All questions of January Week 1 for NEET Exam

The ans is D).PCT.
Acc. to NCERT nearly all the essential nutrients and 70-80% of the electrolytes and water are reabsorbed by this segment.i.e. PCT

The renal vein takes blood away from the kidney. The process starts with renal artery which enters the kidney as afferent arteriole. It carries the urea loaded blood into the glomerulus of the kidney. The blood is filtered by the glomerulus into the Bowman's capsule and runs parallel to the loop of Henle. The urea is absorbed into the nephric filtrate by the process of tubular secretion in the loop of Henle, distal convulated tubule and collecting duct. The process of tubular secretion helps to secrete the urea from the blood to the collecting duct which is finally excreted in form of urine. The purified blood comes from the kidney through the renal vein and drained into vena cava outside kidney.
So, the correct answer is 'Renal vein'.

In heterolytic cleavage, a covalent bond breaks in such a way that one fragment gets both of the shared electrons. In homolytic cleavage, a covalent bond breaks in such a way that each fragment gets one of the shared electrons. The word heterolytic comes from the Greek heteros, "different", and lysis, "loosening".

Renin also known as an angiotensinogenase is an aspartic protease protein and enzyme secreted by the kidneys in to the circulation in the response to the renal hypotension and hypernatremia sympathetic nerve activation

Carbocation:

A carbocation is a species that contains a positively charged carbon atom. It is formed when a carbon atom loses a pair of electrons, leaving it with only six electrons in its valence shell. This electron deficiency makes the carbon atom highly reactive and prone to attracting electrons from nearby atoms or molecules.

Structure and Bonding:

In a carbocation, the carbon atom is attached to three other atoms or groups. It forms three sigma bonds by overlapping its atomic orbitals with the orbitals of the other atoms or groups. These sigma bonds provide stability to the positively charged carbon atom.

The carbon atom in a carbocation possesses only six electrons in its valence shell, which results in an incomplete octet. It is called a sextet because it has six valence electrons instead of the usual eight. The positive charge on the carbon atom indicates that it has lost an electron, resulting in a deficiency of negative charge.

Reactivity:

Carbocations are highly reactive species due to their electron deficiency. They are electron acceptors and can react with nucleophiles, which are electron-rich species. The nucleophile donates a pair of electrons to the positively charged carbon atom, neutralizing the charge and forming a new bond.

The reactivity of a carbocation depends on its stability. Carbocations can be classified into three types based on the number of alkyl groups attached to the positively charged carbon atom:

1. Primary carbocation: It has one alkyl group attached to the carbon atom.
2. Secondary carbocation: It has two alkyl groups attached to the carbon atom.
3. Tertiary carbocation: It has three alkyl groups attached to the carbon atom.

Tertiary carbocations are more stable than secondary carbocations, and secondary carbocations are more stable than primary carbocations. This stability is due to the electron-donating nature of the alkyl groups, which helps to disperse the positive charge on the carbon atom.

Applications:

Carbocations are intermediates in many organic reactions, including electrophilic additions, rearrangements, and substitution reactions. Understanding their reactivity and stability is crucial in organic chemistry for predicting reaction mechanisms and designing synthetic routes.

Reaction Mechanism

The correct answer is option 'A', reaction mechanism. A reaction mechanism provides a detailed account of each step involved in a chemical reaction, including the movement of electrons, the energetics during bond cleavage and bond formation, and the rates of transformation of reactants into products. It explains how reactant molecules rearrange and bond with each other to form products.

Electron Movement

In a chemical reaction, electrons play a crucial role in the formation and breaking of chemical bonds. The movement of electrons determines the reactivity and stability of molecules. The reaction mechanism describes how electrons are transferred or shared between atoms during a reaction. It explains the movement of electrons from high energy orbitals to low energy orbitals, leading to the formation of new bonds and the breaking of existing bonds.

Energetics during Bond Cleavage and Bond Formation

During a chemical reaction, bonds between atoms are broken and new bonds are formed. The reaction mechanism explains the energy changes associated with these processes. Bond cleavage requires an input of energy, known as bond dissociation energy, as bonds are broken. This energy is absorbed from the surroundings. On the other hand, bond formation releases energy, known as bond formation energy, as new bonds are created. The reaction mechanism describes the energy changes during these processes and how they influence the overall energetics of the reaction.

Rates of Transformation (Kinetics)

The reaction mechanism also provides information about the rates of transformation of reactants into products. It describes the individual steps involved in the reaction and the order in which they occur. Each step in the mechanism has a specific rate constant associated with it, which determines how fast that step proceeds. The overall rate of the reaction is determined by the slowest step, known as the rate-determining step. The reaction mechanism helps to identify this step and understand the factors that control the reaction rate.

Conclusion

In summary, a reaction mechanism is a detailed account of the steps involved in a chemical reaction. It describes the movement of electrons, the energetics during bond cleavage and bond formation, and the rates of transformation of reactants into products. Understanding the reaction mechanism is crucial for predicting and controlling chemical reactions.

Because at temperature 0K nearly all molecular motion happen to stop. insisting the internal energy to be simple.
I hope it helped

Actually carbanions are filled with octet, so they are stable and less reactive, in case of polar ions already they are stable, and free radicle is heptet i.e, near to octet whereas carbocation is sextet in nature, so in order to gain to octet it is more reactive and less stable

Once a reactive free radical is generated, it can react with stable molecules to form new free radicals. These new free radicals go on to generate yet more free radicals, and so on. Propagation steps often involve hydrogen abstraction or addition of the radical to double bonds.

Both the statements are correct
kidney and ureter are paired structure whereas urinary bladder is a single structure
and kidneys typically extend from T12 to L3, although the right kidney is often situated slightly lower due to the presence of the liver. Each kidney is approximately three vertebrae in length.

A carbanion has a negatively charged, trivalent carbon atom that has eight electrons in its valence shell. Thus, a carbanion is not electron deficient. As a result, carbanions have pyramidal geometry. Carbocations, radicals, and carbanions can be stabilized by resonance.

SHOW THAT THE AVERAGE TRANSLATIONAL KINETIC ENERGY OF THE MOLECULES OF A GAS IS DIRECTLY PROPORTIONAL TO ABSOLUTE TEMPERATURE. kinetic energy of the molecules of a gas is directly proportional to absolute temperature.

Understanding the Nephron's Function
The nephron is the functional unit of the kidney, responsible for filtering blood and producing urine. Each nephron has several segments, each with specific roles in maintaining the body’s electrolyte balance and acid-base homeostasis.
Role of the Distal Convoluted Tubule
The distal convoluted tubule (DCT) plays a crucial role in the reabsorption of bicarbonate (HCO3-), which is essential for maintaining the body's pH balance. Here’s how it works:
- Bicarbonate Reabsorption: The DCT is responsible for the reabsorption of bicarbonate ions from the filtrate back into the blood. This process helps to buffer the acid-base balance in the body.
- Acid-Base Regulation: By adding HCO3- to the filtrate, the DCT helps neutralize excess hydrogen ions (H+), thereby preventing acidosis.
- Hormonal Influence: The reabsorption of bicarbonate in the DCT is regulated by hormones such as aldosterone, which increases sodium reabsorption and indirectly influences bicarbonate levels.
Other Nephron Components
- Bowman's Capsule: This structure is primarily involved in the initial filtration of blood but does not add bicarbonate to the filtrate.
- Loop of Henle: Its main functions include concentrating urine and reabsorbing water and salts, but it does not directly manage bicarbonate levels.
- Collecting Duct: Primarily involved in the final adjustments of water and electrolyte balance but not in the direct addition of bicarbonate.
Conclusion
The key function of adding bicarbonate to the filtrate occurs in the distal convoluted tubule, making option 'D' the correct answer. Understanding this function is vital for comprehending kidney physiology and its role in maintaining acid-base balance in the body.

Cortical nephrons are the nephron which lies on the cortex region or most of the parts lies in the cortical region. Therefore, in cortical nephrons, vasa recta is absent or reduced in medulla part.

I think kidney transplant... because increase in body wastes could be due to malfunctioning of kidney.

In SI units, P is measured in pascals, V is measured in cubic metres, n is measured in moles, and T in kelvins (the Kelvin scale is a shifted Celsius scale, where 0.00 K = −273.15 degreeC, the lowest possible temperature). R has the value 8.314 J/(K. mol) ≈ 2 cal/(K. mol), or 0.08206 L.