BIOCHEM Finals (Batch 2026)

Question 1

Which of the following measures height and weight?
A. Body mass index (BMI)
B. Central obesity
C. Waist circumference
D. Body composition

Answer 1

A. Body mass index (BMI)
Rationale: BMI is a measure that uses height and weight to estimate a person’s body fat. It is calculated by dividing a person’s weight in kilograms by the square of their height in meters.

Question 2

A lack of intrinsic factor may lead to:
A. Beriberi
B. Pellagra
C. Pernicious anemia
D. Atrophic gastritis

Answer 2

C. Pernicious anemia
Rationale: Pernicious anemia is caused by a deficiency of vitamin B12, which is often due to the lack of intrinsic factor, a protein necessary for the absorption of vitamin B12 in the stomach.

Question 3

Vitamin C serves as a/an:
A. Coenzyme
B. Antagonist
C. Antioxidant
D. Intrinsic factor

Answer 3

C. Antioxidant
Rationale: Vitamin C is known for its antioxidant properties, meaning it helps protect cells from damage caused by free radicals.

Question 4

The body can make niacin from:
A. Tyrosine
B. Serotonin
C. Carnitine
D. Tryptophan

Answer 4

D. Tryptophan
Rationale: Tryptophan, an amino acid, can be converted by the body into niacin (vitamin B3), which is essential for energy metabolism.

Question 5

The form of vitamin A active in vision is:
A. Retinal
B. Retinol
C. Rhodopsin
D. Retinoic acid

Answer 5

A. Retinal
Rationale: Retinal is the form of vitamin A that is essential for vision, as it is involved in the formation of rhodopsin, a pigment in the retina that is necessary for seeing in low-light conditions.

Question 6

Vitamin D can be synthesized from a precursor that the body makes from:
A. Bilirubin
B. Tocopherol
C. Cholesterol
D. Beta-carotene

Answer 6

C. Cholesterol
Rationale: The body synthesizes vitamin D from cholesterol when the skin is exposed to sunlight.

Question 7

A significant amount of vitamin K comes from:
A. Vegetable oils
B. Sunlight exposure
C. Bacterial synthesis
D. Fortified grain products

Answer 7

C. Bacterial synthesis
Rationale: A significant amount of vitamin K is produced by bacteria in the intestines, in addition to being obtained from dietary sources.

Question 8

The principal cation in extracellular fluids is:
A. Sodium
B. Chloride
C. Potassium
D. Phosphorus

Answer 8

A. Sodium
Rationale: Sodium is the main cation (positively charged ion) found in extracellular fluids, where it plays a crucial role in maintaining fluid balance and transmitting nerve impulses.

Question 9

The role of chloride in the stomach is to help:
A. Support nerve impulses
B. Convey hormonal messages
C. Maintain a strong acidity
D. Assist in muscular contraction

Answer 9

C. Maintain a strong acidity
Rationale: Chloride, as part of hydrochloric acid (HCl), helps maintain the acidic environment of the stomach, which is necessary for digestion and killing pathogens.

Question 10

Cretinism is caused by a deficiency of:
A. Iron
B. Zinc
C. Iodine
D. Selenium

Answer 10

C. Iodine
Rationale: Cretinism is a condition resulting from severe iodine deficiency during pregnancy, leading to impaired physical and mental development in the child.

Question 11

The mineral best known for its role as an antioxidant is:
A. Copper
B. Selenium
C. Manganese
D. Molybdenum

Answer 11

B. Selenium
Rationale: Selenium is a crucial component of antioxidant enzymes, such as glutathione peroxidase, which help protect cells from oxidative damage.

Question 12

To help prevent neural tube defects, grain products are now fortified with:
A. Iron
B. Folate
C. Protein
D. Vitamin C

Answer 12

B. Folate
Rationale: Folate (or folic acid) is essential for DNA synthesis and cell division, and its deficiency during pregnancy is associated with neural tube defects in the developing fetus.

Question 13

Vitamin K consumption should be consistent in patients using:
A. Tetracycline
B. Isoniazid
C. Warfarin
D. Lithium

Answer 13

C. Warfarin
Rationale: Warfarin is an anticoagulant that works by inhibiting vitamin K. Consistent vitamin K intake is crucial to maintain stable blood clotting levels while on warfarin therapy.

Question 14

Calcitonin is synthesized in the:
A. Adrenals
B. Thyroid
C. Thymus
D. Ovaries

Answer 14

B. Thyroid
Rationale: Calcitonin is a hormone produced by the C-cells of the thyroid gland and helps regulate calcium levels in the blood.

Question 15

During a fast, when glycogen stores have been depleted, the body begins to synthesize glucose from:
A. Acetyl CoA
B. Amino acids
C. Fatty acids
D. Ketone bodies

Answer 15

B. Amino acids
Rationale: When glycogen stores are depleted, the body starts gluconeogenesis, a process where amino acids are converted into glucose to provide energy.

Question 16

Marasmus develops from:
A. Too much fat clogging the liver
B. Mega doses of amino acid supplements
C. Inadequate protein and energy intake
D. Excessive fluid intake

Answer 16

C. Inadequate protein and energy intake
Rationale: Marasmus is a form of severe malnutrition caused by a deficiency in calorie and protein intake, leading to significant weight loss and muscle wasting.

Key Differences:

•	Nutritional Deficiency: Marasmus is due to a total caloric deficiency, while kwashiorkor results from a specific protein deficiency despite sufficient caloric intake.
•	Appearance: Marasmus presents with extreme thinness and wasting, whereas kwashiorkor presents with edema and a swollen appearance.
•	Serum Albumin: Marasmus usually has normal or slightly low serum albumin, while kwashiorkor has significantly low serum albumin.

Question 17

Isoleucine, leucine, and lysine are:
A. Proteases
B. Polypeptides
C. Essential amino acids
D. Complementary proteins

Answer 17

C. Essential amino acids
Rationale: Isoleucine, leucine, and lysine are essential amino acids, meaning they cannot be synthesized by the body and must be obtained from the diet.

Question 18

Which of the following is NOT true? Fats:
A. Contain glucose
B. Provide energy
C. Protect against organ shock
D. Carry vitamins A, D, E, and K

Answer 18

A. Contain glucose
Rationale: Fats do not contain glucose. They provide energy, protect organs from shock, and carry fat-soluble vitamins (A, D, E, and K).

Question 19

The lipoprotein most associated with a high risk of heart disease is:
A. CHD
B. HDL
C. LDL
D. LPL

Answer 19

C. LDL
Rationale: Low-density lipoprotein (LDL) is often referred to as “bad cholesterol” because high levels of LDL can lead to plaque buildup in arteries and increase the risk of heart disease.

Question 20

Carbohydrates are found in virtually all foods except:
A. Milk
B. Meat
C. Bread
D. Fruit

Answer 20

B. Meat
Rationale: Meat does not contain carbohydrates. Carbohydrates are primarily found in plant-based foods such as fruits, vegetables, grains, and legumes, as well as in milk.

Question 21

Behaviors such as smoking, dietary habits, physical activity, and alcohol consumption that influence the development of disease are known as:
A. Risk factors
B. Chronic cases
C. Preventive agents
D. Disease description

Answer 21

A. Risk factors
Rationale: Risk factors are behaviors or conditions that increase the likelihood of developing a disease or health disorder.

Question 22

A deficiency caused by inadequate dietary intake is a/an:
A. Overt deficiency
B. Covert deficiency
C. Primary deficiency
D. Secondary deficiency

Answer 22

C. Primary deficiency
Rationale: A primary deficiency is directly caused by an inadequate intake of a nutrient from the diet.

Question 23

An RDA represents the:
A. Highest amount of a nutrient that appears safe for most healthy people
B. Lowest amount of a nutrient that will maintain a specified criterion of adequacy
C. Average amount of a nutrient considered adequate to meet the known nutrient needs of practically all healthy people
D. Average amount of a nutrient that will maintain a specific biochemical or physiological function for half the people

Answer 23

C. Average amount of a nutrient considered adequate to meet the known nutrient needs of practically all healthy people
Rationale: The Recommended Dietary Allowance (RDA) is the average daily level of intake sufficient to meet the nutrient requirements of nearly all (97-98%) healthy individuals.

Question 24

The energy-yielding nutrients are:
A. Fats, minerals, and water
B. Minerals, proteins, and vitamins
C. Carbohydrates, fats, and vitamins
D. Carbohydrates, fats, and proteins

Answer 24

D. Carbohydrates, fats, and proteins
Rationale: Carbohydrates, fats, and proteins are the macronutrients that provide energy (calories) to the body.

Question 25

The inorganic nutrients are:
A. Proteins and fats
B. Vitamins and minerals
C. Minerals and water
D. Vitamins and proteins

Answer 25

C. Minerals and water
Rationale: Inorganic nutrients, which do not contain carbon, include minerals and water.

Question 26

A segment of DNA that reads the same forward and backward is called:
A. Palindromic DNA
B. Plasmid DNA
C. Complementary DNA
D. Copy DNA

Answer 26

A. Palindromic DNA
Rationale: Palindromic DNA sequences are the same when read forward or backward, and they are often recognition sites for restriction enzymes.

Question 27

Electrophoresis, a technique used in DNA fingerprinting, helps to separate:
A. DNA segments
B. Cells from DNA
C. Tissues
D. RNA from DNA

Answer 27

A. DNA segments
Rationale: Electrophoresis is a method used to separate DNA fragments based on their size and charge.

Question 28

Restriction enzymes cut DNA at specific sites called:
A. Ligation site
B. Ori
C. Recognition sequence
D. Replication site

Answer 28

C. Recognition sequence
Rationale: Restriction enzymes recognize and cut DNA at specific nucleotide sequences known as recognition sequences.

Question 29

Which group of enzymes are popularly called “Molecular Stitchers”:
A. Restriction endonuclease
B. RNA polymerase
C. Ligases
D. DNA polymerases

Answer 29

C. Ligases
Rationale: Ligases are enzymes that facilitate the joining of DNA strands together by forming phosphodiester bonds, thus “stitching” together fragments of DNA.

Question 30

An extrachromosomal, self-replicating, double-stranded, closed, circular DNA molecule is called:
A. Plasmid
B. Phage
C. Virus
D. Cosmid

Answer 30

A. Plasmid
Rationale: Plasmids are small, circular, double-stranded DNA molecules that exist independently of the chromosomal DNA and can replicate on their own.

Question 31

31. Restriction enzymes have the ability to cut:
    A. DNA at random sites
    B. RNA at random sites
    C. DNA at specific sites
    D. RNA at specific sites

Answer 31

C. DNA at specific sites
Rationale: Restriction enzymes recognize specific nucleotide sequences in DNA and make cuts at or near these sites.

Question 32

32. A recombinant DNA molecule is produced by joining together:
    A. A mRNA with a DNA segment
    B. Two mRNA molecules
    C. A mRNA with a tRNA segment
    D. Two DNA segments

Answer 32

D. Two DNA segments
Rationale: Recombinant DNA technology involves combining DNA from two different sources to create a new genetic combination.

Question 33

33. Which repair mechanism of DNA involves more gene products:
    A. Mismatch repair
    B. Base excision repair
    C. Nucleotide excision repair
    D. Double-strand break repair

Answer 33

C. Nucleotide excision repair
Rationale: Nucleotide excision repair is a complex mechanism involving multiple gene products to recognize and excise damaged DNA, then fill in the gap with new nucleotides.

Question 34

34. Which of the following proteins is involved in the approximation of the two separate ends of double-strand break repair?
    A. KU
    B. DNA protein kinase
    C. Exonuclease
    D. Ligase

Answer 34

B. DNA protein kinase
Rationale: DNA protein kinase (DNA-PK) plays a critical role in non-homologous end joining (NHEJ), a pathway that repairs double-strand breaks in DNA.

Question 35

35. In the depurination of DNA, which specific enzyme can recognize abnormal bases and remove them from the DNA:
    A. Endonuclease
    B. Glycosylase
    C. DNA polymerase
    D. Ligase

Answer 35

B. Glycosylase
Rationale: DNA glycosylase recognizes and removes damaged bases by cleaving the bond between the base and the sugar in the DNA backbone.

Question 36

36. Which repair mechanism of DNA uses the GATC endonuclease:
    A. Mismatch repair
    B. Base excision repair
    C. Nucleotide excision repair
    D. Double-strand break repair

Answer 36

A. Mismatch repair
Rationale: In bacteria, the mismatch repair system involves the recognition of the GATC sequence and the correction of mismatched nucleotides.

Question 37

37. This occurs when one or two nucleotides are either deleted or added to the coding region, producing a different amino acid sequence:
    A. Point mutation
    B. Frameshift mutation
    C. Transposons
    D. Trinucleotide repeat expansion

Answer 37

B. Frameshift mutation
Rationale: Frameshift mutations result from insertions or deletions of nucleotides that change the reading frame of the genetic code, leading to an altered amino acid sequence.

Question 38

38. True of Chargaff’s Rule, except:
    A. In any sample of dsDNA molecules, the concentration of deoxyadenosine nucleotides equals that of thymidine nucleotides
    B. The concentration of deoxyguanosine nucleotides equals that of deoxycytidine nucleotides
    C. The concentration of deoxyadenosine nucleotides equals that of uracil nucleotides
    D. The total purine content in double-stranded DNA is always equal to pyrimidine content.

Answer 38

C. The concentration of deoxyadenosine nucleotides equals that of uracil nucleotides
Rationale: Chargaff’s Rule states that in DNA, the amount of adenine equals thymine and the amount of guanine equals cytosine. Uracil is found in RNA, not DNA.

Question 39

39. The codon (UCA) is given a different base to become (UAA), what point mutation will occur?
    A. Missense mutation
    B. Nonsense mutation
    C. Silent mutation
    D. Transition

Answer 39

B. Nonsense mutation
Rationale: A nonsense mutation occurs when a codon is changed to a stop codon (UAA in this case), leading to premature termination of translation.

Question 40

40. The codon (CCA) is given a different base to become (UCA), what point mutation will occur?
    A. Missense mutation
    B. Nonsense mutation
    C. Silent mutation
    D. Transversion

Answer 40

A. Missense mutation
Rationale: A missense mutation results in a change of one amino acid to another. In this case, the codon CCA (proline) changes to UCA (serine), altering the protein sequence.

Question 41

The codon (UCC) is given a different base to become (UCG), what point mutation will occur?
A. Missense mutation
B. Nonsense mutation
C. Silent mutation
D. Transition

Answer 41

C. Silent mutation
Rationale: Both UCC and UCG code for the same amino acid, serine, so the mutation does not change the amino acid sequence.

Question 42

The codon containing the changed base may become a termination codon, what point mutation has occurred?
A. Missense mutation
B. Nonsense mutation
C. Silent mutation
D. Transition

Answer 42

B. Nonsense mutation
Rationale: A nonsense mutation occurs when a codon is changed to a stop codon, leading to premature termination of translation.

UGA = U Go Away.
UAA = U Are Away.
UAG = U Are Gone.

Question 43

The codon containing the changed base may code for a different amino acid:
A. Missense mutation
B. Nonsense mutation
C. Silent mutation
D. Transition

Answer 43

A. Missense mutation
Rationale: A missense mutation results in a codon that codes for a different amino acid, potentially altering the function of the protein.

Question 44

Which among major types of RNA that participate in the process of protein synthesis make up about 80% of the total RNA in the cell?
A. Ribosomal RNA (rRNA)
B. Transfer RNA (tRNA)
C. Messenger RNA (mRNA)
D. Noncoding RNA (ncRNA)

Answer 44

A. Ribosomal RNA (rRNA)
Rationale: rRNA makes up the majority of RNA in the cell and is a key component of ribosomes, which are essential for protein synthesis.

Question 45

They are integrated into the DNA, which can cause profound changes in the genes into which they insert and in adjacent genes:
A. Point mutation
B. Frameshift mutation
C. Transposons
D. Trinucleotide repeat expansion

Answer 45

C. Transposons
Rationale: Transposons, or “jumping genes,” can insert themselves into various locations within the genome, causing mutations and altering the function of genes.

Question 46

Which is not a repair enzyme in DNA mutation?
A. Ligase
B. DNA polymerase
C. Exonuclease
D. DNA primase

Answer 46

D. DNA primase
Rationale: DNA primase is involved in DNA replication, not repair. It synthesizes a short RNA primer to initiate DNA synthesis.

Question 47

An example of cross-linkage reaction that causes mutation to DNA:
A. Oxidative free radical formation
B. Between DNA and protein molecules (e.g., histones)
C. Alkylation of base
D. Ionizing radiation

Answer 47

B. Between DNA and protein molecules (e.g., histones)
Rationale: Cross-linking can occur between DNA and proteins, such as histones, leading to structural changes and potential mutations.

Question 48

An example of chain breaks reaction that leads to mutation of DNA:
A. UV light-induced pyrimidine dimer
B. Oxidative free radical formation
C. Base-analog incorporation
D. Between bases in the same or opposite strands

Answer 48

B. Oxidative free radical formation
Rationale: Oxidative free radicals can cause single or double-strand breaks in DNA, leading to mutations.

Question 49

A replication fork is:
A. Only seen in bacterial cells
B. A Y-shaped structure where both DNA strands are replicated simultaneously
C. A site where one DNA strand serves as a template, but the other strand is not replicated
D. Created by the action of the enzyme RNA polymerase

Answer 49

B. A Y-shaped structure where both DNA strands are replicated simultaneously
Rationale: The replication fork is the area where the DNA double helix is unwound, and both strands are simultaneously replicated.

Question 50

The TATA box in eukaryotes is located:
A. 10 base pairs (bp) upstream from the transcription start site (TSS)
B. 35 bp upstream from the TSS
C. 25-30 bp upstream from the TSS
D. 5 bp upstream from the TSS

Answer 50

C. 25-30 bp upstream from the transcription start site (TSS)
Rationale: The TATA box is a DNA sequence found about 25-30 base pairs upstream of the transcription start site and is crucial for the initiation of transcription.

Question 51

True of the characteristics of antibodies, EXCEPT:
A. Expressed on the surface of B-lymphocytes
B. Predominate the primary immune response to antigens
C. Molecules with a single, defined amino acid sequence
D. Are glycoproteins

Answer 51

C. Molecules with a single, defined amino acid sequence
Rationale: Antibodies are glycoproteins that are expressed on the surface of B-lymphocytes and predominate in the primary immune response to antigens. They have variable regions allowing for diversity in antigen binding, not a single defined amino acid sequence.

Question 52

An important feature of a cell-mediated immune response against an antigen:
A. Requires first exposure to an antigen
B. A latent period follows the initial exposure to an antibody generator
C. Helper T-cells synthesize and secrete chemokines like interleukin, interferon
D. A particular response may last for years

Answer 52

C. Helper T-cells synthesize and secrete chemokines like interleukin, interferon
Rationale: Helper T-cells are crucial in cell-mediated immunity as they release chemokines such as interleukins and interferons to activate other immune cells.

Question 53

A cell whose primary function is the development of cell-mediated immunity:
A. Granulocytes
B. Macrophages
C. T lymphocytes
D. Monocytes

Answer 53

C. T lymphocytes
Rationale: T lymphocytes are primarily responsible for cell-mediated immunity, recognizing and responding to infected or abnormal cells.

Question 54

An example of a natural type of immunity:
A. Acquired from the mother
B. After having vaccinated
C. Result from exposure to antigen
D. Injection of IgG

Answer 54

A. Acquired from the mother
Rationale: Natural immunity includes passive immunity acquired from the mother through the placenta or breast milk.

Question 55

Humoral immune response is initiated by:
A. Antigen-antibody complex formation on the surface of mature B cell
B. Antigen binds antibody on the surface of mature T cell
C. Upon the formation of plasma cells that secrete antibodies
D. Upon secretion of immunoglobulins

Answer 55

A. Antigen-antibody complex formation on the surface of mature B cell
Rationale: The humoral immune response begins when an antigen binds to antibodies on the surface of B cells, leading to their activation and the production of plasma cells that secrete antibodies.

Question 56

The Ig involved in host defense against helminthic infections:
A. IgM
B. IgG
C. IgA
D. IgE

Answer 56

D. IgE
Rationale: IgE plays a crucial role in the defense against parasitic helminths and is also involved in allergic reactions.

Question 57

The antibody present in secretions like tears, saliva, and colostrum is:
A. IgM
B. IgG
C. IgA
D. IgE

Answer 57

C. IgA
Rationale: IgA is the main immunoglobulin found in mucosal secretions, providing protection against pathogens at mucosal surfaces.

Question 58

Which of the following statement/s is/are true of IgM?
A. It is a pentamer and is called the ‘natural antibody’
B. Exists as a monomer on B cell surface
C. Is involved in early primary immune response
D. All of the above

Answer 58

D. All of the above
Rationale: IgM is a pentamer and acts as the ‘natural antibody’, exists as a monomer on the B cell surface, and is involved in the early primary immune response.

Question 59

Which is the Ig that crosses the placenta and provides passive immunity to newborns?
A. IgM
B. IgG
C. IgA
D. IgE

Answer 59

B. IgG
Rationale: IgG is the only immunoglobulin that can cross the placenta, providing passive immunity to the fetus and newborn.

Question 60

Which of the following IgG is targeted against polysaccharides of encapsulated bacteria?
A. IgG1
B. IgG2
C. IgG3
D. IgG4

Answer 60

B. IgG2
Rationale: IgG2 is particularly effective against polysaccharide antigens of encapsulated bacteria.

Question 61

Hemostasis and thrombosis have phases that are common to each other, which includes:
A. Formation of a loose and temporary platelet aggregate at the site of injury
B. Formation of a fibrin mesh that binds to the platelet aggregate, forming a more stable hemostatic plug or thrombus
C. Partial or complete dissolution of the hemostatic plug or thrombus by plasmin
D. All of the above

Answer 61

D. All of the above
Rationale: Hemostasis and thrombosis both involve the formation of a platelet aggregate, the creation of a fibrin mesh, and the eventual dissolution of the clot by plasmin.

Question 62

This stage of hemostasis is considered to be the primary hemostatic mechanism:
A. Vascular phase
B. Platelet phase
C. Coagulation phase
D. All of the above

Answer 62

B. Platelet phase
Rationale: The platelet phase is the initial response to vascular injury, involving the adhesion, activation, and aggregation of platelets to form a temporary plug.

Question 63

Disseminated fibrin deposits are mostly found in:
A. Very small blood vessels or capillaries
B. Arteries
C. Veins
D. All of the above

Answer 63

A. Very small blood vessels or capillaries
Rationale: Disseminated fibrin deposits, as seen in disseminated intravascular coagulation (DIC), are primarily found in small blood vessels and capillaries.

Question 64

Thrombosis occurs when the endothelium lining the blood vessels is damaged or removed. The resulting red thrombus from this event is usually characterized as:
A. Composed of platelets and fibrin
B. Relatively poor in erythrocytes
C. It forms at the site of an injury or abnormal vessel wall, particularly in areas where blood flow is rapid
D. None of the above

Answer 64

D. None of the above
Rationale: A red thrombus, typically rich in erythrocytes, forms under conditions of low flow and is often found in venous thrombosis rather than arterial.

Question 65

The coenzyme for cytochrome P450 is:
A. FADH
B. NADH
C. NADPH
D. GSH

Answer 65

C. NADPH
Rationale: NADPH provides the reducing equivalents for cytochrome P450 enzymes involved in oxidative reactions.

Question 66

Cytochrome P450s are located in what part of the cell?
A. Cytosol
B. Nucleus
C. Smooth endoplasmic reticulum
D. Lysosomes

Answer 66

C. Smooth endoplasmic reticulum
Rationale: Cytochrome P450 enzymes are primarily found in the smooth endoplasmic reticulum of cells, particularly in the liver.

Question 67

All of the following are properties of human cytochrome P450s, EXCEPT:
A. All are hemoproteins
B. Exhibit broad substrate specificity
C. Catalyze reactions involving the introduction of two atoms of oxygen into the substrate and one into water
D. Extremely versatile catalysts

Answer 67

C. Catalyze reactions involving the introduction of two atoms of oxygen into the substrate and one into water
Rationale: Cytochrome P450 enzymes typically catalyze the introduction of one atom of oxygen into the substrate and reduce the other atom to water.

Question 68

The main organ involved in the metabolism of xenobiotics:
A. Adrenal glands
B. Stomach
C. Kidney
D. Liver

Answer 68

D. Liver
Rationale: The liver is the primary organ responsible for the metabolism of xenobiotics, using enzymes such as cytochrome P450s.

Question 69

Conversion of xenobiotics from inactive to biologically active compounds:
A. Conjugation
B. Epoxidation
C. Metabolic transformation
D. Metabolic activation

Answer 69

D. Metabolic activation
Rationale: Metabolic activation refers to the conversion of xenobiotics to their active forms, which can sometimes be more toxic than the parent compound.

Question 70

In Phase 1 of the metabolism of Xenobiotics, the major reaction involved is:
A. Deamination
B. Epoxidation
C. Hydroxylation
D. Methylation

Answer 70

C. Hydroxylation
Rationale: Phase 1 metabolism often involves hydroxylation, which introduces an OH group to the xenobiotic, increasing its solubility and preparing it for further reactions.

Phase I metabolism consists of reduction, oxidation, or hydrolysis reactions.

Question 71

In Phase 2 of the metabolism of Xenobiotics, the products of Phase 1 are converted by specific enzymes to various metabolites by the process of:
A. Conjugation
B. Methylation
C. Peroxygenation
D. Dehalogenation

Answer 71

A. Conjugation
Rationale: Phase 2 metabolism involves conjugation, where Phase 1 metabolites are linked with endogenous molecules to increase their solubility and facilitate excretion.

Question 72

What determines the class of an immunoglobulin?
A. The heavy chain type
B. The protein present in the structure
C. The antigen that it binds
D. The carbohydrate (CHO) attached to the light chains

Answer 72

A. The heavy chain type
Rationale: The class of an immunoglobulin (IgA, IgG, IgM, etc.) is determined by the type of heavy chain it contains.

Question 73

Light chains are:
A. Specific for each class of antibody
B. Reactive with the antigen
C. Not specific for each class of antibody
D. Composed of one constant region

Answer 73

C. Not specific for each class of antibody
Rationale: Light chains (either kappa or lambda) are not class-specific and can be found in all classes of antibodies.

Question 74

The final product of DNA replication is:
A. mRNA, tRNA, and rRNA molecules
B. A wide variety of proteins
C. DNA molecule
D. 2 DNA molecules, each of which contains one new and one old DNA strand

Answer 74

D. 2 DNA molecules, each of which contains one new and one old DNA strand
Rationale: DNA replication results in two DNA molecules, each composed of one original strand and one newly synthesized strand (semi-conservative replication).

Question 75

Prokaryotic transcription promoters are:
A. Can have variable location
B. Responsible for both initiation and termination
C. Located downstream of the gene
D. Located upstream of the gene.

Answer 75

D. Located upstream of the gene.
Rationale: Promoters in prokaryotes are sequences located upstream (5’ direction) of the gene they regulate.

Question 75

Removal of intervening sequences and splicing together of final sequences are done by:
A. Spliceosome
B. Nucleosome
C. Ribosome
D. None

Answer 75

A. Spliceosome
Rationale: Spliceosomes are complexes responsible for removing introns (intervening sequences) and splicing exons together in pre-mRNA.

Question 75

What does the term DNA cloning refer to?
A. Ligating a DNA fragment of interest into a vector, such as a plasmid
B. Cutting DNA molecules with restriction nucleases
C. The act of making many identical copies of a DNA molecule
D. Putting a foreign gene into a cell

Answer 75

C. The act of making many identical copies of a DNA molecule
Rationale: DNA cloning involves making multiple identical copies of a DNA segment.

Question 76

Which of these is referred to as a linker histone?
A. H1
B. H2
C. H3
D. H4

Answer 76

A. H1
Rationale: Histone H1 is known as the linker histone because it binds to the linker DNA between nucleosomes, helping to compact the chromatin.

Question 77

The chemical nature of RNA differs from that of DNA:
A. Ribonucleic acid (RNA) is a polymer of purine and pyrimidine ribonucleotides linked together by 3-5’-phosphodiester bonds analogous to those in DNA
B. In RNA, the sugar moiety to which the phosphates and purine and pyrimidine bases are attached is the 2’-deoxyribose of DNA rather than ribose
C. The pyrimidine components of RNA are similar to those of DNA
D. Both DNA and RNA can be hydrolyzed by alkali to 2’-3’ cyclic diesters of the mononucleotides

Answer 77

A. Ribonucleic acid (RNA) is a polymer of purine and pyrimidine ribonucleotides linked together by 3-5’-phosphodiester bonds analogous to those in DNA
Rationale: RNA consists of ribonucleotides linked by 3’-5’ phosphodiester bonds, similar to DNA, but with ribose as the sugar.

Question 78

The termination protein is also called:
A. Psi factor
B. Rho factor
C. Sigma factor
D. Alpha factor

Answer 78

B. Rho factor
Rationale: The Rho factor is a protein involved in terminating transcription in prokaryotes.

Rho = Termination
Sigma = Initiation

Question 79

The coding strand is also called the:
A. Template strand
B. Non-template strand
C. Double-strand
D. None

Answer 79

B. Non-template strand
Rationale: The coding strand (or non-template strand) is the DNA strand whose base sequence corresponds to the base sequence of the RNA transcript produced (though with thymine replaced by uracil).

Question 80

Follows the Watson-Crick base pairing rule for RNA synthesis:
A. Adenine to Uracil
B. Cytosine to Adenine
C. Guanosine to Uracil
D. Adenine to Thymine

Answer 80

A. Adenine to Uracil
Rationale: In RNA synthesis, adenine pairs with uracil instead of thymine.

Question 81

Which of the following best describes a benign tumor?
A. Invades surrounding tissues
B. Spreads via lymphatics
C. Cells clustered in a single enclosed mass
D. Metastasizes

Answer 81

C. Cells clustered in a single enclosed mass
Rationale: Benign tumors are typically characterized by cells that remain clustered in a single mass and do not invade surrounding tissues or metastasize.

Question 82

Which pathway is more active in cancer cells compared to non-cancer cells?
A. Glycogenesis
B. Glycolysis
C. Pentose phosphate pathway
D. Lipogenesis

Answer 82

B. Glycolysis
Rationale: Cancer cells often have increased glycolysis rates to meet their high energy demands, even in the presence of oxygen (known as the Warburg effect).

Question 83

Which cell does not have regenerative capacity?
A. Neuron
B. Nephron
C. Hepatocyte
D. Enterocyte

Answer 83

A. Neuron
Rationale: Neurons generally do not regenerate once they are lost, unlike other cells such as hepatocytes and enterocytes.

Question 84

These carcinogens act by introducing novel genes into normal cells:
A. Radiant energy
B. Chemicals
C. Oncogenic viruses
D. None of the above

Answer 84

C. Oncogenic viruses
Rationale: Oncogenic viruses can introduce new genes into host cells, leading to uncontrolled cell growth and cancer.

Question 85

Which statement is not associated with an enhanced risk of developing skin cancer?
A. Increases with increased frequency of exposure
B. Increases with increased intensity of exposure
C. Increases with increased melanin content of skin
D. Increases depending on the time of exposure to the sun

Answer 85

C. Increases with increased melanin content of skin
Rationale: Increased melanin content actually provides some protection against UV radiation and lowers the risk of skin cancer.

Question 86

Which does NOT characterize White thrombi?
A. Have a fast rate of formation
B. Have a firm consistency
C. Associated in the arterial system of circulation
D. Have a hard consistency

Answer 86

A. Have a fast rate of formation
Rationale: White thrombi typically form slowly under high shear stress conditions found in arterial circulation. They are characterized by a firm consistency, are associated with the arterial system of circulation, and have a hard consistency, but they do not have a fast rate of formation.

Question 87

Which statement does NOT characterize the phases common to both Hemostasis and Thrombosis?
A. Formation of a loose and Permanent platelet aggregate at the site of injury
B. Formation of a fibrin mesh that binds to the platelet aggregate, forming a more stable hemostatic plug or thrombus
C. Partial dissolution of the hemostatic plug or thrombus by plasmin
D. Complete dissolution of the hemostatic plug or thrombus by plasmin

Answer 87

A. Formation of a loose and Permanent platelet aggregate at the site of injury
Rationale: The formation of a loose and temporary platelet aggregate is part of the initial response, not a permanent solution.

Question 88

Which is not a feature of von Willebrand factor?
A. Glues platelets to damaged endothelium
B. Binds and protects Factor IX
C. Is secreted by endothelial cells into the plasma
D. None of the above

Answer 88

B. Binds and protects Factor IX
Rationale: von Willebrand factor primarily binds and protects Factor VIII, not Factor IX. It also glues platelets to damaged endothelium and is secreted by endothelial cells into the plasma.

Question 89

The entropy will usually increase when:
A. A molecule is broken into two or more smaller molecules.
B. A reaction occurs that results in an increase in the number of moles of gas.
C. A solid changes to a liquid.
D. A liquid changes to a gas.
E. All of the above

Answer 89

E. All of the above
Rationale: Entropy increases when a molecule is broken into smaller molecules, when a reaction increases the number of gas moles, when a solid changes to a liquid, and when a liquid changes to a gas.

Question 90

Which one of the following thermodynamic quantities is not a state function?
A. Gibbs free energy
B. Enthalpy
C. Entropy
D. Internal energy
E. Work

Answer 90

E. Work
Rationale: Work is not a state function because it depends on the path taken, whereas Gibbs free energy, enthalpy, entropy, and internal energy are state functions.

Question 91

These encode proteins that normally suppress cell growth but are inactivated when altered by mutations:
A. Procarcinogen
B. Proto-oncogenes
C. Tumor suppressor genes
D. Oncogenes

Answer 91

C. Tumor suppressor genes
Rationale: Tumor suppressor genes encode proteins that regulate cell growth and division, preventing tumor formation. When these genes are mutated, they lose this regulatory ability.

Question 92

Basal metabolic rate:
A. Energy used during digestion, absorption, and metabolism of food
B. Energy needed to maintain basic physiologic functions under standard conditions
C. Energy used during movement and muscle contraction
D. Energy used for muscles and growth of body organs

Answer 92

B. Energy needed to maintain basic physiologic functions under standard conditions
Rationale: Basal metabolic rate (BMR) is the amount of energy expended while at rest in a neutrally temperate environment, in the post-absorptive state.

Question 93

Wernicke-Korsakoff Syndrome:
A. Defective transketolase enzyme
B. Seen primarily in alcoholics
C. Masked chronic thiamine deficiency
D. All of the above

Answer 93

D. All of the above
Rationale: Wernicke-Korsakoff Syndrome is associated with a defective transketolase enzyme, is seen primarily in alcoholics, and is caused by chronic thiamine deficiency.

Question 94

The genetic code is said to be unambiguous because:
A. A specific codon always codes for the same amino acid
B. The genetic code has been conserved from the very early stages of evolution
C. All amino acids always have only one triplet code
D. The code is always read from a fixed starting point

Answer 94

A. A specific codon always codes for the same amino acid
Rationale: The genetic code is unambiguous because each codon specifies only one amino acid.

Question 95

Which laboratory test measures the intrinsic pathway?
A. Partial thromboplastin time (aPTT or PTT)
B. Prothrombin time (PT)
C. Thrombin time (TT)
D. Bleeding time (BT)

Answer 95

A. Partial thromboplastin time (aPTT or PTT)
Rationale: aPTT is used to measure the intrinsic pathway of coagulation.

Question 96

The final common pathway in the complement system involves which of the following?
A. The formation of the membrane attack complex
B. Increased vasodilation and permeability of capillary beds
C. Vasodilation and permeability of capillary beds
D. All are true

Answer 96

A. The formation of the membrane attack complex
Rationale: The final common pathway in the complement system involves the formation of the membrane attack complex (MAC), which creates pores in the cell membrane of pathogens, leading to cell lysis.

Question 97

Responsible for removing introns in primary RNA transcripts:
A. Endonuclease
B. Exonuclease
C. Ribozymes
D. P bodies

Answer 97

A. Endonuclease
Rationale: Endonucleases are enzymes that cut RNA at specific internal sites, which is a crucial step in the process of removing introns from primary RNA transcripts. Spliceosomes, which include ribonucleoproteins with endonuclease activity, carry out this process.

Question 98

This inhibits the Carboxylation of Vitamin K-Dependent Factors:
A. Coumarin Anticoagulants
B. Vitamin K
C. Heparin
D. Protamine

Answer 98

A. Coumarin Anticoagulants
- Rationale: Coumarin anticoagulants, such as warfarin, inhibit the carboxylation of vitamin K-dependent clotting factors, thereby preventing blood clot formation.