Biology Test - 14

B-form DNA is the common form of DNA exists under normal physiological condition. The double strands of B-DNA run in opposite directions. In a DNA molecule, the two strands are not parallel but intertwined with each other. Each strand looks like a helix.This structure, also known as the B form, the helix makes a turn every\(3.4 \mathrm{~nm}\).

Nif is a nitrogen fixation gene that occurs in Rhizobium. It fixes atmospheric nitrogen into a form of nitrogen available to living organisms. The Nif genes are found in both free-living nitrogen-fixing bacteria and symbiotic bacteria associated with various plants.

(+,+) Mutualism : In this interaction, both the interacting species are benefitted.
(+,0) Commensalism : Only one species is benefitted and the other species remains unharmed.
(−,0) Amensalism : Neither species is benefitted. One remains unharmed and the other is harmed.
(+,−) Parasitism : One species is benefitted and other is negatively effected.

The most basic amino acid is Histidine. Only Arginine and Histidine are basic amino acids even out of these two, histidine is weakly charged under physiological ph.  Histidine is one of that type of amino acids that can be converted to intermediates of the tricarboxylic acid (TCA) cycle. Histidine, along with some other amino acids such as proline and arginine, takes part in deamination, which is a process in which its amino group is removed. The biosynthesis of the histidine has been majorly studied in prokaryotes like E. coli.

When a solute is dissolved in water, water molecules are less likely to diffuse away via osmosis than when there is no solute. A solution will have a lower and hence more negative water potential than that of pure water.

Disadvantage of deforestation is increase in soil erosion.

Increase in soil erosion:

• Deforestation is one of the major causes of soil erosion.
• Plants keep soils bound in locks of roots, and thus, prevent erosion.
• They also add humus to the soil by shedding leaves and twigs.
• Forests have been denuded practically in most parts of India but their effect on soil erosion is more in hilly parts of the country.

The correct sequence of taxonomic categories is:

Division \(\rightarrow\) Class \(\rightarrow\) Order \(\rightarrow\) Family \(\rightarrow\) Genus \(\rightarrow\) Species

The taxonomic category is also called the Linnaean hierarchy because it was proposed by Linnaeus. Hierarchy of categories is the classification of organisms in a definite sequence of categories (taxonomic categories) in descending order, starting from the kingdom and reaching up to species or an ascending order from species to kingdom.The number of similar characters of categories decreases from lowest rank (species) to highest rank (kingdom). The hierarchy includes seven obligate categories: kingdom, division or phylum, class, order, family, genus and species.The categories are arranged in the descending sequence, keeping the kingdom at the top.

Sucrosedoes not reduce Benedict's solution.

The membrane around the vacuole is known as tonoplast.

The tonoplast is the cytoplasmic membrane surrounding a vacuole, separating the vacuolar contents from the cell's cytoplasm. It is also known as vacuolar membrane. As a membrane, it is mainly involved in regulating the movements of ions around the cell, and isolating materials that might be harmful or a threat to the cell.

Gause's 'Competitive Exclusion Principle' states that two closely related species competing for the same resources cannot co-exist indefinitely and the competitively inferior one will be eliminated eventaully. Thus, statement I is correct.
Statement II is incorrect as in general, herbivores and plants appear to be more adversely affected by competition than carnivores.