Mixed Deck — All Agricultural/Bioengineering Topics Flashcards
100 cards from real Agricultural/Bioengineering practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 20 Mixed Deck — All Agricultural/Bioengineering Topics flashcards as text
Which of the following materials has the highest modulus of elasticity (stiffness) and is commonly used in agricultural machinery frames?
Answer: Structural steel
Structural steel has a modulus of elasticity of approximately 200 GPa, far higher than the other options.
Which milling process for wheat produces flour by gradually reducing grain through multiple roller passages?
Answer: Roller milling (gradual reduction)
The gradual reduction roller mill system separates bran from endosperm in stages to produce refined wheat flour.
Water activity (aₓ) of a food product is defined as:
Answer: The ratio of the partial pressure of water in the food to the vapor pressure of pure water at the same temperature
Water activity equals p/p₀, the equilibrium relative humidity divided by 100, and determines microbial growth potential and chemical reaction rates.
In photovoltaic systems, what is the function of a maximum power point tracker (MPPT)?
Answer: Continuously adjusts operating voltage to extract maximum power from panels
An MPPT algorithm adjusts the electrical load impedance to keep PV panels operating at their peak power point under varying conditions.
How many elastic constants will there be in an isotropic, linear material?
Answer: 2
For an isotropic, linear elastic material, only two independent elastic constants are needed to fully describe its mechanical behavior. These two constants are typically Young's modulus (E), which relates stress to strain in uniaxial tension/compression, and Poisson's ratio (ν), which describes transverse contraction. Other elastic constants like the shear modulus (G) and bulk modulus (K) can be derived from E and ν.
A rectangular wooden beam used in a greenhouse structure has width b = 100 mm and depth d = 200 mm. What is its moment of inertia about the horizontal (strong) axis?
Answer: 133.3 × 10⁻⁶ m⁴
I = bd³/12 = (0.1)(0.2)³/12 = 0.0008/12 ≈ 66.7 × 10⁻⁶ m⁴ — the strong axis (d=200mm) gives I = (0.1)(0.2)³/12 = 6.67×10⁻⁵ m⁴ = 66.7×10⁻⁶ m⁴.
The unit operations are which of the following?
Answer: Distillation, evaporation, centrifugation
Unit operations are fundamental physical processes used in chemical and food engineering to transform raw materials into finished products. Distillation separates components based on boiling points, evaporation removes solvent (usually water) by vaporization, and centrifugation separates components based on density using centrifugal force. These are classic examples of physical separation and concentration techniques widely applied in food processing.
Which psychrometric property of air is held constant during adiabatic (isenthalpic) humidification in a spray-drying system?
Answer: Wet-bulb temperature
During adiabatic saturation, enthalpy is constant and the process follows a constant wet-bulb temperature line on the psychrometric chart.
Ethylene gas plays what role in fruit post-harvest management?
Answer: Triggers ripening and senescence in climacteric fruits
Ethylene is a plant hormone that accelerates ripening, color development, and senescence in climacteric fruits such as bananas and apples.
What is the primary role of a digestate separator in a farm biogas system?
Answer: Separates digestate into liquid fertilizer and solid fiber fractions
A screw press or centrifuge separator divides digestate into solid fiber (compost feedstock) and liquid (nutrient-rich fertilizer).
The D-value in food microbiology is defined as:
Answer: The time in minutes at a given temperature to reduce the microbial population by 90% (one log cycle)
D-value (decimal reduction time) is the time needed at a constant temperature to destroy 90% of a specific microbial population.
A high Damköhler number (Da >> 1) in a bioprocess indicates that the system is limited by:
Answer: Mass transfer rate
Da = reaction rate / mass transfer rate; when Da >> 1, the biochemical reaction proceeds faster than mass transfer can supply substrate or remove product, making mass transfer the limiting step.
What kind of test is used to evaluate a material's resistance to scuffing, abrasion, deformation, and indentation?
Answer: Hardness test
A hardness test is specifically designed to evaluate a material's resistance to localized plastic deformation. This includes resistance to indentation, scratching, abrasion, and scuffing. These tests provide a measure of a material's surface durability and its ability to withstand wear and tear from contact with other objects.
Which of the following fermentation products is produced under strictly anaerobic conditions to achieve maximum yield?
Answer: Bioethanol
Yeast fermentation of sugars to ethanol requires anaerobic conditions; the presence of oxygen triggers aerobic respiration (Pasteur effect), diverting carbon away from ethanol and reducing yield.
Which safety device is required on all tractor PTOs in the US to prevent entanglement injuries?
Answer: Shield guard over the PTO shaft
OSHA and ASABE standards require a non-rotating plastic or metal shield covering the PTO stub shaft and the implement driveline when in use.
A biological tissue scaffold in an agricultural bioengineering application exhibits viscoelastic behavior. This means the scaffold:
Answer: Shows both elastic (spring-like) and viscous (dashpot-like) mechanical responses
Viscoelastic materials combine elastic energy storage with viscous energy dissipation, making their response time- and rate-dependent.
What is the function of a separator (centrifuge) in a fluid dairy processing line?
Answer: It separates milk into cream and skim milk by exploiting the density difference between fat and plasma
A centrifugal separator applies g-forces up to 6,000–10,000 × g to exploit the ~100 kg/m³ density difference between fat globules and skim milk, yielding cream and skim milk streams.
In bioengineering, which enzyme complex is responsible for breaking down cellulose into fermentable sugars?
Answer: Cellulase
Cellulase is the enzyme complex (including endoglucanase, exoglucanase, and β-glucosidase) that hydrolyzes cellulose into glucose.
In a bioengineering application, a bone scaffold made from a porous polymer has an apparent modulus of elasticity much lower than the bulk material. This is primarily because:
Answer: Porosity reduces the effective cross-sectional area carrying load
Porosity removes load-bearing material, lowering the effective stiffness and apparent modulus of the scaffold structure.
What could possibly be the case against the government getting involved in the milk marketing?
Answer: To reduce the consumption
Government involvement in milk marketing, often through price controls or subsidies, can have various economic consequences. One potential argument against such intervention is that it can distort market prices, leading to higher costs for consumers. These increased prices might then reduce consumer demand and overall milk consumption, counteracting other policy goals.