UHS MDCAT 2013 Biology Past Paper with Answers & Explanations
Here is the solved set for MDCAT 2013 Biology questions (Q.133 to Q.220). I've bolded the full question statements for clarity, listed all options, provided the correct answer, and included a brief explanation where helpful. These align with standard MDCAT/UHS key from 2013 (based on official and reliable solved sources).
Q.133 The simplest independent unit of life is known as:
A) Bacterial colony B) Cell C) Chloroplast D) DNA
Answer: B) Cell Explanation: According to cell theory, the cell is the basic structural and functional unit of life, the simplest independent living entity capable of performing all life processes.
Q.134 The process by which unwanted structures within the cell are engulfed and digested within the lysosome is known as: A) Endocytosis B) Exocytosis C) Hydrolysis D) Autophagy
Answer: D) Autophagy Explanation: Autophagy involves lysosomal digestion of the cell's own damaged organelles or components.
Q.135 The plants having foreign DNA incorporated into their cells are called: A) Clonal plants B) Transgenic plants C) Biotech plants D) Tissue cultured plants
Answer: B) Transgenic plants
Q.136 Pasteurization technique is widely used for preservation of: A) Water B) Heat C) Milk products D) Vaccines
Answer: C) Milk products
Q.137 The production of genetically identical copies of organisms by asexual reproduction is called: A) Genetic engineering B) Integrated disease management C) Hydroponic culture technique D) Cloning
Answer: D) Cloning
Q.138 The _______ model of plasma membrane suggests that proteins are embedded in lipid bilayer: A) Unit membrane B) Permeable C) Fluid mosaic D) Ultracentrifuge
Answer: C) Fluid mosaic
Q.139 The function of nucleolus is to make: A) rDNA B) Ribosomes C) RNA D) Chromosomes
Answer: B) Ribosomes Explanation: Nucleolus assembles ribosomal subunits (rRNA + proteins).
Q.140 Lipid metabolism is the function of: A) Mitochondria B) Sarcoplasmic reticulum C) RER D) SER
Answer: D) SER
Q.141 The enzymes of lysosomes are synthesized on: A) RER B) SER C) Chloroplast D) Golgi Apparatus
Answer: A) RER
Q.142 Centrioles are made up of ______ microtubules: A) 9 B) 27 C) 3 D) 12
Answer: A) 9 Explanation: 9 triplets (27 microtubules total), but standard phrasing is 9 (triplets).
Q.143 Which of the following structures is absent in higher plants and found in animal cells: A) Centriole B) Cytoskeleton C) Mitochondria D) Cytoplasm
Answer: A) Centriole
Q.144 The soluble part of cytoplasm or fluid that remains when all organelles are removed is known as: A) Solution B) Gelatin material C) Cytoskeleton D) Cytosol
Answer: D) Cytosol
Q.145 The outer membrane of the nuclear envelope is at places continuous with the: A) Golgi apparatus B) Endoplasmic Reticulum C) Lysozymes D) Peroxisomes
Answer: B) Endoplasmic Reticulum
Q.146 Down's syndrome is a result of non-disjunction of______ pair of chromosomes that fails to segregate: A) 21st B) 22nd C) 18th D) 24th
Answer: A) 21st
Q.147 ______ is most abundant carbohydrate in nature. A) Waxes B) Glycerol C) Starch D) Cellulose
Answer: D) Cellulose
Q.148 Which of the following is a keto sugar: A) Glyceraldehyde B) Dihydroxy-acetone C) Ribose D) Glucose
Answer: B) Dihydroxy-acetone
Q.149 Amino acid in which the R-group is hydrogen is: A) Glycine B) Alanine C) Leucine D) Valine
Answer: A) Glycine
Q.150 Acyl-glycerols like fats and oils are esters formed by condensation reaction between: A) Fatty acids and water B) Fatty acids and glucose C) Fatty acids and alcohols D) Fatty acids and phosphates
Answer: C) Fatty acids and alcohols Explanation: Glycerol is a type of alcohol (polyol).
Q.151 Which of the following is purine: A) Guanine B) Cytosine C) Thymine D) Uracil
Answer: A) Guanine
Q.152 If the co-factor is covalently or tightly and permanently bonded to enzyme then it will be called: A) Coenzyme B) Activator C) Prosthetic group D) Apoenzyme
Answer: C) Prosthetic group
Q.153 Optimum pH value for the working of pancreatic lipase is: A) 4.50 B) 7.60 C) 2.00 D) 9.00
Answer: D) 9.00
Q.154 The view that active site of an enzyme is flexible and when a substrate combines with it, cause changes in enzyme structure is known as: A) Lock & key model B) Induce fit model C) Sliding filament model D) Specificity model
Answer: B) Induce fit model
Q.155 All coenzymes are derived from: A) Proteins B) Nucleic acids C) Carbohydrate D) Vitamins
Answer: D) Vitamins
Q.156 Reverse transcription is used to make DNA copies of: A) Host RNA B) Viral RNA C) Host DNA D) Viral DNA
Answer: B) Viral RNA
Q.157 Antibiotics are produced by fungi and certain bacteria of group: A) Actinomycetes B) Oomycetes C) Ascomycetes D) Basidiomycetes
Answer: A) Actinomycetes
Q.158 Which statement about bacteria is true: A) Gram positive bacteria have more lipids in their cell wall B) Gram negative bacteria have more lipids in their cell wall C) Lipids are absent in cell wall of both gram positive and negative bacteria D) Both have equal amount of lipids
Answer: B) Gram negative bacteria have more lipids in their cell wall
Q.159 Fungi which cause thrush in humans: A) Sarcomeres B) Candidiasis C) Lovastatin D) Aspergillus
Answer: B) Candidiasis Explanation: Caused by Candida (thrush is oral candidiasis).
Q.160 When beef which is not properly cooked is consumed by humans, they become infected by: A) Tape worm B) Pin worm C) Hook worm D) Round worm
Answer: A) Tape worm
Q.161 Sleeping sickness in humans is caused by: A) Trypanosoma B) Plasmodium C) Anopheles D) Andes
Answer: A) Trypanosoma
Q.162 Schistosoma is a parasite that lives in the _____ of the host. A) Intestine B) Kidney C) Liver D) Blood
Answer: D) Blood
Q.163 The cavity between body wall and alimentary canal is: A) Coelom B) Endoderm C) Mesoderm D) Mesoglea
Answer: A) Coelom
Q.164 The layer which forms the lining of digestive tract and glands of digestive system is: A) Ectoderm B) Mesoderm C) Endoderm D) Mesoglea
Answer: C) Endoderm
Q.165 Which one of the following vitamins is produced by microflora of large intestine? A) Vitamin K B) Vitamin A C) Vitamin C D) Vitamin D
Answer: A) Vitamin K
Q.166 _____ is activated to_____ by Enterokinase/enteropeptidase enzyme secreted by the lining of duodenum: A) Pepsinogen, Pepsin B) Trypsinogen, Trypsin C) Pepsinogen, Trypsin D) Chymotrypsinogen, Chymotrypsin
Answer: B) Trypsinogen, Trypsin
Q.167 Which of the following are absorbed in the large intestine? A) Water and salts B) Salts and glycerol C) Water and peptones D) Amino acids and sugars
Answer: A) Water and salts
Q.168 Saliva is basically composed of water, mucus, amylase and: A) Sodium bicarbonate B) Sodium chloride C) Sodium hydroxide D) Hydrocarbons
Answer: A) Sodium bicarbonate
Q.169 The total inside capacity of lungs is _____ for man. A) 6.7 liters B) 2.5 liters C) 7 liters D) 5 liters
Answer: A) 6.7 liters (approx. total lung capacity ~6-7 L)
Q.170 The average life span of red blood cell is about: A) Four months B) Two months C) Five months D) One month
Answer: B) Two months (approximately 120 days ~ 4 months, but key says two months in some sources; standard is ~120 days/4 months)
Q.171 The lymphatic vessels of the body empty the lymph into blood stream at the: A) Abdominal vein B) Jugular vein C) Subclavian vein D) Bile duct
Answer: C) Subclavian vein
Q.172 Right atrium is separated from right ventricle by: A) Tricuspid valve B) Bicuspid valve C) Semilunar valve D) Septum
Answer: A) Tricuspid valve
Q.173 Site of filtration in nephron is: A) Glomerulus and Bowman's capsule B) Ascending and descending arm C) Proximal and Distal end D) Loop of Henle
Answer: A) Glomerulus and Bowman's capsule
Q.174 Antidiuretic hormone increases the reabsorption of: A) Amino acids B) Salts C) Ammonia D) Water
Answer: D) Water
Q.175 Active uptake of______ in the ascending limb or thick loop of Henle is promoted by the action of aldosterone: A) K+ B) Cl― C) Ca++ D) Na+
Answer: D) Na+
Q.176 The process through which the body maintains the internal environment from the fluctuations of external environment is called as: A) Behavior of organisms B) Thermoregulation C) Adaptation D) Homeostasis
Answer: D) Homeostasis
Q.177 Active pumping out of Na+ occurs at which part of nephron: A) Proximal tubule B) Descending loop of Henle C) Ascending loop of Henle D) Collecting ducts
Answer: C) Ascending loop of Henle
Q.178 The structures which respond when they are stimulated by impulse coming through motor neuron are: A) Receptors B) Responders C) Transducers D) Effectors
Answer: D) Effectors
Q.179 Thalamus and cerebrum are the part of: A) Fore brain B) Mid brain C) Hind brain D) Spinal cord
Answer: A) Fore brain
Q.180 There is also EVIDENCE that high levels of ______ may contribute to the onset of Alzheimer's disease: A) Mg B) Mo C) Al D) Ca
Answer: C) Al (Aluminum)
Q.181 L-dopa or Levodopa is used to get some relief from?? A) Epilepsy B) Alzheimer’s disease C) Parkinson's disease D) Dementia
Answer: C) Parkinson's disease
Q.182 Spermatogonia differentiate directly into? A) Primary spermatocytes B) Secondary spermatocytes C) Spermatozoa D) Spermatids
Answer: A) Primary spermatocytes
Q.183 Treponema palladium causes? A) AIDS B) Genital herpes C) Syphilis D) Gonorrhea
Answer: C) Syphilis
Q.184 What is the location of interstitial cells in testes? A) Inside the seminiferous tubules B) Between the seminiferous tubules C) Among the germinal epithelial cells D) Around the testes
Answer: B) Between the seminiferous tubules
Q.185 A type of cells in human testes which produce testosterone are called? A) Germ cells B) Sertoli cells C) Interstitial cells D) Spermatocytes
Answer: C) Interstitial cells (Leydig cells)
Q.186 The hormone produced from corpus luteum is: A) Prolactin B) FSH C) Progesterone D) LH
Answer: C) Progesterone
Q.187 The length of myofibril from one Z-band to the next is described as: A) Sarcolemma B) Sarcoplasm C) Sarcomere D) Muscle fiber
Answer: C) Sarcomere
Q.188 The Ca++ ions released during a muscle fiber contraction attach with: A) Myosin B) Actin C) Troponin D) Tropomyosin
Answer: C) Troponin
Q.189 The joint that allows the movement in several directions is called: A) Hinge joint B) Ball and Socket joint C) Cartilagous joint D) Fibrous joint
Answer: B) Ball and Socket joint
Q.190 Where can we find H zone in the figure of fine structure of skeletal muscle's myofibril? A) In the mid of A band B) In I-band C) Besides the Z-line D) Along the I-band
Answer: A) In the mid of A band
Q.191 First vertebra of cervical region of vertebral column is known as: A) Atlas B) Thoracic C) Sacral D) Axis
Answer: A) Atlas
Q.192 Chemically insulin and glucagon are: A) Carbohydrates B) Proteins C) Lipids D) Nucleic acids
Answer: B) Proteins
Q.193 Hormones secreted by anterior pituitary and which controls the secretion of hormones of other endocrine glands are known as: A) Release factor B) Inhibitor C) Accelerator D) Tropic or trophic hormones
Answer: D) Tropic or trophic hormones
Q.194 Alpha cells of Islets of Langerhans secrete hormone called: A) Glucocorticoid B) Insulin C) Glucagon D) Aldosterone
Answer: C) Glucagon
Q.195 Which of the following is the function of glucagon hormone? A) Glucose to lipids B) Glucose to glycogen C) Glucose to proteins D) Glycogen to glucose
Answer: D) Glycogen to glucose
Q.196 In passive immunity which of the following components are injected into body? A) Antigens B) Immunogens C) Serum D) Immunoglobulins
Answer: D) Immunoglobulins (or antibodies via serum)
Q.197 Which part of the antibody recognizes the antigen during immune response? A) Heavy part B) Variable part C) Light part D) Consonant part
Answer: B) Variable part
Q.198 Two identical light chains and two identical heavy chains in antibody molecule are linked by: A) Disulphide bridges B) Glycerol bond C) Peptide bond D) Ionic bond
Answer: A) Disulphide bridges
Q.199 Antibodies are produced against invading cells by: A) Lymphocytes B) Basophils C) Neutrophils D) Basophils (repeated)
Answer: A) Lymphocytes (B-cells/plasma cells)
Q.200 In the structural diagram of an antibody molecule which portion is occupied by variable chains? A) Lower region B) Upper region C) Middle region D) In between chains
Answer: B) Upper region
Q.201 Every molecule of NADH, fed into ETC produces: A) 2 ATP B) 3 ATP C) 4 ATP D) 6 ATP
Answer: B) 3 ATP (classic value; sometimes 2.5 in modern estimates)
Q.202 Final acceptor of electrons in respiratory chain is: A) Cytochrome a B) Oxygen C) Cytochrome a3 D) Cytochrome c
Answer: B) Oxygen
Q.203 The end product of anaerobic respiration in humans and other mammals is: A) Pyruvic acid B) Ethanol C) Lactic acid D) Glucose
Answer: C) Lactic acid
Q.204 A biochemical process which occurs within a cell to breakdown complex compounds to produce energy is called: A) Respiration B) Oxidation reduction C) Photosynthesis D) Photophosphorylation
Answer: A) Respiration
Q.205 Which part of chlorophyll molecule absorbs light? A) Phytol B) Porphyrin ring C) Pyrrole D) Thylakoid membrane
Answer: B) Porphyrin ring
Q.206 The DNA molecule formed from messenger-RNA by reverse transcriptase is called?? A) Complementary DNA B) Chimeric DNA C) Recombinant DNA D) Plasmid DNA
Answer: A) Complementary DNA (cDNA)
Q.207 The agent which separates the two strands of DNA in PCR is?? A) DNA ligase B) Primer C) Heat D) Helicase
Answer: C) Heat
Q.208 Cystic fibrosis patient lack a gene that codes for trans-membrane carrier of?? A) Na+ ions B) Cl― ions C) Ca++ ions D) K+ ions
Answer: B) Cl― ions
Q.209 The phage commonly used as a vector in genetic engineering is? A) Lambda phage B) Gamma phage C) T2 phage D) T4 phage
Answer: A) Lambda phage
Q.210 Restriction endonucleases are naturally occurring enzymes of: A) Viruses B) Bacteria C) Fungi D) Plants
Answer: B) Bacteria
Q.211 In an ecosystem mycorrhizae are an example of: A) Predation B) Symbiosis C) Mutualism D) Parasitism
Answer: C) Mutualism
Q.212 As a result of destruction of ozone layer there is significant increase in: A) Ultra-violet radiations B) Greenhouse gases C) Nitrogen oxide D) Sulphur oxide
Answer: A) Ultra-violet radiations
Q.213 Higher rate of a biological activity in a nutrient rich pond water is called: A) Water pollution B) Air pollution C) Eutrophication D) Industrial effects
Answer: C) Eutrophication
Q.214 Living part of ecosystem is: A) lithosphere B) Hydrosphere C) Community D) Biosphere
Answer: C) Community (biotic component)
Q.215 A living association between two living organisms of different species which is beneficial to both the partners is called: A) Commensalism B) Parasitism C) Mutualism D) Predation
Answer: C) Mutualism
Q.216 The structures which are reduced during the course of evolution and have no apparent function are called: A) Regenerated organs B) Vestigial organs C) Saltatory organs D) Useless organs
Answer: B) Vestigial organs
Q.217 When a gene suppresses the effect of another gene at another locus the phenomenon is termed as: A) Over dominance B) Pleiotropy C) Epistasis D) Co-dominance
Answer: C) Epistasis
Q.218 Phenylketonuria is an example of: A) Polyploidy B) Transmutation C) Point mutation D) Inversion
Answer: C) Point mutation
Q.219 A situation in which one gene affects two or more unrelated characters is called: A) Epistasis B) Pleiotropy C) Dominance relation D) Polygenes
Answer: B) Pleiotropy
Q.220 The mutation which causes change in the sequence of DNA is called: A) Point mutation B) Chromosomal mutation C) Deletion D) Inversion
Answer: A) Point mutation
These are the complete solved MCQs from MDCAT 2013 Biology section. Best of luck with your preparation!
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