Practice Question An atom has 14 protons and 20 neutrons. What is its atomic number?
A. 20
B. 17
C. 10
D. 14
Therefore, the Correct Answer is D.
More Questions on TEAS 7 Science
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Q #1: Metabolism of proteins Which of the following substances is excreted by sweat glands in response to the breakdown of proteins and the formation of ammonia?
A. Sebum
B. Urea
C. Lysozymes
D. Water
Answer Explanation
Proteins are nitrogen-based compounds, which when broken down release ammonia. Ammonia is a toxic substance to the body, and sebaceous glands coverts it to urea.
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Q #2: Which of the following are structural features of the trachea?
A. C-shaped cartilage
B. Smooth muscle fibers
C. Cilia
D. All of the above
Answer Explanation
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Q #3: Which of the following best describes the result of using a catalyst in a chemical reaction?
A. A more desirable product is often formed
B. The reaction is completed in a shorter amount of time
C. The yield of product is increased
D. A greater amount of energy is released by the reaction
Answer Explanation
A catalyst is substance that speeds up the rate of converting reactants to products. They do by decreasing the activation energy of a reaction. If a catalyst increases the rate of reaction, then it means that the reaction takes a smaller time to come into completion.
Catalysts can be metals, ions or biological also known as enzymes. Catalysts are not consumed when the reaction is taking place. -
Q #4: Pathogens Which of the following microorganisms lack their own metabolic pathways and can only reproduce inside of a host cell?
A. Bacteria
B. Viruses
C. Helminths
D. Protozoa
Answer Explanation
The disease-causing microorganisms are known as pathogens, which include bacteria, fungi, protozoa, worms, viruses and prions. These organisms have distinguishing cell structures from each other. The most notable difference between viruses and other pathogens is that viruses lack a metabolism mechanism of their own and ability to produce proteins encoded by their DNA or RNA. However, they viruses rely on machinery of the host cell to produce their proteins and replicate their genomes.
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Q #5: Nitrogen gas is an extremely stable molecule because its structure contains which of the following?
A. Resonance bonds
B. Ionic bonds
C. Triple covalent bonds
D. Hydrogen bonds
Answer Explanation
The Lewis structure of nitrogen gas is shown below. Triple bonds are stronger than double or single bonds. Therefore, we can infer that the triple bond between the two nitrogen atoms makes nitrogen gas more stable.
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Q #6: In a plant in which fuzzy leaves (F) are dominant over smooth leaves (f), which of the following crosses will produce only offspring with smooth leaves?
A. Ff x ff
B. Ff x Ff
C. FF x FF
D. ff x ff
Answer Explanation
Crossing is the breeding of parents to produce an offspring. Given that f is a recessive allele of smooth leaves while F is the dominant allele of fuzzy leaves. Therefore, where there is F crossing with f, the offspring will have fuzzy leaves over smooth one.
Therefore, for an offspring to have smooth leaves, ff and ff must cross to produce an offspring with smooth leaves. -
Q #7: Gel electrophoresis To separate genomic DNA fragments by size, which of these laboratory methods is most useful?
A. Filtration
B. Titration
C. Electrophoresis
D. Spectrophotometry
Answer Explanation
Electrophoresis is a lab method that is commonly used to separate charge molecules based on their size. Some of the charged molecules include DNA, RNA, and proteins.
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Q #8: Which of the following best describes veins?
A. thick walled, small lumens, low pressure, lack valves
B. thin walled, large lumens, low pressure, have valves
C. thin walled, small lumens, high pressure, have valves
D. thick walled, large lumens, high pressure, lack valves
Answer Explanation
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Q #9: Which of these organs is not considered an accessory digestive structure?
A. mouth
B. salivary glands
C. pancreas
D. liver
Answer Explanation
Accessory organs of the digestive system comprise of organs that empty secretions into the alimentary canal. These organs include salivary glands, liver, gallbladder and pancreas. The mount if path of the alimentary canal.
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Q #10: The process that moves nutrients into the blood or lymph is
A. digestion
B. ingestion
C. elimination
D. absorption
Answer Explanation
Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma.
Ingestion is the process of taking food, drink, or another substance into the body by swallowing or absorbing it.
Elimination refers to the removal of indigestible wastes through the anus, in the form of feaces.
