Biochemistry

Question 1

What are the three states of matter in the human body?

Answer 1

1. Liquid – Blood plasma, interstitial fluid, intracellular fluid
2. Solid – Bones, teeth, and other rigid structures
3. Gas – Oxygen, carbon dioxide, nitrogen (important for respiration)

Question 2

What is the difference between a molecule and a compound?

Answer 2

• Molecule: Two or more atoms held together (e.g., H₂, O₂).
• Compound: A molecule made of different elements (e.g., H₂O, CO₂).

Question 3

What are the three main macronutrients?

Answer 3

Carbohydrates, lipids (fats), and proteins.

Question 4

What is the most important carbohydrate for life, and why?

Answer 4

Glucose – It is the primary source of ATP for cells, especially neurons and red blood cells.

Question 5

How is excess glucose stored in the body?

Answer 5

• Glycogenesis – Converts glucose to glycogen for storage.
• Lipogenesis – Converts glucose to fat.

Question 6

What are the main types of lipids and their functions?

Answer 6

1. Triglycerides – Energy storage in adipose tissue.
2. Phospholipids – Cell membrane structure.
3. Steroids – Cholesterol-based hormones.
4. Eicosanoids – Prostaglandins (inflammation, muscle contraction).
5. Lipoproteins – Transport cholesterol and fatty acids (HDL, LDL).

Question 7

What is the basic structure of a protein?

Answer 7

Amino acids linked together by peptide bonds.

Question 8

What are the two main types of proteins?

Answer 8

• Fibrous proteins – Structural (e.g., collagen, keratin).
• Globular proteins – Functional (e.g., enzymes, hormones).

Question 9

What are the two ways to express solute concentration?

Answer 9

1. Percentage (%) – Parts per 100 (e.g., 0.9% NaCl solution).
2. Molarity (mol/L) – Moles of solute per liter of solution.

Question 10

What is the molar mass of glucose (C₆H₁₂O₆)?

Answer 10

180.156 g/mol.

Question 11

How do you calculate moles from mass?

Answer 11

n = mass/ molar mass

Question 12

How do you calculate molarity (M)?

Answer 12

M = moles of solute/ volume of solution

Question 13

What is a nutrient?

Answer 13

A substance that promotes growth, maintenance, and repair.

Question 14

What are the two categories of essential nutrients?

Answer 14

1. Macronutrients – Carbohydrates, proteins, lipids, water.
2. Micronutrients – Vitamins, minerals.

Question 15

What is the glycaemic index (GI)?

Answer 15

A measure of how much specific foods raise blood glucose levels.

Question 16

What are essential fatty acids?

Answer 16

Linoleic and linolenic acids – Must be ingested from food.

Question 17

What is cholesterol’s role in the body?

Answer 17

It stabilizes cell membranes and is a precursor for steroid hormones.

Question 18

What is the daily protein intake recommendation?

Answer 18

0.8 g per kg of body weight.

Question 19

What is the “all-or-none” rule of protein synthesis?

Answer 19

All essential amino acids must be present simultaneously for protein synthesis.

Question 20

What is metabolism?

Answer 20

All chemical reactions in the body necessary to maintain life.

Question 21

What are the two types of metabolic reactions?

Answer 21

• Anabolism – Building larger molecules from smaller ones.
• Catabolism – Breaking down molecules for energy.

Question 22

What are the three stages of metabolism?

Answer 22

1. Digestion – Breaks food into nutrients.
2. Anabolism & Catabolism – Builds macromolecules or breaks them down for energy.
3. Oxidative breakdown – Uses oxygen to generate ATP.

Question 23

What are the three main pathways of glucose metabolism?

Answer 23

1. Glycolysis – Breaks glucose into pyruvic acid (anaerobic).
2. Citric Acid Cycle (Krebs Cycle) – Generates electron carriers.
3. Electron Transport Chain – Produces ATP.

Question 24

What is the final ATP yield from one molecule of glucose?

Answer 24

36 ATP molecules.

Question 25

What is gluconeogenesis?

Answer 25

The formation of new glucose from non-carbohydrate sources (e.g., proteins, fats).

Question 26

What is the difference between glycogenesis and glycogenolysis?

Answer 26

• Glycogenesis – Converts glucose to glycogen for storage. • Glycogenolysis – Breaks down glycogen into glucose.

Question 27

What is lipolysis?

Answer 27

The breakdown of stored triglycerides to release energy.

Question 28

What is the main role of the liver in lipid metabolism?

Answer 28

• Synthesizes lipoproteins. • Produces cholesterol. • Forms bile salts.

Question 29

What happens to proteins when carbohydrate intake is low?

Answer 29

The body breaks down proteins for energy, leading to muscle loss.

Question 30

Why should dietary fats be limited to 30% of total caloric intake?

Answer 30

Excess fat increases the risk of cardiovascular diseases

Question 31

What are electrolytes, and why are they important?

Answer 31

Electrolytes are ions that conduct electricity in solution (e.g., Na⁺, K⁺, Cl⁻). They help regulate nerve function, muscle contractions, and fluid balance.

Question 32

What is an isotope?

Answer 32

A chemical element with the same number of protons but a different number of neutrons.

Question 33

What is the equation for diluting a solution?

Answer 33

C1V1 = C2V2 (where C = concentration, V = volume).

Question 34

How many moles are in 117g of NaCl? (Molar mass = 58.441 g/mol)

Answer 34

2 moles

Question 35

What is the glycaemic load?

Answer 35

A measure that considers both the glycaemic index (GI) and the amount of carbohydrates in a serving of food.

Question 36

What is insulin’s role in glucose metabolism?

Answer 36

Insulin lowers blood glucose by promoting glucose uptake into cells and stimulating glycogenesis.

Question 37

What is glucagon’s role in glucose metabolism?

Answer 37

Glucagon raises blood glucose by stimulating glycogenolysis and gluconeogenesis.

Question 38

What happens during Type 1 Diabetes?

Answer 38

The pancreas does not produce insulin, leading to high blood glucose levels.

Question 39

What are the two essential fatty acids that must be obtained from the diet?

Answer 39

Linoleic acid (omega-6) and Linolenic acid (omega-3).

Question 40

What is ketosis?

Answer 40

A metabolic state where the body burns fat for energy, producing ketones.

Question 41

How does HDL differ from LDL?

Answer 41

• HDL (High-Density Lipoprotein) – “Good” cholesterol, removes cholesterol from arteries. • LDL (Low-Density Lipoprotein) – “Bad” cholesterol, contributes to plaque buildup in arteries.

Question 42

What are trans fats, and why are they harmful?

Answer 42

Trans fats are artificially hydrogenated fats that increase LDL and lower HDL, raising the risk of heart disease.

Question 43

What are the nine essential amino acids?

Answer 43

1. Histidine 2. Isoleucine 3. Leucine 4. Lysine 5. Methionine 6. Phenylalanine 7. Threonine 8. Tryptophan 9. Valine

Question 44

What is deamination?

Answer 44

The removal of an amino group from an amino acid, producing ammonia and a keto acid.

Question 45

How does the body excrete excess nitrogen from protein metabolism?

Answer 45

The liver converts ammonia into urea, which is excreted in urine.

Question 46

What is beta-oxidation?

Answer 46

The process of breaking down fatty acids to generate Acetyl-CoA for the Krebs cycle.

Question 47

What is the role of NAD⁺ and FAD in metabolism?

Answer 47

These coenzymes act as electron carriers in redox reactions.

Question 48

What happens if oxygen is not available during glycolysis?

Answer 48

Pyruvate is converted into lactic acid instead of entering the citric acid cycle.

Question 49

What is the role of the electron transport chain?

Answer 49

It generates ATP by transferring electrons and creating a proton gradient.

Question 50

What is the difference between water-soluble and fat-soluble vitamins?

Answer 50

• Water-soluble (B-complex, C) – Absorbed in the GI tract, not stored. • Fat-soluble (A, D, E, K) – Stored in fat, absorbed with lipids.

Question 51

What is the function of Vitamin C?

Answer 51

• Antioxidant • Supports immune function • Aids in collagen synthesis

Question 52

What is the function of Vitamin D?

Answer 52

• Regulates calcium and phosphate metabolism. • Essential for bone health.

Question 53

Why is Vitamin B12 important, and how is it absorbed?

Answer 53

It is needed for red blood cell formation and requires intrinsic factor for absorption in the stomach.

Question 54

What are the major functions of calcium (Ca²⁺) in the body?

Answer 54

• Bone and teeth formation • Muscle contraction • Nerve signalling • Blood clotting

Question 55

What mineral is essential for oxygen transport in the blood?

Answer 55

Iron (Fe²⁺) – It is a key component of hemoglobin.

Question 56

Why is albumin an important protein in the blood?

Answer 56

It maintains oncotic pressure and transports substances like hormones and drugs.

Question 57

What happens in metabolic acidosis?

Answer 57

• Causes: Uncontrolled diabetes, kidney failure, lactic acid buildup. • Symptoms: Low blood pH, rapid breathing, confusion.