In the following data table of an experiment carried out at 4°C (39.2 F) over 4 hours Solution in bag Solution outside bag Bag mass change (g): water Water -0.2 20% sucrose Water +2.4 , 40% sucrose Water +4.3 , 60% sucrose water +5.8 Which of the following options represents the dependent variable?
A. Duration
B. Temperature
C. Bag mass change
D. Solution used outside
Bag mass change is the dependent variable in this experiment.
In an experiment, the dependent variable is the variable that is being measured and is expected to change in response to changes in the independent variable(s).
In this case, the bag mass change is being measured and is expected to change in response to changes in the independent variable (sucrose concentration).
Choice A is incorrect because duration is not a variable in this experiment.
Choice B is incorrect because temperature is not a variable in this experiment.
Choice D is incorrect because sucrose concentration is an independent variable, not a dependent variable.
An independent variable is a variable that is manipulated by the experimenter to see how it affects the dependent
Therefore, the Correct Answer is C.
More Questions on TEAS 7 Science
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Q #1: Which of the following physiological responses is caused by the release of antidiuretic hormone?
A. Increase in the concentration of calcium in the glomerulus.
B. Increase in water reabsorption in the collecting duct
C. Decrease in the concentration of calcium in the glomerulus.
D. Decrease in water reabsorption in the collecting duct
Answer 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.
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Q #2: Which of the following substances protects the skin from ultraviolet radiation?
A. Melanin
B. Perspiration
C. Sebum
D. Keratin
Answer Explanation
Melanin.
Melanin is a pigment produced by cells called melanocytes in the skin.
It protects the skin from ultraviolet (UV) radiation by absorbing and dissipating over 99.9% of absorbed UV radiation.
This helps to prevent DNA damage and other adverse effects of UV radiation on the skin.
Choice B.
Perspiration is not correct because it is a fluid produced by sweat glands in the skin that helps to regulate body temperature, but it does not protect the skin from UV radiation.
Choice C.
Sebum is not correct because it is an oily substance produced by sebaceous glands in the skin that helps to lubricate and protect the skin, but it does not protect the skin from UV radiation.
Choice D.
Keratin is not correct because it is a fibrous protein that provides strength and durability to the skin, hair and nails, but it does not protect the skin from UV radiation.
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Q #3: Which of the following indicates the function of sodium bicarbonate secreted by the pancreas?
A. Sodium bicarbonate is a protease that digests carbohydrates.
B. Sodium bicarbonate stimulates the pyloric sphincter.
C. Sodium bicarbonate inhibits peristalsis.
D. Sodium bicarbonate neutralizes the acidity of chyme.
Answer 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.
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Q #4: Which of the following glands synthesizes antidiuretic hormone?
A. Pineal gland
B. Thymus
C. Hypothalamus
D. Pancreas
Answer Explanation
The hypothalamus is a region of the brain that synthesizes antidiuretic hormone (ADH), also known as vasopressin.
ADH is then transported to the posterior pituitary gland via neurohypophysial capillaries, where it is stored until it is ready to be secreted into the circulation.
Choice A.
Pineal gland is not correct because it is a small endocrine gland located in the brain that secretes the hormone melatonin, which regulates sleep-wake cycles, but it does not synthesize ADH.
Choice B.
Thymus is not correct because it is a gland located in the chest that produces hormones involved in immune system development, but it does not synthesize ADH.
Choice D.
Pancreas is not correct because it is a gland located behind the stomach that secretes hormones such as insulin and glucagon, which regulate blood sugar levels, but it does not synthesize ADH.
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Q #5: Which of the following is the atomic number of an atom that has 12 protons and 12 neutrons?
A. 24
B. 12
C. 1
D. 144
Answer Explanation
The atomic number of an atom is equal to the number of protons in its nucleus.
In this case, the atom has 12 protons, so its atomic number is 12.
Choice A, 24, is not the correct answer because it represents the sum of the number of protons and neutrons in the atom’s nucleus, which is known as the mass number.
Choice C, 1, is not the correct answer because it does not represent the number of protons in the atom’s nucleus.
Choice D, 144, is not the correct answer because it represents the square of the mass number and does not represent any property of the atom.
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Q #6: The cytoskeleton of a cell is comprised of which of the following macromolecules?
A. Carbohydrates
B. Nucleic acids
C. Lipids
D. Proteins
Answer Explanation
The cytoskeleton of a cell is comprised of protein fibers that provide structural support and help maintain the shape of the cell.
These protein fibers include microfilaments, intermediate filaments, and microtubules.
Choice A.
Carbohydrates is not the correct answer because carbohydrates are a type of macromolecule that provides energy to cells and are not a component of the cytoskeleton.
Choice B.
Nucleic acids is not the correct answer because nucleic acids are macromolecules that store and transmit genetic information and are not a component of the cytoskeleton.
Choice C.
Lipids is not the correct answer because lipids are a type of macromolecule that makes up cell membranes and are not a component of the cytoskeleton.
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Q #7: Which of the following ions binds to the troponin complex, initiating contraction of a muscle?
A. Potassium.
B. Calcium.
C. Phosphorus.
D. Sodium
Answer Explanation
Calcium ions play a crucial role in initiating muscle contraction.
When a muscle cell is stimulated to contract by an action potential, calcium channels open in the sarcoplasmic membrane and release calcium into the sarcoplasm.
Some of this calcium attaches to troponin, which causes it to change shape.
This shape change exposes binding sites for myosin on the actin filaments.
Myosin’s binding to actin causes crossbridge formation, and contraction of the muscle begins.
The other ions mentioned in the question do not have this specific role in muscle contraction.
Potassium ions are important for maintaining the resting membrane potential of cells, but they do not bind to the troponin complex.
Phosphorus ions are important for energy metabolism, but they do not bind to the troponin complex.
Sodium ions are important for generating action potentials, but they do not bind to the troponin complex.
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Q #8: Which of the following structures is present in both prokaryotic and eukaryotic cells?
A. Cell membrane
B. Golgi apparatus
C. Chloroplasts
D. Endoplasmic reticulum
Answer Explanation
The cell membrane is present in both prokaryotic and eukaryotic cells.
The cell membrane is a thin, flexible barrier that surrounds all cells and separates the inside of the cell from the outside environment.
It is composed of a lipid bilayer and regulates the movement of substances into and out of the cell.
Choice B is incorrect because the Golgi apparatus is not present in prokaryotic cells.
The Golgi apparatus is an organelle found in eukaryotic cells that is involved in modifying, sorting, and packaging proteins and lipids for transport to other parts of the cell or to be secreted outside the cell.
Choice C is incorrect because chloroplasts are not present in prokaryotic cells.
Chloroplasts are organelles found in plant cells and some algae that are responsible for photosynthesis.
Choice D is incorrect because the endoplasmic reticulum is not present in prokaryotic cells.
The endoplasmic reticulum is an organelle found in eukaryotic cells that is involved in protein synthesis and lipid metabolism.
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Q #9: Which of the following vessels carries oxygenated blood?
A. Superior vena cava
B. Inferior vena cava.
C. Pulmonary artery
D. Pulmonary vein
Answer Explanation
The pulmonary veins are the vessels that carry oxygenated blood from the lungs to the left atrium of the heart.
Choice A is not correct because the superior vena cava carries deoxygenated blood from the upper body to the right atrium of the heart.
Choice B is not correct because the inferior vena cava carries deoxygenated blood from the lower body to the right atrium of the heart.
Choice C is not correct because the pulmonary artery carries deoxygenated blood from the right ventricle of the heart to the lungs.
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Q #10: In a hypertonic solution, water flows through aquaporins embedded in the plasma membrane of the cell. This type of transport is best known as which of the following?
A. Facilitated diffusion
B. Active transport
C. Osmosis
D. Diffusion
Answer 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.
