The H3.H4 tetramers and H2A.H2B dimers each interact with a particular region of the DNA within the nucleosome.

I. Histone H3.H4 tetramers occupy a key position in the nucleosome by binding the middle and both ends of the DNA.

II. The amino-terminal region of H3 most proximal to the histone-fold region forms a fourth a-helix that interacts with the final 13 bp at each end of the bound DNA.

III. The relatively short length of DNA bound by H2A.H2B dimers is sufficient to prepare the DNA for H3.H4 tetramer binding.

IV. The H3.H4 tetramer forms the bottom part of the histone octamer located across the disc from the DNA ends whereas two H2A.H2B dimer occupies the top part.

Which of the following represents the correct binding of the histones with the DNA?

#Question id: 10215

#Unit 6. System Physiology – Plant

Chloroplast movement is widespread among algae, mosses, and leaves of higher plants, what will be the orientation of chloroplast in dark as well as in light?

a.) In dark, chloroplasts gather at the cell surfaces parallel to the plane of the leaf so that they are aligned perpendicularly to the incident light

b.) Under high light, , the chloroplasts move to the cell surfaces that are parallel to the incident light, thus avoiding excess absorption of light

c.) the orientation of the chloroplasts in the dark is such that maximizes absorption of light

d.) the orientation of the chloroplasts in the high light is such that maximizes absorption of light

Which of the following statements is correct?

#Question id: 10216

#Unit 6. System Physiology – Plant

One of the mechanism that is thought to be involved in protecting the photosynthetic machinery against overexcitation and subsequent damage such mechanism is known as

#Question id: 10217

#Unit 6. System Physiology – Plant

Another effect that appears to be a major factor in the stability of the photosynthetic apparatus, which occurs when excess excitation arriving at the PSII reaction center leads to its inactivation and damage is known as

#Question id: 10218

#Unit 6. System Physiology – Plant

An effect that appears to be a major factor in the stability of the photosynthetic apparatus is photoinhibition, which occurs when excess excitation arriving at the PSII reaction center leads to its inactivation and damage due to

#Question id: 10219

#Unit 6. System Physiology – Plant

The PSII reaction center leads to easily  inactivation and damage by photoinhibition process while Photosystem I Is Protected from Active Oxygen Species, Why PSI protect from active oxygen species in compare to PSII

#Question id: 10220

#Unit 6. System Physiology – Plant

Thylakoid membranes contain a protein kinase that can phosphorylate a specific threonine residue on the surface of LHCII. How the kinase is activated?