Biology tests – MU Sofia Exam preparation

Welcome to your Biology

1. The protein chain is supported by:

1. phosphodiester bonds between amino acids

2. covalent bonds between nucleotides

3. covalent bonds between monosaccharides

4. peptide bonds between amino acids

2. The molecule of alpha amino acids carries:

1. phosphate group, nitrogenous base and ribose

2. monosaccharide, nitrogenous base and a phosphate group

3. hydrophilic head and two hydrophobic tails

4. amino group, carboxyl group and a side chain

3. The peptide bond is formed between:

1. nucleotides

2. monosaccharides

3. amino acids

4. phospholipids

4. What is the type of peptide bond?

1. Ionic

2. Covalent

3. High energy

4. Noncovalent

5. Amino acids in polypeptide chains are bound by:

1. covalent bonds

2. ionic bonds

3. hydrogen bonds

4. disulfide bonds

6. The primary structure of proteins is related to:

1. formation of alpha helix

2. folding in a beta sheet

3. the sequence of amino acids

4. formation of phosphate and hydroxyl ends

7. Disulfide bonds take part in:

1. primary protein structure

2. alpha helical and beta sheet folding of the protein

3. tertiary structure of the protein

4. secondary structure of the protein

8. The linear sequence of amino acids in the protein determines:

1. its primary structure

2. its secondary structure

3. its tertiary structure

4. its quaternary structure

9. Which protein structure requires covalent bonds only?

1. Primary

2. Secondary

3. Tertiary

4. Quaternary

10. Which protein structure requires hydrogen bonds only?

1. Primary

2. Secondary

3. Tertiary

4. Quaternary

11. Which function is performed by specific proteins?

1. Templates for RNA synthesis

2. Support and motility apparatus of animal cells

3. Storage of genetic information

4. Templates for DNA synthesis

12. Which function is specific for enzymes?

1. To carry oxygen in blood

2. To bring amino acids to the ribosome

3. To catalyze reactions in the cell To store energy

4. To store eneregy

13. Which of the following proteins is an enzyme?

1. Lipase

2. Hemoglobin

3. Insulin

4. Collagen

14. Denaturation is a process in which proteins:

1. are misfolded

2. are synthesized

3. remain unchanged

4. are degraded to amino acids

15. Renaturation is a process in which proteins:

1. are synthesized

2. remain unchanged

3. are misfolded

4. recover their native state

16. Which of the following combinations of bases is NOT present in DNA?

1. thymine and adenine

2. uracil and adenine

3. cytosine and guanine

4. guanine and cytosine

17. Which of the statements below are valid for both DNA and RNA?

1. They form alpha helices and beta sheets

2. They are made of nucleotides

3. They are double helices

4. They are made of polypeptide chains

18. Which nitrogenous base is NOT found in RNA?

1. adenine

2. thymine

3. cytosine

4. uracil

19. The DNA of prokaryotes is:

1. Linear

2. Single-stranded

3. In their nucleolus

4. In their nucleoid

20. The DNA of eukaryotes is:

1. Single-stranded

2. Circular

3. In their nucleus

4. In their nucleoid

21. Transfer RNA takes part in:

1. bringing amino acids to the ribosome

2. DNA replication

3. cell division

4. the structure of the ribosome

22. Anticodon of tRNA is complementary to:

1. DNA double helix

2. codon of mRNA

3. the anticodon of the next tRNA

4. rRNA

23. Ribosomal RNA takes part in:

1. bringing amino acids to the ribosome

2. DNA replication

3. cell division

4. the structure of the ribosome

24. Anticodons are located in:

1. mRNA

2. tRNA

3. rRNA

4. ribosomal proteins

25. Codons are located in:

1. rRNA

2. ribosomal proteins

3. mRNA

4. tRNA

26. In which of the following examples is the base pairing correct?

1. thymine - guanine

2. adenine - uracil

3. cytosine - cytosine

4. uracil - cytosine

27. Messenger RNA:

1. is a template for transcription

2. forms a double helix

3. is a template for translation

4. forms the subunits of the ribosome

28. Which nitrogenous base is NOT found in DNA?

1. adenine

2. thymine

3. cytosine

4. uracil

29. Bonds between complementary nitrogenous bases in DNA are:

1. covalent

2. disulfide

3. hydrogen

4. peptide

30. In which of the following examples is the base pairing correct?

1. thymine -guanine

2. adenine - thymine

3. cytosine - cytosine

4. uracil - cytosine

31. Complementary bound (double stranded) regions could be formed within the chain of:

1. mRNA

2. polypeptides

3. rRNA and tRNA

4. polysaccharides

32. Which disease is caused by a virus?

1. Hepatitis B

2. Atherosclerosis

3. Tuberculosis

4. Down syndrome

33. Viruses are:

1. the simplest type of prokaryotes

2. supramolecular complexes of nucleic acids and proteins

3. free living organisms

4. colonial organisms

34. Viruses cannot multiply outside of a host cell because:

1. of the difference in temperature

2. no viruses exist outside the cell

3. of the high oxygen level

4. they need the cell anabolic apparatus

35. The term capsid is used for:

1. the viral DNA

2. the viral RNA

3. the protein shell of DNA/RNA

4. the major viral enzyme

36. Viruses infect cells by:

1. injecting their nucleic acid into the cell or entry via phagocytosis or fusion

2. dissolving the cell membrane using enzymes

3. using infected bacteria to get into the eukaryotic cells secreting antibodies

4. secreting antibodies

37. What is NOT true about viruses?

1. Some viruses have an outer envelope similar to the cell membrane

2. Some viruses have both DNA and RNA

3. Viruses can infect animal, plant and even bacterial cells

4. Viruses cannot infect other viruses

38. What is NOT true about bacteriophages?

1. The infected cell usually dies

2. They infect prokaryotes

3. They are a group of viruses

4. They can infect animal cells

39. The HIV virus:

1. is a DNA virus

2. is an RNA virus

3. can be transmitted by mosquitos

4. is controlled by immunization

40. What is the structure of prions?

1. A single strand of DNA

2. DNA or RNA coated with proteins

3. RNA coated with a lipid membrane

4. Only proteins

41. The prions are:

1. made of RNA and infect plant cells

2. made of DNA and infect skin cells

3. made of proteins and infect brain cells

4. none of the above

42. What is the most important feature of prokaryotes?

1. They have no membrane-bound nucleus

2. They can multiply only inside a host cell

3. They lack ribosomes

4. They have multiple chromosomes

43. Which disease is caused by a bacterium?

1. Haemophilia

2. AIDS

3. Tuberculosis

4. Diabetes

44. Which disease is caused by a bacterium?

1. Ebola

2. Mucoviscidosis (cystic fibrosis)

3. Meningitis

4. Haemophilia

45. The bacterial genome consists of:

1. one linear chromosome

2. several linear chromosomes

3. homologous pairs of chromosomes

4. one circular chromosome

46. The bacterial cell is surrounded by:

1. capsid

2. cell membrane and cell wall

3. cell membrane only

4. double membrane envelope

47. Which statement is NOT true about bacteria?

1. Some species can endure extreme conditions

2. In favorable conditions bacteria can divide every 20 minutes

3. Bacteria cannot be attacked by viruses

4. Some species have flagella

48. Osmosis can transport across the cell membrane:

1. carbon dioxide, oxygen and ions

2. non-polar and hydrophobic molecules or compounds

3. specific proteins

4. water molecules

49. Diffusion can transport across the cell membrane:

1. monosaccharides

2. carbon dioxide and oxygen

3. amino acids

4. specific proteins

50. Diffusion:

1. can be simple or facilitated

2. transports specific proteins across the cell membrane

3. can be active or passive

4. transports the solutes from lower to the higher concentration

51. Cell membrane is completely permeable for:

1. proteins

2. glycoproteins

3. ions

4. small uncharged molecules

52. In hypertonic environment:

1. water enters the cell, causing it to swell and even to rupture

2. the cell loses water and shrinks

3. water crosses the membrane at the same rate in and out of the cell

4. water is brought into the cell by active transport

53. In hypotonic environment:

1. the cell loses water and shrinks

2. water crosses the membrane at the same rate in and out of the cell

3. water enters the cell, causing it to swell and even to rupture

4. water is brought out of the cell by active transport

54. In isotonic environment:

1. water enters the cell, causing it to swell and even to rupture

2. the cell loses water and shrinks

3. cell membrane becomes impermeable to water

4. water crosses the membrane at the same rate in and out of the cell

55. For the active transport across the cell membrane is NOT true that:

1. It is ATP dependent

2. It is ATP independent

3. It uses protein transporters

4. It is against the concentration gradient

56. The rough endoplasmic reticulum is involved in:

1. protein synthesis

2. phospholipid, fat, and steroid synthesis

3. detoxification of some toxins and alcohol

4. cell division

57. The smooth endoplasmic reticulum is involved in:

1. intracellular digestion

2. phospholipid, fat, and steroid synthesis

3. nucleic acids synthesis

4. protein synthesis

58. Which of the following does NOT take place in the smooth endoplasmic reticulum?

1. Phospholipid, fat, and steroid synthesis

2. Accumulation of calcium ions

3. Detoxification of some toxins and alcohol

4. Protein synthesis

59. The Golgi complex:

1. takes part in endocytosis

2. has ribosomes on its membrane

3. forms vesicles with secretions

4. takes part in oxidative phosphorylation

60. Which of the organelles has single membrane?

1. Ribosome

2. Mitochondrion

3. Lysosome

4. Centrosome

61. Proteins to be secreted are synthesized:

1. by ribosomes bound to rough endoplasmic reticulum

2. by ribosomes free in the cytosol

3. within the Golgi complex

4. in the smooth endoplasmic reticulum

62. In which cells would you expect to find most abundant lysosomes?

1. Prokaryotic cells

2. Ovarian cells that produce hormones

3. Phagocytes that engulf bacteria

4. Muscle cells

63. Enclosed by a double membrane is:

1. the eukaryotic cell

2. the nucleus

3. the nucleolus

4. the prokaryotic cell

64. Enclosed by a double membrane is:

1. the eukaryotic cell

2. the nucleolus

3. the mitochondrion

4. the prokaryotic cell

65. In eukaryotic cell, oxidative phospholysation takes place in the:

1. cytosol

2. rough endoplasmic reticulum

3. Golgi complex

4. mitochondria

66. Which of the following processes does NOT take place in mitochondria?

1. glycolysis

2. oxidative phosphorylation

3. ATP synthesis

4. Krebs cycle

67. Which of the following structures is NOT a part of mitochondria?

1. ATP synthase complex

2. Electron transport chain

3. Histones

4. Double membrane

68. Where are electron transport chains located?

1. In the membrane of the rough endoplasmic reticulum

2. In the outer nuclear membrane

3. In the inner mitochondrial membrane

4. In the outer mitochondrial membrane

69. In eukaryotic cells, glycolysis takes place in:

1. the cytosol

2. the intermembrane space of mitochondria

3. the matrix of mitochondria

4. the nucleoplasm

70. In eukaryotic cells, the Krebs cycle takes place in:

1. the cytosol

2. the intermembrane space of mitochondria

3. the matrix of mitochondria

4. the nucleoplasm

71. Adenosine triphosphate (ATP) has:

1. one high energy bond

2. two high energy bonds

3. three high energy bonds

4. deoxyribose, adenine and three phosphates

72. Which process takes place in the cytosol of eukaryotic cells?

1. Oxidative phosphorylation

2. Transcription

3. Glycolysis

4. Krebs cycle

73. Which process occurs in the mitochondrial matrix?

1. Glycolysis

2. Krebs cycle

3. Photosynthesis

4. Fermentation

74. What is oxidative phosphorylation?

1. Production of phospholipids

2. ATP production in mitochondria

3. Oxidation of NAD (nicotinamide adenine dinucleotide)

4. ATP production in the cytosol

75. Substrate-level phosphorylation takes place in:

1. the lumen of smooth endoplasmic reticulum

2. the intermembrane space of mitochondria

3. the respiratory chains of the inner mitochondrial membrane

4. the cytosol during glycolysis

76. Glycolysis harvests chemical energy by:

1. converting glucose into two molecules of pyruvate

2. oxidizing glucose to $CΟ_2$

3. oxidative phosphorylation

4. alcoholic fermentation

77. Which of the following is NOT true for glycolysis?

1. It is a metabolic pathway of converting pyruvate to alcohol or lactic acid

2. It is performed by both aerobic and anaerobic organisms

3. It is an anaerobic catabolic pathway

4. It is a metabolic pathway of converting glucose to pyruvate

78. Glycolysis is:

1. anaerobic catabolic pathway in the lysosomes

2. aerobic metabolic cycle in the cytosol

3. process of oxidative phosphorylation in the mitochondrial matrix

4. anaerobic catabolic pathway in the cytosol

79. The redox reactions of electron transport (respiratory) chain:

1. connect glycolysis to the Krebs cycle

2. produce a net amount of 2 ATP per glucose molecule

3. take place in the mitochondrial matrix

4. provide energy to ATP synthase

80. Oxidative phosphorylation:

1. is an anaerobic process of converting glucose to pyruvate

2. phosphorylates ADP to ATP in mitochondria

3. reduces $NAD^+$ (nicotinamide adenine dinucleotide) to NAD.H

4. provides the ATP harvest of glycolysis

81. The enzyme ATP synthase:

1. transports electrons in respiratory chains

2. pumps $H^+$ into the intermembrane space of mitochondria

3. is a protein complex of the inner mitochondrial membrane

4. produces $Η_2Ο$ as a final product of the glucose catabolism

82. Fats and proteins become substrates for catabolism by:

1. passing through the mitochondrial membrane to enter the Krebs cycle

2. being converted to glucose by enzymes

3. being oxidized in the electron transport chain

4. being converted to intermediates of glycolysis or the Krebs cycle

83. Electron transport chains are NOT located in:

1. the thylakoid membrane of chloroplasts

2. the cristae of mitochondria

3. the inner membrane of mitochondria

4. the inner nuclear membrane

84. The ATP synthase is NOT located in:

1. the thylakoid membrane of chloroplasts

2. the cristae of mitochondria

3. the inner membrane of mitochondria

4. the inner nuclear membrane

85. The nuclear envelope:

1. surrounds the nucleolus

2. has ribosomes on its inner membrane

3. is connected to the membranes of Golgi complex

4. fuses its outer membrane to the rough endoplasmic reticulum

86. The cell nucleus:

1. is a site of transcription and translation

2. is a site of replication and transcription

3. is surrounded by a single membrane

4. is not surrounded by a membrane

87. The nuclear envelope:

1. surrounds the nucleolus

2. is formed by outer and inner membranes

3. contains the ATP synthase

4. is connected to the membranes of Golgi complex

88. The nucleolus:

1. is a site of ribosomal protein synthesis

2. is surrounded by a single membrane

3. is a site of ribosomal RNA synthesis

4. is surrounded by a double membrane envelope

89. The nucleus:

1. contains the circular chromosome of prokaryotes

2. is surrounded by a single membrane in prokaryotes

3. is a site of ribosomal protein synthesis in eukaryotes

4. contains the linear chromosomes of eukaryotes

90. The chromatin of eukaryotes:

1. is located in their cytosol

2. is a complex of linear DNA and ribosomes

3. exists as circular DNA molecules

4. is a complex of linear DNA and proteins

91. The human karyotype consists of:

1. 23 pairs of chromosomes including two sex chromosomes

2. 24 pairs of chromosomes including two sex chromosomes

3. 23 pairs of chromosomes plus two sex chromosomes

4. 24 pairs of chromosomes plus two sex chromosomes

92. The eukaryotic chromosomes are NOT made of:

1. one or two DNA molecules depending of the period of the cell cycle

2. one DNA molecule after replication

3. one DNA molecule before replication

4. two sister chromatids attached at the centromeric region

93. The human karyotype consists of:

1. 22 pairs of autosomes including two sex chromosomes

2. 22 pairs of autosomes plus two sex chromosomes

3. 23 pairs of autosomes plus two sex chromosomes

4. 24 pairs of autosomes including two sex chromosomes

94. Centromere:

1. is the structure that forms the spindle during cell division

2. is a primary constriction dividing the chromosome into two arms

3. contains the ribosomal RNA genes of the cell

4. is the organizing center of microtubule cytoskeleton in eukaryotic cell

95. Nucleolar organizer:

1. is the primary constriction dividing the chromosome into two arms

2. is a chromosomal region attached to the nuclear envelope

3. is a region of chromosomes that contain ribosomal RNA genes

4. is a complex of proteins forming the nuclear pores

96. Chromosomes are called homologous if:

1. one of them is X (from the oocyte) and the other is Y (from the sperm)

2. originate from one of the parents only

3. they resemble each other but one is maternal and the other is paterna

4. they are inherited by siblings of the same parents

97. Haploid set of human chromosomes:

1. contains 23 pairs of chromosomes

2. contains 22 autosomes plus two sex chromosomes (XX or XY)

3. is made of 22 chromosomes

4. is made of 22 autosomes plus one sex chromosome (X or Y)

98. Diploid set of chromosomes have:

1. the cells after the second meiotic division

2. the cells before and after meiosis

3. somatic cells dividing by mitosis

4. the cells after the first meiotic division

99. Diploid set of chromosomes is formed if:

1. diploid precursor cells undergo meiosis

2. haploid cells are fused to form a zygote

3. oocyte divides its cytoplasm unevenly extruding a first polar body

4. oocyte divides its cytoplasm unevenly extruding a second polar body

100. Which of the following is NOT true for the karyotype?

1. It can be studied in actively dividing cells

2. It is species-specific

3. It describes the number, size and morphology of chromosomes

4. The normal human karyotype is: 48 chromosomes including XX or XY

101. DNA replication:

1. takes place during interphase of the cell cycle

2. lasts until the end of mitotic cell division

3. occurs in prokaryotic cells only

4. occurs in eukaryotic cells only

102. During replication of DNA:

1. free nucleotides are covalently bound to the template DNA strand

2. both daughter DNA strands are synthesized continuously

3. only one of the DNA strands is used as a template

4. hydrogen bonds between the template and free nucleotides are formed

103. DNA polymerase connects the nucleotides by:

1. hydrogen bonds

2. phosphodiester bonds

3. non-covalent bonds

4. peptide bonds

104. Replication of DNA:

1. is a catabolic process

2. takes place in the cytosol of eukaryotes

3. forms the two sister chromatids

4. takes place during both mitosis and meiosis

105. Transcription:

1. is a process of RNA synthesis on RNA template

2. produces mRNA as a copy of tRNA and rRNA

3. is performed by DNA polymerase

4. is performed by RNA polymerase

106. Transcription:

1. is end to end copying of genomic DNA

2. synthesizes DNA copies of genes only

3. produces the mRNA, rRNA or tRNA as copies of their genes in DNA

4. synthesizes mRNA only

107. The enzyme RNA polymerase:

1. synthesizes RNA copy using mRNA as a template

2. copies the nucleotide sequence of a gene incorporating T instead of U

3. makes a complementary copy of a gene incorporating U instead of T

4. synthesizes copies of both complementary DNA strands

108. RNA polymerase connects the nucleotides by:

1. hydrogen bonds

2. peptide bonds

3. non-covalent bonds

4. phosphodiester bonds

109. In transcription:

1. mRNA is the template

2. tRNA carries the monomers

3. new RNA is made of anticodons complementary to codons

4. a gene in DNA is copied into RNA

110. Which of the following is true for both replication and transcription?

1. They use polymerase to synthesize polypeptide chain

2. They both take place in the cytosol

3. They both are catabolic processes

4. They use polymerase to synthesize polynucleotide chain

111. Ribosomes are organelles:

1. surrounded by a single membrane

2. located on the inner nuclear membrane

3. located on the rough endoplasmic reticulum

4. that synthesize polynucleotide chain

112. The ribosome is NOT:

1. supramolecular complex of rRNA and proteins

2. the organelle that connects amino acids by peptide bonds

3. found on the outer nuclear membrane

4. supramolecular complex of DNA and proteins

113. Synthesis of rRNA takes place in the:

1. ribosomes

2. rough endoplasmic reticulum

3. nucleolus

4. inner nuclear membrane

114. The genetic code:

1. is necessary for transcription

2. consists of 16 nucleotide triplets called codons

3. is necessary for DNA replication

4. consists of 64 nucleotide triplets called codons

115. The difference between transcription and translation is that:

1. transcription uses DNA template (a gene) and translation uses mRNA

2. transcription copies both DNA strands and translation just one of them

3. transcription takes place in the ribosomes and translation in thc nucleus

4. transcription produces protein and translation produces RNA

116. Anticodon is:

1. a triplet of ribonucleotides in mRNA

2. recognized by a codon of rRNA

3. a triplet of ribonucleotides in tRNA

4. recognized by a codon in DNA

117. Translation uses as adaptor molecules:

1. ribosomal proteins

2. transfer RNAs

3. ribosomal RNAs

4. amino acids

118. The genetic code is defined as redundant (synonymous) because:

1. almost all organisms share the same genetic code

2. the codons consist of 3 nucleotides

3. two or more codons may specify the same amino acid

4. there are no separation signals between codons

119. Interphase:

1. consists of Gl, S and G2 periods of the eukaryotic cell cycle

2. is the phase of mitotic spindle formation in prokaryotic cells

3. is the period of cytokinesis in eukaryotes

4. is the phase of sister chromatid segregation in eukaryotes

120. During the cell cycle, replication takes place during:

1. G2 period of interphase

2. Metaphase

3. S period of interphase

4. Prophase

121. The periods of interphase of the cell cycle are:

1. prophase, metaphase, anaphase and telophase

2. initiation, elongation and termination

3. diploid to haploid state transition during meiosis

4. G1, S and G2

122. Which is the correct order of the cell cycle periods in dividing cells?

1. G1 G2, S

2. Cytokinesis, G1, S,G2, Prophase

3. Prophase, anaphase, metaphase, telophase

4. Anaphase, telophase, metaphase, prophase

123. Chromosomes attach to the mitotic spindle by their:

1. centromere

2. long arm

3. short arm

4. end (telomere)

124. Mitotic spindle is made of:

1. actin microfilaments

2.chromatin fibers

3.collagecn fibers

4. microtubules

125. What is segregated during mitotic anaphase:

1. the two sister chromatids of each chromosome

2. the two homologues of each bivalent

3. the two arms of each chromosome

4. the nuclei of the two daughter cells

126. During prophase of mitosis, chromosomes are:

1. synthesized

2. condensed

3. replicated

4. segregated

127. Replication takes place:

1. between the interphase and the prophase

2. before each of the two meiotic divisions

3. after the first meiotic division

4. before the first but not before the second meiotic division

128. Crossing over takes place during:

1. mitotic metaphase

2. I meiotic metaphase

3. I meiotic prophase

4. Il meiotic prophase

129. Which is true for meiosis but NOT for mitosis:

1. DNA is replicated before the division starts

2. Chromosomes are moved by a spindle

3. Chromosomes are condensed and become compact

4. The number of chromosomes is changed by the division

130. Which process does NOT take place in meiotic prophase l:

1. chromosome condensation

2. DNA replication

3. chromosome conjugation

4. crossing over

131. When do homologous chromosomes segregate during meiosis:

1. in prophase I

2. in anaphase I

3. in metaphase Il

4. in anaphase Il

132. What is NOT true for conjugating homologous chromosomes during meiosis:

1. they form a homologous pair

2. they form a circle

3. they form a tetrad

4. they form a bivalent

133. Crossing over takes place in:

1. meiotic metaphase I

2. mitotic metaphase

3. meiotic prophase Il

4. meiotic prophase I

134. To become functional, the spermatozoa must:

1. lose most of their cytoplasm and organelles (ribosomes, ER etc)

2. expand the volume of their cytoplasm

3. extrude two polar bodies

4. be surrounded by protecting envelope (zona pellucida)

135. Which of the following is NOT true for spermatogenesis:

1. the cytoplasm is evenly distributed between gametes

2. meiosis starts at puberty

3. meiosis starts before birth

4. it results in four functional gametes

136. At the moment of ovulation, the oocyte:

1. is a large cell with one polar body

2. is arrested at prophase I of meiosis

3. Is a large cell with two polar bodies

4. is arrested at metaphase I of meiosis

137. The differences between oogenesis and spermatogenesis do NOT concern:

1. accumulation of nutritions and mRNA in one of daughter cells

2. the cytoplasmic volume distribution between the daughter cells

3. the mechanism of chromosome distribution to become haploid

4. morphological differentiation of spermatozoa after meiosis

138. Meiosis of oocytes:

1. starts at puberty

2. is arrested during metaphase I

3. is completed in the fetal ovarium

4. starts in the fetal ovarium

139. Meiosis of spermatogenesis:

1. starts at puberty

2. undergoes arrest during metaphase I

3. is completed in the fetal testis

4. starts in the fetal testis

140. Mammalian fertilization takes place in the:

1. uterus

2. fallopian tubes (oviducts)

3. ovarian cortex

4. ovarian follicle

141. The sex of mammalian embryo:

1. is determined after implantation

2. depends on the oocyte genome

3. occurs at the puberty

4. is determined at fertilization

142. The sex of mammalian embryo depends on:

1. the number of X chromosomes in the oocyte

2. X or Y sex chromosome of the spermatozoon

3. X or Y sex chromosome of the polar body

4. X or Y sex chromosome of the oocyte

143. The number of embryonic germ layers during gastrulation:

1. divides the animals into diploblastic and triploblastic

2. depends on the quantity of yolk stored in the oocyte

3. divides the animals into aquatic and terrestrial

4. depends on the sex chromosome provided by the spermatozoon

144. Which of the following is called cleavage stage of embryogenesis?

1. Formation of the primary mouth of the embryo (blastopore)

2. Formation of the primitive gut of the embryo (archenteron)

3. Series of mitotic divisions resulting in blastula formation

4. Differentiation of ectoderm, mesoderm and endoderm cells

145. Which of the following does NOT take place during gastrulation?

1. Formation of the primary mouth of the embryo (blastopore)

2. Series of mitotic divisions resulting in formation of blastula

3. Formation of the primitive gut of the embryo (archenteron)

4. Differentiation of ectoderm, mesoderm and endoderm

146. The developing mammalian embryo becomes fetus:

1. at cleavage stage of embryogenesis

2. during formation of the ectoderm, mesoderm and endoderm

3. before implantation

4. after formation of all the major body organs

147. Complete metamorphosis is:

1. the process of embryonic germ layer differentiation

2. formation of embryonic archenteron (primitive gut) and blastopore

3. development by nymph stages before the adult form

4. development with a stage enclosed in a cocoon before the adult form

148. Incomplete metamorphosis is:

1. the process of embryonic germ layer differentiation

2. formation of embryonic archenteron (primitive gut) and blastopore

3. development by nymph stages before the adult form

4. development with a stage enclosed in a cocoon before the adult form

149. Two different alleles of the same gene can be found in:

1. one chromosome

2. one organism

3. one gamete

4. one chromatid

150. Normally, two alleles of the same gene CANNOT be found in:

1. one organism

2. one somatic cell

3. one gamete

4. one chromosomal set

151. A gene can exist in several forms called:

1. alleles

2. chromatids

3. nucleotides

4. codons

152. Normally, the number of dominant alleles of the same gene in a genotype CANNOT be:

1. zero

2. one

3. two

4. three

153. A diploid organism having only one copy of a particular allele is called:

1. homozygous

2. hemizygous

3. heterozygous

4. inbred

154. How many different types of gametes can be produced by an organism with genotype Aa?

1. one

2. two

3. three

4. four

155. How many different types of gametes can be produced by an organism with genotype AABB?

1. one

2. two

3. three

4. four

156. When only one allele of a gene is phenotypically expressed in the heterozygote, this interaction is called:

1. complete dominance

2. incomplete dominance

3. intermediate inheritance

4. codominance

157. When both alleles of a gene are phenotypically expressed in the heterozygote, this interaction is called:

1. complete dominance

2. incomplete dominance

3. intermediate inheritance

4. codominance

158. Which inter-allelic interaction makes the heterozygote phenotypically indistinguishable from one of the homozygotes:

1. complete dominance

2. incomplete dominance

3. intermediate inheritance

4. codominance

159. The alternative forms of a gene are called:

1. codons

2. sister chromatids

3. bivalents

4. alleles

160. The position of a particular gene in the chromosome is called:

1. allele

2. locus

3. centromere

4. promoter

161. In Aa x Aa cross, what will be the proportion of AA individuals in the next generation:

1. 25%

2. 50%

3. 75%

4. 100%

162. In Aa x aa cross, what will be the proportion of heterozygotes in the next generation:

1. 25%

2. 50%

3. 75%

4. 100%

163. In AA x Aa cross, what will be the proportion of individuals with the dominant trait in the next generation:

1. 25%

2. 50%

3. 75%

4. 100%

164. In AA x Aa cross, what will be the proportion of individuals carrying the recessive allele in the next generation:

1. 0%

2. 25%

3. 50%

4. 75%

165. Which cross will produce phenotypic ratio 1:1?

1. AA xaa

2. AA x aa

3. Aa x Aa

4. Aa x aa

166. Different phenotypes are NOT found in:

1. natural populations

2. Fl hybrids

3. F2 hybrids

4. progeny of test cross

167. The state of X-Iinked genes in males is called

1. homozygous

2. hemizygous

3. heterozygous

4. native

168. Sex-linked genetic disorders:

1. are manifested only in males

2. are manifested only in females

3. are determined by genes located in the mitochondria

4. are determined by genes located in the X chromosome

169. If a male has a particular X-Iinked mutation, it will be transmitted to:

1. all of his daughters

2. half of his daughters

3. all of his sons

4. all of his children

170. If a female has a particular X-Iinked mutation, it will be transmitted to:

1. all of her daughters

2. half of her daughters

3. all of her sons

4. all of her children

171. Two healthy parents have a son with haemophilia, an X-Iinked recessive disorder. From which parent is the condition inherited:

1. the father

2. the mother

3. either parent

4. both parents

172. Two healthy parents have a son with sickle-cell anemia, an autosomal recessive disorder. From which parent is the condition inherited:

1. the father

2. the mother

3. either parent

4. both parents

173. Males receive their X-Iinked genes from:

1. their mother

2. their father

3. either parent

4. both parents

174. Males receive their Y-linked genes from:

1. their mother

2. their father

3. either parent

4. both parents

175. Two genes are called linked if they are located:

1. in the same locus

2. in the same chromosome

3. in the same gamete

4. in the same genotype

176. Gene linkage can disrupt:

1. the health of the individual

2. sex determination in the offspring

3. the 9:3:3:1 ratio in F2 hybrids in a dihybrid cross

4. the gene expression

177. Two genes CANNOT be linked if:

1. one is represented by a dominant and the other by a recessive allele

2. one is represented by a normal and the other by a mutant allele

3. one is autosomal and the other is sex-linked

4. one is in heterozygous and the other is in homozygous state

178. Crossing over is NOT possible between genes that are:

1. linked

2. sex-linked

3. X-Iinked

4. not linked

179. Gene mutations can be:

1. aneuploidies or polyploidies

2. structural or numerical

3. dominant or recessive

4. linear or circular

180. Structural chromosomal mutations include:

1. changed nucleotides within a gene

2. extra or lost chromosomes in the karyotype

3. additional sets of chromosomes in the karyotype

4. lost, repeated or inverted fragment of a chromosome

181. Which process is the ultimate source of all genetic variability:

1. cell division

2. mutation

3. recombination

4. crossing over

182. Sickle-cell anemia is caused by:

1. deletion

2. trisomy

3. recombination

4. gene mutation

183. Numerical chromosomal mutations can be:

1. aneuploidies or polyploidies

2. inversions or translocations

3. deletions or duplications

4. dominant or recessive

184. Structural chromosomal mutations do NOT include:

1. deletions

2. substitutions

3. inversions

4. duplications

185. Gene mutations CANNOT be:

1. dominant or recessive

2. autosomal or sex-linked

3. monosomies or trisomies

4. deletions, insertions or substitutions

186. Structural chromosomal mutations do NOT include:

1. deletion

2. duplication

3. inversion

4. crossing over

187. Numerical chromosomal mutations do NOT include:

1. triploidy

2. diploidy

3. trisomy

4. monosomy

188. X-Iinked mutations CANNOT be transmitted:

1. from father to son

2. from mother to son

3. from father to daughter

4. from mother to daughter

189. The karyotype 45, XO causes:

1. Turner syndrome

2. Klinefelter syndrome

3. Down syndrome

4. early embryonic death

190. The karyotype 45, YO causes:

1. Turner syndrome

2. Klinefelter syndrome

3. Down syndrome

4. early embryonic death

191. Which condition is caused by a gene mutation:

1. Turner syndrome

2. Klinefelter syndrome

3. Down syndrome

4. hemophilia

192. Antibodies are produced by:

1. phagocytes

2. erythrocytes

3. B lymphocytes

4. T lymphocytes

193. People of blood group O:

1. could be homozygous or heterozygous for the allele O ($Ι^Ο$ )

2. are always homozygous for the allele O ($Ι^Ο$)

3. contain no anti-A and anti-B antibodies in their plasma

4. accept transfused blood of any group

194. People of blood group AB:

1. have genotype AO or BO ($I^A I^Ο or I^BI^O$)

2. have no A or B antigens on their erythrocytes

3. have both A and B antigens on their erythrocytes

4. contain both anti-A and anti-B antibodies in their plasma

195. People of blood group B:

1. have antigen B on their erythrocytes

2. contain anti-B antibodies in their plasma

3. have both A and B antigens on their erythrocytes

4. contain both anti-A and anti-B antibodies in their plasma

196. Cell-mediated immunity is based on:

1. T cells

2. B cells

3. plasma cells

4. antibodies

197. The process of evolution is:

1. reversible

2. reproducible

3. gradual

4. pre-determined

198. Which factor creates the variation needed for evolution:

1. different environmental conditions

2. natural selection

3. interspecific interactions

4. mutation

199. The chimpanzee is:

1. a species closely related to the human

2. a species distantly related to the human

3. a species that is ancestral to the human

4. a species similar to the human because of similar environment

200. Mutations occurring in a population are:

1. mostly beneficial

2. caused by factors to which the population must adapt

3. random

4. caused by the need to have diversity