, P_FR induces flowering.

TLS Online TPP Program

#Id: 5002

#Unit 6. System Physiology – Plant

Circadian rhythm in the diurnal movements of Albizia leaves.

TLS Online TPP Program

#Id: 5004

#Unit 6. System Physiology – Plant

During phytochrome-mediated leaflet closure, the apoplastic pH of the dorsal motor cells (the cells that swell during leaflet closure) decreases, while the apoplastic pH of the ventral motor cells (the cells that shrink during leaflet closure) increases. 

TLS Online TPP Program

#Id: 5005

#Unit 6. System Physiology – Plant

Continuous red light absorbed by phyB stimulates de-etiolation by maintaining high levels of PfrB.