Which of the following is the number of protons in a lithium atom?
A. 7
B. 3
C. 12
D. 4
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.
Therefore, the Correct Answer is B.
More Questions on TEAS 7 Science
-
Q #1: Which of the following is the number of protons in a lithium atom?
A. 7
B. 3
C. 12
D. 4
Answer 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.
-
Q #2: Which of the following processes causes most of the carbon dioxide from the blood to move into the alveoli?
A. Conversion to carbon monoxide.
B. Diffusion down a concentration gradient.
C. Passive transport using carrier proteins.
D. Active transport using energy.
Answer Explanation
Diffusion down a concentration gradient causes most of the carbon dioxide from the blood to move into the alveoli.
The alveoli are tiny air sacs in the lungs where gas exchange occurs.
Carbon dioxide is a waste product of cellular respiration and is carried by the blood to the lungs to be exhaled.
In the lungs, carbon dioxide diffuses from the blood (where its concentration is high) into the alveoli (where its concentration is lower) down its concentration gradient.
Choice A is incorrect because carbon dioxide is not converted to carbon monoxide in the body.
Choice C is incorrect because passive transport using carrier proteins is not the primary mechanism by which carbon dioxide moves from the blood into the alveoli.
Choice D is incorrect because active transport using energy is not involved in the movement of carbon dioxide from the blood into the alveoli.
-
Q #3: What is the approximate threshold value for mammalian neurons?
A. -55 mV
B. -80 mV
C. +35 mV
D. 0 mV
Answer Explanation
The approximate threshold value for mammalian neurons is -55 mV.
The threshold potential is the critical level to which a membrane potential must be depolarized to initiate an action potential.
Most often, the threshold potential is a membrane potential value between –50 and –55 mV
The membrane potential of a neuron is determined by the distribution of ions across the cell membrane.
At rest, the inside of a neuron is more negative than the outside due to the presence of negatively charged proteins and other molecules.
The movement of ions across the cell membrane can change the membrane potential.
For example, when sodium ions enter the cell, they make the inside of the cell more positive (less negative), causing depolarization.
Choice B is incorrect because -80 mV is below the typical threshold value for mammalian neurons.
Choice C is incorrect because +35 mV is above the typical threshold value for mammalian neurons.
Choice D is incorrect because 0 mV is above the typical threshold value for mammalian neurons.
-
Q #4: 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.
-
Q #5: Which of the following is the process in which an ovarian follicle matures and releases a reproductive egg?
A. Menstruation
B. Fertilization
C. Ovulation
D. Oogenesis
Answer Explanation
Ovulation is the process in which an ovarian follicle matures and releases a reproductive egg.
During ovulation, a mature egg is released from the female ovary, enabling it to be fertilized by male sperm cells 1.
Choice A is incorrect because menstruation is the process of shedding the uterine lining, which occurs when an egg is not fertilized.
Choice B is incorrect because fertilization is the process of a sperm cell joining with an egg cell to form a zygote.
Choice D is incorrect because oogenesis is the process of forming female gametes (eggs) in the ovaries.
-
Q #6: Which of the following represents the complementary strand of a DNA sequence 3' TCGATCGCA 5'?
A. 3' AGCTAGCGT 5'
B. 5’ AGCTAGCGT 3’
C. 5' UCGAUCGCA 3'
D. 3' TCGUTCGCU 3'
Answer 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.
-
Q #7: A myocardial infarction affects which of the following blood vessels of the heart?
A. Coronary
B. Aorta
C. Pulmonary
D. Vena cava
Answer Explanation
A myocardial infarction affects the coronary blood vessels of the heart.
A myocardial infarction, commonly known as a heart attack, occurs when blood flow decreases or stops in the coronary artery of the heart, causing damage to the heart muscle 1.
Choice B is incorrect because the aorta is not a blood vessel of the heart.
The aorta is the main artery that carries oxygenated blood from the heart to the rest of the body.
Choice C is incorrect because the pulmonary blood vessels are not affected by a myocardial infarction.
The pulmonary blood vessels carry deoxygenated blood from the heart to the lungs.
Choice D is incorrect because the vena cava is not a blood vessel of the heart.
The vena cava is a large vein that carries deoxygenated blood from the body to the heart.
-
Q #8: Which of the following is the structure through which blood exits the glomerulus?
A. Efferent arteriole
B. Proximal tubule
C. Distal tubule
D. Afferent arteriole
Answer 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.
-
Q #9: Which of the following substances is excreted by sweat glands in response to the breakdown of proteins and the formation of ammonia?
A. Urea
B. Sebum
C. Water
D. Lysozymes
Answer Explanation
Urea is a substance that is excreted by sweat glands in response to the breakdown of proteins and the formation of ammonia.
When proteins are broken down, they produce ammonia, which is a highly toxic compound for the body.
Ammonia is then converted into urea and released out of the body through sweat glands.
Choice B.
Sebum is not correct because it is an oily substance secreted by sebaceous glands to lubricate and protect the skin, but it is not related to the breakdown of proteins or the formation of ammonia.
Choice C.
Water is not correct because while it is a component of sweat, it is not specifically related to the breakdown of proteins or the formation of ammonia.
Choice D.
Lysozymes are not correct because they are enzymes found in tears, saliva and other body fluids that have antibacterial properties, but they are not related to the breakdown of proteins or the formation of ammonia.
-
Q #10: 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.
