To separate genomic DNA fragments by size, which of these laboratory methods is most useful?
Titration
Electrophoresis
Filtration
Spectrophotometry
Correct Answer : B
Electrophoresis is the most useful laboratory method for separating genomic DNA fragments by size.
Electrophoresis is a technique that uses an electric field to separate charged molecules, such as DNA fragments, based on their size and charge.
Choice A is not correct because titration is a laboratory method used to determine the concentration of a solution.
Choice C is not correct because filtration is a laboratory method used to separate solids from liquids.
Choice D is not correct because spectrophotometry is a laboratory method used to measure the absorbance of light by a solution.
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Related Questions
Correct Answer is B
Explanation
Antidiuretic hormone (ADH), also known as vasopressin, is a hormone that helps regulate the amount of water in your body.
It works to control the amount of water your kidneys reabsorb as they filter out waste from your blood.
Choice A is not correct because an increase in the concentration of calcium in the glomerulus is not a physiological response caused by the release of antidiuretic hormone.
Choice C is not correct because a decrease in the concentration of calcium in the glomerulus is not a physiological response caused by the release of antidiuretic hormone.
Choice D is not correct because a decrease in water reabsorption in the collecting duct is not a physiological response caused by the release of antidiuretic hormone.
Correct Answer is D
Explanation
Sodium bicarbonate neutralizes the acidity of chyme.
The pancreas secretes large amounts of sodium bicarbonate, which protects the duodenum by neutralizing the acid that comes from the stomach.
This compound helps neutralize stomach acid generated during the digestive process.
Choice A is incorrect because sodium bicarbonate is not a protease that digests carbohydrates.
Proteases are enzymes that break down proteins, while sodium bicarbonate is a chemical compound that helps neutralize stomach acid.
Choice B is incorrect because sodium bicarbonate does not stimulate the pyloric sphincter.
The pyloric sphincter is a ring of smooth muscle that separates the stomach from the duodenum and regulates the passage of partially digested food (chyme) into the small intestine.
Choice C is incorrect because sodium bicarbonate does not inhibit peristalsis.
Peristalsis is a series of wave-like muscle contractions that move food through the digestive tract.
Correct Answer is B
Explanation
In DNA, the nitrogenous bases adenine (A) and thymine (T) pair together, while cytosine (C) and guanine (G) pair together.
Therefore, the complementary strand of the given DNA sequence 3' TCGATCGCA 5' would have the complementary nitrogenous bases as:
5’ AGCTAGCGT 3’
NOTE: The 5’ to 3’ direction of the complementary strand is opposite to that of the given strand.
Choice A.
3’ AGCTAGCGT 5’ is not correct because it is not complementary to the given strand.
Choice C.
5’ UCGAUCGCA 3’ is not correct because it contains uracil (U), which is a nitrogenous base found in RNA, not DNA.
Choice D.
3’ TCGUTCGCU 3’ is not correct because it also contains uracil (U), which is a nitrogenous base found in RNA, not DNA.
Correct Answer is D
Explanation
Testosterone is classified as an androgen hormone.
Androgens are a type of sex hormone that primarily regulates the development and maintenance of male characteristics, such as body hair growth, muscle mass, and deepening of the voice.
Testosterone is produced primarily in the testes in males and in smaller amounts in the ovaries and adrenal glands in females.
Option A, estrogen, is a female hormone that regulates the development of female sexual characteristics, such as breast growth and menstruation.
While estrogen and testosterone are both steroid hormones and can be converted to one another in the body, testosterone is not categorized as estrogen.
Option B, progestin, is a synthetic form of the hormone progesterone.
Progesterone is a female hormone that plays a role in the menstrual cycle and pregnancy.
Testosterone and progestin are not related, and testosterone is not categorized as progestin.
Option C, aldosterone, is a mineralocorticoid hormone that regulates salt and water balance in the body.
It is produced in the adrenal gland and plays a role in regulating blood pressure.
Testosterone and aldosterone are not related, and testosterone is not categorized as aldosterone.
Correct Answer is B
Explanation
The atomic number of an element represents the number of protons in the nucleus of an atom of that element.
Since lithium has an atomic number of 3, it has 3 protons in its nucleus.
Choice A is not correct because 7 is the mass number of lithium, not the number of protons.
Choice C is not correct because 12 is not the atomic number or mass number of lithium.
Choice D is not correct because 4 is not the atomic number or mass number of lithium.
Correct Answer is C
Explanation
Osmosis is the movement of water molecules across a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration.
In a hypertonic solution, the concentration of solutes outside the cell is higher than inside the cell, so water flows out of the cell through aquaporins embedded in the plasma membrane to balance the concentration gradient.
Choice A.
Facilitated diffusion is not correct because it is a type of passive transport that involves the movement of molecules across a membrane through specific transport proteins, but it does not specifically refer to the movement of water molecules.
Choice B.
Active transport is not correct because it is a type of transport that involves the movement of molecules against their concentration gradient and requires energy in the form of ATP, but osmosis is a passive process that does not require energy.
Choice D.
Diffusion is not correct because it refers to the movement of molecules from an area of higher concentration to an area of lower concentration, but it does not specifically refer to the movement of water molecules.
Correct Answer is A
Explanation
A catalyst is a substance that increases the rate of a chemical reaction without being consumed by the reaction.
As a result, the reaction is completed in a shorter amount of time.
Choice B is not correct because using a catalyst does not necessarily result in the formation of a more desirable product.
Choice C is not correct because using a catalyst does not necessarily result in the release of a greater amount of heat energy by the reaction.
Choice D is not correct because using a catalyst does not necessarily increase the yield of product.
Correct Answer is A
Explanation
The glomerulus is the main filtering unit of the kidney.
It is formed by a network of small blood vessels (capillaries) enclosed within a sac called the Bowman’s capsule.
The blood supply to the glomerulus is provided via the afferent arteriole.
The blood then flows through the capillary network, where it gets filtered, and then leaves the glomerulus via the efferent arteriole.
Choice B.
Proximal tubule is not correct because it is where the ultrafiltrate collected in the Bowman’s space drains directly into.
Choice C.
Distal tubule is not correct because it is not mentioned in relation to blood exiting the glomerulus.
Choice D.
Afferent arteriole is not correct because it provides blood supply to the glomerulus.
Correct Answer is D
Explanation
The polarity of water molecules explains its solvent abilities for certain substances.
Water is a polar molecule because it has a partial positive charge on one end and a partial negative charge on the other end due to the unequal sharing of electrons between the oxygen and hydrogen atoms.
This polarity allows water to dissolve other polar substances and ionic compounds.
Choice A.
Kinetic energy of liquid water molecules is not the correct answer because kinetic energy refers to the energy of motion and does not directly explain water’s solvent abilities.
Choice B.
High specific heat is not the correct answer because specific heat refers to the amount of heat required to raise the temperature of a substance and does not directly explain water’s solvent abilities.
Choice C.
High surface tension is not the correct answer because surface tension refers to the cohesive forces between liquid molecules and does not directly explain water’s solvent abilities.
Correct Answer is C
Explanation
The pH scale is a logarithmic scale that measures the acidity or alkalinity of a solution.
A solution with a pH of 7 is neutral, while a solution with a pH less than 7 is acidic and a solution with a pH greater than 7 is alkaline.
Because the pH scale is logarithmic, each whole number change in pH represents a tenfold change in acidity or alkalinity.
Therefore, a substance with a pH of 3 is 10 times more acidic than a substance with a pH of 4.
Choice A.
A substance with a pH of 3 is two times more alkaline than a substance with a pH of 4 is not correct because it incorrectly states that the substance with a lower pH is more alkaline and also incorrectly states the magnitude of the difference in acidity or alkalinity.
Choice B.
A substance with a pH of 3 is two times more acidic than a substance with a pH of 4 is not correct because it correctly states that the substance with a lower pH is more acidic but incorrectly states the magnitude of the difference in acidity.
Choice D.
A substance with a pH of 3 is 10 times more alkaline than a substance with a pH of 4 is not correct because it incorrectly states that the substance with a lower pH is more alkaline.
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