Answer:
Cyanobacteria, Anabaena and Azotobactor are called Nitrogen fixing bacteria. These bacteria change the nitrogen in the atmosphere into a form that is used by the plants to make proteins. Plants take nitrogen in the form of nitrates. The atmospheric nitrogen is first converted into ammonia after that ammonia is converted into nitrates and this nitrates use by the plants to make proteins.
Carbohydrates are broken down and they release energy.
Answer: Option E) polar
Amino acid-derived and peptide hormones are unable to diffuse across a cell membrane because they are polar
Explanation:
Amino acid-derived and peptide hormones such as serotonin, epinephrine, dopamine etc, are unable to diffuse across a cell membrane because they consist of several repeating units of amino acids with positively charged or negatively charged side chains.
Thus, the side chains make these hormones water-loving (hydrophilic), and impassable to the hydrophobic layer of the cell membrane.
The electrons in the outermost shell of the covalent compounds are shared by nearby atoms. As there are no free electrons for conducting electricity, the covalent compounds are perfect insulators at absolute zero. As the temperature increases, some electrons move from valence band to conduction band. This gives rise to conductivity. But as the numbers of charge carriers are very low, covalent compounds are poor conductors. On the other hand metals are good conductors cause of their bonding. Metallic bonding consists of a sea of electrons rather than discreet bonds. The free electrons are able to move freely. Since electricity and heat need electrons to move, the bonding promotes conductivity.
