FMGE 2018 - Biochemistry Practice Questions

Q: Steps of PCR in sequence are?

Denature DNA, Anneal Primers, Extend DNA. ***Denature DNA, Anneal Primers, Extend DNA*** - This sequence represents the three fundamental steps of each PCR cycle, ensuring accurate and efficient **DNA amplification**. - **Denaturation** separates the double-stranded DNA template, **annealing** allows primers to bind to specific sequences, and **extension** synthesizes new DNA strands. *Denature DNA, Extend DNA, Anneal Primers* - This order is incorrect because **primer annealing** must occur before DNA extension can begin. - Primers provide the necessary starting points for the **DNA polymerase** to synthesize the new strands. *Anneal Primers, Extend DNA, Denature DNA* - This sequence is incorrect as the **template DNA** must first be denatured to separate the strands before primers can anneal to them. - If the DNA is not denatured, the primers cannot access their target sequences. *Extend DNA, Anneal Primers, Denature DNA* - This order is incorrect because **DNA extension** is the final step, occurring only after denaturation and primer annealing. - The polymerase requires both a denatured template and bound primers to initiate synthesis.

Q: Atherosclerosis is associated with:

Homocysteine. ***Homocysteine*** - Elevated plasma levels of **homocysteine**, known as hyperhomocysteinemia, are an independent **risk factor for atherosclerosis** and cardiovascular disease. - While the precise mechanism is complex, homocysteine is thought to promote endothelial damage, oxidative stress, and lipid peroxidation, contributing to **plaque formation**. *Histidine* - **Histidine** is an essential amino acid involved in various metabolic processes, including the synthesis of **histamine** and carnosine. - It is not directly associated with the pathogenesis or risk factors for atherosclerosis. *Lysine* - **Lysine** is an essential amino acid important for **protein synthesis** and many bodily functions. - There is no established direct link between lysine levels and the development or progression of atherosclerosis. *Leucine* - **Leucine** is a branched-chain amino acid (BCAA) crucial for **muscle protein synthesis** and energy metabolism. - While some studies hint at associations between BCAAs and metabolic health, leucine itself is not a known direct risk factor or etiologic agent for atherosclerosis.

Q: Intellectual disability is seen in?

Phenylketonuria. ***Phenylketonuria*** - **Phenylketonuria (PKU)** is an inherited metabolic disorder where the body cannot process the amino acid **phenylalanine**, leading to its accumulation in the blood and brain. - Untreated PKU results in severe neurological problems, including **intellectual disability**, seizures, and developmental delays. *Von Gierke disease* - **Von Gierke disease** is a type of glycogen storage disease primarily affecting the liver and kidneys, causing **hypoglycemia** and **lactic acidosis**. - It does not typically involve intellectual disability; cognitive development is usually normal if metabolic complications are managed. *Alkaptonuria* - **Alkaptonuria** is an inherited disorder characterized by the accumulation of **homogentisic acid**, leading to dark urine, ochronosis (bluish-black discoloration of cartilage and connective tissue), and arthritis. - It does not cause intellectual disability. *Albinism* - **Albinism** is a group of inherited disorders characterized by a reduced or complete lack of **melanin pigment** in the skin, hair, and eyes. - While it causes vision problems, such as photosensitivity and nystagmus, it is not associated with intellectual disability.

Q: Essential fatty acid:

Linoleic acid. ***Linoleic acid*** - **Linoleic acid** is an **omega-6 fatty acid** that is considered essential because the human body cannot synthesize it and must obtain it through diet. - It is a precursor for other important fatty acids like **arachidonic acid**, which are involved in inflammation and blood clotting. *Citric acid* - **Citric acid** is an organic acid found in citrus fruits and is a key intermediate in the **Krebs cycle** (citric acid cycle), a central metabolic pathway, but it is not a fatty acid. - It is readily synthesized by the body and is therefore not considered an essential nutrient. *Palmitic acid* - **Palmitic acid** is a **saturated fatty acid** with 16 carbon atoms, which is the most common fatty acid in animals and plants. - It can be synthesized by the human body from excess carbohydrates and proteins, hence it is not an essential fatty acid. *Stearic acid* - **Stearic acid** is another common **saturated fatty acid** with 18 carbon atoms, found in various animal and plant fats. - Like palmitic acid, it can be endogenously synthesized by the body and is not considered essential.

Q: Energy reserve of the body is:

Triglyceride. ***Triglyceride*** - **Triglycerides** are the primary form of **energy storage** in the body, stored predominantly in **adipose tissue**. - They provide a highly concentrated and long-term energy reserve, crucial for periods of fasting or increased energy demand. *Fibres* - **Dietary fibers** are indigestible plant-derived carbohydrates that contribute to digestive health but do not serve as a direct energy reserve for the body. - They are important for maintaining gut motility and regulating blood sugar, but are not metabolized for energy. *Carbohydrate* - **Carbohydrates** (primarily **glycogen**) serve as the **body's most immediate energy source**, stored in the liver and muscles. - However, glycogen stores are limited and are depleted much faster than triglyceride stores during prolonged energy needs. *Proteins* - **Proteins** have numerous structural and functional roles in the body, but are typically used for energy only in cases of **prolonged starvation** when carbohydrate and fat reserves are severely depleted. - Their primary function is not energy storage, and their breakdown for energy can lead to **muscle wasting** and compromise essential body functions.

Question 1

Steps of PCR in sequence are?

Accepted Answer

Denature DNA, Anneal Primers, Extend DNA

Answer

Denature DNA, Extend DNA, Anneal Primers

Answer

Anneal Primers, Extend DNA, Denature DNA

Answer

Extend DNA, Anneal Primers, Denature DNA

Question 2

Atherosclerosis is associated with:

Accepted Answer

Homocysteine

Answer

Histidine

Answer

Lysine

Answer

Leucine

Question 3

Intellectual disability is seen in?

Accepted Answer

Phenylketonuria

Answer

Von Gierke disease

Answer

Alkaptonuria

Answer

Albinism

Question 4

Essential fatty acid:

Accepted Answer

Linoleic acid

Answer

Citric acid

Answer

Palmitic acid

Answer

Stearic acid

Question 5

Energy reserve of the body is:

Accepted Answer

Triglyceride

Answer

Fibres

Answer

Carbohydrate

Answer

Proteins

FMGE 2018 — Biochemistry