Biochemical Techniques — MCQs

Biochemical Techniques Indian Medical PG Practice Questions and MCQs

Question 271: Which assay is specifically used to test for lipid peroxidation?

A. Ames test
B. MTT assay
C. Guthrie test
D. Fox assay (Correct Answer)

Explanation: ***Fox assay*** - The **Fox assay** specifically measures **ferrous oxidation** in the presence of **xylenol orange**, which is used to detect **lipid hydroperoxides**. - It is a common and sensitive method for directly quantifying **lipid peroxidation** end-products in biological samples. *Ames test* - The Ames test is a biological assay used to assess the **mutagenic potential** of chemical compounds. - It detects whether a given chemical causes **mutations** by observing the reversal of a *Salmonella typhimurium* strain's histidine auxotrophy. *MTT assay* - The **MTT assay** (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) is a colorimetric assay for assessing **cell metabolic activity** and viability. - It measures the activity of **mitochondrial reductase enzymes**, which reduce MTT to a purple formazan product in living cells. *Guthrie test* - The **Guthrie test** is a bacterial inhibition assay used for the **newborn screening** of metabolic disorders, primarily **phenylketonuria (PKU)**. - It detects elevated levels of specific amino acids (like **phenylalanine**) in dried blood spots.

Question 272: What defines a free radical in terms of its electronic structure?

A. A charged particle with unpaired electrons
B. An atom with an even number of paired electrons
C. A chemically stable atom with paired electrons
D. An atom or molecule with an unpaired electron in its outer shell (Correct Answer)

Explanation: ***An atom or molecule with an unpaired electron in its outer shell*** - The presence of an **unpaired electron** in the outermost orbital is the defining characteristic of a free radical, making it highly reactive. - This electronic configuration leads to its quest for stability by participating in reactions to pair the electron. *A charged particle with unpaired electrons* - While some free radicals can be charged (e.g., superoxide anion), being charged is not a universal defining characteristic; the **unpaired electron** is the key feature. - Not all charged particles are free radicals, and not all free radicals are charged particles. *An atom with an even number of paired electrons* - An atom with an even number of paired electrons is typically **stable** and does not possess the high reactivity associated with free radicals. - This describes a **stable molecule** or atom, not a free radical. *A chemically stable atom with paired electrons* - This statement describes a **non-radical species** and is the opposite of a free radical, which is inherently unstable and reactive due to its unpaired electron. - **Paired electrons** contribute to stability, whereas free radicals are unstable due to their unpaired electron.

Question 273: Which of the following methods is commonly used for DNA estimation?

A. Spirometer
B. Spectrophotometer (Correct Answer)
C. pH meter
D. Sphygmomanometer

Explanation: ***Spectrophotometer*** - A spectrophotometer measures the **absorption of light** at specific wavelengths, which is used to quantify the concentration of DNA or RNA in a solution. - **Nucleic acids** absorb UV light strongly at **260 nm**, allowing for their accurate estimation. *Spirometer* - A spirometer is used to **measure lung function**, specifically the volume of air an individual can inhale and exhale. - It is a tool for assessing **respiratory health** and has no role in DNA estimation. *pH meter* - A pH meter is used to measure the **acidity or alkalinity** of a solution, expressed as pH. - It works by measuring the **hydrogen ion concentration** and is unrelated to quantifying DNA. *Sphygmomanometer* - A sphygmomanometer is a medical device used to measure **blood pressure**. - It consists of an inflatable cuff and a manometer and is not involved in biochemical assays like DNA estimation.

Practice by Chapter

Spectrophotometry and Colorimetry

Practice Questions

Chromatography Techniques

Practice Questions

Electrophoresis and Applications

Practice Questions

Centrifugation and Ultracentrifugation

Practice Questions

Radioisotope Techniques

Practice Questions

Enzyme-Linked Immunosorbent Assay (ELISA)

Practice Questions

Polymerase Chain Reaction (PCR)

Practice Questions

Blotting Techniques: Southern, Northern, Western

Practice Questions

Mass Spectrometry in Biochemistry

Practice Questions

Recombinant DNA Technology

Practice Questions

DNA Sequencing

Practice Questions

Proteomics and Metabolomics

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free