Base of questions of KROK-1 Exam
Medical Biology
1. The cells of an organism content a nucleus surrounded by a nuclear membrane. Their genetic material is chromosomes, composed of DNA and proteins. Cells divide by mitosis. What kind of the organism is it?
A. *Eukaryotes
B. Bacteriophages
C. Prokaryotes
D. Viruses
E. Bacteria
2. A group of researchers experimentally obtained the mutant cells with no nucleus. Synthesis of what compounds will disturbed first of all?
A. *Ribosomal RNA
B. Transfer RNA
C. Lipids
D. Monosaccharides
E. Polysaccharides
3. The students have detected the oval double-membrane organelles at the electron micrograph. Their outer membranes are smooth, while inner membranes form cristae that contain ATP synthetase enzyme. These organelles are:
A. *Mitochondria
B. Golgi complex
C. Lysosomes
D. Centrioles
E. Ribosomes
4. The microscopic analysis of human heart cells revealed some oval organelles. They have two membranes. The external one is smooth, and the internal one forms cristae. Biochemical analysis determined the presence of ATP-synthetase enzyme. What organelles were analysed?
A. *Mitochondria
B. Lysosomes
C. Ribosomes
D. Endoplasmic reticulum
E. Centrosomes
5. A cell has been treated with a substance that blocks nucleotide phosphorilation in the mitochondria. What metabolic process will be disturbed initially?
A. * Oxidative phosphorilation
B. Oxidative modification of protein
C. Synthesis of mitochondrial proteins
D. Integration of functional protein molecules
E. Fragmentation of big mitochondrions into lesser ones
6. 6. A 28-year-old patient suffers from hepatocerebral degeneration. A biochemical test revealed a deficiency of ceruloplasmin protein. The disturb synthesis of the protein is associated with the following organelle:
A. *Rought (granular) endoplasmic reticulum
B. Smooth (agranular ) endoplasmic reticulum
C. Mitochondrion
D. Lysosome
E. Golgi complex
7. Golgi complex exports substances from a cell via fusion of a membrane vesicle with cell membrane. The vesicle content excrets. What process is it?
A. *Exocytosis
B. Endocytosis
C. Active transport
D. Facilitated diffusion
E. All answers are false
8. Students have studied a stained smear of mouse blood during the class. They saw leukocytes phagocyting the bacteria. What cell organelle takes part in digestion of the bacteria?
A. *Lisosome
B. Mitochondrion
C. Granular endoplasmic reticulum
D. Golgi apparatus
E. Ribosome
9. An electron microscopic study of cells revealed the spherical vesicles. The vesicles are surrounded by membrane and contain a lot of hydrolytic enzymes. It is known that these organelles provide intracellular digestion and protective functions. These vesicles are:
A. *Lysosomes
B. Centrosomes
C. Endoplasmic reticulum
D. Ribosomes
E. Mitochondria
10. A cell with vitamin E deficiency was treated by ionizing radiation. It resulted an intensified release of hydrolytic enzymes into the cytoplasm and thus a complete destruction of intracellular structures - autolysis. What organelles caused this phenomenon?
A. *Lysosomes
B. Endoplasmic reticulum
C. Golgi complex
D. Microbodies
E. Mitochondria
11. Ionizing radiation or vitamin E deficiency may increase the permeability of lysosome membranes. What consequences of it are possible?
A. *Partial or complete cell disintegration
B. Intensive protein synthesis
C. Intense energy synthesis
D. Restoration of the cytoplasmic membrane
E. Formation of cleavage spindle
12. A tissue sample of benign tumor was studied under the electron microscope. A lot of small (15-20 nm) spherical bodies consisting of 2 unequal subunits were detected. These bodies are:
A. *Ribosomes
B. Golgi complex
C. Smooth endoplasmic reticulum
D. Microtubules
E. Mitochondria
13. A 50-year-old woman had her tooth removed. The tissues than regenerated. What organelles are the most active in the regeneration?
A. *Ribosomes
B. Centrosomes
C. Postlysosomes
D. Agranular endoplasmic reticulum
E. Lysosomes
14. At the dental clinic, a 36-year-old patient had his tooth removed. After two weeks the stratified squamous epithelium regenerated at this site. What organelles participated in regeneration of the mucous membrane?
A. *Ribosomes
B. Centrosomes
C. Postlysosomes
D. Smooth ER
E. Mitochondria
15. The formation of ribosome subunits cell was experimentally disturbed by activated mutagenic factors. It will affect the metabolic process:
A. *Protein biosynthesis
B. Carbohydrate biosynthesis
C. ATP synthesis
D. Photosynthesis
E. Biological oxidation
16. In laboratory experiment, the leukocyte culture had been mixed with staphylococci. The neutrophile leukocytes engulfed and digested the bacterial cells. This process is termed:
A. *Phagocytosis
B. Pinocytosis
C. Diffusion
D. Facilitated diffusion
E. Osmosis
17. A patient is being operated under inhalation narcosis with nitrous oxide. It is known that this substance has evident lipophilic properties. What mechanism is responsible for transport of this medication across biological membranes?
A. *Passive diffusion
B. Active transport
C. Facilitated diffusion
D. Filtration
E. Pinocytosis
18. a drug with apparent lipophilic properties has been administered to a patient. What is the main mechanism of absorption of this drug?
A. *Passive diffusion
B. Filtration
C. Active transport
D. Pinocytosis
E. Facilitated diffusion
19. A blood drop has been put into a test tube with 0.3% solution of NaCl. What will happen to erythrocytes?
A. *Osmotic haemolysis
B. Shrinkage
C. Mechanical haemolysis
D. Any changes will be observed
E. Biological haemolysis
20. Testosterone and its analogs increase the mass of skeletal muscles that allows to use these medications for treatment of dystrophy. What cell structures interact with these hormones?
A. *Nuclear receptors
B. Membrane receptors
C. Ribosomes
D. Chromatin
E. Proteins-activators of transcription
21. Ionizing radiation damaged nucleoli in tissue culture. Regeneration of what organelles will be disturbed in this case?
A. *Ribosomes
B. Lysosomes
C. Golgi apparatus
D. Endoplasmic reticulum
E. Microtubules
22. A low level of albumin and fibrinogen has been detected in a patient’s blood. Decreased activity of what organelles caused it?
A. *Rough (granular) endoplasmic reticulum
B. Smooth (agranular) endoplasmic reticulum
C. Mitochondria
D. Golgi complex
E. Lysosomes
23. Analysis of an electron diffraction pattern of a cell revealed mitochondria destruction. This might affect of the process of:
A. *Oxidation of organic substances
B. Nuclear division
C. Crossing over
D. Cleavage
E. Protein synthesis
24. How many ATP molecules does one molecule of glucose produce in complete degradation (glycolysis and oxidative phosphorylation)?
A. *38
B. 8
C. 12
D. 52
E. 58
25. On an electron micrograph, a scientist has identified a structure formed by DNA and proteins. DNA molecule makes about 1.75 turns around eight histone proteins. Which structure has been identified by the scientist?
A. *Nucleosome
B. Elemetary fibril
C. Half-chromatid
D. Chromatid
E. Chromosome
26. Nucleolus organizer regions of human chromosomes 13-15, 21, 22 include about 200 gene clusters that synthesize RNA. What type of RNA do these regions control?
A. *rRNA
B. tRNA
C. mRNA
D. snRNA
E. tRNA + rRNA
27. Cytogenetic analysis established that a patient has 47, XYY karyotype. The extra chromosome has a centromere located very close to one of the chromosome ends so that one chromosomal arm is much shorter than the other one. This type of chromosome is called:
A. *Acrocentric
B. Metacentric
C. Submetacentric
D. Telocentric
E. Submetacentric with a satellite
28. Life cycle of cell includes the process of DNA replication. As a result of it, monochromatid chromosomes turn into bichromatid ones. What period of cell cycle does this phenomenon fall into?
A. *S
B. G0
C. G1
D. G2
E. -
29. Normal, actively dividing cells of human red bone marrow are analyzed. What number of chromosomes is typical for G1 period?
A. *46
B. 48
C. 47
D. 45
E. 23
30. An electron micrograph presents a cell that has no nucleoli and nuclear membrane. The chromosomes has free position, centrioles migrate to the poles. What phase of cell cycle is it typical for?
A. *Prophase
B. Anaphase
C. Metaphase
D. Telophase
E. Interphase
31. An electron microphotography represents a cell without nucleoli and nuclear membrane. The chromosomes are loosely scattered, the centrioles migrate to the poles. What phase of cell cycle is it?
A. *Prophase
B. Anaphase
C. Metaphase
D. Telophase
E. Interphase
32. During the examination of a two-month-old boy a pediatrician noticed that the child’s cry sounds like cat’s mewing; he also revealed microcephalia and valvular defect. He determined the child’s karyotype by cytogenetic method – 46, ХY, 5р-. At what stage of mitosis was the patient’s karyotype analyzed?
A. *Metaphase
B. Prometaphase
C. Prophase
D. Anaphase
E. Telophase
33. A specimen of an onion rootlet includes a cell in which the fully condensed chromosomes making an aster are located in the equatorial plane. What phase of mitotic cycle is the cell in?
A. *Metaphase
B. Early telophase
C. Prophase
D. Interphase
E. Late telophase
34. While studying the mitotic cycle phases of an onion root tip, the researchers revealed a cell with chromosomes arranged as an aster in equatorial plane. What phase of mitosis is it?
A. *Metaphase
B. Prophase
C. Anaphase
D. Telophase
E. Interphase
35. While the maximally spiralized chromosomes of human karyotype were studied, the process of cell division was stopped at the following phase:
A. *Metaphase
B. Prophase
C. Interphase
D. Anaphase
E. Telophase
36. The movement of sister chromatids to the poles of cell is observed in the mitotically dividing cell. What stage of the mitotic cycle is this cell in?
A. *Anaphase
B. Metaphase
C. Telophase
D. Prophase
E. Interfase
37. According to the rule of constant chromosome number, each species of most animals has a definite and constant number of chromosomes. The mechanism providing this constancy in sexual reproduction of the organisms is called:
A. *Meiosis
B. Schizogony
C. Amitosis
D. Regeneration
E. Gemmation
38. During the postsynthetic period of mitotic cycle, the synthesis of tubulin proteins was disturbed. These proteins take part in construction of mitotic spindle. It can lead to the disturbance of:
A. *Chromosome disjunction
B. Spiralization of chromosomes
C. Cytokinesis
D. Despiralization of chromosomes
E. Mitosis duration
39. Students study the stages of gametogenesis. They analyze a cell having a haploid number of chromosomes, and each chromosome consists of two chromatids. The chromosomes are located in the equatorial plane of the cell. Such situation is typical for the following stage of meiosis:
A. *Metaphase of the second division
B. Metaphase of the first division
C. Anaphase of the first division
D. Anaphase of the second division
E. Prophase of the first division
40. During the electron microscopic analysis of salivary gland, the cell fragments were revealed. They are surrounded by a membrane and contain the condensed particles of nuclear substance and solitary organelles. The inflammatory reaction around these cells is absent. What process does it correspond to?
A. *Apoptosis
B. Karyorhexis
C. Coagulative necrosis
D. Karyopyknosis
E. Karyolysis
41. During embryogenesis, epithelial band also known as vestibular plate gives rise to development of vestibule of mouth. What biological mechanism of the programmed cell death provides growth of buccolabial sulcus from epithelial plate?
A. *Apoptosis
B. Necrosis
C. Meiosis
D. Paranecrosis
E. Amitosis
42. The blood samples of a child and putative father were referred to forensic medical examination for affiliation. What chemical components should be analyzed in the blood in the examination?
A. *DNA
B. Transfer RNA
C. Ribosomal RNA
D. Messenger RNA
E. SnRNA
43. Ability to divide is characteristic of prokaryotic and eukaryotic cells. Prokaryotic cell division is different from that of eukaryotic, but there is one molecular process that is common both cell division processes. Name this process.
A. *DNA replication
B. Reparation
C. Gene amplification
D. Translation
E. Transcription
44. Epithelial regeneration of mucous membrane of oral cavity (cell reproduction) is accompanied by semiconservative DNA replication (self-reproduction). The nucleotides of a new DNA chain are complementary to:
A. *Maternal chain
B. Sense codons
C. DNA polymerase enzyme
D. Introns
E. RNA polymerase enzyme
45. An experiment proved that UV-irradiated skin cells of patients with xeroderma pigmentosum repair the native structure of DNA slower than the cells of healthy people due to defect in repair enzyme. What enzyme takes part in DNA repair process?
A. *Endonuclease
B. RNA ligase
C. Photolyase
D. RNA polymerase
E. DNA gyrase
46. Patients with xeroderma pigmentosum have anomalously high sensitivity to ultraviolet rays. It causes skin cancer as a result of incapability of enzyme systems to restore the damages of hereditary apparatus of cells. Which process is this pathology related to?
A. *DNA repair
B. Genetic conversion
C. DNA recombination
D. Genetic complementation
E. DNA replication
47. Skin of patients with xeroderma pigmentosum is very sensitive to sun radiation; there is a risk of skin cancer development. The cause is hereditary deficiency of UV-endonuclease. As a result of this defect the following process is disturbed:
A. *DNA repair
B. Transcription
C. DNA replication
D. Translation
E. Initiation
48. In evolution, molecular mechanism for correction of damaged DNA molecules developed. This process is called:
A. *Repair
B. Transcription
C. Translation
D. Replication
E. Processing
49. According to the model of double helix of DNA suggested by Watson and Creek, it was established that one of strand would not be lost during replication and the second strand would be synthesized complementary to the first one. What way of replication is it?
A. *Semiconservative
B. Analogous
C. Identical
D. Dispersed
E. Conservative
50. During cell division, DNA replication is initiated by a signal from the cytoplasm, and a specific site of DNA helix unwinds and splits into two individual strands. What enzyme facilitates this process?
A. *Helicase
B. RNA polymerase
C. Ligase
D. Restrictase
E. DNA polymerase
51. DNA replication occurs during the cell division when a signal is received from the cytoplasm, and a specific site of the DNA helix is unwound and divided into two strand. The helix is unwound by the following enzyme:
A. *Helicase
B. RNA polymerase
C. Ligase
D. Restrictase
E. DNA polymerase
52. An RNA-containing virus (HIV) penetrated into a leukocyte and forced a cell to synthetize a viral DNA by means of reverse transcriptase. This process is based upon:
A. *Reverse transcription
B. Operon repression
C. Reverse translation
D. Operon depression
E. Convariant replication
53. During reproduction of some RNA-containing viruses that cause tumors in animals, genetic information can be transmitted in the opposite direction − from RNA to DNA − via a specific enzyme. The enzyme of reverse transcription is called:
A. *Reverse transcriptase
B. DNA polymerase
C. Ligase
D. Primase
E. Topoisomerase
54. It was revealed that HIV affected T-lymphocytes. A viral enzyme − reverse transcriptase (RNA-dependent DNA-polymerase) − catalyzes the synthesis of:
A. *DNA on the matrix of viral mRNA
B. Viral informational RNA on the matrix of DNA
C. DNA on viral ribosomal RNA
D. Viral DNA on DNA matrix
E. mRNA on the matrix of viral protein
55. RNA-polymerase B (II) is blocked due to amanitine poisoning (poison of deathcup). It disturbs:
A. *Synthesis of mRNA
B. Synthesis of tRNA
C. Reverse transcription
D. Primers synthesis
E. Maturation of mRNA
56. It was found that some compounds, for instance fungi toxins and some antibiotics, can inhibit activity of RNA polymerase. What process in a cell will be disturbed if activity of this enzyme is supressed?
A. *Transcription
B. Processing
C. Replication
D. Translation
E. Reparation
57. Examination of a patient revealed reduced contents of magnesium ions which are necessary for ribosomes attachment to the granular endoplasmic reticulum. It results in protein biosynthesis disturbance. What stage of protein biosynthesis will be disturbed?