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In terms of cellular structure, what is the difference between plant and animal cell?
- Plant cell have:
- 1. Chloroplasts
- 2. Cell wall
- 3. Vacuoles
- Size:
- -plant cells are bigger than animal cells
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Explain why the dialysate gave a positive reaction with silver nitrate and a negative reaction with iodine solution.
Ions were able to pass the cellophane but not starch, it remains inside the cellophane
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Explain how soaps lower the surface tension of fats on oils.
Soaps are amphipathic substances. It has hydrophobic tail and hydrophilic head.
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How does the kidney maintain the body's internal environment?
- kidney filters the blood, absorbs nutrient and secretes hormones
- controlling the water concentration in the blood plasma
- regulates salt level concentration
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How does the kidney maintain the body's internal environment?
Hypotonic cell swell or burst and Isotonic has no visible changes.
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Explain how soaps lower the surface tension of fats on oils.
- boiled: eliminate CO2
- cooled: heat affects the electron use to determine the pH
- because it contains carbon dioxide which can make the water acid from carbonic acid
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What are the factors that affect buffer capacity?
- temperature
- ratio of the conjugate base to the weak acid (buffer capacity is optimal when ratio is 1:1 or pH = pKa
- the relative concentration of the weak acid and its conjugate base (the greater concentration of the conjugate acid-base pair = the greater the buffer capacity)
- nearness of pKa of the buffer to pH solution
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At what pH does buffer solution exhibit maximum buffer capacity?
when the pH = pKa of the buffer
(having equal concentration of acid and basic components will mean that it will be easier to resist drastic change)
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What is the Henderson-Hasselbalch equation?
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Using the Henderson-Hasselbalch equation, calculate the volume of 0.2 M acetic acid and 0.2 M sodium acetate, needed to prepare 50 ml of 0.1 M acetate buffer solution (pH = 4.5). pKa of acetic acid is 4.74
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Surgical instruments are sterilized by heating them and alcohol is used as disinfectant in cleansing the skin prior to an injection. Why are these methods effective against microorganisms?
- heat denatures the protein, alcohol disrupts the hydrogen bonds
- microorganisms can't withstand immense heat, they can't survive temperature above 45 degrees
- microorganisms aren't used to acidity, and alcohol is sometimes acidic that can dissolve the cell membrane of microorganism
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Egg white and milk are used as an antidote for heavy metal poisining. Offer an explanation.
- heavy metal binds to egg white/milk ; chelating reagent
- the poison acts on the protein of the milk/egg rather than on the protein sites and tissues of mouth, stomach, esophagus
- egg white and milk have sulfhydryl which can bind the poison and rid of the body
- egg white absorbs metal, milk neutralizes stomach acid = results into vomiting
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Both picric acid and tannic acids are used in the treatment of burns. Offer an explanation.
- picric acid produces astringent, shrink tissue and was very useful for superficial burns providing a protective and soothing dressing and preventing cross infection
- tannic acids is best suitable in management of burns, it reduced the degree of toxemia, it includes relieving the pain, preventing loss of plasma and limit secondary infection
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Suppose you were given two jars one containing an amino acid and the other contains a polypeptide. Tell how you would distinguish between them by the use of ninhydrin and biuret reagent.
Ninhydrin – detection of amino acid and produces blue-violet
Biuret – detection of polypeptides and produces violet
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Why does nitric acid stain the skin yellow?
this is because the reaction of nitric acid with protein keratin present in the skin called Xanthoproteic reaction
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What is the formula of the colored precipitate obtained in the sulfur test or lead acetate test?
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"Little Miss Muffet sat on a tuffet, eating her curds and whey." What was she eating and where did it come from?
- she was eating cottage cheese/skimmed milk
- curd is the solid lump, whey is the liquid from which the curds were separated
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In order for the ninhydrin test to work, what functional group must be present?
- Amines (including a-amino acids)
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According to the equation for the ninhydrin reaction with an amino acid, an aldehyde and CO2 are products. What parts of the amino acid give rise to these products?
- carboxylic acid group
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Using the percentage you obtained for casein in milk, how many grams of casein are in a glass of milk (175 g)?
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Why should this amino acid give a yellow color with concentrated nitric acid? What part of the molecule becomes nitrated?
- it gives a yellow color because it is the way to show the activation of phenyl ring
- the part of the molecule that becomes nitrated is the 4-or-para-position and z-or-ortho-position
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Does albumin and casein contain tyrosine? How do you know?
Yes, through Xanthoproteic test and Nillons test
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For what purpose is the developing solvent used?
Mobile phase, transfers or moves the solute
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What factors affect the Rf value of the different solute used?
- Temperature,
- particle size,
- paper quality,
- concentration of solute and solvent,
- activation technique,
- type of chromatography
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Explain the Rf value obtained on the basis of the structure of amino acid used.
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