Explanation

• Insulin is a peptide hormone produced by the beta cells of the pancreas.
• Mature insulin consists of two polypeptide chains: A chain (21 amino acids) and B chain (30 amino acids).
• These two chains are held together by two interchain disulphide bonds.
• One additional disulphide bond is present within the A chain.
• Disulphide bonds help maintain the proper three-dimensional structure and biological activity of insulin.

Last verified on 31-10-2026

Explanation

• Both plant and animal cells are eukaryotic cells and contain a nucleus.
• Both contain cytoplasm, where many important cellular chemical reactions take place.
• Both contain mitochondria, which produce ATP through cellular respiration.
• Chloroplasts are present in photosynthetic plant cells but are absent in animal cells.

Last verified on 31-10-2026

Explanation

• Restriction enzymes are also called molecular scissors because they cut DNA at specific recognition sequences.
• They recognize particular short DNA sequences, often 4–8 base pairs long.
• These enzymes may produce sticky ends or blunt ends after cutting DNA.
• They are widely used in genetic engineering, recombinant DNA technology, and gene cloning.
• Example: EcoRI is a restriction enzyme that recognizes the sequence GAATTC.

Last verified on 31-10-2026

Explanation

• Deamination is the process of removing the amino group (–NH₂) from amino acids.
• This process produces ammonia, which is toxic to the body.
• The liver converts ammonia into urea through the urea cycle.
• Urea is transported through the blood to the kidneys and eliminated in urine.
• The remaining carbon skeleton can be used for energy production or converted into glucose or ketone bodies.

Last verified on 31-10-2026

Explanation

• The electrical impulse originates in the SA node, the natural pacemaker of the heart.
• It takes approximately 0.03 seconds for the impulse to travel from the SA node to the AV node.
• The AV node itself produces a delay of about 0.09 seconds.
• An additional delay of approximately 0.04 seconds occurs in the penetrating part of the AV bundle (Bundle of His).
• Total delay = 0.03 + 0.09 + 0.04 = 0.16 seconds, commonly rounded to approximately 0.15 seconds.

Last verified on 31-10-2026

Explanation

• Lithonephritis refers to inflammation of the kidney associated with kidney stones.
• Kidney stones are also called renal calculi or nephroliths.
• Stones may irritate or obstruct the urinary tract, causing pain, bleeding, and sometimes infection.
• Nephritis is a general term for inflammation of the kidneys.

Last verified on 31-10-2026

Explanation

Explanation

• All standard amino acids have a central carbon called the alpha carbon (α-carbon).
• The alpha carbon is attached to four groups: an amino group (–NH₂), a carboxyl group (–COOH), a hydrogen atom, and a variable R group.
• The R group determines the chemical properties and identity of each amino acid.
• There are 20 standard amino acids commonly used to build proteins.

Last verified on 31-10-2026

Explanation

• Glucose is filtered from the blood at the glomerulus.
• In a healthy person, almost all filtered glucose is reabsorbed into the blood in the proximal convoluted tubule (PCT).
• Glucose may appear in urine when blood glucose exceeds the renal threshold, commonly associated with diabetes mellitus.

Last verified on 31-10-2026

Explanation

• ADH (Antidiuretic Hormone) is produced by the hypothalamus and released by the posterior pituitary gland.
• ADH increases water reabsorption in the kidney collecting ducts, helping the body conserve water.
• Very low ADH causes less water reabsorption, resulting in a large volume of dilute urine.
• This condition is called central diabetes insipidus.
• Excessive thirst and dehydration may also occur due to increased water loss.

Last verified on 31-10-2026