Instant Notes: Plant Biology

gravity), but non-phototropic. Shoots are generally positivelyphototropic, but either non-or negatively gravitropic.Leaves, orie ...

under gravity and respond by allowing a calcium gradient to be set up. It may also be that stretch activated channels in the ER ...

have confirmed a redistribution of auxin in seedlings experiencing altering gravitational forces. The mechanism of action of aux ...

Section G – Sensing and responding to the environment G3 Nastic responses Nastic responses Nastic responsesare plant movements i ...

Nyctinasty Flowers of many species close at night and leaves of some, including the prayer plant (Maranta),Coleusand French bean ...

phytochrome is involved in entraining (‘setting’) the endogenous clock to coincide with light and dark in the 24 h period (Topic ...

Section G – Sensing and responding to the environment G4 Abscission Abscissiondescribes the removal of plant parts (leaves, flow ...

attaching the organ to the plant (Fig. 1). Within it, one or two layers of cells, the abscission layer, forms as the zone develo ...

Section G – Sensing and responding to the environment G5 Stress avoidance and adaptation The vegetative form of many higher plan ...

opment is plastic; in other words, it is not predetermined to a rigid path as mammalian development is. The presence of persiste ...

Table 2. Some toxic ions and their effects Toxic ion Circumstances in which toxicity occurs Effect Aluminum Acid soils below pH ...

Table 4. Effects of atmospheric pollutants Pollutant Direct effect Indirect effect Sulfur dioxide (precipitates from the Interve ...

Salinity Toxicity due to NaCl has considerable impact on agriculture. Both Na+and Cl– are toxic and occur in excess where land i ...

Section H – Floral development and reproductive physiology H1 Physiology of floral initiation and development Floral meristems F ...

Floral evocation Forming a flower requires the differentiation (Topic F1) of the vegetative shoot meristem into a floral meriste ...

Section H – Floral development and reproductive physiology H2 Breeding systems Most flowering plant species bear hermaphrodite f ...

physiologicalself-incompatibility(SI) system (Topic H3). In most plants with an SI system that have been extensively studied, a ...

inbreeding. In a few plants self-fertilized seeds have slightly different properties from cross-fertilized seeds (e.g. larger an ...

the range of the genus. Numerous different agamospermous clones, differing in minor ways, have appeared and these present a prob ...

Section H – Floral development and reproductive physiology H3 Self incompatibility Many hermaphrodite and monoecious plants have ...