Free Iowa Test of Basic Skills (ITBS) 8th Grade Questions and Answers — Questions and Answers
Question 1: Get the LCM of 224 and 280.
- 280
- 504
- 2240
- 1120 (Correct answer)
Correct answer: 1120
To find the Least Common Multiple (LCM) of 224 and 280, first determine their prime factorizations: 224 = 2^5 × 7 and 280 = 2^3 × 5 × 7. The LCM is found by taking the highest power of all prime factors present in either number. Thus, LCM = 2^5 × 5^1 × 7^1 = 32 × 5 × 7 = 1120.
Question 2: A cube has a 725-cubic-centimeter volume. Which of the following comes closest to describing how long each cube edge is?
- 8 centimeters
- 9 centimeters (Correct answer)
- 7 centimeters
- 10 centimeters
Correct answer: 9 centimeters
The volume of a cube is calculated by cubing the length of one of its edges (V = s³). To find the edge length, you need to calculate the cube root of the volume. The cube root of 725 is approximately 8.98 centimeters. Among the given options, 9 centimeters is the closest whole number to this value.
Question 3: Which of the ensuing figures makes a perfect square?
- 25 (Correct answer)
- 75
- 50
- 20
Correct answer: 25
A perfect square is an integer that can be expressed as the product of an integer multiplied by itself. Among the given options, 25 is a perfect square because it is the result of 5 multiplied by 5 (5 × 5 = 25). The other numbers are not products of an integer multiplied by itself.
Question 4: 8 is reduced by adding a number, n, and the product of 5. Which expression best encapsulates this assertion?
- 8 + (n + 5)
- 8 (n + 5) (Correct answer)
- (n + 5) + 8
- (n + 5) 8
Correct answer: 8 (n + 5)
The phrase 'adding a number, n, and the product of 5' can be interpreted as 'adding n and 5,' which forms the sum (n + 5). The phrase '8 is reduced by' means that this sum is subtracted from 8. Therefore, the expression that best encapsulates this assertion is 8 - (n + 5).
Question 5: What is considered to be an error or alteration in an organism's DNA?
- Environmental Selection
- Mutation (Correct answer)
- Natural Selection
- Evolution
Correct answer: Mutation
A mutation is defined as a change or alteration in the DNA sequence of an organism. These changes can be small, like a single base pair change, or large, involving entire sections of chromosomes. Mutations are the fundamental source of genetic variation within a population.
Question 6: What is the process that enables organisms to survive and pass on their genetic features when they are most compatible with their environment.
- Mutation
- Natural Selection (Correct answer)
- Environmental Selection
- Evolution
Correct answer: Natural Selection
Natural selection is the evolutionary process where organisms that are better adapted to their environment tend to survive and produce more offspring. This leads to the differential survival and reproduction of individuals based on their traits, ensuring that advantageous genetic features are passed on and become more prevalent in a population over time.
Question 7: What among the following leads to extinction?
- Agriculture
- Deforestation
- Habitat Fragmentation
- All options are correct (Correct answer)
Correct answer: All options are correct
Extinction is the complete disappearance of a species, and human activities are major drivers of this process. Agriculture leads to habitat loss, deforestation destroys forests and their inhabitants, and habitat fragmentation breaks up continuous habitats into smaller, isolated patches, all of which reduce biodiversity and contribute to species extinction.
Question 8: A species is considered to have _________ when it becomes more adapted to its surroundings.
- grown
- mutated
- adapted (Correct answer)
- evaporated
Correct answer: adapted
When a species becomes more compatible with its surroundings, it is described as having adapted. Adaptation is the evolutionary process where organisms develop traits that enhance their survival and reproduction in a specific environment, often through natural selection over generations.
Question 9: Which word has the incorrect spelling?
- stationery
- disciplinery (Correct answer)
- exemplary
- machinery
Correct answer: disciplinery
The correct spelling of the word is "disciplinary," not "disciplinery." The suffix "-ary" is used to form adjectives meaning "relating to" or "of the nature of," as in "military" or "primary." The suffix "-ery" is typically used for nouns denoting a place, occupation, or collection, such as "bakery" or "machinery."
Question 10: Which line has a mistake in the spelling?
- patios, radios, heros (Correct answer)
- altos, pianos, solos
- rodeos, videos, sopranos
- potatoes, tomatoes, concertos
Correct answer: patios, radios, heros
The plural of most nouns ending in -o preceded by a vowel is formed by adding -s, as seen in "patios" and "radios." However, "hero" is an exception to this rule. Its correct plural form is "heroes," which is created by adding -es, making "heros" a misspelling.
Question 11: Which of the following could be used in a sentence as an adjective?
- inspiration
- inspires
- inspirational (Correct answer)
- inspirationally
Correct answer: inspirational
An adjective is a word that describes or modifies a noun or pronoun. "Inspirational" fits this role, meaning something that provides inspiration (e.g., 'an inspirational speech'). In contrast, "inspiration" is a noun, "inspires" is a verb, and "inspirationally" is an adverb.
Question 12: What phrase use a superlative adverb?
- Gerald reads quietly in the window seat.
- Beth completed the process very efficiently.
- Sally works more quickly than most.
- Out of the entire class, Grace works most carefully. (Correct answer)
Correct answer: Out of the entire class, Grace works most carefully.
A superlative adverb describes an action to the highest degree, typically comparing three or more entities. It is usually formed by placing "most" before the adverb (e.g., 'most carefully,' 'most quickly'). In the sentence, "most carefully" indicates that Grace works with the highest degree of carefulness compared to everyone else in the class.
Question 13: Which of the following is NOT written properly?
- Liz seldom uses the dictionary.
- James drives more slowly than the average driver.
- Gail drives cautious on icy roads. (Correct answer)
- Braxton never seems to make it to the bus stop on time.
Correct answer: Gail drives cautious on icy roads.
Adverbs are used to modify verbs, adjectives, or other adverbs, describing how, when, where, or to what extent an action occurs. In the sentence "Gail drives cautious on icy roads," "cautious" is an adjective. To properly modify the verb "drives," an adverb is needed, so the correct word should be "cautiously."
Question 14: Some individuals dislike using computers. They believe it to be too difficult, and they frequently lose it. Don't they understand how much time and effort computers save us? These computer-haters must be perplexed. What premise does this sentence rest on?
- Computers can help educate students.
- Everyone should use and appreciate computers. (Correct answer)
- Most computers don’t break down.
- People are breaking the computers.
Correct answer: Everyone should use and appreciate computers.
The passage highlights the benefits of computers, stating they "save us" time and effort, and questions why "computer-haters" don't understand this. This rhetorical approach implies the author's strong belief that computers are universally beneficial and that everyone should therefore use and appreciate them for their efficiency.
Question 15: The man had changed. The plane that flew past without saving him had utterly altered him. He was no longer the same and would never again be. The new Peter was stronger and would not give up, unlike the weak old Peter who needed to survive. How has Peter changed, in your opinion?
- Peter is angry because he’s made mistakes.
- Peter has not changed at all.
- Peter felt sorry for himself and wanted to give up.
- Peter was stronger, more aware and careful. (Correct answer)
Correct answer: Peter was stronger, more aware and careful.
The text explicitly states that "The new Peter was stronger and would not give up, unlike the weak old Peter." This indicates a significant transformation towards increased strength and resilience. The traumatic experience of being abandoned by the plane likely fostered a greater sense of self-reliance and caution, making him more aware and careful.
Question 16: Christine noticed the stunning, fresh, white snow that was covering the ground outside as she peered out of her bedroom window. She hurriedly put on her clothes and dashed outside to build the first snowman of the season. "Remember to bring your gloves! She heard her mother say, "Your fingers will freeze!" as the door shut. Don't require them! Christine shouted, "No time!" as she leaped into the snow. Christine spent around five minutes building the snowman with her bare hands before she noticed that her fingers were growing painfully chilly. What is most likely Christine's next move?
- Take off her coat and boots.
- Go back in the house for her coat.
- Ask her mother to help her make the snowman.
- Go back in the house for her gloves. (Correct answer)
Correct answer: Go back in the house for her gloves.
Christine initially ignored her mother's warning about her fingers freezing, but after five minutes, her fingers became "painfully chilly." This discomfort confirms her mother's prediction. The most logical next action for Christine would be to retrieve the gloves she initially refused, as they would alleviate the pain and allow her to continue building the snowman comfortably.
Free Iowa Test of Basic Skills (ITBS) 8th Grade Questions and Answers
Get the LCM of 224 and 280.