According to the current hypothesis, the gradient in phototropin phosphorylation induces the movement of auxin to the shaded side of the coleoptile. Once the auxin reaches the shaded side of the tip, it is transported basipetally to the elongation zone, where it stimulates cell elongation. The acceleration of growth on the shaded side and the slowing of growth on the illuminated side (differential growth) give rise to the curvature toward light.

#Id: 7750

#Unit 1. Molecules and their Interaction Relevant to Biology

The greater the effective nuclear charge the more tightly an electron is held in by the nucleus because there is less electron shield between the valence electrons and the nucleus, and so, the smaller the radius.

#Id: 7751

#Unit 1. Molecules and their Interaction Relevant to Biology

Ranks the following in increasing atomic radius

S, Mg, Al

S: 16-10 +6

Mg: 12-10 = +2

Al: 13-10 +3

So: S < AlMg

#Id: 7752

#Unit 1. Molecules and their Interaction Relevant to Biology

Electron affinity: The enthalpy change that results from adding an electron to a gaseous atom.

Electron affinity is becoming less negative (less exothermic) and less likely to gain an electron. 

#Id: 7753

#Unit 1. Molecules and their Interaction Relevant to Biology

Electron affinity: The enthalpy change that results from adding an electron to a gaseous atom.

Electron affinity is becoming less negative (less exothermic) and less likely to gain an electron. 

#Id: 7754

#Unit 1. Molecules and their Interaction Relevant to Biology

#Id: 7755

#Unit 1. Molecules and their Interaction Relevant to Biology

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. The Pauling scale is the most commonly used.