ACT Science Exam 3

1. What is the name for the regions in space where gravity is so intense that nothing can escape?

Dark matter

Black holes

Dwarf stars

Light-years

B. Black holes are regions in space with such intense gravity that nothing, not even light, can escape. See Lesson: Astronomy.

Explanation

B. Black holes are regions in space with such intense gravity that nothing, not even light, can escape. See Lesson: Astronomy.

2. What is the basis for classifying an organism as either an autotroph or a heterotroph?

The way an organism obtains its energy

The organism’s ranking in the taxonomic system

The type of ecosystem in which an organism lives

Whether the organism is unicellular or multicellular

A. Organisms are classified as either autotrophs or heterotrophs according to how they obtain energy. Autotrophs obtain energy through sunlight, whereas heterotrophs obtain energy through food. See Lesson: Cell Structure, Function, and Type.

Explanation

A. Organisms are classified as either autotrophs or heterotrophs according to how they obtain energy. Autotrophs obtain energy through sunlight, whereas heterotrophs obtain energy through food. See Lesson: Cell Structure, Function, and Type.

3. How can an organism have two alleles for each trait but only one of those alleles is expressed?

One of the alleles is hidden in the chromosome.

One of the alleles is dominant over the other allele.

It depends on which allele is obtained from a parent first.

The allele closest to the top of the chromosomes is expressed.

B. One of the alleles is dominant, so it is expressed. See Lesson: Genetics and DNA.

Explanation

B. One of the alleles is dominant, so it is expressed. See Lesson: Genetics and DNA.

4. What is a characteristic of eukaryotes?

These organisms are all unicellular.

They lack a membrane-bound nucleus.

Many organelles are in their cytoplasm.

Bacteria and plants are examples of eukaryotes.

C. Eukaryotic cells are unicellular or multicellular organisms that contain a membrane-bound nucleus. Eukaryotic cells contain several different organelles. See Lesson: Cell Structure, Function, and Type.

Explanation

C. Eukaryotic cells are unicellular or multicellular organisms that contain a membrane-bound nucleus. Eukaryotic cells contain several different organelles. See Lesson: Cell Structure, Function, and Type.

5. Given the heating curve of iron, what are the approximate melting and boiling points?

900°C, 2300°C

1500°C, 2900°C

2300°C, 3100°C

2900°C, 3400°C

B. The line between B and C is the melting point, around 1500°C, and the line between D and E is the boiling point, around 2900°C. See Lesson: States of Matter.

Explanation

B. The line between B and C is the melting point, around 1500°C, and the line between D and E is the boiling point, around 2900°C. See Lesson: States of Matter.

6. What is the velocity of a 70 kg runner with a momentum of ?

Explanation

7. What is the Celsius value for 85 K?

−145

−188

−205

−358

B. Using the following formula, K = °C + 273: 85 − 273 = −188. See Lesson: Temperature and the Metric System.

Explanation

B. Using the following formula, K = °C + 273: 85 − 273 = −188. See Lesson: Temperature and the Metric System.

8. If someone needs ATP desperately and has run out of oxygen, what could help?

Meiosis

Calvin cycle

Fermentation

Electron transport chain

C. Fermentation is a metabolic process that produces ATP in the absence of oxygen. Thus, it is an anaerobic form of respiration. See Lesson: Cellular Reproduction, Cellular Respiration, and Photosynthesis.

Explanation

C. Fermentation is a metabolic process that produces ATP in the absence of oxygen. Thus, it is an anaerobic form of respiration. See Lesson: Cellular Reproduction, Cellular Respiration, and Photosynthesis.

9. Which of the following bonds involves elements with the greatest difference in electronegativity?

Silicon and chlorine

Sodium and chlorine

Aluminum and chlorine

Phosphorus and chlorine

B. Electronegativity increases moving across a period. Therefore, out of the elements in period 3, sodium has the lowest electronegativity, and chlorine has the highest. The difference between their electronegativities will be greatest. See Lesson: Chemical Bonds.

Explanation

B. Electronegativity increases moving across a period. Therefore, out of the elements in period 3, sodium has the lowest electronegativity, and chlorine has the highest. The difference between their electronegativities will be greatest. See Lesson: Chemical Bonds.

10. What type of reaction will occur between hexane (C₆H₁₄) and oxygen (O₂)?

Synthesis

Combustion

Decomposition

Single-replacement

B. Hexane contains carbon and hydrogen, which means it can be the fuel in a combustion reaction when it reacts with oxygen. See Lesson: Chemical Solutions.

Explanation

B. Hexane contains carbon and hydrogen, which means it can be the fuel in a combustion reaction when it reacts with oxygen. See Lesson: Chemical Solutions.

11. How many electrons does a neutral atom of iodine have?

53

74

126

127

A. In a neutral atom, the number of electrons is equal to the number of protons. Because the atomic number of iodine is 53, there are 53 protons and 53 electrons to balance the charge. See Lesson: Scientific Notation.

Explanation

A. In a neutral atom, the number of electrons is equal to the number of protons. Because the atomic number of iodine is 53, there are 53 protons and 53 electrons to balance the charge. See Lesson: Scientific Notation.

12. Net water movement through a membrane in response to the concentration of a solute is called _____.

Bonding

Diffusion

Osmosis

Polarity

C. Net water movement through a membrane in response to the concentration of a solute is called osmosis. See Lesson: Properties of Matter.

Explanation

C. Net water movement through a membrane in response to the concentration of a solute is called osmosis. See Lesson: Properties of Matter.

13. What is geology?

The study of all life on Earth

The study of weather patterns

The study of the moon, stars, and other objects in space

The study of Earth and its physical components and their interactions over time

D. Geology is the study of Earth and its physical components and their interactions over time. See Lesson: Geology.

Explanation

D. Geology is the study of Earth and its physical components and their interactions over time. See Lesson: Geology.

14. What metric base unit would be used to record the height of a person?

Gram

Inch

Meter

Milliliter

C. Meter is the metric base unit for length. See Lesson: Designing an Experiment.

Explanation

C. Meter is the metric base unit for length. See Lesson: Designing an Experiment.

15. A pharmacist is preparing a 50 μl solution. This value is equivalent to _____.

0.000005 liters

0.0005 deciliters

0.005 milliliters

0.05 centiliters

B. A microliter is much smaller than a deciliter. There are 10 deciliters in one liter but 1,000,000 microliters in one liter. That means 1 deciliter equals 100,000 microliters. Using this as the equivalency value, 50 microliters divided by 100,000 yields 0.0005 deciliters. See Lesson: Temperature and the Metric System.

Explanation

B. A microliter is much smaller than a deciliter. There are 10 deciliters in one liter but 1,000,000 microliters in one liter. That means 1 deciliter equals 100,000 microliters. Using this as the equivalency value, 50 microliters divided by 100,000 yields 0.0005 deciliters. See Lesson: Temperature and the Metric System.

16. What is a benefit of a taxonomic system?

Researchers can describe how living things behave.

Researchers can develop names for new organisms.

Living things can be distinguished from nonliving things.

Living things can be classified based on their molecular traits.

B. The purpose of a taxonomic system is to classify, describe, and name living things in an organized manner. See Lesson: An Introduction to Biology.

Explanation

B. The purpose of a taxonomic system is to classify, describe, and name living things in an organized manner. See Lesson: An Introduction to Biology.

17. Which of the following is produced during the Citric Acid Cycle?

Electrons

NADH

Pyruvate

Cellulose

C. After pyruvate molecules from glycolysis are produced, these sugar molecules are used to make 2 ATP molecules, 6 carbon dioxide molecules, and 6 NADH molecules. While cellulose is a carbohydrate like glucose, it is not used to produce pyruvate. Electrons are created during oxidative phosphorylation. See Lesson: An Introduction to Biology.

Explanation

C. After pyruvate molecules from glycolysis are produced, these sugar molecules are used to make 2 ATP molecules, 6 carbon dioxide molecules, and 6 NADH molecules. While cellulose is a carbohydrate like glucose, it is not used to produce pyruvate. Electrons are created during oxidative phosphorylation. See Lesson: An Introduction to Biology.

18. What are the three parts of a nucleotide?

Sulfate group, five-carbon sugar molecule, and nitrogen base

Phosphate group, five-carbon sugar molecule, and oxygen base

Nitrogen base, phosphate group, and six-carbon sugar molecule

Five-carbon sugar molecule, phosphate group, and nitrogen base

D. Each nucleotide has three parts: a five-carbon sugar molecule, a phosphate group, and a nitrogen base. See Lesson: Genetics and DNA.

Explanation

D. Each nucleotide has three parts: a five-carbon sugar molecule, a phosphate group, and a nitrogen base. See Lesson: Genetics and DNA.

19. When a sample of dry ice (solid carbon dioxide) undergoes sublimation in a sealed bucket, what happens to its shape and volume?

It retains its original shape and its original volume.

It changes both its shape and its volume to fit those of the bucket.

It retains its original shape, but its volume expands to fit that of the bucket.

It changes its shape to fit that of the bucket, but its volume does not change.

B. As the dry ice sublimes, it goes from a solid that has a fixed shape and volume to a gas, which takes both the shape and volume of its container. See Lesson: States of Matter.

Explanation

B. As the dry ice sublimes, it goes from a solid that has a fixed shape and volume to a gas, which takes both the shape and volume of its container. See Lesson: States of Matter.

20. The graph below shows the energy of the species involved in a chemical reaction as the reaction proceeds. What is the activation energy required in this reaction?

30 kJ

40 kJ

70 kJ

100 kJ

B. The activation energy is the amount of energy required for the reactants to form the transition state. In other words, it is the difference in energy between the reactants (30 kJ) and the transition state (70 kJ). See Lesson: Chemical Solutions.

Explanation

B. The activation energy is the amount of energy required for the reactants to form the transition state. In other words, it is the difference in energy between the reactants (30 kJ) and the transition state (70 kJ). See Lesson: Chemical Solutions.

21. An acid that dissociates into hydrogen ions is defined as a(n)

Weak acid.

Arrhenuis acid.

Conjugate acid.

Brønsted-Lowry acid.

B. According to the Arrhenius theory for acids, these substances dissociate into hydrogen ions when dissolved in water. Arrhenius bases dissociate into hydroxide ions. See Lesson: Acids and Bases.

Explanation

B. According to the Arrhenius theory for acids, these substances dissociate into hydrogen ions when dissolved in water. Arrhenius bases dissociate into hydroxide ions. See Lesson: Acids and Bases.

22. A particle in uniform circular motion has an angular frequency of 7.06 x 10⁴ hertz. What is its period?

1.42 x 10–5 s

8.90 x 10–5 s

1.12 x 104 s

4.44 x 105 s

B. The angular frequency ω of an object in uniform circular motion is equal to 2πf, where f is its frequency. Furthermore, f is equal to 1/T, where T is the period. Use these relationships to solve for T in seconds.

See Lesson: Friction.

Explanation

B. The angular frequency ω of an object in uniform circular motion is equal to 2πf, where f is its frequency. Furthermore, f is equal to 1/T, where T is the period. Use these relationships to solve for T in seconds.

See Lesson: Friction.

23. What is the electric field 3.0 m 10² meters from a 5.0 m 10^–3-coulomb charge? (Assume the electric constant is 9 m 10⁹ when using units of newtons, coulombs, and meters.)

2.5 newtons per coulomb

5.0 × 102 newtons per coulomb

1.5 × 105 newtons per coulomb

2.3 × 105 newtons per coulomb

Explanation

24. What is the conjugate base in the following reaction? HNO₂ + H₂O ⟷ ?

OH-

NO2-

H3O+

HNO3-

B. The conjugate base is NO₂^- because the acid HNO₂ donates a hydrogen ion during the reaction. See Lesson: Acids and Bases.

Explanation

B. The conjugate base is NO₂^- because the acid HNO₂ donates a hydrogen ion during the reaction. See Lesson: Acids and Bases.

25. Which process is part of photosynthesis?

Anaphase

Glycolysis

Calvin cycle

Pyruvate oxidation

C. Photosynthesis consists of light reactions and dark reactions. The dark reactions are referred to as the Calvin cycle. See Lesson: Cellular Reproduction, Cellular Respiration, and Photosynthesis.

Explanation

C. Photosynthesis consists of light reactions and dark reactions. The dark reactions are referred to as the Calvin cycle. See Lesson: Cellular Reproduction, Cellular Respiration, and Photosynthesis.

26. _____ is dependent not only on the temperature, but also on the amount of substance available.

Condensation

Deposition

Evaporation

Melting

C. Unlike condensation, deposition, and melting, evaporation is dependent not only on the temperature, but also on the amount of a substance available. See Lesson: Properties of Matter.

Explanation

C. Unlike condensation, deposition, and melting, evaporation is dependent not only on the temperature, but also on the amount of a substance available. See Lesson: Properties of Matter.

27. Octane in gasoline has the formula C₈H₁₈. What type of compound is it, and why?

Ionic, because it contains a metal

Covalent, because it contains a metal

Ionic, because it does not contain a metal

Covalent, because it does not contain a metal

D. Octane is a covalent compound that is formed from atoms of two nonmetals, carbon and hydrogen. See Lesson: Chemical Bonds.

Explanation

D. Octane is a covalent compound that is formed from atoms of two nonmetals, carbon and hydrogen. See Lesson: Chemical Bonds.

28. A nanometer is equal to 1 × 10-9 meter. How is this value written in standard notation?

0.0000000001 m

0.000000001 m

1,000,000,000 m

10,000,000,000 m

B. The exponent is negative 9, which means that the decimal point moves to the left nine spaces when converting to standard notation. See Lesson: Scientific Notation.

Explanation

B. The exponent is negative 9, which means that the decimal point moves to the left nine spaces when converting to standard notation. See Lesson: Scientific Notation.

29. What is the acceleration of a 9.7-kilogram object moving at a velocity (2.3, 8.9) meters per second and subject to a net force of (3.2, –1.8) newtons?

(–0.093, 1.1) m/s2

(0.24, 0.92) m/s2

(0.33, –0.19) m/s2

(0.56, 0.73) m/s2

Explanation

30. A particle moves at a constant speed on a circular path at a frequency of 25 hertz. If the radius of the circle is 14 meters, what is the particle's speed?

3.5 m/s

11 m/s

350 m/s

2,200 m/s

Explanation

31. A scientist has measured a sound wave traveling at 7.2 m 10⁴ feet per minute at a frequency of 1.0 m 10³ hertz. What is the wavelength?

0.014 feet

0.083 feet

1.2 feet

72 feet

Explanation

32. What causes the circulation of wind in the atmosphere?

Earth’s rotation and gravity

Earth’s rotation and erosion

The rise and fall of sea levels

Earth’s rotation and the influx of energy from the sun

D. The circulation of the atmosphere is caused by Earth’s rotation and the influx of energy from the sun. See Lesson: Meteorology.

Explanation

D. The circulation of the atmosphere is caused by Earth’s rotation and the influx of energy from the sun. See Lesson: Meteorology.

33. A researcher notices a positive correlation between the height of a plant and nutrient concentration over time. Based on this observation, what conclusion does he reach?

The height of a plant increases in the absence and presence of the nutrients.

When the amount of nutrients available to the plant decreases, its height increases.

The amount of nutrients available to a plant is independent of how tall the plant gets.

When the amount of nutrients available to the plant increases, its height also increases.

D. Because this is a positive correlation, if the nutrient concentration increases or decreases, plant height will either increase or decrease accordingly. See Lesson: Designing an Experiment.

Explanation

D. Because this is a positive correlation, if the nutrient concentration increases or decreases, plant height will either increase or decrease accordingly. See Lesson: Designing an Experiment.

34. What is the purpose of RNA polymerase?

To become a protein

To become a nucleotide

To function as an enzyme

To develop into a terminator

C. The RNA polymerase functions as an enzyme. See Lesson: Genetics and DNA.

Explanation

C. The RNA polymerase functions as an enzyme. See Lesson: Genetics and DNA.

35. A ray traveling in air strikes water at an angle of 30.0° from the normal. What will its angle be in the water? (Assume air has a refractive index of 1.00 and water has a refractive index of 1.30.)

22.6°

23.1°

39.0°

40.5°

Explanation

36. If an object experiences a northward force of 5.0 newtons and an eastward force of 12 newtons, what is the magnitude of the resultant force?

6.5 newtons

7.0 newtons

13 newtons

17 newtons

C. A simple approach to this problem is to note that the two forces are perpendicular to each other. Therefore, placing the head of one on the tail of the other and drawing the resultant (sum) force creates a right triangle with the resultant force as the hypotenuse. Use the Pythagorean theorem to calculate the resultant force in newtons:

See Lesson: Nature of Motion.

Explanation

C. A simple approach to this problem is to note that the two forces are perpendicular to each other. Therefore, placing the head of one on the tail of the other and drawing the resultant (sum) force creates a right triangle with the resultant force as the hypotenuse. Use the Pythagorean theorem to calculate the resultant force in newtons:

See Lesson: Nature of Motion.

37. A roller coaster car loaded with riders has a mass of 1490 kg. The car reaches its top speed of 26.8 m/s at the bottom of the first hill (along ground level). What was the height of the previous hill?

2.73 m

19.2 m

36.6 m

73.4 m

Explanation

38. The electric field at a certain location is 100 newtons per coulomb. What would be the electric force exerted on an electrically neutral object placed at that location?

0 newtons

50 newtons

100 newtons

200 newtons

A. Uncharged (electrically neutral) objects neither exert nor experience electric forces. Therefore, the force on the object will be 0 regardless of the field strength. See Lesson: Electricity and Magnetism.

Explanation

A. Uncharged (electrically neutral) objects neither exert nor experience electric forces. Therefore, the force on the object will be 0 regardless of the field strength. See Lesson: Electricity and Magnetism.

39. A 5.0-volt battery delivers 0.020 amps to a resistor. What is the resistance of the resistor?

4.0× 10–3 ohms

0.10 ohms

10 ohms

250 ohms

Explanation

40. What is the period of a wave with a wavelength of 10 miles and a frequency of 10⁵ hertz?

10–5 hertz

10–5 miles

10–5 seconds

10–5 miles per second

C. The period is the time between successive crests or troughs of a wave. It is the reciprocal of the frequency—in this case, it is 10^–5 seconds. See Lesson: Waves and Sounds.

Explanation

C. The period is the time between successive crests or troughs of a wave. It is the reciprocal of the frequency—in this case, it is 10^–5 seconds. See Lesson: Waves and Sounds.

ACT Science Exam 3

1. What is the name for the regions in space where gravity is so intense that nothing can escape?

2.

What first name or nickname would you like us to use?

2. What is the basis for classifying an organism as either an autotroph or a heterotroph?

3. How can an organism have two alleles for each trait but only one of those alleles is expressed?

4. What is a characteristic of eukaryotes?

5. Given the heating curve of iron, what are the approximate melting and boiling points?

6. What is the velocity of a 70 kg runner with a momentum of ?

7. What is the Celsius value for 85 K?

8. If someone needs ATP desperately and has run out of oxygen, what could help?

9. Which of the following bonds involves elements with the greatest difference in electronegativity?

10. What type of reaction will occur between hexane (C6H14) and oxygen (O2)?

11. How many electrons does a neutral atom of iodine have?

12. Net water movement through a membrane in response to the concentration of a solute is called _____.

13. What is geology?

14. What metric base unit would be used to record the height of a person?

15. A pharmacist is preparing a 50 μl solution. This value is equivalent to _____.

16. What is a benefit of a taxonomic system?

17. Which of the following is produced during the Citric Acid Cycle?

18. What are the three parts of a nucleotide?

19. When a sample of dry ice (solid carbon dioxide) undergoes sublimation in a sealed bucket, what happens to its shape and volume?

20. The graph below shows the energy of the species involved in a chemical reaction as the reaction proceeds. What is the activation energy required in this reaction?

21. An acid that dissociates into hydrogen ions is defined as a(n)

22. A particle in uniform circular motion has an angular frequency of 7.06 x 104 hertz. What is its period?

23. What is the electric field 3.0 m 102 meters from a 5.0 m 10–3-coulomb charge? (Assume the electric constant is 9 m 109 when using units of newtons, coulombs, and meters.)

24. What is the conjugate base in the following reaction? HNO2 + H2O ⟷ ?

25. Which process is part of photosynthesis?

26. _____ is dependent not only on the temperature, but also on the amount of substance available.

27. Octane in gasoline has the formula C8H18. What type of compound is it, and why?

28. A nanometer is equal to 1 × 10-9 meter. How is this value written in standard notation?

29. What is the acceleration of a 9.7-kilogram object moving at a velocity (2.3, 8.9) meters per second and subject to a net force of (3.2, –1.8) newtons?

30. A particle moves at a constant speed on a circular path at a frequency of 25 hertz. If the radius of the circle is 14 meters, what is the particle's speed?

31. A scientist has measured a sound wave traveling at 7.2 m 104 feet per minute at a frequency of 1.0 m 103 hertz. What is the wavelength?

32. What causes the circulation of wind in the atmosphere?

33. A researcher notices a positive correlation between the height of a plant and nutrient concentration over time. Based on this observation, what conclusion does he reach?

34. What is the purpose of RNA polymerase?

35. A ray traveling in air strikes water at an angle of 30.0° from the normal. What will its angle be in the water? (Assume air has a refractive index of 1.00 and water has a refractive index of 1.30.)

36. If an object experiences a northward force of 5.0 newtons and an eastward force of 12 newtons, what is the magnitude of the resultant force?

37. A roller coaster car loaded with riders has a mass of 1490 kg. The car reaches its top speed of 26.8 m/s at the bottom of the first hill (along ground level). What was the height of the previous hill?

38. The electric field at a certain location is 100 newtons per coulomb. What would be the electric force exerted on an electrically neutral object placed at that location?

39. A 5.0-volt battery delivers 0.020 amps to a resistor. What is the resistance of the resistor?

40. What is the period of a wave with a wavelength of 10 miles and a frequency of 105 hertz?

10. What type of reaction will occur between hexane (C₆H₁₄) and oxygen (O₂)?

22. A particle in uniform circular motion has an angular frequency of 7.06 x 10⁴ hertz. What is its period?

23. What is the electric field 3.0 m 10² meters from a 5.0 m 10^–3-coulomb charge? (Assume the electric constant is 9 m 10⁹ when using units of newtons, coulombs, and meters.)

24. What is the conjugate base in the following reaction? HNO₂ + H₂O ⟷ ?

27. Octane in gasoline has the formula C₈H₁₈. What type of compound is it, and why?

31. A scientist has measured a sound wave traveling at 7.2 m 10⁴ feet per minute at a frequency of 1.0 m 10³ hertz. What is the wavelength?

40. What is the period of a wave with a wavelength of 10 miles and a frequency of 10⁵ hertz?