ANWSER
Question 1:
Mention two methods used to induce loss of sensitivity to pain in the body.
Answer:
1. Administration of local anesthetics (e.g., lidocaine).
2. Use of general anesthesia (e.g., propofol or isoflurane).
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Question 2:
Mention 4 blood collection methods in mouse.
Answer:
1. Tail vein bleeding.
2. Retro-orbital bleeding.
3. Cardiac puncture.
4. Saphenous vein bleeding.
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Question 3:
How would you identify a male and female mouse?
Answer:
1. Male mouse: Presence of a larger anogenital distance and visible testes (scrotal sacs) in adults.
2. Female mouse: Smaller anogenital distance and the presence of a vaginal opening.
3. In neonates, males have a more pronounced genital papilla than females.
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Question 4:
What do you understand by the term ‘acclimatization’?
Answer:
Acclimatization refers to the process of allowing animals to adapt to a new environment (e.g., laboratory conditions) for a specific period before experimentation to reduce stress-induced variability.
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Question 5:
Mention 4 methods of sacrificing rats.
Answer:
1. Cervical dislocation.
2. Decapitation.
3. Carbon dioxide (CO₂) asphyxiation.
4. Overdose of anesthesia (e.g., pentobarbital).
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Question 6:
With relevant examples, what is the importance of isotonic solution in tissue preparation?
Answer:
Isotonic solutions (e.g., 0.9% saline or phosphate-buffered saline) prevent osmotic damage to cells by maintaining osmotic balance. For example, using isotonic solutions in tissue homogenates prevents cell shrinkage or swelling, preserving cellular integrity for accurate biochemical analysis.
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Question 7:
Why is Bovine Serum Albumin (BSA) used as a standard in the determination of protein concentration?
Answer:
BSA is used because it is readily available, stable, and has a consistent composition. Its well-characterized properties and linear response in colorimetric assays (e.g., Bradford or Biuret) make it ideal for creating calibration curves.
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Question 8:
In animal feeding, the Latin word ‘ad libitum’ means?
Answer:
“Ad libitum” means allowing animals unrestricted access to food and water.
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Question 9:
What is the importance of replication in an experiment?
Answer:
Replication reduces experimental errors, validates results, and ensures reliability by accounting for biological and technical variability.
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Question 10:
What is the difference between precision and accuracy?
Answer:
– Precision: Consistency of repeated measurements (e.g., similar results in replicates).
– Accuracy: Closeness of measurements to the true value (e.g., correct concentration).
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Question 11:
Explain the principle behind using Biuret method in the determination of protein concentration in tissue homogenate.
Answer:
The Biuret method relies on the reaction of peptide bonds with copper ions (Cu²⁺) in an alkaline solution, forming a violet complex. The intensity of the color (measured spectrophotometrically) is proportional to protein concentration.
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Question 12:
The Optical Density (O.D) and concentration of standard BSA is 0.383 and 10 mg/ml, respectively. If the O.D of test sample is 0.285, what is the concentration of the test sample?
Answer:
Using the formula:
\[ \text{Concentration of test} = \left( \frac{\text{O.D of test}}{\text{O.D of standard}} \right) \times \text{Concentration of standard} \]
\[ = \left( \frac{0.285}{0.383} \right) \times 10 \, \text{mg/ml} = 7.44 \, \text{mg/ml} \]
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Question 13:
What is Proximate Analysis?
Answer:
Proximate analysis is a method to quantify major components in food/biomass, including moisture, ash, fat, protein, fiber, and carbohydrates, to evaluate nutritional composition.
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Question 14:
The weight of a sample before drying was 2.10 g. The weight of the crucible used for drying the sample was 22.73 g. After drying, the weight of the crucible and dried sample was 23.55 g. Calculate the percentage moisture in the sample.
Answer:
1. Initial total weight = Crucible + Wet sample = 22.73 g + 2.10 g = 24.83 g.
2. Final weight (dried) = 23.55 g.
3. Moisture lost = 24.83 g – 23.55 g = 1.28 g.
4. % Moisture = \(\left( \frac{1.28 \, \text{g}}{2.10 \, \text{g}} \right) \times 100 = 60.95\%\).
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Question 15:
Why is the determination of moisture content and ash content of food important?
Answer:
– Moisture content: Affects shelf life, texture, and microbial growth (e.g., high moisture promotes spoilage).
– Ash content: Indicates mineral composition and purity (e.g., detects adulteration or nutritional quality).