Molecular Computing MCQs (Multiple-Choice Questions)

1. What is molecular computing?

1. A computing method based exclusively on mechanical gears
2. A computing approach that uses molecules and their interactions to represent or process information
3. A method that relies only on magnetic disks for computation
4. A technique that uses conventional silicon transistors exclusively

Answer: B) A computing approach that uses molecules and their interactions to represent or process information

Explanation:

Molecular computing uses molecular properties, chemical reactions, or interactions to encode and manipulate information. It includes approaches such as DNA computing, chemical reaction networks, and molecular logic systems.

2. Which scientific disciplines are particularly relevant to molecular computing?

1. Geography and cartography only
2. Architecture and civil engineering only
3. Literature and linguistics only
4. Chemistry, biology, computer science, and nanotechnology

Answer: D) Chemistry, biology, computer science, and nanotechnology

Explanation:

Molecular computing combines computational models with the behavior of molecules and chemical systems. Chemistry explains molecular reactions, biology contributes molecular tools and systems, and computer science provides algorithms and logical frameworks.

3. What is the main purpose of information encoding in molecular computing?

1. To represent data using identifiable molecular states, structures, or concentrations
2. To prevent molecules from interacting
3. To convert every molecule into a conventional transistor
4. To eliminate the need for computational rules

Answer: A) To represent data using identifiable molecular states, structures, or concentrations

Explanation:

A molecular computing system must define how input information is represented. Depending on the design, data may be encoded through molecular identity, chemical concentration, reaction state, molecular structure, or nucleic acid sequence.

4. Which of the following can represent a binary state in a molecular logic system?

1. The color of a computer keyboard
2. The number of files on a hard disk
3. The presence or absence of a particular molecular species above a defined detection threshold
4. The physical size of a computer monitor

Answer: C) The presence or absence of a particular molecular species above a defined detection threshold

Explanation:

A molecular logic system can associate the presence of a detectable molecular species with logical 1 and its absence or low concentration with logical 0. The thresholds and measurement procedures must be defined carefully because real molecular systems can exhibit noise and incomplete reactions.

5. What is a molecular logic gate?

1. A conventional electrical switch made only from copper wires
2. A molecular system designed to produce an output based on one or more inputs according to a logical rule
3. A device used only to store magnetic data
4. A mechanical component that controls the movement of gears

Answer: B) A molecular system designed to produce an output based on one or more inputs according to a logical rule

Explanation:

A molecular logic gate uses molecular interactions or chemical reactions to implement a logical function. Its inputs may be chemical species, concentrations, light, or other stimuli, while its output may be a measurable change in fluorescence, color, or chemical composition.

6. Which molecular computing approach uses DNA sequences to encode information and perform operations?

1. DNA computing
2. Mechanical computing
3. Magnetic computing exclusively
4. Conventional transistor switching only

Answer: A) DNA computing

Explanation:

DNA computing is a form of molecular computing that uses DNA sequences and biochemical processes to represent data and carry out operations. It can exploit complementary base pairing, amplification, and molecular selection to solve selected computational problems.

7. What is molecular recognition?

1. The conversion of a chemical substance into a computer file
2. The removal of all interactions between molecules
3. The process of manufacturing a silicon transistor
4. The selective interaction of molecules based on properties such as shape, charge, or chemical compatibility

Answer: D) The selective interaction of molecules based on properties such as shape, charge, or chemical compatibility

Explanation:

Molecular recognition occurs when molecules interact selectively because of complementary chemical or structural properties. This principle can be used to detect specific substances, identify molecular targets, and implement selective operations in molecular computing.

8. What is the primary role of a chemical reaction in reaction-based molecular computing?

1. To guarantee that every input produces the same output regardless of conditions
2. To replace all molecular species with electrical wires
3. To transform input molecular states into output states according to defined reaction rules
4. To eliminate the need for representing information

Answer: C) To transform input molecular states into output states according to defined reaction rules

Explanation:

Reaction-based molecular computing uses chemical transformations as computational steps. Reactants represent molecular states, and reaction pathways produce new species that can encode intermediate or final results.

9. Which molecule is commonly used as an information carrier in DNA-based molecular computing?

1. Glucose only
2. Deoxyribonucleic acid (DNA)
3. Ordinary table salt
4. Carbon dioxide only

Answer: B) Deoxyribonucleic acid (DNA)

Explanation:

DNA contains an ordered sequence of nucleotide bases that can encode information. Its complementary base-pairing properties also support selective binding and molecular operations, making it a useful medium for certain molecular computing approaches.

10. Which property of DNA enables complementary strands to bind selectively?

1. Its ability to conduct electricity like a metal
2. Its magnetic polarity alone
3. Its ability to generate mechanical motion without interactions
4. Complementary base pairing between nucleotide sequences

Answer: D) Complementary base pairing between nucleotide sequences

Explanation:

In DNA, adenine pairs with thymine, while cytosine pairs with guanine. These complementary interactions allow matching sequences to bind through hybridization, supporting sequence recognition and molecular information processing.

11. What does a chemical reaction network describe?

1. A collection of chemical species and the reactions connecting them
2. A list of computer network passwords
3. A physical arrangement of electrical sockets
4. A storage system based exclusively on magnetic domains

Answer: A) A collection of chemical species and the reactions connecting them

Explanation:

A chemical reaction network specifies the species involved in a system and the reactions through which they are transformed. In molecular computing, reaction networks can be designed to implement logical operations, dynamical behavior, or calculations.

12. Which statement best describes molecular parallelism?

1. Every molecular reaction must occur one at a time
2. Only a single molecule can participate in a computation
3. Large populations of molecules can participate in reactions concurrently
4. Molecular systems cannot process multiple inputs

Answer: C) Large populations of molecules can participate in reactions concurrently

Explanation:

Many molecules can interact simultaneously within the same reaction mixture. This provides potential parallelism, but the overall performance depends on reaction kinetics, resource availability, noise, and the method used to identify the output.

13. What is one potential advantage of molecular computing?

1. It automatically eliminates all computational errors
2. It can support high information density and computation at molecular scales
3. It removes the need for experimental validation
4. It guarantees instant results for all problems

Answer: B) It can support high information density and computation at molecular scales

Explanation:

Molecules can represent information at very small physical scales, and some molecular systems support large populations of simultaneous interactions. However, high information density and molecular parallelism do not guarantee low cost, fast execution, or superior performance for every workload.

14. Which factor can limit the accuracy of a molecular computing system?

1. Incomplete reactions, unwanted interactions, and measurement noise
2. The complete absence of chemical reactions
3. The fact that molecules have physical properties
4. The existence of molecular structures

Answer: A) Incomplete reactions, unwanted interactions, and measurement noise

Explanation:

Real molecular systems can experience incomplete conversion, side reactions, contamination, concentration variation, and imperfect measurements. These factors can cause the output to differ from the intended computational result.

15. What is a molecular switch?

1. A mechanical switch used to operate laboratory lights
2. A storage disk that records information magnetically
3. A device that converts every molecule into a computer processor
4. A molecular system that can transition between distinguishable states in response to a stimulus

Answer: D) A molecular system that can transition between distinguishable states in response to a stimulus

Explanation:

A molecular switch can change its state when exposed to a stimulus such as light, a change in pH, a chemical substance, or an electrical input. If the states can be detected and assigned logical values, the switch may be used in molecular information processing.

16. Which of the following can serve as an input stimulus for a molecular logic system?

1. Only the number of computer files
2. Only the color of a keyboard
3. A chemical species, light, or a change in pH
4. Only the size of a computer monitor

Answer: C) A chemical species, light, or a change in pH

Explanation:

Molecular logic systems can respond to a variety of stimuli. Depending on the design, chemical concentrations, ions, light, temperature, or pH changes can influence molecular states and determine the output.

17. How can fluorescence be used to read the output of a molecular computation?

1. By measuring an optical signal emitted by a fluorescent molecule after suitable excitation
2. By measuring the weight of a computer keyboard
3. By converting every molecule into a magnetic disk
4. By assuming that all molecular outputs are invisible

Answer: A) By measuring an optical signal emitted by a fluorescent molecule after suitable excitation

Explanation:

Fluorescent molecules emit light after absorbing excitation energy. A detector can measure changes in fluorescence intensity or other optical properties to determine whether a molecular state or reaction product is present.

18. What is the purpose of a molecular sensor?

1. To replace every biochemical reaction with a software instruction
2. To detect a particular chemical or biological target through a measurable response
3. To prevent all molecular interactions
4. To store data only on a magnetic surface

Answer: B) To detect a particular chemical or biological target through a measurable response

Explanation:

A molecular sensor detects a target through a chemical or physical interaction that produces a measurable signal. Molecular computing and sensing can overlap when target detection is combined with logic operations or decision-making rules.

19. What is meant by a molecular logic circuit?

1. A conventional computer motherboard made only from metal
2. A biological sample that contains no measurable information
3. A network of molecular components designed to implement logical operations
4. A mechanical device that can only measure distance

Answer: C) A network of molecular components designed to implement logical operations

Explanation:

A molecular logic circuit combines molecular elements or reactions to implement one or more logical functions. Such circuits may use chemical inputs and measurable molecular outputs to perform simple decision operations or more complex sequences of reactions.

20. Which statement about molecular computing and conventional electronic computing is correct?

1. Molecular computing has replaced all electronic processors
2. Electronic computers cannot process molecular data
3. Molecular computing never needs measurement equipment
4. Molecular computing uses chemical or molecular processes and may complement conventional electronic systems

Answer: D) Molecular computing uses chemical or molecular processes and may complement conventional electronic systems

Explanation:

Molecular computing relies on molecular interactions or chemical reactions rather than exclusively on electronic switching. Electronic computers and instruments can still be used to control experiments, measure outputs, analyze data, and perform other parts of a computational workflow.

21. What is a major challenge when connecting molecular computing systems to electronic computers?

1. Converting molecular states into reliable, measurable electronic or digital signals
2. The impossibility of measuring any chemical property
3. The fact that electronic computers cannot represent binary values
4. The inability of molecular systems to contain inputs

Answer: A) Converting molecular states into reliable, measurable electronic or digital signals

Explanation:

A molecular system may produce a change in concentration, fluorescence, electrical response, or another physical property. Sensors and measurement electronics must translate that response into usable data, and this interface can add delay, complexity, and noise.

22. Which type of molecular computing uses DNA, RNA, or related nucleic acid molecules as computational components?

1. Mechanical computing
2. Nucleic-acid computing
3. Magnetic storage computing only
4. Conventional optical character recognition

Answer: B) Nucleic-acid computing

Explanation:

Nucleic-acid computing uses DNA, RNA, or related molecular structures to represent information or carry out operations. Sequence recognition and strand interactions can be programmed to perform selected logical and computational tasks.

23. What is a chemical reaction's activation energy?

1. The amount of information stored in a molecule
2. The number of bits represented by a chemical species
3. The energy barrier that reactants must overcome for a reaction to proceed
4. The electrical capacity of a computer battery

Answer: C) The energy barrier that reactants must overcome for a reaction to proceed

Explanation:

Activation energy is the energy barrier associated with a chemical reaction. It influences reaction rates and can affect how quickly a molecular computing system moves from input states to output states.

24. Why are reaction kinetics important in molecular computing?

1. They determine the color of computer screens
2. They guarantee that every reaction occurs instantaneously
3. They remove the need to define computational outputs
4. They influence how quickly molecular reactions proceed and how the system evolves over time

Answer: D) They influence how quickly molecular reactions proceed and how the system evolves over time

Explanation:

Reaction kinetics describes the rates of chemical reactions and how those rates depend on factors such as concentration, temperature, and reaction mechanisms. In molecular computing, reaction rates affect response time, intermediate states, and the reliability of the final output.

25. What is one purpose of using enzymes in molecular computing?

1. To catalyze specific biochemical reactions that manipulate molecular information
2. To eliminate all chemical transformations
3. To convert every molecule directly into a silicon transistor
4. To guarantee that all outputs are correct regardless of input

Answer: A) To catalyze specific biochemical reactions that manipulate molecular information

Explanation:

Enzymes catalyze biochemical reactions and can provide useful selectivity. In nucleic-acid computing, enzymes such as polymerases, ligases, and restriction enzymes can synthesize, join, or cut DNA, supporting molecular information processing.

26. What is an important application of molecular computing in biosensing?

1. Replacing all medical measurements with unverified estimates
2. Combining the detection of molecular targets with logical decision operations
3. Preventing sensors from responding to chemical substances
4. Eliminating the need to validate diagnostic systems

Answer: B) Combining the detection of molecular targets with logical decision operations

Explanation:

Molecular computing can help combine multiple sensing signals into a logical output. For example, a system might be designed to produce a detectable response only when specified molecular conditions are present. Such applications require careful validation and control of false-positive and false-negative responses.

27. What does nanoscale refer to?

1. Objects that are always measured in kilometers
2. Devices that are necessarily larger than buildings
3. Dimensions typically on the order of nanometers, where 1 nanometer equals 10⁻⁹ meters
4. Information that cannot be represented numerically

Answer: C) Dimensions typically on the order of nanometers, where 1 nanometer equals 10⁻⁹ meters

Explanation:

A nanometer is one-billionth of a meter. Molecular computing operates with components or structures at molecular scales, where nanoscale physical and chemical properties can be used to represent and manipulate information.

28. What is one limitation of using chemical concentration to represent numerical values?

1. Concentration can never be measured
2. Concentration is unrelated to the number of molecules present
3. Every concentration automatically represents the same value
4. Measurement noise, diffusion, and reaction changes can make concentrations difficult to control precisely

Answer: D) Measurement noise, diffusion, and reaction changes can make concentrations difficult to control precisely

Explanation:

Concentration-based computing can represent values through the amounts of chemical species present. However, measurement uncertainty, fluctuations in molecule counts, diffusion, and ongoing reactions can affect the accuracy and stability of the represented values.

29. What is the role of a threshold in a concentration-based molecular logic gate?

1. To determine which measured concentration range is interpreted as a logical state
2. To prevent all chemical reactions from occurring
3. To convert every molecular species into a computer file
4. To guarantee that molecular concentrations remain constant forever

Answer: A) To determine which measured concentration range is interpreted as a logical state

Explanation:

A threshold maps a measured molecular quantity to a logical output. For example, concentrations above a specified threshold may represent logical 1, while concentrations below it represent logical 0. Threshold selection must account for noise and variability.

30. What is a molecular machine?

1. A conventional desktop computer with no moving parts
2. A molecular-scale structure capable of controlled motion or performing a specific task in response to stimuli
3. A storage disk that operates only through magnetism
4. A device that converts all chemical substances into electrical wires

Answer: B) A molecular-scale structure capable of controlled motion or performing a specific task in response to stimuli

Explanation:

Molecular machines are structures that perform controlled movements or tasks at the molecular scale. Some can change conformation, transport molecular components, or respond to chemical and physical stimuli. Their behavior can be explored for specialized information-processing applications.

31. Why is selectivity important in molecular computing?

1. It forces all molecules to react with every other molecule
2. It makes all molecular states indistinguishable
3. It helps intended reactions occur while reducing unwanted interactions
4. It eliminates the need for input encoding

Answer: C) It helps intended reactions occur while reducing unwanted interactions

Explanation:

Selectivity allows a molecular system to distinguish between intended and unintended reaction partners. Good selectivity improves the reliability of logical operations and helps reduce erroneous outputs caused by side reactions or nonspecific binding.

32. What is a key challenge in scaling a molecular computing system to more complex tasks?

1. Molecules cannot undergo multiple reactions
2. Complex systems cannot contain more than one molecular species
3. All chemical reactions are independent of their surroundings
4. Managing reaction pathways, unwanted interactions, accumulated errors, and output detection becomes more difficult

Answer: D) Managing reaction pathways, unwanted interactions, accumulated errors, and output detection becomes more difficult

Explanation:

As a molecular system becomes more complex, additional reactions and intermediate states can introduce unwanted interactions and error sources. Designing reliable pathways and detecting the intended final state become increasingly important.

33. Which statement best describes DNA hybridization as a computational operation?

1. It can use complementary sequences to recognize and bind selected molecular inputs
2. It converts every DNA strand into a metal wire
3. It prevents sequence-specific molecular interactions
4. It guarantees that every candidate sequence is correct

Answer: A) It can use complementary sequences to recognize and bind selected molecular inputs

Explanation:

DNA hybridization allows complementary nucleic acid sequences to bind. A molecular computing design can use this property to recognize particular sequences, assemble structures, or distinguish candidates according to their encoded information.

34. What is the purpose of error correction in molecular information processing?

1. To ensure that every reaction occurs at the same speed
2. To detect or recover information affected by molecular or measurement errors
3. To eliminate the need for output measurement
4. To guarantee that molecular systems never degrade

Answer: B) To detect or recover information affected by molecular or measurement errors

Explanation:

Molecular operations may produce errors because of unintended reactions, incomplete conversion, synthesis defects, or noisy measurements. Error-detection and correction techniques add structure or redundancy to help identify and recover the intended information.

35. Which statement about molecular computing and energy consumption is most accurate?

1. Molecular computing always uses zero energy
2. Only the molecules themselves matter when evaluating total system energy
3. Energy requirements depend on the molecular process and may include preparation, environmental control, and measurement
4. Molecular computing eliminates every need for laboratory equipment

Answer: C) Energy requirements depend on the molecular process and may include preparation, environmental control, and measurement

Explanation:

Although molecular operations can occur at very small scales, the complete system may require energy for reagent preparation, heating or cooling, fluid handling, detection, and electronic control. Overall energy use must be evaluated across the complete workflow.

36. What is a chemical reaction's equilibrium state?

1. A state in which all molecules have disappeared
2. A condition where every reaction must stop permanently
3. A state that always contains only reactants
4. A state in which forward and reverse reaction rates are equal for a reversible reaction

Answer: D) A state in which forward and reverse reaction rates are equal for a reversible reaction

Explanation:

At chemical equilibrium, the forward and reverse reaction rates are equal, so the concentrations remain constant over time under fixed conditions. Molecular computing designs must account for equilibrium behavior when it affects the desired output or reaction dynamics.

37. How can light control a molecular computing system?

1. By triggering light-sensitive molecules to change state or initiate a reaction
2. By guaranteeing that every molecule remains unchanged
3. By replacing every molecule with a transistor
4. By eliminating the need to encode input information

Answer: A) By triggering light-sensitive molecules to change state or initiate a reaction

Explanation:

Some molecules respond to light by changing their structure or chemical state. These photoresponsive behaviors can provide controllable inputs or switching mechanisms for molecular logic and information-processing systems.

38. Which application combines molecular recognition with computational decision-making?

1. Formatting a computer hard disk
2. A molecular diagnostic system that evaluates multiple biomarker signals
3. Mechanical sorting of metal objects without sensors
4. Increasing a monitor's refresh rate

Answer: B) A molecular diagnostic system that evaluates multiple biomarker signals

Explanation:

A molecular diagnostic system can detect specific biological targets and combine the results through logical rules. Such a design might distinguish between different target combinations, although its accuracy depends on the selectivity and validation of the underlying reactions and measurements.

39. Why can molecular computing be useful in specialized nanoscale applications?

1. It guarantees that every physical process becomes digital
2. It removes all limitations associated with small-scale devices
3. Molecular components can interact directly with chemical or biological environments
4. It prevents chemical information from being measured

Answer: C) Molecular components can interact directly with chemical or biological environments

Explanation:

Molecular computing can use chemical interactions to sense, classify, or process information in environments where molecular recognition is useful. Potential applications include biosensing and specialized molecular systems, but practical use depends on reliability, control, and measurement requirements.

40. What is the role of a mathematical model in molecular computing?

1. To replace every molecule with a mechanical component
2. To ensure that experimental results never differ from predictions
3. To remove the need for understanding reaction mechanisms
4. To describe and predict system behavior using variables, equations, and reaction rules

Answer: D) To describe and predict system behavior using variables, equations, and reaction rules

Explanation:

Mathematical models help researchers describe reaction rates, molecular concentrations, logical states, and system dynamics. They support simulation and design, while experimental measurements are needed to validate whether the physical system behaves as predicted.

41. What is one important difference between digital and analog molecular computing?

1. Digital molecular computing uses distinguishable states, while analog molecular computing can represent values through continuously varying quantities such as concentration
2. Digital molecular computing cannot represent information
3. Analog molecular computing never uses physical measurements
4. Both approaches require every value to be represented by a mechanical switch

Answer: A) Digital molecular computing uses distinguishable states, while analog molecular computing can represent values through continuously varying quantities such as concentration

Explanation:

Digital molecular systems map molecular states to discrete values such as 0 and 1. Analog systems may represent information through quantities such as concentration or reaction rate. Analog designs can be sensitive to noise and measurement precision, while digital designs must reliably distinguish their states.

42. What is one purpose of a molecular computing simulator?

1. To guarantee that a physical experiment will succeed without testing
2. To predict possible reaction behavior and test computational designs before laboratory implementation
3. To convert all chemical reactions into mechanical gears
4. To prevent researchers from changing system parameters

Answer: B) To predict possible reaction behavior and test computational designs before laboratory implementation

Explanation:

A simulator can model reaction pathways, concentration changes, and logical behavior. Simulation helps compare designs and identify potential problems before experiments, but its predictions depend on the accuracy of the model and the parameters supplied.

43. Why is reproducibility important in molecular computing experiments?

1. It guarantees that every chemical substance has identical properties
2. It eliminates the need to record experimental conditions
3. It helps establish whether a computational result can be obtained consistently under comparable conditions
4. It ensures that molecular reactions never produce unwanted products

Answer: C) It helps establish whether a computational result can be obtained consistently under comparable conditions

Explanation:

Reproducibility means that experiments can produce consistent results when repeated under comparable conditions. It is essential for evaluating whether a molecular computing design works reliably rather than producing an isolated or accidental outcome.

44. Which statement correctly distinguishes molecular computing from quantum computing?

1. All molecular computing systems must use quantum entanglement as their computational mechanism
2. Quantum computing cannot use physical molecules
3. Molecular computing is identical to conventional transistor-based computing
4. Molecular computing uses molecular states and chemical processes, while quantum computing relies on controlled quantum states and operations

Answer: D) Molecular computing uses molecular states and chemical processes, while quantum computing relies on controlled quantum states and operations

Explanation:

Molecular computing commonly uses chemical reactions, molecular recognition, or molecular structures to process information. Quantum computing uses quantum states and operations to perform computation. Although molecular systems are governed by quantum physics at the microscopic level, that does not make every molecular computer a quantum computer.

45. What is a key challenge in reading the result of a molecular computation?

1. Converting the resulting molecular state into a detectable and interpretable signal
2. The impossibility of measuring any molecular property
3. The fact that every molecular output is always visible to the naked eye
4. The absence of any need to identify the output state

Answer: A) Converting the resulting molecular state into a detectable and interpretable signal

Explanation:

Molecular outputs may need to be read through fluorescence, absorbance, electrical measurements, sequencing, or other analytical methods. Detection sensitivity, background noise, and the complexity of the sample can affect how reliably the result is interpreted.

46. What does modularity mean in the design of a molecular computing system?

1. Using only one molecule for every possible function
2. Dividing a system into components with defined functions that can be combined
3. Preventing individual components from interacting
4. Removing all intermediate computational states

Answer: B) Dividing a system into components with defined functions that can be combined

Explanation:

Modularity allows a molecular system to be designed from components with specific roles, such as input recognition, logic operations, and output generation. However, modules must be compatible, and unintended chemical interactions between them can complicate integration.

47. Why can temperature affect the behavior of a molecular computing system?

1. Temperature has no effect on chemical reactions
2. Temperature always makes every molecule stable
3. It can influence reaction rates, molecular binding, and the stability of molecular structures
4. It determines the number of files stored in electronic memory

Answer: C) It can influence reaction rates, molecular binding, and the stability of molecular structures

Explanation:

Temperature affects molecular motion, reaction kinetics, and the stability of many molecular interactions. Changes in temperature may alter the speed or selectivity of reactions, so molecular computing experiments often require controlled environmental conditions.

48. Which statement best describes the future potential of molecular computing?

1. It will necessarily replace all conventional computers immediately
2. It cannot be used for any practical research
3. It guarantees that all computational problems can be solved without energy
4. It may support specialized applications in molecular sensing, biochemical logic, and nanoscale information processing

Answer: D) It may support specialized applications in molecular sensing, biochemical logic, and nanoscale information processing

Explanation:

Molecular computing is being explored for applications that benefit from molecular-scale interactions and chemical selectivity. Its future impact depends on improvements in reliability, scalability, measurement, integration, and the practical advantages it offers for particular workloads.

49. A molecular logic experiment begins with 800 molecular units. A filtering operation removes 35% of the initial units. How many units remain?

1. 280 units
2. 520 units
3. 565 units
4. 765 units

Answer: B) 520 units

Explanation:

Initial number of molecular units = 800.

Percentage removed = 35%.

Number removed = 800 × 35/100 = 280.

Remaining units = 800 − 280 = 520.

Therefore, 520 molecular units remain after filtering.

50. A molecular computing system represents each input using 4 distinct molecular states. If a computation must encode all possible combinations of 3 independent inputs, with each input able to take any of the 4 states, how many input combinations are possible?

1. 12 combinations
2. 27 combinations
3. 64 combinations
4. 81 combinations

Answer: C) 64 combinations

Explanation:

Each of the 3 independent inputs can take 4 possible states.

Total combinations = Number of states per input raised to the number of inputs.

Total combinations = 4 × 4 × 4 = 4³ = 64.

Therefore, 64 distinct input combinations are possible.