Laboratory Measurement Techniques
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Questions and Answers

What is the effect of canker on citrus plants?

  • It primarily affects only sweet oranges.
  • It enhances the fruit quality and size.
  • It causes large warty projections on fruits.
  • It results in circular lesions with a yellow halo on leaves. (correct)

    • Which rootstocks are susceptible to Citrus tristeza virus?

  • Trifoliate orange and citrange.
  • Lemon and acid lime.
  • Rangpur lime and rough lemon.
  • Grapefruit and sour orange. (correct)

    • How should the management of tristeza in sweet orange and mandarin be approached?

  • Avoid susceptible rootstocks. (correct)
  • Use any available rootstock.
  • Grow exclusively in greenhouse conditions.
  • Only use infected bud wood.

    • What management strategy is recommended for controlling canker lesions?

    <p>Apply Streptomycin sulphate or copper oxychloride.</p> Signup and view all the answers

    What does Exocortis of scaly butt primarily affect?

    <p>The bark of the entire rootstock.</p> Signup and view all the answers

    Which insect is identified as an important vector for the transmission of Citrus tristeza virus?

    <p>Aphid.</p> Signup and view all the answers

    What is the appearance of symptoms on lime affected by tristeza?

    <p>Thin and elongated translucent areas in leaf veins.</p> Signup and view all the answers

    How can one manage the effect of Toxoptera citricida during cultivo?

    <p>Apply systemic insecticides to control aphids.</p> Signup and view all the answers

    What is the purpose of a viscometer?

    <p>To determine the viscosity of liquids</p> Signup and view all the answers

    Which type of viscometer is often used for quality control in viscosity measurements?

    <p>Rotational viscometer</p> Signup and view all the answers

    What does a rotational viscometer measure to calculate viscosity?

    <p>The mechanical resistance against rotational movement</p> Signup and view all the answers

    Which of the following viscosity measurements can a rotational viscometer display?

    <p>Viscosity, temperature, and spindle speed</p> Signup and view all the answers

    What range of viscosity can the example viscometer from PCE Instruments measure?

    <p>3 to 13,000,000 mPas</p> Signup and view all the answers

    What is a requirement for effective measurement with a rotational viscometer?

    <p>The probe tip must be submerged in the liquid</p> Signup and view all the answers

    Which of the following types of viscometers measures dynamic viscosity specifically?

    <p>Rotational viscometer</p> Signup and view all the answers

    How does the measurement principle of a rotational viscometer differ from that of a capillary viscometer?

    <p>It measures resistance against rotational movement</p> Signup and view all the answers

    What type of management is recommended for controlling Fruit Spot caused by Cercospora sp.?

    <p>Collection and destruction of diseased panicles</p> Signup and view all the answers

    Which of the following symptoms is associated with Powdery Mildew caused by Oidium erysiphoides?

    <p>White powdery mass on young leaves</p> Signup and view all the answers

    What is a common symptom of Fruit Blight caused by Colletotrichum gloesporioides?

    <p>Irregular, water-soaked spots on leaves and fruitlets</p> Signup and view all the answers

    What is the primary management strategy for controlling the Alternaria leaf spot?

    <p>Spraying Mancozeb at 0.25%</p> Signup and view all the answers

    Which treatment is effective for controlling fruit rotting caused by Alternaria alternata?

    <p>Mancozeb at 0.25%</p> Signup and view all the answers

    What symptom is typically observed in plants affected by Powdery Mildew?

    <p>Premature dropping of affected young fruits</p> Signup and view all the answers

    What is a recommended interval for spraying Mancozeb to manage Fruit Blight?

    <p>Every 15 days</p> Signup and view all the answers

    What symptom is NOT associated with Fruit Spot caused by Alternaria alternata?

    <p>Water-soaked spots on leaves</p> Signup and view all the answers

    What is the optimum temperature range for sensitivity to taste-producing substances?

    <p>30-40°C</p> Signup and view all the answers

    What effect does the temperature of the milk have when judging its taste?

    <p>Should be around 60°F to avoid distractions</p> Signup and view all the answers

    Which of the following structures is least likely to yield a sour taste?

    <p>Alkaline compounds</p> Signup and view all the answers

    What type of media is believed to enhance the intensity of taste?

    <p>Aqueous media</p> Signup and view all the answers

    How can changes in chemical structure affect taste?

    <p>Minor changes can switch taste from sweet to bitter.</p> Signup and view all the answers

    Which basic taste qualities are commonly recognized?

    <p>Bitter, sweet, salty, and sour</p> Signup and view all the answers

    What is the role of temperature in taste perception according to the content?

    <p>Extreme temperatures can cause temporary insensitivity.</p> Signup and view all the answers

    Which type of taste response is least supported by chemical specificity?

    <p>Alkaline tastes</p> Signup and view all the answers

    What effect does sugar have on bitterness and sourness?

    <p>Reduces bitterness and sourness</p> Signup and view all the answers

    How does age affect taste sensitivity?

    <p>Sweet and sour sensitivity decreases after age 60</p> Signup and view all the answers

    Which group of individuals is said to be 'taste-blind' to PTC?

    <p>1/4th of the population</p> Signup and view all the answers

    What is the impact of lack of sleep on taste perception?

    <p>Does not affect sensitivity to sour and salt but raises sour threshold</p> Signup and view all the answers

    What happens to taste sensitivity in patients with adrenal insufficiency?

    <p>It may cause increased sensitivity to all tastes</p> Signup and view all the answers

    How does chronic alcoholism affect taste sensitivity?

    <p>It does not affect sensitivity to sucrose</p> Signup and view all the answers

    How does smoking influence taste preferences?

    <p>Increases sensitivity to bitter tastes</p> Signup and view all the answers

    What is the primary effect of salt when sprinkled on fruits?

    <p>Increases apparent sweetness of sucrose</p> Signup and view all the answers

    Study Notes

    Viscosity Measurement

    • Laboratory measurements often require random sampling; some applications need selective or continuous (inline) measurement.
    • Data storage and transfer capabilities are crucial; viscometers with RS-232 interfaces and PC software are available.
    • PCE Instruments produces viscometers suitable for the food, chemical, and cosmetics industries, measuring viscosities between 3 and 13,000,000 mPas with an accuracy of ±1%.

    Types of Viscometers

    • Capillary Viscometers: Measure liquid flow through a narrow tube.
    • Rotational Viscometers: Measure mechanical resistance against spindle rotation to determine dynamic viscosity.
    • Falling Body Viscometers: Evaluate viscosity based on the time a ball takes to fall through a liquid.
    • Process Viscometers: Designed for real-time measurement in ongoing processes.
    • Viscosity Flow Cups: Determine viscosity by timing the flow of liquid through an orifice.

    Rotational Viscometers

    • Work by assessing torque resulting from liquid resistance against spindle movement.
    • Display parameters like temperature, spindle speed, and measurement range on an LCD.
    • Models such as PCE-RVI 1, PCE-RVI 2, and PCE-RVI 3 are durable and versatile for various liquid mediums.

    Citrus Diseases

    • Canker (Xanthomonas campestris pv. citri): Affects leaves, twigs, and fruits leading to circular yellow lesions; management includes sprays of streptomycin sulfate and copper oxychloride.
    • Tristeza Virus (Citrus tristeza virus -CTV): Causes stunted growth and reduces fruit size; prevention includes selecting resistant rootstocks and using pre-immunized seedlings.
    • Viroid (Exocortis): Affects rootstocks with vertical cracks and scaling; management includes using virus-free budwood.

    Fungal and Bacterial Diseases

    • Powdery Mildew (Oidium erysiphoides f.sp.zizyphi): Young leaves exhibit white powdery growth, management involves specific fungicide applications.
    • Fruit Spot (Cercospora sp.): Leads to irregular black spots on fruits; management includes timely removal of diseased panicles and fungicidal sprays.

    Taste Perception

    • Taste sensitivity and threshold can be influenced by health, age, and other factors.
    • Health Impacts: Conditions like diabetes can alter taste perception; sleep deprivation may affect sourness sensitivity.
    • Age Effects: Taste differentiation is limited in newborns, with sensitivity generally declining after 60 years.
    • Smoking Influence: Alters taste preferences mainly for bitter flavors without significantly impacting thresholds for sweet, sour, or salty tastes.
    • Temperature Effects: Optimal taste sensitivity occurs between 30-40°C; extreme temperatures can impair taste perception.

    Basic Taste Qualities

    • Four primary tastes: sweet, salt, sour, and bitter, each associated with specific receptor locations on the tongue.
    • Additional tastes such as alkaline, metallic, and meaty may exist but are not universally acknowledged.

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    Description

    This quiz explores various laboratory measurement techniques used for the production of raw materials, focusing on random measurements versus selective inline measurements. It also covers the importance of data storage and transfer, highlighting specific tools such as viscometers with RS-232 interfaces. Ideal for those in the food, chemical, and cosmetics industries.

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