MDCAT 2024 Biology

MDCAT 2024 Biology Past Paper MCQs with Answers

192 Biology MCQs that appeared in MDCAT 2024, arranged unit by unit in syllabus order. Tap “Show answer” under any question for the correct option and a short solution.

Acellular Life

1.An example of a virus having a polyhedral capsid with 252 capsomeres is: (MDCAT 2024)

  1. adenovirus
  2. tobacco mosaic virus
  3. influenza virus
  4. bacteriophage
Show answer

Correct answer: (a) adenovirus

The adenovirus capsid is an icosahedron built of 252 capsomeres.

2.The causative organism of measles is: (MDCAT 2024)

  1. poxvirus
  2. papovavirus
  3. picornavirus
  4. paramyxovirus
Show answer

Correct answer: (d) paramyxovirus

Measles is caused by the measles virus, a paramyxovirus.

3.In the life cycle of a bacteriophage, lysozyme is required in which step of the infection process? (MDCAT 2024)

  1. release of the new phages
  2. penetration
  3. replication
  4. adsorption
Show answer

Correct answer: (b) penetration

The enzyme digests a hole in the bacterial wall so the phage DNA can be injected.

4.Example of viruses having a polyhedral capsid that is with 252 capsomeres is: (UHS MDCAT 2024)

  1. Adenovirus
  2. Tobacco Mosaic Virus
  3. Influenza virus
  4. Bacteriophage
Show answer

Correct answer: (a) Adenovirus

The adenovirus capsid is an icosahedron built of 252 capsomeres.

5.In the life cycle of a bacteriophage, the lysozymes are required in which of the following steps of infection process? (UHS MDCAT 2024)

  1. Genome injection
  2. Penetration
  3. Replication
  4. Adsorption
Show answer

Correct answer: (b) Penetration

The tail lysozyme digests a hole in the bacterial wall so the genome can be driven in.

6.The genetic code of ________ is bound by a lipid membrane? (KMU MDCAT 2024)

  1. Enterovirus
  2. Flu virus
  3. Hepatitis A virus
  4. Polio virus
Show answer

Correct answer: (b) Flu virus

The influenza virus takes a lipid envelope from the host membrane; the picornaviruses are naked.

7.Viruses Can NOT _______. (KMU MDCAT 2024)

  1. Crystalize
  2. Excrete
  3. Infect bacteria
  4. Mutate
Show answer

Correct answer: (b) Excrete

A virus has no metabolism of its own, so it neither feeds nor excretes.

8.Which of the following is NOT true about viruses? (KMU MDCAT 2024)

  1. Contain DNA
  2. Can replicate on their own
  3. Can infect bacteria
  4. They have a sub-cellular structure
Show answer

Correct answer: (b) Can replicate on their own

A virus can only be copied inside a host cell, using the machinery of that cell.

9.Which of the following virus has a double stranded DNA genome? (NUMS MDCAT 2024)

  1. Rubella
  2. Influenza
  3. HIV
  4. Small pox
Show answer

Correct answer: (d) Small pox

The smallpox virus carries double stranded DNA; the other three are RNA viruses.

10.Which one is transmitted through infected blood and hypodermic syringes? (MDCAT 2024)

  1. HIV
  2. influenza virus
  3. morbillivirus (measles)
  4. Vibrio cholerae (cholera)
Show answer

Correct answer: (a) HIV

HIV travels in blood and body fluids, so shared needles pass it on.

11._______ is transmitted through infected blood and hypodermic syringes. (UHS MDCAT 2024)

  1. HIV
  2. Influenza Virus
  3. Morbilli Virus (Measles)
  4. Vibrio Cholerae (Cholera)
Show answer

Correct answer: (a) HIV

HIV travels in blood, so transfusions and shared needles carry it.

12.Where are the enzymes required for the replication of HIV virus located? (KMU MDCAT 2024)

  1. In the protein spikes
  2. Surrounding the viral core
  3. Inside the capsid
  4. Outside the capsid
Show answer

Correct answer: (c) Inside the capsid

Reverse transcriptase and integrase are packed inside the capsid with the RNA.

Bioenergetics

13.The process of ATP synthesis through a combination of electrochemical and osmotic events is known as: (KMU MDCAT 2024)

  1. Fermentation
  2. Glycolysis
  3. Oxidative phosphorylation
  4. Oxidation of pyruvate to acetyl CoA
Show answer

Correct answer: (c) Oxidative phosphorylation

Electrons passed down the chain pump protons, and their return through ATP synthase makes the ATP.

14.During glycolysis, isomerization takes place in the formation of: (NUMS MDCAT 2024)

  1. Dihydroxyacetone phosphate and 2-phosphoglycerate
  2. G3P and fructose 6-phosphate
  3. PEP and pyruvate
  4. Fructose 6-phosphate and 3-phosphoglycerate
Show answer

Correct answer: (b) G3P and fructose 6-phosphate

Glucose 6-phosphate is isomerized to fructose 6-phosphate, and dihydroxyacetone phosphate to G3P.

15.Fats and proteins are metabolized via — which of the following serves as common duct for both metabolisms? (NUMS MDCAT 2024)

  1. Acetyl-CoA
  2. Pyruvate
  3. G3P
  4. Lactate
Show answer

Correct answer: (a) Acetyl-CoA

Fatty acids and most amino acids are cut down to acetyl coenzyme A before entering the Krebs cycle.

Biological Molecules

16.What is the percentage of water in bone cells? (MDCAT 2024)

  1. 70%
  2. 20%
  3. 98%
  4. 60%
Show answer

Correct answer: (b) 20%

Bone is the least watery of the tissues, with about a fifth of its weight as water.

17.Monosaccharides have a general formula represented by: (MDCAT 2024)

  1. $\mathrm{C_n(H_2O)_n}$
  2. $\mathrm{C(H_2O)_n}$
  3. $\mathrm{C_6(H_2O)_n}$
  4. $\mathrm{C_n(H_2O)}$
Show answer

Correct answer: (a) $\mathrm{C_n(H_2O)_n}$

A monosaccharide carries one water for every carbon, which is what "carbohydrate" means.

18.Polysaccharides in plants are synthesized by the process of: (MDCAT 2024)

  1. hydrolysis
  2. oxidation
  3. condensation
  4. glycolysis
Show answer

Correct answer: (c) condensation

Each glycosidic bond is made by removing a molecule of water between two sugars.

19.Which monosaccharide will from a gluco pyranose ring in solution? (UHS MDCAT 2024)

  1. Fructose
  2. Glucose
  3. Ribose
  4. Deoxyribose
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Correct answer: (b) Glucose

Glucose closes into a six membered ring, the glucopyranose form.

20.Sugarcane contains ________. (KMU MDCAT 2024)

  1. Fructose
  2. Glucose
  3. Ribose
  4. Sucrose
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Correct answer: (d) Sucrose

Cane sugar is sucrose, a disaccharide of glucose and fructose.

21.Loss of reactivity of sucrose is due to its: (NUMS MDCAT 2024)

  1. High solubility in water
  2. Polar nature
  3. Unavailability of functional group
  4. Alpha 1-2 Glycosidic linkage
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Correct answer: (d) Alpha 1-2 Glycosidic linkage

Both anomeric carbons are locked in the alpha 1,2 link, so sucrose has no free aldehyde group left.

22.Which of the following processes is involved in the breakdown of protein into amino acids? (MDCAT 2024)

  1. condensation
  2. hydrolysis
  3. glycolysis
  4. fixation
Show answer

Correct answer: (b) hydrolysis

A molecule of water is added across each peptide bond to break it.

23.Which of the following process Is involved in breakdown of protein into Amino acids? (UHS MDCAT 2024)

  1. Condensation
  2. Hydrolysis
  3. Glycolysis
  4. Fixation
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Correct answer: (b) Hydrolysis

Hydrolysis adds water across each peptide bond and frees the amino acids.

24.Sickle cell anaemia results from? (KMU MDCAT 2024)

  1. Reduction in oxygen carrying capacity of haemoglobin
  2. Linkage between the polypeptide chains
  3. Single amino acid substitution in the haemoglobin molecule
  4. Viral infections of RNA viruses
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Correct answer: (c) Single amino acid substitution in the haemoglobin molecule

A single valine in place of glutamic acid in the beta chain is the whole of the change.

25.Which is INCORRECT about the globular proteins? (KMU MDCAT 2024)

  1. Abundantly found in hair
  2. Are spherical in shape
  3. Have polypeptide chains
  4. Soluble in water
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Correct answer: (a) Abundantly found in hair

Hair is keratin, a fibrous protein; globular proteins are the soluble, rounded ones.

26.Protein present in haemoglobin has _______ structure. (KMU MDCAT 2024)

  1. Primary
  2. Secondary
  3. Tertiary
  4. Quaternary
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Correct answer: (d) Quaternary

Haemoglobin has four polypeptide chains fitted together, which is quaternary structure.

27.Proteins with tertiary structure are helpful in: (NUMS MDCAT 2024)

  1. Carrying messages from glands to target organs
  2. Maintaining epithelial lining of skin
  3. Making the matrix of connective tissue
  4. Helping muscle contraction
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Correct answer: (a) Carrying messages from glands to target organs

Peptide hormones are globular proteins folded into a tertiary shape that their receptors recognize.

28.Rebounding is process of straightening the curly hairs. Which bond is targeted by oxidizing agents used during this process? (NUMS MDCAT 2024)

  1. Peptide bond
  2. Ionic bond
  3. Disulphide bridge
  4. Hydrogen bond
Show answer

Correct answer: (c) Disulphide bridge

The curl of hair is held by disulphide bridges, and the oxidizing agent breaks and remakes them.

29.Ions of heavy metal are harmful for living organisms because of their ability to: (NUMS MDCAT 2024)

  1. Cleave nucleic acid
  2. Interfere with fat metabolism
  3. Break glycosidic bonds
  4. Destabilize proteins
Show answer

Correct answer: (d) Destabilize proteins

Heavy metal ions bind the sulphydryl groups and unfold the protein.

30.When glycerol reacts with a fatty acid, which type of chemical bond is formed? (MDCAT 2024)

  1. ester bond
  2. ether bond
  3. hydrogen bond
  4. ionic bond
Show answer

Correct answer: (a) ester bond

The acid and the alcohol condense to an ester, with water as the other product.

31.The hydrophilic end of a phospholipid molecule is polar because of the presence of: (MDCAT 2024)

  1. glycerol
  2. an amine group
  3. a fatty acid
  4. a phosphate group
Show answer

Correct answer: (d) a phosphate group

The charged phosphate head is what faces the water.

32.When glycerol reacts with fatty acid, which type of chemical bond will form? (UHS MDCAT 2024)

  1. Ester Bond
  2. Ether Linkage
  3. Hydrogen Bond
  4. Ionic Bond
Show answer

Correct answer: (a) Ester Bond

A fatty acid and an alcohol group condense into an ester linkage, with water lost.

33.The hydrophilic end of phospholplid molecule is polar because of the presence of (UHS MDCAT 2024)

  1. Glycerol
  2. Amine group
  3. Fatty Acid
  4. Phosphate group
Show answer

Correct answer: (d) Phosphate group

The phosphate group carries a charge, which is what makes that end water loving.

34.What is the ester of fatty acids and long chain alcohol called? (KMU MDCAT 2024)

  1. Acylglycerol
  2. Glycerol
  3. Phospholipid
  4. Wax
Show answer

Correct answer: (d) Wax

A wax is the ester of a long chain fatty acid with a long chain alcohol.

35.Lipids, which do not contain fatty acid are: (KMU MDCAT 2024)

  1. Neutral lipids
  2. Phosphatidic acids
  3. Steroids
  4. Waxes
Show answer

Correct answer: (c) Steroids

Steroids are built on a four ring skeleton and carry no fatty acid at all.

Cell Structure and Function

36.Plasma membrane is differentially permeable membrane due to the presence of? (KMU MDCAT 2024)

  1. Carbohydrates
  2. Lipids
  3. Proteins
  4. Vitamins
Show answer

Correct answer: (b) Lipids

The lipid bilayer lets small non-polar molecules through and holds ions and polar molecules back.

37.Which function cannot be attributed to plasma membrane lipids? (NUMS MDCAT 2024)

  1. Recognition of cells having non-self surface markers
  2. Maintaining cell membrane flexibility
  3. Control of metabolic reaction across cell membrane
  4. Binding ligands for intracellular response
Show answer

Correct answer: (c) Control of metabolic reaction across cell membrane

Lipids make the bilayer and keep it fluid; controlling what crosses it is the work of the proteins.

38.Which one is the function of plasma membrane proteins? (NUMS MDCAT 2024)

  1. Restrict entry of polar molecules
  2. Prevention of freezing during cold weather
  3. Movement of ions in and out of the cell
  4. Maintenance of membrane flexibility
Show answer

Correct answer: (c) Movement of ions in and out of the cell

Channel and carrier proteins are what let ions cross the lipid bilayer.

39.Prokaryotic cells lack: (MDCAT 2024)

  1. mesosomes
  2. ribosomes
  3. storage bodies
  4. membrane bound organelles
Show answer

Correct answer: (d) membrane bound organelles

They have ribosomes and inclusions, but no nucleus, mitochondria or other membrane bound organelle.

40.Which option is CORRECT about an endospore? (MDCAT 2024)

  1. it has a short dormant period
  2. it contains moisture for survival
  3. it is metabolically active
  4. it endures extreme conditions
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Correct answer: (d) it endures extreme conditions

The endospore is dry and dormant, and survives heat, drought and disinfectants for years.

41.Mesosomes are invaginations of which bacterial cell structure? (MDCAT 2024)

  1. cell wall
  2. cell membrane
  3. plasmid
  4. cyst
Show answer

Correct answer: (b) cell membrane

They are folds of the plasma membrane that carry respiratory enzymes.

42.Respiration in Pseudomonas bacteria is (UHS MDCAT 2024)

  1. Aerobic
  2. Anaerobic
  3. Facultative
  4. Microaerophili
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Correct answer: (a) Aerobic

Pseudomonas needs oxygen to respire, so it is an aerobe.

43.Bacterial genome becomes diploid: (UHS MDCAT 2024)

  1. After fertilization of gametes
  2. Before spore formation
  3. During binary fission
  4. After binary fission
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Correct answer: (c) During binary fission

The chromosome is copied before the cell divides, so for a while there are two of it.

44.Which option is CORRECT about endospore? (UHS MDCAT 2024)

  1. Has a short dormant period
  2. Contains moisture for survival
  3. Metabolically actively
  4. Endures extreme condition
Show answer

Correct answer: (d) Endures extreme condition

An endospore has almost no water and a tough coat, so it survives heat and drying for years.

45.Bacteria divide at exponential rate during which growth phase? (UHS MDCAT 2024)

  1. Lag
  2. Log
  3. Stationary
  4. Decline
Show answer

Correct answer: (b) Log

Numbers double at a constant interval in the log, or exponential, phase.

46.Mesosomes are the invagination of bacterial cell structure (UHS MDCAT 2024)

  1. Cell wall
  2. Cell membrane
  3. Plasmid
  4. Cysts
Show answer

Correct answer: (b) Cell membrane

A mesosome is an infolding of the cell membrane of a bacterium.

47.The peptidoglycan cell wall is specific to. (KMU MDCAT 2024)

  1. Amoeba
  2. Bacteria
  3. Protozoa
  4. Virus
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Correct answer: (b) Bacteria

Peptidoglycan, a mesh of sugars and peptides, is the bacterial cell wall.

48.Bacteria that lack flagella are called? (KMU MDCAT 2024)

  1. Amphitrichous
  2. Atrichious
  3. Lopho
  4. Peritrichous
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Correct answer: (b) Atrichious

A bacterium with no flagellum at all is atrichous.

49.Antibiotics can be used against: (KMU MDCAT 2024)

  1. Herpes simplex
  2. Influenza
  3. Polio
  4. Salmonella typhi
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Correct answer: (d) Salmonella typhi

Antibiotics act on bacteria such as Salmonella typhi; they do nothing to viruses.

50.Which of the following is NOT true about plasmids found in streptococci? (KMU MDCAT 2024)

  1. Carry fewer genes than the chromosome
  2. Replicate autonomously from the chromosome
  3. They are considered as genetic element
  4. The bacterial chromosome depends on plasmids for replication
Show answer

Correct answer: (d) The bacterial chromosome depends on plasmids for replication

A plasmid copies itself; the chromosome does not depend on it for anything.

51.Which of the following bacteria produces endospores? (KMU MDCAT 2024)

  1. Both gram negative and positive bacteria
  2. Gram negative
  3. Gram positive
  4. Mycobacteria
Show answer

Correct answer: (c) Gram positive

Endospores are made by gram positive genera such as Bacillus and Clostridium.

52.All are the characteristics responsible for better survival of encapsulated bacteria except: (NUMS MDCAT 2024)

  1. High pathogenicity
  2. Withstand dehydration
  3. Strict adhesion to internal surfaces
  4. Easy recognition by host
Show answer

Correct answer: (d) Easy recognition by host

The capsule hides the surface markers, so it makes the bacterium harder for the host to recognize.

53.Chloroplasts are membrane bound bodies containing: (MDCAT 2024)

  1. enzymes
  2. cisternae
  3. pigment
  4. cristae
Show answer

Correct answer: (c) pigment

The thylakoid membranes carry chlorophyll and the accessory pigments.

54.Which of the following is the function of the Golgi complex? (MDCAT 2024)

  1. intracellular digestion
  2. autophagy
  3. autolysis
  4. processing of cell secretions
Show answer

Correct answer: (d) processing of cell secretions

The Golgi apparatus modifies, sorts and packages what the cell is about to secrete.

55.The organelles found only at the seedling stage in oil seed plants are: (MDCAT 2024)

  1. peroxisomes
  2. glyoxisomes
  3. microbodies
  4. vacuoles
Show answer

Correct answer: (b) glyoxisomes

Glyoxisomes turn stored fat into sugar while the seedling has no leaves of its own.

56.One of the following is CORRECT regarding flagella: (MDCAT 2024)

  1. they are made up of macrofilaments
  2. they contain a centriole
  3. they originate from basal bodies
  4. they are immotile
Show answer

Correct answer: (c) they originate from basal bodies

A eukaryotic flagellum grows from a basal body of the same nine-triplet structure as a centriole.

57.Which of the following is the function of Golgi Complex? (UHS MDCAT 2024)

  1. Intracellular digestion
  2. Autophagy
  3. Autolysis
  4. Processing of cell secretions
Show answer

Correct answer: (d) Processing of cell secretions

The Golgi body modifies, packages and dispatches the secretions of the cell.

58.The organelles only found at seeding stage in oil seed plants are (UHS MDCAT 2024)

  1. Peroxiosomes
  2. Glyoxisomes
  3. Microbodies
  4. Vacuoles
Show answer

Correct answer: (b) Glyoxisomes

Glyoxysomes appear in germinating oil seeds, where they turn stored fat into sugar.

59.Which organelle contribute towards steroid production? (KMU MDCAT 2024)

  1. Endoplasmic Reticulum
  2. Golgi apparatus
  3. Lysosome
  4. Ribosomes
Show answer

Correct answer: (a) Endoplasmic Reticulum

Steroid hormones are made on the smooth endoplasmic reticulum.

60.The lysosomes found in eukaryotes contain: (KMU MDCAT 2024)

  1. Hydrolytic enzymes
  2. Meiotic enzymes
  3. Oxidative enzymes
  4. Mitotic enzymes
Show answer

Correct answer: (a) Hydrolytic enzymes

A lysosome is a bag of hydrolytic enzymes.

61.Which cytoplasmic organelle make their own proteins? (KMU MDCAT 2024)

  1. Chromosomes
  2. Golgi apparatus
  3. Mitochondria
  4. Smooth endoplasmic reticulum
Show answer

Correct answer: (c) Mitochondria

Mitochondria carry their own DNA and ribosomes and make some of their own proteins.

62.The active mass movement of mitochondria in the cytoplasm is due to (KMU MDCAT 2024)

  1. Cyclosis
  2. Endoplasmic streaming movements
  3. Golgi apparatus
  4. Transfer RNA
Show answer

Correct answer: (a) Cyclosis

Cyclosis is the streaming of the cytoplasm that carries the organelles round the cell.

63.Choose the option showing the correct set of characteristics for Intermediate filaments: (NUMS MDCAT 2024)

  1. Diameter 8-10nm, Vimentin, Mechanical support
  2. Diameter 0.2-25um, Vimentin, Cilia flagella
  3. Diameter 8-10nm, Tubulin, Muscle contraction
  4. Diameter 7nm, Tubulin, Cyclosis
Show answer

Correct answer: (a) Diameter 8-10nm, Vimentin, Mechanical support

Intermediate filaments are about $8$ to $10\,\mathrm{nm}$ across, made of proteins such as vimentin, and give mechanical strength.

64.The nucleus takes up dyes because of the presence of: (MDCAT 2024)

  1. chromatin
  2. lipid
  3. metal ions
  4. thylakoids
Show answer

Correct answer: (a) chromatin

Chromatin, the DNA with its histones, is what the basic stains bind to.

65.Chromosomes were first observed by: (MDCAT 2024)

  1. T. H. Morgan
  2. Griffith
  3. Walther Flemming
  4. Mendel
Show answer

Correct answer: (c) Walther Flemming

Flemming saw and named the stained threads in dividing cells.

66.The nucleus takes dyes due to the presence of (UHS MDCAT 2024)

  1. Chromatin
  2. Lipid
  3. Metal ions
  4. Thylakoids
Show answer

Correct answer: (a) Chromatin

Chromatin is the DNA and histone that take up basic stains.

67.Chromosomal abnormality in Turner syndrome is represented by? (UHS MDCAT 2024)

  1. XXX
  2. XYY
  3. XO
  4. XXY
Show answer

Correct answer: (c) XO

Turner syndrome is a single X with no second sex chromosome.

68.The chromosomes was first observed by; (UHS MDCAT 2024)

  1. T. H Morgan
  2. Griffith
  3. Walther
  4. Mendel
Show answer

Correct answer: (c) Walther

Walther Flemming first saw and described the chromosomes in dividing cells.

69.Where are spindle fibres attached on a chromosome during cell division (KMU MDCAT 2024)

  1. Centromere
  2. Histone proteins
  3. Nucleolus
  4. Telomere
Show answer

Correct answer: (a) Centromere

The spindle fibres attach at the kinetochore of the centromere.

70.Chromosome is typically made up from a combination of? (KMU MDCAT 2024)

  1. DNA and protein
  2. DNA and RNA
  3. RNA and lipids
  4. RNA and proteins
Show answer

Correct answer: (a) DNA and protein

A chromosome is DNA wound on histone protein.

71.Nucleo proteins are involved in: (NUMS MDCAT 2024)

  1. Cell to cell recognition
  2. Passing hereditary information to next generation
  3. Ensuring fast speed of nerve impulse
  4. Acting as a cell surface marker
Show answer

Correct answer: (b) Passing hereditary information to next generation

Nucleoproteins are the DNA and histone of the chromosomes, which carry the inheritance.

Coordination and Control

72.A taste receptor is an example of a: (MDCAT 2024)

  1. mechanoreceptor
  2. nociceptor
  3. photoreceptor
  4. chemoreceptor
Show answer

Correct answer: (d) chemoreceptor

It responds to dissolved chemicals, which is what a chemoreceptor does.

73.Taste receptor is an example of (UHS MDCAT 2024)

  1. Mechano receptors
  2. Nociceptors
  3. Photo receptors
  4. Chemo receptors
Show answer

Correct answer: (d) Chemo receptors

Taste buds respond to molecules dissolved in saliva, so they are chemoreceptors.

74.In human myelinated fibres a nerve impulse travels at how many metres per second? (MDCAT 2024)

  1. 100-120
  2. 130-150
  3. 160-180
  4. 190-210
Show answer

Correct answer: (a) 100-120

Saltatory conduction along a myelinated fibre reaches about $100$-$120\ \mathrm{m\,s^{-1}}$.

75.Nissl's granules are groups of: (MDCAT 2024)

  1. mesosomes
  2. lysosomes
  3. ribosomes
  4. chromosomes
Show answer

Correct answer: (c) ribosomes

They are stacks of rough endoplasmic reticulum with their ribosomes in the cell body of a neuron.

76.During the non-conducting state, the neuron membrane is permeable to the efflux of: (MDCAT 2024)

  1. $\mathrm{K^+}$
  2. $\mathrm{Na^+}$
  3. $\mathrm{Ca^{2+}}$
  4. $\mathrm{Cl^-}$
Show answer

Correct answer: (a) $\mathrm{K^+}$

At rest the membrane leaks potassium outwards, which is what leaves the inside negative.

77.Which of the following neurotransmitters lies outside the central nervous system? (MDCAT 2024)

  1. acetylcholine
  2. endorphins
  3. dopamine
  4. gamma-aminobutyric acid
Show answer

Correct answer: (a) acetylcholine

Acetylcholine is the transmitter at the neuromuscular junction and in the autonomic ganglia.

78.Depolarization during the conduction of a nerve impulse is due to: (MDCAT 2024)

  1. inward movement of $\mathrm{Na^+}$
  2. inward movement of $\mathrm{K^+}$
  3. outward movement of $\mathrm{K^+}$
  4. outward movement of $\mathrm{Na^+}$
Show answer

Correct answer: (a) inward movement of $\mathrm{Na^+}$

The sodium gates open and sodium floods in, reversing the sign of the membrane potential.

79.In human myelinated fibers nerve impulse travels at _____ meters per second. (UHS MDCAT 2024)

  1. 100-120
  2. 130-150
  3. 160-180
  4. 190-210
Show answer

Correct answer: (a) 100-120

Saltatory conduction along a myelinated fibre reaches about $100$ to $120\,\mathrm{m\,s^{-1}}$.

80.During non-conducting state, the neuron membrane is permeable to efflux of (UHS MDCAT 2024)

  1. K+
  2. Na+
  3. Ca+
  4. Cl-
Show answer

Correct answer: (a) K+

The resting membrane leaks potassium outwards far more readily than it leaks sodium in.

81.Which of the following neurotransmitters is lying outside the central nervous system? (UHS MDCAT 2024)

  1. Acetylcholine
  2. Endorphins
  3. Dopamine
  4. Gamma - aminobutyric acid
Show answer

Correct answer: (a) Acetylcholine

Acetylcholine is the transmitter of the neuromuscular junction and of the autonomic ganglia.

82.Depolarization during conduction of nerve impulse is due to (UHS MDCAT 2024)

  1. Inward movement of Na+
  2. Inward movement of K+
  3. Outward movement of K+
  4. Outward movement of Na+
Show answer

Correct answer: (a) Inward movement of Na+

Sodium rushing in reverses the charge across the membrane.

83.Which of the following is NOT a feature of Autonomic Nervous System? (UHS MDCAT 2024)

  1. Regulate response of visceral organs
  2. Regulate response of skeletal muscles
  3. Regulate response of glands
  4. Regulate response of smooth muscles
Show answer

Correct answer: (b) Regulate response of skeletal muscles

The autonomic system serves smooth muscle, cardiac muscle and glands; skeletal muscle is voluntary.

84.The following function/activity is NOT controlled by the autonomic nervous system. (KMU MDCAT 2024)

  1. Cardiac muscles contraction
  2. Salivation
  3. Smooth muscles contraction
  4. Thoughts and emotions
Show answer

Correct answer: (d) Thoughts and emotions

The autonomic system serves the viscera; thought and emotion belong to the cerebrum.

85.A motor neuron: (KMU MDCAT 2024)

  1. Carries impulse from effectors to CNS
  2. Carries impulse from receptors to CNS
  3. Carries impulse from CNS to muscles
  4. Connects sensory nerves to ganglions.
Show answer

Correct answer: (c) Carries impulse from CNS to muscles

A motor neuron carries the impulse out from the central nervous system to the effector.

86.Diffusion _______ across the post synaptic membrane causes it to depolarise: (KMU MDCAT 2024)

  1. Calcium ions
  2. Chloride ions
  3. Potassium ions
  4. Sodium ions
Show answer

Correct answer: (d) Sodium ions

The transmitter opens sodium channels, and the inrush of sodium depolarizes the membrane.

87.A reflex action, does not involve the: (KMU MDCAT 2024)

  1. Brain
  2. Motor neuron
  3. Sensory neuron
  4. Spinal cord
Show answer

Correct answer: (a) Brain

A spinal reflex is completed in the cord; the brain learns of it only afterwards.

88.The neurotransmitter________ is hydrolysed by monoamine oxidase (KMU MDCAT 2024)

  1. Acetylcholine
  2. Adrenaline
  3. Gluamate
  4. Serotin
Show answer

Correct answer: (b) Adrenaline

Monoamine oxidase breaks down the catecholamines, of which adrenaline is one.

89.Most of the neurons in the CNS are? (KMU MDCAT 2024)

  1. Bipolar
  2. Multipolar
  3. Pseudounipolar
  4. Unipolar
Show answer

Correct answer: (b) Multipolar

Most neurons of the central nervous system have many dendrites and one axon, so they are multipolar.

90.What is the fate of a neurotransmitter after the transmission of nerve impulse across synapse? (NUMS MDCAT 2024)

  1. It is taken into post synaptic neuron
  2. Released to post synaptic membrane
  3. Released into the synaptic cleft
  4. Broken down by enzymes
Show answer

Correct answer: (d) Broken down by enzymes

An enzyme in the cleft breaks the transmitter down at once, so the signal does not linger.

91.Which immediate change is brought about in the post synaptic membrane on binding with excitatory neurotransmitter? (NUMS MDCAT 2024)

  1. Calcium gates open
  2. Sodium gates open
  3. Sodium gates close
  4. Sodium potassium pump ceases to work
Show answer

Correct answer: (b) Sodium gates open

The transmitter opens sodium gates, and the inrush begins to depolarize the membrane.

92.During the conduction of nerve impulse, hyperpolarization would not occur if: (NUMS MDCAT 2024)

  1. Sodium gates didn't close in time
  2. Potassium gates were not so lousy
  3. Sodium potassium pump stopped working
  4. Calcium gates open instantly
Show answer

Correct answer: (b) Potassium gates were not so lousy

The potassium gates are slow to shut, so too much potassium leaves and the inside goes past its resting value.

93.Which of the following is a characteristic of electrical synapse? (NUMS MDCAT 2024)

  1. Presence of neurotransmitters
  2. Transmission of nerve impulse
  3. Sodium potassium gradient
  4. Absence of neurotransmitter
Show answer

Correct answer: (d) Absence of neurotransmitter

An electrical synapse passes the current directly through gap junctions, with no transmitter at all.

94.Which option given below characterizes refractory period? (NUMS MDCAT 2024)

  1. Reversal of charges across neural membrane
  2. Change in the type of ions across the membrane
  3. Next impulse can be conducted
  4. Membrane potential +50mV
Show answer

Correct answer: (a) Reversal of charges across neural membrane

During the refractory period the membrane is restoring its charges and cannot carry another impulse.

95.The medulla oblongata is a part of the: (MDCAT 2024)

  1. forebrain
  2. midbrain
  3. hindbrain
  4. hippocampus
Show answer

Correct answer: (c) hindbrain

With the cerebellum and pons it makes up the hindbrain, and it holds the vital centres.

96.Medulla Oblongata is a part of: (UHS MDCAT 2024)

  1. Forebrain
  2. Mid brain
  3. Hind brain
  4. Hippocampus
Show answer

Correct answer: (c) Hind brain

The medulla oblongata, the pons and the cerebellum make up the hindbrain.

97.Which part of the brain is controlling your sense of balance? (KMU MDCAT 2024)

  1. Amygdala
  2. Cerebellum
  3. Hippocampus
  4. Medulla Oblongata
Show answer

Correct answer: (b) Cerebellum

The cerebellum keeps posture and balance.

98.During complex activity of flight, birds require coordination of many skeletal muscles. Which part of their brain has to be well developed? (NUMS MDCAT 2024)

  1. Amygdala
  2. Cerebrum
  3. Cerebellum
  4. Thalamus
Show answer

Correct answer: (c) Cerebellum

The cerebellum coordinates the muscles, and in a flying bird it is very large.

99.Which part of the brain is actively used by mathematician trying to formulate a new equation? (NUMS MDCAT 2024)

  1. Hippocampus
  2. Cerebrum
  3. Amygdala
  4. Pons
Show answer

Correct answer: (b) Cerebrum

Reasoning and abstract thought belong to the cerebral cortex.

Enzymes

100.What happens to the enzyme after an enzyme-catalysed reaction? (KMU MDCAT 2024)

  1. Reduced to inactive form
  2. Becomes inert
  3. Changes into substrate
  4. Used for another reaction
Show answer

Correct answer: (d) Used for another reaction

An enzyme is not used up, so it is free to catalyse the next molecule.

101.An enzyme is capable of acting on a wide range of related substrates. Which of the following is a property of this enzyme? (NUMS MDCAT 2024)

  1. Inflexible active site
  2. Regulatory enzyme
  3. Non-regulatory enzyme
  4. Highly specific enzyme
Show answer

Correct answer: (c) Non-regulatory enzyme

A broad specificity belongs to the ordinary non-regulatory enzymes; the regulatory ones are tightly controlled.

102.The induced fit model of enzyme activity suggests that an enzyme: (MDCAT 2024)

  1. cannot modify its active site
  2. can bind to a single substrate
  3. can catalyze related reactions
  4. usually belongs to the non-regulatory enzymes
Show answer

Correct answer: (c) can catalyze related reactions

The active site is flexible and moulds itself around the substrate, so related substrates can be accepted.

103.The enzymes enable the conversion of substrates into products by (KMU MDCAT 2024)

  1. Changing equilibrium in the direction of the substrate
  2. Increasing the activation energy
  3. Increasing the substrate concentration
  4. Lowering the activation energy
Show answer

Correct answer: (d) Lowering the activation energy

An enzyme offers a path over a lower energy barrier; it does not shift the equilibrium.

104.Which of the following statements is incorrect regarding the rate of enzymatic action? (MDCAT 2024)

  1. an increase in enzyme concentration increases the rate
  2. an increase in enzyme concentration reduces the rate
  3. all enzymes work at their maximum rate at their optimum temperature
  4. all enzymes work at their maximum rate at their optimum pH
Show answer

Correct answer: (b) an increase in enzyme concentration reduces the rate

More enzyme means more active sites, so with substrate to spare the rate rises rather than falls.

105.Which of the following statement is incorrect regarding rate of enzymatic action (UHS MDCAT 2024)

  1. Increase in enzyme concentration increases the rate
  2. Increase in enzyme concentration reduces the rate
  3. All enzymes work at their maximum rate at optimum temperature
  4. All enzymes work at their maximum rate at optimum pH
Show answer

Correct answer: (b) Increase in enzyme concentration reduces the rate

More enzyme means more active sites, so the rate rises, not falls.

106.Optimum pH for pancreatic lipase is: (KMU MDCAT 2024)

  1. 2
  2. 4
  3. 6
  4. 8
Show answer

Correct answer: (d) 8

Pancreatic lipase works in the alkaline intestine, at about pH 8.

107.Catalase can be activated at pH: (KMU MDCAT 2024)

  1. 1
  2. 3
  3. 5
  4. 7
Show answer

Correct answer: (d) 7

Catalase works best at about neutral pH.

108.Enzymatic activity can be inhibited by? (KMU MDCAT 2024)

  1. Heavy metal ions
  2. Methane
  3. Mutase
  4. Noble gases
Show answer

Correct answer: (a) Heavy metal ions

Heavy metal ions bind the sulphydryl groups of the enzyme and destroy its shape.

109.A competitive inhibitor: (KMU MDCAT 2024)

  1. Accelerates the chemical reaction
  2. Competes with the enzyme
  3. Is irreversible
  4. Is reversible
Show answer

Correct answer: (d) Is reversible

A competitive inhibitor merely occupies the active site for a while and can be displaced by more substrate.

110.In competitive inhibition, the inhibitor (KMU MDCAT 2024)

  1. Binds with substrate
  2. Competes with enzyme
  3. Competes with substrate
  4. Irreversibly binds with enzyme
Show answer

Correct answer: (c) Competes with substrate

A competitive inhibitor resembles the substrate and takes its place in the active site.

Evolution

111.The change in frequency of alleles at a locus that occurs by chance is known as: (UHS MDCAT 2024)

  1. Mutation
  2. Genetic Drift
  3. Non Random mating
  4. Speciation
Show answer

Correct answer: (b) Genetic Drift

Genetic drift is the chance change in allele frequency from one generation to the next.

112.The formula calculating the frequency of genotypes and alleles in a population gene pool is known as: (UHS MDCAT 2024)

  1. Hardy-Weinberg Equation
  2. Lamarck Equation
  3. Darwin Equation
  4. James Hutton Equation
Show answer

Correct answer: (a) Hardy-Weinberg Equation

The Hardy-Weinberg equation relates allele frequencies to genotype frequencies in a population.

113.According to endosymbiosis theory, flagella may have derived by the ingestion of prokaryotes similar to (UHS MDCAT 2024)

  1. Amoeboid prokaryote
  2. Aerobic bacterium
  3. Spirochete
  4. Spirillum
Show answer

Correct answer: (c) Spirochete

The theory traces flagella to spirochaetes taken up and kept by an early cell.

114.The idea of inheritance of acquired characteristics was presented by: (MDCAT 2024)

  1. Jean Baptiste Lamarck
  2. Charles Darwin
  3. Thomas Malthus
  4. Alfred Wallace
Show answer

Correct answer: (a) Jean Baptiste Lamarck

Lamarck held that what an organism gained in its lifetime passed to its offspring.

115.According to Lamarckism, the basis of evolution is: (KMU MDCAT 2024)

  1. Inheritance of acquired characteristics
  2. Mutation
  3. Natural selection
  4. Survival of the fittest
Show answer

Correct answer: (a) Inheritance of acquired characteristics

Lamarck held that characters gained in a lifetime are passed to the offspring.

116.Children of a mason do not inherit strong muscles developed by father due to hard labour. This is an example of: (NUMS MDCAT 2024)

  1. Survival of the fittest
  2. Over production of offspring
  3. Not inheriting acquired characters
  4. Use and disuse of organs
Show answer

Correct answer: (c) Not inheriting acquired characters

Muscle built by work is an acquired character, and acquired characters are not inherited.

117.Which of the following statements about natural selection is not true? (MDCAT 2024)

  1. it acts on variations that are heritable
  2. it is selected by a breeder
  3. it can improve the adaptation of a species
  4. it is regional in nature
Show answer

Correct answer: (b) it is selected by a breeder

Selection by a breeder is artificial selection; natural selection is done by the environment.

118.Identify the correct pair of vestigial organs: (UHS MDCAT 2024)

  1. Ear Muscles & Vermiform appendix
  2. Heart & Liver
  3. Ear Muscles & Liver
  4. Vermiform appendix & Heart
Show answer

Correct answer: (a) Ear Muscles & Vermiform appendix

The ear muscles and the vermiform appendix are reduced remnants of organs once useful.

119.Wings of birds and that of flying lizards provide evidence of: (KMU MDCAT 2024)

  1. Convergent evolution
  2. Divergent evolution
  3. No evolution
  4. Same origin
Show answer

Correct answer: (a) Convergent evolution

Unrelated animals meeting the same problem arrive at the same solution, which is convergence.

120.The embryological stages of ______ show similarity in anatomical features. (KMU MDCAT 2024)

  1. All living things
  2. All non-vertebrates
  3. All vertebrates
  4. Human, jelly fish and mouse
Show answer

Correct answer: (c) All vertebrates

All vertebrate embryos pass through a stage with a notochord, gill slits and a tail.

121.What best describes the hind leg bones seen in the whale? (KMU MDCAT 2024)

  1. Analogous to the fin of living fish
  2. Fossil structure from an extinct ancestor
  3. Homologous structure of the wings of a bat
  4. Vestigial structures that had a function in an ancestor
Show answer

Correct answer: (d) Vestigial structures that had a function in an ancestor

The reduced hind limb bones of a whale are vestiges of the legs of its land ancestors.

Reproduction

122.The female reproductive system consists of all of the following EXCEPT: (MDCAT 2024)

  1. ovaries
  2. oviduct
  3. cervix
  4. seminiferous tubules
Show answer

Correct answer: (d) seminiferous tubules

The seminiferous tubules are in the testis, where sperm are made.

123.Which hormone is responsible for the labour pains in the human female at the time of birth? (MDCAT 2024)

  1. estrogen
  2. progesterone
  3. oxytocin
  4. corticosteroid
Show answer

Correct answer: (c) oxytocin

Oxytocin from the posterior pituitary drives the contractions of the uterus.

124.The fluid secreted by Sertoli cells provides a liquid medium, protection and nourishment to: (MDCAT 2024)

  1. the oocyte
  2. the sperms
  3. the polar body
  4. the spermatogonia
Show answer

Correct answer: (b) the sperms

Sertoli cells nurse the developing sperm inside the seminiferous tubule.

125.The main function of the epididymis is to: (MDCAT 2024)

  1. transport sperms
  2. connect with the urethra
  3. produce semen
  4. hold the process of spermatogenesis
Show answer

Correct answer: (a) transport sperms

Sperm mature and are stored as they pass along it towards the vas deferens.

126.The immediate next stage of spermatogonial differentiation is: (MDCAT 2024)

  1. secondary spermatocyte
  2. spermatids
  3. primary spermatocytes
  4. sperms
Show answer

Correct answer: (c) primary spermatocytes

A spermatogonium grows into a primary spermatocyte before the first meiotic division.

127.Female reproductive system consists all of the following EXCEPT (UHS MDCAT 2024)

  1. Ovaries
  2. Oviduct
  3. Cervix
  4. Seminiferous tubules
Show answer

Correct answer: (d) Seminiferous tubules

Seminiferous tubules are in the testis, which belongs to the male system.

128.Which one of the following hormone is responsible for the labor pains in human female at the time of birth of baby? (UHS MDCAT 2024)

  1. Estrogen
  2. Progesterone
  3. Oxytocin
  4. Corticosteroid
Show answer

Correct answer: (c) Oxytocin

Oxytocin from the posterior pituitary drives the contractions of labour.

129.Fluid secreted by sertoli cells provides liquid medium, protection and nourishment to: (UHS MDCAT 2024)

  1. Oocyte
  2. Sperms
  3. Polar body
  4. Spermatogonia
Show answer

Correct answer: (b) Sperms

The Sertoli cells nurse the developing sperms and feed them.

130.Main function of the epididymis is to: (UHS MDCAT 2024)

  1. Transport sperms
  2. Connect with urethra
  3. Produce semen
  4. Hold the process of spermatogenesis
Show answer

Correct answer: (a) Transport sperms

The epididymis stores the sperms and passes them on to the vas deferens.

131.Immediate next stage of spermatogonia differentiation is: (UHS MDCAT 2024)

  1. Secondary spermatocyte
  2. Spermatids
  3. Primary spermatocytes
  4. Sperms
Show answer

Correct answer: (c) Primary spermatocytes

A spermatogonium grows into a primary spermatocyte before meiosis begins.

132.The ______ in semen facilitate the transport of sperms. (KMU MDCAT 2024)

  1. Androgen
  2. Prostaglandins
  3. Oxytocin
  4. Testosterone
Show answer

Correct answer: (b) Prostaglandins

The prostaglandins of the semen set the female tract contracting and help the sperms along.

133.The acidity of urine is neutralized by? (KMU MDCAT 2024)

  1. Cowpers gland
  2. Prostate gland
  3. Seminal vesicle
  4. Vas deferens
Show answer

Correct answer: (a) Cowpers gland

Cowper’s glands pour an alkaline fluid into the urethra ahead of the semen.

134.The outer layer of uterus is called as: (KMU MDCAT 2024)

  1. Endometrium
  2. Myometrium
  3. Mesometrium
  4. Perimetrium
Show answer

Correct answer: (d) Perimetrium

The perimetrium is the outer serous coat of the uterus.

135.Which of the following would be produced as a result of reduction division during gametogenesis? (NUMS MDCAT 2024)

  1. Oogonium
  2. Primary oocyte
  3. Primary spermatocyte
  4. Secondary oocyte
Show answer

Correct answer: (d) Secondary oocyte

The first meiotic division of the primary oocyte gives the secondary oocyte.

136.The corpus luteum during the female reproductive cycle produces: (MDCAT 2024)

  1. testosterone
  2. follicle stimulating hormone
  3. luteinizing hormone
  4. progesterone
Show answer

Correct answer: (d) progesterone

Progesterone from the corpus luteum holds the uterine lining ready for implantation.

137.Due to the process of follicle atresia: (MDCAT 2024)

  1. follicles reach maximum size
  2. the follicle degenerates
  3. the Graafian follicle ovulates
  4. the follicle starts to mature
Show answer

Correct answer: (b) the follicle degenerates

All but one of the follicles recruited in a cycle break down, and that breakdown is atresia.

138.Corpus luteum during female reproductive cycle produces (UHS MDCAT 2024)

  1. Testosterone
  2. Follicle stimulating hormone
  3. Luteinizing Hormone
  4. Progesterone
Show answer

Correct answer: (d) Progesterone

The corpus luteum secretes progesterone, which holds the endometrium ready.

139.The corpus luteum is essentially formed from (KMU MDCAT 2024)

  1. Graafian follicle
  2. Ovum
  3. Oogonium
  4. Oocyte
Show answer

Correct answer: (a) Graafian follicle

What is left of the Graafian follicle after ovulation becomes the corpus luteum.

140.Choose the mismatched pair: (NUMS MDCAT 2024)

  1. Graffian follicle - progesterone
  2. ICSH - interstitial cell
  3. Estrogen - inhibits FSH
  4. LH - ovulation
Show answer

Correct answer: (a) Graffian follicle - progesterone

The Graafian follicle secretes oestrogen; progesterone comes from the corpus luteum it becomes.

141.If reproductive cycle of a female starts on 10th of July, ovulation is most likely to occur on: (NUMS MDCAT 2024)

  1. 1st August
  2. 28th of July
  3. 24th of July
  4. 5th August
Show answer

Correct answer: (c) 24th of July

Ovulation falls about fourteen days after the cycle begins, that is the 24th of July.

142.____ is spread through sexual contact. (KMU MDCAT 2024)

  1. Gonorrhoea
  2. Influenza
  3. Tuberculosis
  4. Typhoid
Show answer

Correct answer: (a) Gonorrhoea

Gonorrhoea is caused by Neisseria gonorrhoeae and passes by sexual contact.

Support and Movement

143.Which of the following is included in the paired cranial bones? (MDCAT 2024)

  1. temporal
  2. occipital
  3. frontal
  4. vomer
Show answer

Correct answer: (a) temporal

There is a temporal bone on each side; the occipital and the vomer are single.

144.Which of the following is NOT a bone of the upper limb? (MDCAT 2024)

  1. humerus
  2. ulna
  3. femur
  4. radius
Show answer

Correct answer: (c) femur

The femur is the thigh bone of the lower limb.

145.Bone forming cells are: (MDCAT 2024)

  1. osteoblasts
  2. osteocytes
  3. osteoclasts
  4. osteons
Show answer

Correct answer: (a) osteoblasts

Osteoblasts lay down bone matrix; osteoclasts break it down again.

146.What is the percentage of H2O in bone cells? (UHS MDCAT 2024)

  1. 70 %
  2. 20 %
  3. 99 %
  4. 60 %
Show answer

Correct answer: (b) 20 %

Bone cells hold about a fifth of their mass as water, far less than soft tissue.

147.Which of the following is included in paired cranial bones? (UHS MDCAT 2024)

  1. Temporal
  2. Occipital
  3. Frontal
  4. Vomer
Show answer

Correct answer: (a) Temporal

The temporal and parietal bones come in pairs; the frontal and occipital are single.

148.Which of the following is NOT a bone of upper limb? (UHS MDCAT 2024)

  1. Humerus
  2. Ulna
  3. Femur
  4. Radius
Show answer

Correct answer: (c) Femur

The femur is the thigh bone; humerus, radius and ulna are all in the arm.

149.The cells contained in the lacunae of the bone are called (KMU MDCAT 2024)

  1. Chondrocytes
  2. Osteoblast
  3. Osteocytes
  4. Osteoclast
Show answer

Correct answer: (c) Osteocytes

Osteocytes are the mature bone cells, each shut in its own lacuna.

150.Which of the following is correct about hamstring muscles? (NUMS MDCAT 2024)

  1. It is an extensor muscle
  2. Its insertion is on tibia
  3. Originate from pelvic girdle and top of femur
  4. Originate from ilium and femur
Show answer

Correct answer: (b) Its insertion is on tibia

The hamstrings run from the pelvis down behind the thigh and are inserted on the tibia.

151.Which feature is possessed by smooth muscles? (MDCAT 2024)

  1. voluntary control
  2. branched fibres
  3. uninucleate cells
  4. striated appearance
Show answer

Correct answer: (c) uninucleate cells

A smooth muscle cell is spindle shaped with one central nucleus and no striations.

152.Which of the following does NOT relate to smooth muscles? (KMU MDCAT 2024)

  1. Controlled by the autonomic nervous system
  2. Have spindle shaped cells
  3. Line the wall of heart
  4. Lack striations
Show answer

Correct answer: (c) Line the wall of heart

The heart wall is cardiac muscle, which is striated; smooth muscle lines the gut and vessels.

153.The thick filaments in skeletal muscle are composed of: (MDCAT 2024)

  1. actin
  2. myosin
  3. tropomyosin
  4. troponin
Show answer

Correct answer: (b) myosin

Myosin makes the thick filament; actin with tropomyosin and troponin makes the thin one.

154.A sarcomere is the part of a myofibril between: (MDCAT 2024)

  1. two I bands
  2. two A bands
  3. two M lines
  4. two Z lines
Show answer

Correct answer: (d) two Z lines

The sarcomere, the unit of contraction, runs from one Z line to the next.

155.Thick filaments In skeletal muscles are composed of: (UHS MDCAT 2024)

  1. Actin
  2. Myosin
  3. Tropomyosin
  4. Troponin
Show answer

Correct answer: (b) Myosin

The thick filament is myosin; actin makes the thin one.

156.Sarcomere is part of myofibril between: (UHS MDCAT 2024)

  1. Two I bands
  2. Two A bands
  3. Two M lines
  4. Two Z lines
Show answer

Correct answer: (d) Two Z lines

A sarcomere runs from one Z line to the next.

157.The ____ surrounds the muscle fibre of the skeletal muscle. (KMU MDCAT 2024)

  1. Cytoplasm
  2. Lacunae
  3. Myofibrils
  4. Sarcoplasm
Show answer

Correct answer: (d) Sarcoplasm

The sarcoplasm is the cytoplasm around the myofibrils inside the fibre.

158.Choose the correct for muscle in relaxed position: (NUMS MDCAT 2024)

  1. Exposed binding sites on actin
  2. Broad H-zone in sarcomere
  3. Formation of cross bridges
  4. Ca2+ released in cytosol
Show answer

Correct answer: (b) Broad H-zone in sarcomere

At rest the thin filaments are drawn back, so the H zone between them is at its widest.

159.The accumulation of lactic acid in the muscles results in: (MDCAT 2024)

  1. extreme fatigue
  2. muscle contraction
  3. paralysis
  4. convulsion
Show answer

Correct answer: (a) extreme fatigue

Lactic acid builds up when the oxygen supply falls short, and the muscle tires.

160.What happens to calcium when skeletal muscles recover from contraction? (KMU MDCAT 2024)

  1. Released from the sarcoplasmic reticulum
  2. Released from the myosin head
  3. Pumped into the sarcoplasmic reticulum
  4. Exchanged for sodium ions
Show answer

Correct answer: (c) Pumped into the sarcoplasmic reticulum

Calcium pumps return it to the sarcoplasmic reticulum, and the fibre relaxes.

161.Which of the following skeletal disorders is an example of an autoimmune disorder? (MDCAT 2024)

  1. sciatica
  2. spondylosis
  3. rheumatoid arthritis
  4. rickets
Show answer

Correct answer: (c) rheumatoid arthritis

In rheumatoid arthritis the body's own immune system attacks the synovial membranes.

162.Which of the following skeletal disorder Is an example of autoimmune disorder? (UHS MDCAT 2024)

  1. Sciatica
  2. Spondylosis
  3. Rheumatoid arthritis
  4. Rickets
Show answer

Correct answer: (c) Rheumatoid arthritis

In rheumatoid arthritis the immune system attacks the synovial membrane of the joint.

Inheritance

163.The genetic makeup that your parents have transferred to you for your hair color, makes up your: (KMU MDCAT 2024)

  1. Genotype
  2. Karyotype
  3. Phenotype
  4. None of the above
Show answer

Correct answer: (a) Genotype

The alleles inherited are the genotype; what shows is the phenotype.

164.Which term best describes an organism's physical characteristic. (KMU MDCAT 2024)

  1. Allele
  2. Genetic code
  3. Genotype
  4. Trait
Show answer

Correct answer: (d) Trait

A trait is a physical characteristic; the genotype is the alleles behind it.

165.What will be the probability of purple and terminal flower in Pea plant in F2 generation, if we cross true breeding purple axial with white terminal? (NUMS MDCAT 2024)

  1. 1/16
  2. 3/16
  3. 9/16
  4. 1/2
Show answer

Correct answer: (b) 3/16

Purple and axial are dominant, so purple with terminal is $3/4\times1/4$, that is $3/16$.

166.Which is true for an X linked dominant trait? (KMU MDCAT 2024)

  1. All female offspring of the affected father will be affected
  2. Half of the female offsprings of the affected father will be affected
  3. No male offspring of an affected mother will be affected
  4. No female offspring of the affected father will be affected
Show answer

Correct answer: (a) All female offspring of the affected father will be affected

An affected father passes his only X to every daughter, so all of them show a dominant trait.

167.A carrier female for hemophilia is married to an affected male. What would be the probable percentage for their sons to be affected? (NUMS MDCAT 2024)

  1. 100%
  2. 50%
  3. 25%
  4. 0%
Show answer

Correct answer: (b) 50%

Half her sons take the affected X from her, so half of them are affected.

168.Which is correct for pattern baldness? (NUMS MDCAT 2024)

  1. It is sex linked trait
  2. Occurs due to hormonal differences between sexes
  3. Heterozygous male is normal
  4. Heterozygous female is affected
Show answer

Correct answer: (b) Occurs due to hormonal differences between sexes

Baldness is autosomal but sex influenced: the heterozygote is bald in a man and not in a woman.

169.What is the primary outcome of crossing over during prophase of meiosis I? (KMU MDCAT 2024)

  1. Chromosomes duplicate without any exchange of parts
  2. Homologous chromosomes exchange different pairs leading to recombinant chromatids and increased genetic variation
  3. Homologous chromosomes exchange identical parts, resulting in no genetic variation
  4. Non-homologous chromosomes exchange part
Show answer

Correct answer: (b) Homologous chromosomes exchange different pairs leading to recombinant chromatids and increased genetic variation

Homologues swap segments, so the chromatids that result carry new combinations of alleles.

Circulation

170.Which of the following set of characteristics are related to veins? (NUMS MDCAT 2024)

  1. Valves: Present, Wall thickness: Thick, Diameter: 7-9mm
  2. Valves: Absent, Wall thickness: Thick, Diameter: 40-50mm
  3. Valves: Present, Wall thickness: Thinner, Diameter: 40-50mm
  4. Valves: Absent, Wall thickness: Thinner, Diameter: 40-50mm
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Correct answer: (c) Valves: Present, Wall thickness: Thinner, Diameter: 40-50mm

A vein has a wide bore, a thin wall and valves to stop the blood falling back.

171.Weakened papillary muscles of right ventricle would result in constant back flow of blood into: (NUMS MDCAT 2024)

  1. Right atrium
  2. Left ventricle
  3. Right ventricle
  4. Left atrium
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Correct answer: (a) Right atrium

The papillary muscles hold the tricuspid valve shut, so weak ones let blood back into the right atrium.

172.Which of the following would not be compromised in the absence of lymphatic system? (NUMS MDCAT 2024)

  1. Blood pressure
  2. Oxygen carrying capacity of blood
  3. Blood composition
  4. Defense mechanism
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Correct answer: (b) Oxygen carrying capacity of blood

Oxygen is carried by the red cells of the blood, which the lymphatic system has nothing to do with.

173.The presence of which molecules distinguishes blood from interstitial fluid? (NUMS MDCAT 2024)

  1. Large proteins and electrolytes
  2. Glucose and RBCs
  3. Antibodies and electrolytes
  4. RBCs and large proteins
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Correct answer: (d) RBCs and large proteins

Red cells and the plasma proteins stay in the vessel; the rest of the plasma filters out as tissue fluid.

Immunity

174.In an inflammatory response, bradykinin causes? (KMU MDCAT 2024)

  1. Activation of natural killer cells
  2. Blockage in blood vessels
  3. Constriction of blood vessels
  4. Leakage of fluid from blood vessels
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Correct answer: (d) Leakage of fluid from blood vessels

Bradykinin makes the capillaries leaky, so fluid escapes into the tissue and it swells.

175.Which of the following is an example of passive immunity? (KMU MDCAT 2024)

  1. Antibodies from mother's milk
  2. Previous chickenpox infection
  3. Inactivated polio vaccine
  4. Live polio vaccine
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Correct answer: (a) Antibodies from mother's milk

Antibodies received ready made, as in breast milk, give passive immunity.

176.What directly triggers the activation of natural killer cells? (KMU MDCAT 2024)

  1. Free radicals
  2. Hydrogen peroxide
  3. Interferons
  4. Oxygen
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Correct answer: (c) Interferons

Interferons released by infected cells rouse the natural killer cells.

177.During Covid-19 epidemic, plasma of recovered patients was injected in covid patients. Which component of plasma was responsible for this? (NUMS MDCAT 2024)

  1. Plasminogen
  2. Interferons
  3. Antibodies
  4. Interleukin-I
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Correct answer: (c) Antibodies

The plasma of a recovered patient carries ready made antibodies against the virus.

178.Choose the one which is an example of artificial active immunity: (NUMS MDCAT 2024)

  1. Fetus receiving antibodies of mother through placenta
  2. Mother receiving antibodies
  3. Baby receiving MMR shots
  4. Prevention of disease due to previous infection
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Correct answer: (c) Baby receiving MMR shots

A vaccine makes the body raise its own antibodies, so the immunity is active and artificially induced.

179.Which of the following type of T cells are required for the activation of B cells? (NUMS MDCAT 2024)

  1. Helper T cells
  2. Cytotoxic T cells
  3. Suppressor T cells
  4. Memory T cells
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Correct answer: (a) Helper T cells

A helper T cell must recognize the antigen before the B cell will divide and make antibody.

Respiration

180.About 70% of the carbon dioxide is carried in the blood as: (MDCAT 2024)

  1. carbonate
  2. bicarbonate
  3. carbaminohaemoglobin
  4. dissolved gas in plasma
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Correct answer: (b) bicarbonate

Most of it travels as hydrogen carbonate ions in the plasma.

181.The range of normal total lung capacity in humans is: (MDCAT 2024)

  1. 5-6 litres
  2. 8-9 litres
  3. 10-11 litres
  4. 12-13 litres
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Correct answer: (a) 5-6 litres

Total lung capacity is about 5 to 6 litres in an adult.

182.About 70% of the carbon dioxide is carried in blood as: (UHS MDCAT 2024)

  1. Carbonate
  2. Bicarbonate
  3. Tricarbonate
  4. Carbonic anhydrase
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Correct answer: (b) Bicarbonate

Most carbon dioxide is carried as hydrogen carbonate ions in the plasma.

183.Range of normal total lung capacity in humans is (UHS MDCAT 2024)

  1. 5-6 liter
  2. 8-9 liter
  3. 10-11 liter
  4. 12-13 liter
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Correct answer: (a) 5-6 liter

Total lung capacity in an adult is about five to six litres.

184.Most CO2 in blood is transported as bicarbonate ions. Choose the event NOT taking place during gaseous exchange at tissue level: (NUMS MDCAT 2024)

  1. Formation of HHb
  2. Formation of sodium bicarbonate
  3. Formation of oxyhemoglobin
  4. Chloride shift
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Correct answer: (c) Formation of oxyhemoglobin

At the tissues oxyhaemoglobin is giving up its oxygen, not being formed.

Digestion

185.Which enzyme is secreted in the active form? (KMU MDCAT 2024)

  1. Amylase
  2. Lipase
  3. Peptidase
  4. Protease
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Correct answer: (a) Amylase

Salivary amylase is poured out ready to work; the protein digesting enzymes are secreted as inactive precursors.

186.Which hormone stimulates the secretion of gastric juice? (KMU MDCAT 2024)

  1. Cholecystokinin
  2. Gastrin
  3. Insulin
  4. Secretin
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Correct answer: (b) Gastrin

Gastrin from the stomach lining calls out the gastric juice.

187.Which is true about the cells found in gastric glands lining the stomach wall? (KMU MDCAT 2024)

  1. Chief cells secrete gastrin
  2. Hormone cells secrete intrinsic factor
  3. Mucus cells secrete mucin
  4. Parietal cells secrete pepsinogen
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Correct answer: (c) Mucus cells secrete mucin

The mucus cells make mucin, which protects the lining from the acid.

188.Activation of all of the following enzymes need a regulatory molecule except: (NUMS MDCAT 2024)

  1. Pepsinogen
  2. Trypsinogen
  3. Erepsin
  4. Chymotrypsinogen
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Correct answer: (c) Erepsin

Erepsin is secreted ready to work; the other three are zymogens needing activation.

189.A person with a removed gall bladder experiences difficulty in fat digestion due to: (NUMS MDCAT 2024)

  1. Absence of Bile
  2. Uncontrolled release of Bile
  3. Reduced alkalinity of bile
  4. Absence of bile pigments
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Correct answer: (b) Uncontrolled release of Bile

Without the gall bladder the bile trickles in continuously instead of being stored and released with a meal.

Homeostasis

190.A desert mammal faces severe dehydration in a hot sunny day. Which internal condition would lead to secretion of ADH? (NUMS MDCAT 2024)

  1. High osmotic pressure of blood
  2. High blood pressure
  3. Low osmotic pressure of blood
  4. Low solute potential of blood
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Correct answer: (a) High osmotic pressure of blood

Losing water concentrates the blood, and the osmoreceptors answer that by calling for ADH.

Biotechnology

191._______ is used in the production of Humulin? (KMU MDCAT 2024)

  1. Bacteria
  2. Fungi
  3. Protozoa
  4. Virus
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Correct answer: (a) Bacteria

Humulin is human insulin made by a genetically engineered bacterium.

192.Probiotics in infants formula milk keep babies healthy by doing all of the following actions except: (NUMS MDCAT 2024)

  1. Produce important vitamins
  2. Kill pathogenic bacteria
  3. Prevent colonization of pathogens
  4. Enhance immunity
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Correct answer: (b) Kill pathogenic bacteria

Probiotics crowd the pathogens out and feed the host, but they do not kill.

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