TBAT Quiz Categories

TBAT E-Placement Test

แบบทดสอบทางวิทยาศาสตร์สำหรับผู้ต้องการเข้าศึกษาหลักสูตรนานาชาติ ศึกษาต่อในระดับปริญญาตรี หลักสูตรนานาชาติ คณะแพทยศาสตร์ คณะทันตแพทยศาสตร์ คณะเภสัชศาสตร์ คณะสัตว์แพทยศาสตร์ คณะสหเวชศาสตร์
โดย Chulalongkorn University Academic Test Center

แบบทดสอบทั้งหมด 138 ข้อ (จับเวลา 180 นาที)
1 Physics (30 ข้อ)
2 Chemistry (53 ข้อ)
3 Biology (55 ข้อ)


1 / 138

TBAT Physics

1. A measuring cylinder contains water.
The diagrams show the measuring cylinder before and after some of the water is poured into a

How much water has been poured into the beaker?

2 / 138

TBAT Physics

2. The diagram shows the speed–time graph for a car.

Which row describes the motion of the car at point X and at point Y?

3 / 138

TBAT Physics

3. A ball is dropped in a vacuum from a height of 4.0 m above the surface of Mars. The acceleration of the ball at a height of 2.0 m is 3.8 m/s2 .

What is the acceleration of the ball at a height of 1.0 m above the surface of Mars?

4 / 138

TBAT Physics

4. Two objects are placed on a balance, one on each side, as shown.

Which properties of the objects can be compared using the balance?

5 / 138

TBAT Physics

5. A rectangular swimming pool is 50 m long and 25 m wide.

It contains water at a depth of 2 m.

The density of the water is 1000 kg/m3.

What is the mass of the water in the pool?

6 / 138

TBAT Physics

6. An object is rising vertically at constant speed through water. There are three vertical forces
acting on it: the weight W, the drag force D, and the upward force U.

Which diagram shows the magnitude and direction of the vertical forces acting on the object?

7 / 138

TBAT Physics

7. Which force produces heating during contact with a moving object?

8 / 138

TBAT Physics

8. A metre rule is balanced at its midpoint.

It remains balanced when a 3.0 N load is hung from the 40 cm mark and a second load is hung
from the 80 cm mark.

What is the weight of the second load?

9 / 138

TBAT Physics

9. A student measures the length of a spring. She then attaches different weights to the spring. She measures the length of the spring for each weight. The table shows her results.

What is the extension of the spring with a weight of 3.0 N attached to it?

10 / 138

TBAT Physics

10. Which power station produces the greatest atmospheric pollution for each unit of energy generated?

11 / 138

TBAT Physics

11. A 500 N weight is raised through a height of 5 cm. How much work is done by the force?

12 / 138

TBAT Physics

12. What is the unit of power?

13 / 138

TBAT Physics

13. The diagram shows a rectangular block of weight 16 N. It is resting on a flat surface.

What is the pressure at the base of the block due to its weight?

14 / 138

TBAT Physics

14. A piston traps a mass of gas inside a cylinder. Initially, the piston is halfway along the length of the cylinder.

The piston is now moved towards the open end of the cylinder. The temperature of the gas remains constant.

How are the density and the pressure of the gas affected by moving the piston?

15 / 138

TBAT Physics

15. Which statement describes what happens to air particles when the air is heated?

16 / 138

TBAT Physics

16. What happens when the temperature of a liquid increases?

17 / 138

TBAT Physics

17. In which states of matter can thermal energy be transferred by convection?

18 / 138

TBAT Physics

18. A transverse wave moves along a rope.

The diagram shows the position of the rope at one particular time.

Which two labelled points are one wavelength apart?

19 / 138

TBAT Physics

19. The diagram shows a ray of light being reflected from a plane mirror.

Which row identifies the angles of incidence and reflection?

20 / 138

TBAT Physics

20. Blue light has a typical wavelength of 5.0 × 10-7 m and frequency of 0.60 × 1015 Hz.

Which row gives a typical wavelength and frequency for red light?

21 / 138

TBAT Physics

21. Which diagram shows what happens when a ray of white light passes through a prism?

22 / 138

TBAT Physics

22. A television (TV) station transmits a signal to a television receiving dish. The television has an on/off indicator light.

The television is switched on by a remote control which changes the indicator light from red to green.

Which electromagnetic wave used in these actions has the longest wavelength?

23 / 138

TBAT Physics

23. A sound wave has a wavelength of 0.024 m.

What is the frequency of this sound wave and is it audible to humans?

24 / 138

TBAT Physics

24. The diagram shows a bar magnet at rest on a smooth horizontal surface. A length of soft-iron wire is held parallel to the magnet.

The wire is released.

What happens?

25 / 138

TBAT Physics

25. A man walks across a carpet. He becomes negatively charged by friction with the carpet.

What happens as he touches a metal object connected to the Earth?

26 / 138

TBAT Physics

26. A laboratory has a standard wire of known resistance. It also has other wires, made from the same material as the standard wire, but of different lengths and diameters.

Which wire would definitely have a resistance of less than the standard wire?

27 / 138

TBAT Physics

27. The diagram shows a circuit.

Which energy transfers occur?

28 / 138

TBAT Physics

28. X, Y and Z are lamps.

In which lamps is there a current?

29 / 138

TBAT Physics

29. The diagram shows a circuit.

Which change causes the bulb in the circuit to become brighter?

30 / 138

TBAT Physics

30. The current in a kettle is 10 A and the kettle is protected by a 13 A fuse.

The owner of the kettle replaces the 13 A fuse with a 3 A fuse.

What happens when the kettle is switched on?

31 / 138

TBAT Chemistry

1. The diagram shows the result of dropping a purple crystal into water.

Which processes take place in this experiment?

32 / 138

TBAT Chemistry

2. Which row about elements, mixtures and compounds is correct?

33 / 138

TBAT Chemistry

3. What are the relative charge and relative mass of an electron?

34 / 138

TBAT Chemistry

4. The atomic structures of four particles, W, X, Y and Z, are shown.

Which particles are isotopes of the same element?

35 / 138

TBAT Chemistry

5. Which row shows the properties of an ionic compound?

36 / 138

TBAT Chemistry

6. Which row describes the formation of single covalent bonds in methane?

37 / 138

TBAT Chemistry

7. Which equation represents the neutralisation of nitric acid using sodium hydroxide?

38 / 138

TBAT Chemistry

8. What is the relative formula mass of ammonium nitrate, NH4NO3?

39 / 138

TBAT Chemistry

9. Concentrated aqueous sodium chloride is electrolysed using inert electrodes.

Gases X and Y are produced at the electrodes shown.

What are X and Y?

40 / 138

TBAT Chemistry

10. Which statement about hydrogen fuel cells is correct?

41 / 138

TBAT Chemistry

11. A reaction pathway diagram is shown.

Which statement about this reaction is correct?

42 / 138

TBAT Chemistry

12. Lumps of calcium carbonate react with dilute hydrochloric acid as shown.

CaCO3 + 2HCl → CaCl2 + H2O + CO2

Which change in conditions decreases the rate of the reaction?

43 / 138

TBAT Chemistry

13. Solid copper(II) sulfate exists in two different forms, anhydrous and hydrated.

One of these forms is blue and the other is white.

The change between these two forms is reversible.

blue form ⇌ white form

What is the blue form and how is the change from the blue form to the white form brought about?

44 / 138

TBAT Chemistry

14. Four redox equations and statements about the equations are shown.

Which statements about the equations are correct?

45 / 138

TBAT Chemistry

15. Sodium hydroxide forms an alkaline solution with a pH of 14.

Which indicator turns yellow when added to this solution?

46 / 138

TBAT Chemistry

16. Which row identifies an acidic oxide and a basic oxide?

47 / 138

TBAT Chemistry

17. A student makes aqueous copper(II) chloride by adding excess copper(II) carbonate to dilute hydrochloric acid.

What is the next step in the method in the formation of solid copper(II) chloride?

48 / 138

TBAT Chemistry

18. Which statements about the trends across a period of the Periodic Table are correct?

  1. Aluminium is more metallic than sodium.
  2. Beryllium is more metallic than carbon.
  3. Boron is more metallic than lithium.
  4. Magnesium is more metallic than silicon.

49 / 138

TBAT Chemistry

19. Which row shows the trend in melting point, density and reactivity as Group I is descended?

50 / 138

TBAT Chemistry

20. Which row describes a similarity and a difference between chlorine and bromine?

51 / 138

TBAT Chemistry

21. Which statement describes transition elements?

52 / 138

TBAT Chemistry

22. Which diagram shows the electronic structure of a noble gas?

53 / 138

TBAT Chemistry

23. Which gas is made when powdered zinc is added to dilute hydrochloric acid?

54 / 138

TBAT Chemistry

24. Which metal is used in aircraft manufacture because it has a low density?

55 / 138

TBAT Chemistry

25. The diagram represents the structure of a solid.

Which solids does the diagram represent?

56 / 138

TBAT Chemistry

26. Three students, X, Y and Z, are told that solid P reacts with dilute acids and also conducts electricity.

The table shows the students’ suggestions about the identity of P.

Which students are correct?

57 / 138

TBAT Chemistry

27. Which substances in the air are needed for iron to rust?

58 / 138

TBAT Chemistry

28. Part of the reactivity series of metals is shown.

Which row shows how each metal is extracted from its ore?

59 / 138

TBAT Chemistry

29. Which gas has the fastest rate of diffusion?

60 / 138

TBAT Chemistry

30. There are two stable isotopes of bromine.

The mass number of isotope 1 is 79.

The mass number of isotope 2 is 81.

Which statement is correct?

61 / 138

TBAT Chemistry

31. Which statement about ions and ionic bonds is correct?

62 / 138

TBAT Chemistry

32. Part of the Periodic Table is shown.

Which type of chemical bonding is present in the oxide of F and in the oxide of G?

63 / 138

TBAT Chemistry

33. Elements X and Y react to form a compound.

Element X loses two electrons and element Y gains one electron.

What is the charge on the ions of elements X and Y and what is the formula of the compound?

64 / 138

TBAT Chemistry

34. Which statement about graphite explains why it is used as an electrode?

65 / 138

TBAT Chemistry

35. Methane, CH4, burns in air to form carbon dioxide and water.

What is the balanced equation for this reaction?

66 / 138

TBAT Chemistry

36. The equation for the thermal decomposition of sodium hydrogencarbonate is shown.

2NaHCO3 → Na2CO3 + H2O + CO2

The Mr of sodium hydrogencarbonate, NaHCO3, is 84.

The Mr of sodium carbonate, Na2CO3, is 106.

In an experiment, 2.1 g of sodium hydrogencarbonate is heated but not all of it decomposes. All of the carbon dioxide is collected and measured at room temperature and pressure. The total volume of carbon dioxide produced is 0.21 dm3.

The volume of 1 mole of a gas at room temperature and pressure is 24 dm3.

Which statement is correct?

67 / 138

TBAT Chemistry

37. An electrolysis experiment is done using carbon electrodes.

Hydrogen and oxygen are formed at the electrodes.

What is the electrolyte?

68 / 138

TBAT Chemistry

38. Concentrated aqueous copper(II) sulfate is electrolysed using copper electrodes.

Which ionic half-equation describes the reaction taking place at the cathode?

69 / 138

TBAT Chemistry

39. When powdered sodium carbonate and aqueous ethanoic acid are mixed, the temperature of the mixture falls.

Which statement about this reaction is correct?

70 / 138

TBAT Chemistry

40. Magnesium powder reacts with an excess of dilute hydrochloric acid to produce hydrogen gas.

Which statements about this reaction are correct?

  1. The smaller the particles of magnesium powder, the more slowly the hydrogen is produced.
  2. The higher the temperature, the faster the magnesium powder disappears.
  3. The lower the concentration of dilute hydrochloric acid, the faster the rate of reaction.
  4. The faster the magnesium powder disappears, the faster the rate of reaction.

71 / 138

TBAT Chemistry

41. The reaction between two aqueous compounds, X and Y, is slow and exothermic.

The graph shows how the rate of this reaction changes with time.

A student suggests that the rate of reaction decreases with time because:

  1. the activation energy decreases
  2. the speed of the molecules of X and Y decreases
  3. the concentration of both X and Y decreases with time.

Which suggestions are correct?

72 / 138

TBAT Chemistry

42. Hydrogen reacts with iodine to form hydrogen iodide.

H2(g) + I2(g) → 2HI(g)

Which statements explain why the reaction is faster when the pressure is increased, at constant temperature?

  1. At higher pressure, the molecules are moving faster.
  2. At higher pressure, more of the molecules have the required activation energy.
  3. At higher pressure, the molecules are closer together.
  4. At higher pressure, the molecules collide more frequently.

73 / 138

TBAT Chemistry

43. Ammonium sulfate is used as a fertiliser.

It is made from ammonia and sulfuric acid.

The ......1...... is made by the ......2...... process in which ......3...... is used as a catalyst.

Which words complete gaps 1, 2 and 3?

74 / 138

TBAT Chemistry

44. The reversible reaction shown takes place in a closed system at constant temperature.

P(g) + Q(g) + R(g) ⇌ S(g) + T(g)

When the reaction has reached equilibrium, more T is added.

After the addition of T, which other substances increase in concentration?

75 / 138

TBAT Chemistry

45. In which equation is the underlined substance acting as a reducing agent?

76 / 138

TBAT Chemistry

46. An aqueous solution reacts with a solid. The products are an alkaline gas, a salt and water.

What are the aqueous solution and the solid?

77 / 138

TBAT Chemistry

47. Butanoic acid partially dissociates in aqueous solution.

Which row about butanoic acid is correct?

Copper(II) sulfate is prepared by adding excess copper(II) carbonate to sulfuric acid.

Why is an excess of copper(II) carbonate added?

78 / 138

TBAT Chemistry

48. Part of the Periodic Table is shown.

Which element has two electrons in its outer shell and three electron shells?

79 / 138

TBAT Chemistry

49. Elements in Group I and Group II show the same trends in their reactions with water and in their density.

Which row shows how the properties of barium compare with calcium?

80 / 138

TBAT Chemistry

50. Which pair of compounds shows a transition element in two different oxidation states?

81 / 138

TBAT Chemistry

51. Which description of brass is correct?

82 / 138

TBAT Chemistry

52. What is the symbol of the metal used in the manufacture of aircraft because of its low density?

83 / 138

TBAT Chemistry

53. Which substances react to form hydrogen gas?

  1. calcium and water
  2. silver and dilute hydrochloric acid
  3. magnesium and steam
  4. zinc and dilute hydrochloric acid

84 / 138

TBAT Biology

1. Living animals release carbon dioxide.

This is an example of which life process?

85 / 138

TBAT Biology

2. Some statements about species are given.

  1. Members of a species all look identical.
  2. Members of a species belong to the same genus.
  3. Members of a species can produce fertile offspring.
  4. Species are named using an international system.

Which statements are correct?

86 / 138

TBAT Biology

3. The table shows some features of different animals.

Which animal is a reptile?

87 / 138

TBAT Biology

4. Which structures are found in the cells of all living organisms?

  1. cell membrane
  2. chloroplast
  3. cytoplasm

88 / 138

TBAT Biology

5. A diagram of a human red blood cell is shown. The length of line XY on the diagram is 40 mm.

The actual width of the cell is 0.008 mm.

What is the magnification of the diagram?

89 / 138

TBAT Biology

6. Which statements are correct for both diffusion and osmosis?

90 / 138

TBAT Biology

7. What is a role of water in digestion?

91 / 138

TBAT Biology

8. The concentration of sodium ions in the soil is lower than the concentration inside root hair cells.

Which process will be used when sodium ions are taken into root hair cells from the soil?

92 / 138

TBAT Biology

9. The diagram represents a protein molecule.

What do the small circles represent?

93 / 138

TBAT Biology

10. Which processes depend on the action of enzymes?

  1. digestion
  2. osmosis
  3. respiration

94 / 138

TBAT Biology

11. Which diagram of an enzyme, active site and substrate is correct?

95 / 138

TBAT Biology

12. Four test-tubes are set up as shown.

Which test-tube contains the least carbon dioxide after one hour?

96 / 138

TBAT Biology

13. Which row shows the uses of some carbohydrates in plants?

97 / 138

TBAT Biology

14. The lack of which component of a balanced diet will lead to the development of scurvy?

98 / 138

TBAT Biology

15. Which structure is the duodenum?

99 / 138

TBAT Biology

16. The food label is from a packet of cereal.

The label can help someone who is concerned about their diet.

A person eats 45g of cereal.

One of the food types listed in the label can help prevent constipation.

How many grams of this food type does the person eat?

100 / 138

TBAT Biology

17. Which pathway is taken by water through a plant?

101 / 138

TBAT Biology

18. Which row shows the transpiration rate for the conditions described?

102 / 138

TBAT Biology

19. The diagram shows the human heart.

Which label shows the left ventricle?

103 / 138

TBAT Biology

20. Which row shows the features of an artery or a vein?

104 / 138

TBAT Biology

21. What are features of gas exchange surfaces in animals?

105 / 138

TBAT Biology

22. Which chemical can be used to show the presence of carbon dioxide gas?

106 / 138

TBAT Biology

23. The diagram represents the exchange of gases during breathing and during respiration in the body.

What is represented by X?

107 / 138

TBAT Biology

24. Which molecule is produced by anaerobic respiration in yeast?

108 / 138

TBAT Biology

25. The diagram shows the human body and some of its organs.

Which structure removes urea from the blood?

109 / 138

TBAT Biology

26. The diagram shows the structures in a reflex arc.

What is X?

110 / 138

TBAT Biology

27. Changes in light intensity cause changes in the diameter of the pupil in the eye.

Which rows show the pupil reflex?

111 / 138

TBAT Biology

28. A hormone is injected into a person to reduce their blood glucose concentration.

Which endocrine gland is not functioning properly in a person who needs to have this injection?

112 / 138

TBAT Biology

29. The table shows which antibiotics are effective against different types of bacteria.

The shaded areas show the antibiotic is effective against that type of bacteria.

A person has a disease caused by a type of Streptococcus bacteria and a second infection caused by a type of Pseudomonas bacteria.

Which antibiotic should be taken?

113 / 138

TBAT Biology

30. The diagram shows one way that a plant can reproduce.

What is a feature of this type of reproduction?

114 / 138

TBAT Biology

31. Which human characteristics are inherited?

115 / 138

TBAT Biology

32. In a sperm cell, which structure contains enzymes that can digest the jelly coat of an egg cell?

116 / 138

TBAT Biology

33. When breeding, which pair of parents will be pure-breeding for a particular characteristic?

117 / 138

TBAT Biology

34. Ina pea plant, the allele for round seeds, R, is dominant to the allele for wrinkled seeds, r.

If plants with the genotype Rr are crossed, what are the likely proportions of offspring?

118 / 138

TBAT Biology

35. Which definition of continuous variation is correct?

119 / 138

TBAT Biology

36. Which term is used to describe an organism that makes its own organic nutrients?

120 / 138

TBAT Biology

37. What is the principal source of energy for most food chains?

121 / 138

TBAT Biology

38. A single tree is food for a large population of caterpillars. Several small birds eat the caterpillars.

The small birds are eaten by a bird of prey.

Which is the pyramid of biomass?

122 / 138

TBAT Biology

39. The diagram shows the results of a survey on the types of animals found along a stretch of river near to a factory.

Which animal lives in the least polluted water?

123 / 138

TBAT Biology

40. Bacteria are useful for manufacturing products for human use.

Which statement explains why they are useful?

124 / 138

TBAT Biology

41. All living organisms release energy from nutrient molecules within their cells.

What is the name of this characteristic?

125 / 138

TBAT Biology

42. The scientific names of some animals are listed.

  1. Arius felis
  2. Felis concolor
  3. Felis rufus
  4. Macropus rufus

Which animals are in the same genus?

126 / 138

TBAT Biology

43. The diagram shows a dichotomous key for arthropods

The organism shown is an arthropod called an isopod.

Which group does the isopod belong to?

127 / 138

TBAT Biology

44. The diagram shows a cross-section through two guard cells of a leaf.

Which labelled structures would also be found in an animal cell?

128 / 138

TBAT Biology

45. Which level of organisation is shown by the heart of a mammal?

129 / 138

TBAT Biology

46. The image shows a single-celled organism called a Paramecium.

The length of the Paramecium in the image is 6 cm. The magnification is x400.

Which calculation will give the correct actual length of the Paramecium, in mm?

130 / 138

TBAT Biology

47. Female moths release chemicals into the air. Male moths detect these chemicals and fly towards the females.

How do the chemicals spread through the air?

131 / 138

TBAT Biology

48. The diagram shows a section through a mesophyll cell of a leaf.

Which part is partially permeable?

132 / 138

TBAT Biology

49. What are the smaller basic units of starch and glycogen molecules?

133 / 138

TBAT Biology

50. What is the correct definition of an enzyme?

134 / 138

TBAT Biology

51. The diagram shows two food tests being carried out on solution X.

Which nutrients are present in solution X?

135 / 138

TBAT Biology

52. Which chemical is a product of photosynthesis that moves out of a green leaf through its stomata?

136 / 138

TBAT Biology

53. A student investigated one of the factors that affects photosynthesis.

Part of a leaf was covered with black paper, as shown.

After two days the student tested the leaf for the presence of starch.

Which factor did the student investigate?

137 / 138

TBAT Biology

54. Which nutrient is required to prevent scurvy?

138 / 138

TBAT Biology

55. Which diagram represents the action of lipase?

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      MCAT Organic Chemistry

      The Robinson annulation reaction is a widely used, multistep process for generating cyclic a, B-unsaturated ketones. The first step (known as a Michael reaction) involves conjugate addition of an enol or enolate to an o. B-unsaturated carbonyl (Molecule1). The reaction then proceeds with ring closure and loss of water (cyclodehydration) to give a cyclic a,B-unsaturated ketone (Molecule 8).
      Scientists have found a way to catalyze the Robinson annulation by using artificial enzymes made from antibodies (Zhong, et. al, (Am. Chem. Soc. 1997, 119, 8131). As shown in Figure 1, these catalytic antibodies speed up the reaction by using a lysine side chain to form an imine with Molecule 3. The imine more readily undergoes tautomerization and cyclodehydration to give Molecule 7, which is easily hydrolyzed to Molecule 8.
      An important result is that Molecule 8 is produced as a single


      MCAT General Chemistry

      The extent to which a salt dissolves in water can be quantified by its solubility product constant, (Ksp) which is defined, for a hypothetical salt Xa Yb as shown in Equation 2. The greater the value of Ksp. the more soluble the compound. The Ksp of a salt is related to the free energy of dissolution by the equationΔG°diss = – RT In(Ksp). Table 1 lists the Ksp values for some insoluble salts.

      When a solid completely dissolves, solute particles are separated and encapsulated by solvent molecules. This process requires several steps:

      1) breaking all solute-solute interactions,

      2) disrupting some solvent-solvent interactions, and

      3) forming new solute-solvent interactions.

      The combination of these processes determines the overall enthalpy change for the dissolution, which can be either exothermic or endothermic regardless of the solubility of the salt. Table 2 shows the enthalpies of dissolution for several soluble salts.

      MCAT Biochemistry

      The complexity of hemoglobin’s function is exemplified by its chemical structure. Multiple factors are believed to affect the kinetics of oxygen binding to the molecule’s active sites.

      It has been proposed that the binding of oxygen (Figure 1) reduces strain on the heme protein superstructure by counterbalancing the pull of the proximal imidazole. Similarly, increasing basicity of the proximal imidazole (e.g., through loss of a hydrogen atom) is believed to exert additional strain on the heme protein in the deoxygenated state by inducing a dome-shaped molecular structure. Because the binding of oxygen relieves this strain, increasing basicity of the proximal imidazole increases the affinity of the heme for oxygen. The hydrophobic pocket created by hydrocarbon-like residues from adjacent heme proteins are also believed to facilitate oxygenation, though it has been proposed steric hindrance may provide an antagonistic effect. The distal imidazole shown below may inhibit dissociation by stabilizing the oxygen molecule in place.



      The net effect of these and other factors affecting oxygen dissociation from hemoglobin can be expressed kinetically:

      Equation 1

      A single heme molecule will associate with O2 to form a heme-O2 complex with rate constant 𝑘’ in a reverse reaction, oxygen will dissociate from the heme-O2 complex with rate constant k. One/study examined the kinetics of association of oxygen at different oxygen-bound states as well as the
      implied equilibrium constants (K02) for each stage of oxygen association (Table 1).



      Another study examined the thermodynamics of the association of hemoglobin dimers (𝛼𝛽) to form the tetrameric hemoglobin protein.

      Figure 2 Free energy coupling for dimer-tetramer association in deoxygenated and oxygenated hemoglobin
      Extrapolating from the respective linear models depieted in Figure 2, specific data for free energy as well as enthalpy and entropy at body temperature (310 K) are shown in Table 2.



      Adapted from Chang, C. K., and Traylor, I. G. Kinetics of oxygen and carbon monoxide binding to synthetic analogs of the myoglobin and hemoglobin active sies: Sp. S. H. C. and Ackers, G. K. Thermodynamic studies on subunit assembly in human hemoglobin.

      MCAT Biology

      Protein synthesis involves a number of complex steps, from transcription of the gene through to translation and post-translational modification. After mRNA is transcribed in eukaryotes, it must be processed (capped, poly-A tailed, and spliced) before it can be translated. Prokaryotes do not need to process their mRNA.

      Due to the exonuclease activity of DNA polymerase, DNA replication is generally a high-fidelity process. Random errors occasionally occur and these mutations are classified as frameshift mutations (insertions or deletions in the base sequence) or point mutations (a single base pair change). Any mutation is subject to natural selection, with advantageous mutations preserved and the most deleterious mutations eliminated quickly. Thus, areas of the genome that appear to evolve very slowly (i.e., have a slower rate of mutation than other areas) do not actually have a slower rate; rather, that area is highly critical to normal functioning of the organism involved.

      Point mutations can be further classified by their final effect on the mature protein. Because of the redundancy of the genetic code, some mutations do not alter the final amino acid sequence of the protein and are referred to as silent mutations. However, it was discovered that all redundant codons are not equal; some are used preferentially to enhance the speed or accuracy of protein translation. tRNAs corresponding to redundant codons are not found equally in the cell, some tRNAs are more common than others. Silent mutations can cause phenotypic changes by altering mRNA stem-and-loop folding, half-life, and splicing sites. Thus, mutations formerly considered “silent” have now been implicated in a number of different disorders, such as Marfan syndrome, phenylketonuria, Seckel syndrome, and increased pain sensitivity.

      Figure 1 The Genetic Code

      MCAT Physic & Math

      Figure 1 shows a thin-walled, cylindrical metal container fitted with a tight-fitting but freely movable lightweight plastic piston and containing 0.25 mol of helium at 0°C and a pressure of
      1 atm.

      The volume, pressure, and temperature of the gas can be changed by various processes, such as by adding weights to the top of the piston or by heating the cylinder with a flame.
      The heat exchanged between the confined helium gas and the surroundings will be denoted by Q, where a positive value of 𝒬 indicates that the heat has been transferred into the gas; if O is negative, heat has been transferred out of the gas. The work done on the gas will be denoted by W, where a positive value of W indicates that the gas does work on its surroundings; if W is negative, this means that the surroundings do work on the gas. The change in the internal energy of the gas is given by the equation.

      𝚫E = 𝒬- W
      Equation 1

      A student conducts the following series of experiments in a chemistry lab.

      Experiment 1
      The student measures the volume of the gas in the cylinder, places a known mass m on top of the piston, and then increases the temperature of the gas at constant pressure to 273°C.

      Experiment 2
      After the gas is allowed to cool back to 0°C at 1 atm pressure the student locks the piston in place, and then increases the temperature of the gas to 273°C.

      Experiment 3
      After Experiment 2 is completed, the student unlocks the piston and a computer-controlled heat source maintains the temperature at a constant 273°

      Experiment 4
      After Experiment 2 is completed, the cylinder is completely wrapped in insulation before the piston is unlocked.

      MCAT Psychology & Sociology

      Recent research has explored the neurophysiological correlates of various therapies to assess their efficacy. Reduced cortical mass in areas associated with negative emotions are interpreted as indications of effective therapeutic intervention. Also, researchers looked at the mass of various regions associated with emotional regulation, such that increased mass in these regions also suggested that the therapies had helped patients improve their ability to modulate emotional experience.

      Study 1: Cognitive Behavioral Therapy
      A team of researchers conducted an fMRI study that looked at activation levels in a cohort of 20 patients who were given a
      10-week treatment protocol, meeting with a psychologist for 45 minutes in each session. During sessions, participants explored maladaptive thought patterns and created a plan for more effective coping mechanisms that was encouraged by positive secondary reinforcement by the therapist at the next session.
      To track thoughts while subjects were alone during the week, participants were told to keep a journal. Pretest and posttest measures of cortical activity were measured and compared.

      Study 2: Psychoanalytic Psychotherapy
      An increase in cortical mass in areas associated with self-awareness and the top-down regulation of emotion was measured through the use of positron emission tomography (PET). At the end of the 3-month program, researchers saw changes in the mass of regions of the prefrontal cortex, amygdala, and hippocampal projections to the sensory cortices. Researchers conducted the study on 10 male and female participants who had grown up in single-parent homes, based on the premise that the absence of a parent made them good candidates for psychoanalytic therapy. Researchers hypothesized that awareness and analysis of repressed thoughts, and not emotional regulation, would mediate the effectiveness of therapy and improve clinical outcomes.

      Study 3: Behavioral Therapy
      A reinforcement schedule was paired with aversion therapy, which was used to rewire the reward circuit in individuals with various types of addiction. 18 male and female undergraduate students who had been diagnosed with alcohol and drug addiction were given treatment. The treatment involved exposure to alcohol or the drug and nasal inhalation of an aversive agent meant to induce mild nausea. Application of the aversive treatment was potentially dangerous, so it was done in a supervised clinical environment twice a week according to a schedule. Researchers also checked in once a week at random times to see if patients had successfully avoided drug or alcohol use and gave points that could be used towards various prizes if they had. Afterward, dopaminergic circuits and the density of regions associated with impulse control were assessed.

      MCAT Critical Analysis & Reasoning Skills
      Passage 2

      It is not easy to define Benjamin Franklin’s religious and moral beliefs; yet it is important to do so, because they are representative of a large body of men of his time, whose worldly success certainly derived from their beliefs. D. H. Lawrence, who was angered by all success, treats Franklin as a hypocrite who found the rules which lead to success and turned them into a religion. This analysis is certainly false, but even if it were true, it would not take us far enough. For it would not tell us what made Franklin respected by men as different as his American friends, his English enemies, and his French admirers. There was something in Franklin’s beliefs which had a symbolic quality for them all.

      The charge that Franklin was a hypocrite can be presented simply. He advocated many virtues at a time when he undoubtedly lapsed into some vices. He began his marriage in 1730 by bringing an illegitimate son into the house. Indeed, he may never have been very vigorous in resisting the temptations of the flesh. These lapses from the conventions of family life would not have outraged D. H. Lawrence if they had not been coupled with a certain priggishness in many of the household maxims which Franklin popularized.

      In 1732, Franklin began publishing Poor Richard’s Almanac, which was by far the most successful work that he wrote, and in some ways the most influential. Like other almanacs, this is stuffed with those plums of wisdom which most people like to taste and few to digest-_”hunger never saw bad bread,” and “well done is better than well said.” It is these crystallized plums, so eminently homely and homemade, which have made Franklin’s beliefs seem commonplace. But this criticism confuses the manner in which Franklin expressed himself and expressed himself at all times with the content of his thought. Franklin had a special gift for putting a thought into a simple and earthy sentence. This is a gift of expression: a rare gift, but Franklin had it to perfection.

      The gift has a drawback, however. In this form, Franklin’s isolated thoughts do indeed wear a simple and sometimes a commonplace air. But it is a crude error to suppose therefore that the totality of Franklin’s thoughts, the system into which the isolated thoughts lock and combine, is commonplace.
      In this respect, the simplicity of Franklin’s sentences is as deceptive as the simplicity of Bertrand Russell’s, and the outlook which they make up all together is equally complex.

      The informality with which Franklin wrote and spoke is, however, just to his thought in one respect: he was opposed to formality and rigidity of belief. It is not merely that he did not care for the fine points of dogma; he thought it wrong in principle to wish to formulate religion in fine points. He did not acknowledge any sectarian monopoly of truth. For example, when, at the age of 83, he stated his belief in God, he coupled it with another belief, “that the most acceptable service we render Him is doing good to His other children.”
      At bottom, it is this tolerance in Franklin’s make-up which we must understand. He was tolerant of others because he recognized in them the same humanity that he knew in himself.

      He never hid his motives from himself, but neither did he belittle the motives of others. We should recognize him as honest because he judges others exactly as he judges himself, with a realistic and generous sense of what can be expected of human beings. Sustained by humanity, he could gain the respect of those as religiously diverse as the anticlerical Tom Paine and the evangelist George Whitfield.

      MCAT Critical Analysis & Reasoning Skills
      Passage 1

      Basketball, a game of constant movement and a thousand
      actions, is a difficult game to remember; Leonard Koppett makes this and other excellent points in All About Basketball.

      Football is a series of set plays, as clear in our minds as moves in chess; and the high drama of a baseball game is often distilled in a single pitch, catch, throw, or hit. We remember baseball and football actions as though the players were etched upon our minds like figures on a distant green. In basketball, by contrast, we remember movement, style, flair, but only occasionally a single play. Perhaps we recall the seventh game of the Lakers-Knicks playoff on May 8, 1970, after the Lakers had pounded the Knicks in the sixth game. Willis Reed was injured and out, it seemed, for the season; and we may remember Reed walking stiffly to the floor for that final game just minutes before warm-ups were concluded; remember the sustained ovation; remember his stilt jumps as he put the hirst two shots of the game through and then had to leave the game in pain; remember that the Knicks, lifted high by his courage, went on to win game seven, bringing to New York basketball a new perspective. But it is hardly ever, even here, an individual plus one remembers. A basketball game plays past like a river,like a song In basketball as in no other sport, Koppett also notes, the referee is part of the drama. Decisions of the scorer and the timer are critical and affect the outcomes of countless games every year.

      But the referee is an agent, an actor; he affects the changing tissue of the drama every instant. He cannot call every infraction, but he must control the game. He needs to gain the players’ and the crowds’ attention, respect, and emotional cohesion. Thus, referees like Pat Kennedy, Sid Borgia, and Mendy Rudolph in the NBA became better known than many of the players. Each blew the whistle in a range of different tones and styles; each had a repertoire of operatic gestures; each had an energy and physical exuberance that added to the total drama. All won respect for coolness under withering emotion.
      Basketball players are visible in every action, Koppett notes, and easily singled out by the spectators as football players are not. They handle the ball scores of times and are physically involved in every moment of offense and defense, as baseball players are not. They are subject to many more flukes than baseball or football players, for they pass and run at high speed constantly, forcing dozens of errors, breaks, and opportunities. “Don’t shoot!” the coach screams in despair, his voice trailing off to “Nice shot” as he sits down.

      Teams move in patterns, in rhythms, at high velocity; one must watch the game abstractly, not focusing on any single individual alone, but upon, as it were, the blurred and intricate designs woven by the paths through which all five together
      cast a spell upon an opposition. The eye watches five men at once, delighting in their unity, groaning at their lapses of concentration. Yet basketball moves so rapidly and so depends on the versatility of each individual in escaping from the defense intended to contain him that the game cannot be choreographed in advance. Twelve men are constantly in movement (counting two referees), the rebounds of the ball are unpredictable, the occasions for passing or dribbling or shooting must be decided instantaneously; basketball players must be improvisers. They have a score, a melody; each team has its own appropriate tempo, a style of game best suited to its talents; but within and around that general score, each individual is free to elaborate as the spirit moves him.
      Basketball is jazz: improvisatory, free, individualistic, corporate, sweaty, fast, exulting, screeching, torrid, explosive, exquisitely designed for letting first the trumpet, then the sax, then the drummer, then the trombonist soar away in virtuosic excellence.

      The point to stress is the mythic line of basketball: a game of fake and feint and false intention; a game of run, run, run; a game of feet, of swift decision, instantaneous reversal, catlike “moves”, cool accuracy, spring and jump. The pace is hot. The rhythm of the game beats with the seconds: a three-second rule, a ten-second rule, a rule to shoot in twenty-four seconds. Only when the ball goes out of bounds, or a point is scored, or a foul is called does the clock stop; the play flows on. Teams do not move by timeless innings as in baseball, nor by set, formal, single plays as in football. Even when a play is called or a pattern is established, the game flows on until a whistle blows, moving relentlessly as lungs heavy and legs weary. It is like jazz.