Because vs. Because of – English Grammar Exercises for B1
Writing an academic essay analyzing the macro-level reasons why wild animals and natural ecosystems are disappearing.
Choose the best option (A, B, C, or D) to complete each sentence. Read the context carefully. Pay close attention to the words immediately following the blank to decide whether you need a conjunction for a full clause (Subject + Verb) or a preposition for a noun phrase (summarizing an environmental phenomenon).
1 Many wild animals are rapidly losing their natural homes ________ deforestation.
(A) because
(B) because of
(C) due
(D) despite
2 Polar bears are currently starving ________ the Arctic ice is melting at an alarming rate.
(A) because of
(B) because
(C) because that
(D) therefore
3 The global population of rhinos has decreased significantly ________ illegal poaching.
(A) because
(B) owing
(C) because of
(D) as a result
4 Sea turtles often suffer and die ________ they mistakenly swallow plastic bags in the ocean.
(A) because of
(B) due to
(C) because
(D) because from
5 Several unique bird species are now extinct ________ severe habitat loss.
(A) because
(B) because of
(C) regardless of
(D) for because
6 Coral reefs are dying all around the world ________ rising ocean temperatures.
(A) because of
(B) because
(C) nevertheless
(D) cause of
7 We must take immediate action ________ the global climate is changing faster than scientists expected.
(A) because of
(B) despite
(C) because
(D) reason
8 The massive forest fires spread uncontrollably last year ________ the extremely dry weather conditions.
(A) because
(B) instead of
(C) because of
(D) because it
9 Many freshwater fish are disappearing ________ there is too much toxic waste in the rivers.
(A) because of
(B) because
(C) due to
(D) because there
10 Local ecosystems become completely unbalanced ________ the sudden introduction of invasive species.
(A) because
(B) because off
(C) although
(D) because of
11 Elephants are heavily hunted in many regions ________ ivory remains highly valuable on the black market.
(A) because of
(B) because
(C) in spite of
(D) because for
12 The local river is entirely polluted ________ massive industrial waste from nearby chemical factories.
(A) because of
(B) because
(C) due
(D) consequently
13 The government officially banned plastic straws ________ they cause severe harm to marine life.
(A) because of
(B) owing to
(C) because
(D) because of they
14 Wild animal populations are shrinking globally ________ the rapid expansion of human cities.
(A) because
(B) however
(C) because of
(D) reason of
15 The air quality in the city is terrible ________ thousands of factories releasing toxic smoke every day.
(A) because
(B) because of
(C) despite
(D) because that
16 Governments must invest heavily in renewable energy ________ the fact that fossil fuels destroy the atmosphere.
(A) because
(B) due
(C) because of
(D) since
17 The national wildlife reserve is temporarily closed ________ the dangerous chemicals that leaked yesterday.
(A) because of
(B) because
(C) resulting
(D) because to
18 The overall health of the ocean is declining ________ massive commercial fishing ships are destroying the sea floor.
(A) because of
(B) because
(C) reason why
(D) owing to
19 Tigers are struggling to survive in the wild ________ humans destroying their primary hunting grounds.
(A) because
(B) therefore
(C) because of
(D) because are
20 We are currently facing a mass extinction event ________ extreme human interference in nature.
(A) because
(B) because of
(C) although
(D) thanks because
ANSWER KEY & EXPLANATIONS
1 (B)
- Why it is correct (The Key): “Deforestation” is a noun. In academic writing, we use the preposition “because of” to introduce a noun phrase that states a cause.
- Error Analysis: (A) “Because” requires a full clause (Subject + Verb) (Common Mistake). (C) “Due” must be followed by “to” (Structural Error). (D) “Despite” means “even though,” which contradicts the cause-and-effect logic (Meaning Trap).
2 (B)
- Why it is correct (The Key): “The Arctic ice is melting” is a complete independent clause (Subject = the Arctic ice, Verb = is melting). We must use the conjunction “because.”
- Error Analysis: (A) “Because of” cannot precede a full clause (Common Mistake). (C) “Because that” is grammatically invalid (Structural Error). (D) “Therefore” indicates a result, not a cause (Meaning Trap).
3 (C)
- Why it is correct (The Key): “Illegal poaching” is a noun phrase summarizing the phenomenon. We use “because of.”
- Error Analysis: (A) “Because” requires a subject and a conjugated verb (Common Mistake). (B) “Owing” is missing “to” (Structural Error). (D) “As a result” introduces an effect, not the root cause (Meaning Trap).
4 (C)
- Why it is correct (The Key): “They mistakenly swallow plastic bags” is a full clause. It requires “because.”
- Error Analysis: (A) & (B) “Because of” and “Due to” cannot precede a full clause (Common Mistake). (D) “Because from” is grammatically invalid (Structural Error).
5 (B)
- Why it is correct (The Key): “Severe habitat loss” is a formal noun phrase summarizing an environmental issue. We use “because of.”
- Error Analysis: (A) “Because” requires a clause (Common Mistake). (C) “Regardless of” means “despite,” which ruins the logical explanation (Meaning Trap). (D) “For because” is redundant and invalid (Structural Error).
6 (A)
- Why it is correct (The Key): “Rising ocean temperatures” is a noun phrase. We use “because of.”
- Error Analysis: (B) “Because” needs a conjugated verb (Common Mistake). (C) “Nevertheless” indicates contrast (Meaning Trap). (D) “Cause of” is highly informal/slang and unacceptable in academic writing (Structural Error).
7 (C)
- Why it is correct (The Key): “The global climate is changing” is a complete clause. We use “because.”
- Error Analysis: (A) “Because of” cannot precede a clause (Common Mistake). (B) “Despite” breaks the cause-and-effect logic (Meaning Trap). (D) “Reason” lacks the necessary prepositional structure (Structural Error).
8 (C)
- Why it is correct (The Key): “The extremely dry weather conditions” is a noun phrase. We use “because of.”
- Error Analysis: (A) “Because” needs a full independent clause (Common Mistake). (B) “Instead of” means replacing something, which is illogical here (Meaning Trap). (D) “Because it” creates a grammatical error since the following phrase lacks a verb for “it” to attach to (Structural Error).
9 (B)
- Why it is correct (The Key): “There is too much toxic waste” is a formal clause (Subject = there, Verb = is). We use “because.”
- Error Analysis: (A) & (C) “Because of” and “Due to” cannot take a full clause (Common Mistake). (D) “Because there” is redundant if “there” is already part of the clause (Structural Error).
10 (D)
- Why it is correct (The Key): “The sudden introduction of invasive species” is a complex noun phrase. We use “because of.”
- Error Analysis: (A) “Because” requires a main verb (Common Mistake). (B) “Because off” is a spelling error (Structural Error). (C) “Although” introduces a contrast, not a reason (Meaning Trap).
11 (B)
- Why it is correct (The Key): “Ivory remains highly valuable” is a full clause (Subject = ivory, Verb = remains). We use “because.”
- Error Analysis: (A) “Because of” cannot take a clause (Common Mistake). (C) “In spite of” gives an opposite, illogical meaning (Meaning Trap). (D) “Because for” is invalid (Structural Error).
12 (A)
- Why it is correct (The Key): “Massive industrial waste from nearby chemical factories” is a long, descriptive noun phrase. There is no conjugated verb. We use “because of.”
- Error Analysis: (B) “Because” needs a subject and a verb (Common Mistake). (C) “Due” is missing “to” (Structural Error). (D) “Consequently” means “as a result” (Meaning Trap).
13 (C)
- Why it is correct (The Key): “They cause severe harm” is a full clause. We use “because.”
- Error Analysis: (A) & (B) “Because of” and “Owing to” require a noun phrase (Common Mistake). (D) “Because of they” is grammatically broken (Structural Error).
14 (C)
- Why it is correct (The Key): “The rapid expansion of human cities” is a noun phrase summarizing the macro issue. We use “because of.”
- Error Analysis: (A) “Because” requires a main verb (Common Mistake). (B) “However” indicates contrast (Meaning Trap). (D) “Reason of” is not a standard prepositional phrase (Structural Error).
15 (B)
- Why it is correct (The Key): “Thousands of factories releasing toxic smoke” is a Noun Phrase modified by a participle (“releasing”). Because “releasing” is not a conjugated main verb, this is not a full clause. We must use “because of.”
- Error Analysis: (A) “Because” is a massive Common Mistake here; learners see “releasing” and assume it’s a verb, but it acts as an adjective describing the factories. (C) “Despite” is illogical (Meaning Trap). (D) “Because that” is a structural error (Structural Error).
16 (C)
- Why it is correct (The Key): “The fact that” acts as a solid noun block. We must place “because of” directly in front of “the fact.”
- Error Analysis: (A) “Because” cannot immediately precede “the fact that” (Common Mistake). (B) “Due” is missing “to” (Structural Error). (D) “Since” acts as a conjunction for a clause, similar to “because,” so it cannot precede “the fact” here without breaking the grammar (Distractor).
17 (A)
- Why it is correct (The Key): “The dangerous chemicals that leaked yesterday” is a noun phrase. Even though there is a relative clause (“that leaked yesterday”) attached to it, the entire block functions as a noun. We use “because of.”
- Error Analysis: (B) “Because” needs to directly introduce an independent clause, not a noun phrase (Common Mistake). (C) “Resulting” requires “from” (Structural Error). (D) “Because to” is invalid (Structural Error).
18 (B)
- Why it is correct (The Key): “Massive commercial fishing ships are destroying the sea floor” is a full independent clause. We use “because.”
- Error Analysis: (A) & (D) “Because of” and “Owing to” cannot take a clause (Common Mistake). (C) “Reason why” is structurally incorrect here (Structural Error).
19 (C)
- Why it is correct (The Key): “Humans destroying their primary hunting grounds” is a Noun Phrase + Participle (“destroying”). There is no main conjugated verb (like “are destroying”). Therefore, we must use “because of.”
- Error Analysis: (A) “Because” requires a full clause with a main verb (Common Mistake). (B) “Therefore” indicates a result (Meaning Trap). (D) “Because are” is grammatically broken (Structural Error).
20 (B)
- Why it is correct (The Key): “Extreme human interference in nature” is a formal academic noun phrase summarizing the crisis. We use “because of.”
- Error Analysis: (A) “Because” needs a full clause (Common Mistake). (C) “Although” introduces a contrast, which is illogical (Meaning Trap). (D) “Thanks because” is an invalid combination (Structural Error).
GRAMMAR POINTS TO REMEMBER
- Academic Summarization (Because of + Noun Phrase):
- In academic essays (IELTS, TOEFL, university papers), you frequently need to discuss macro-level phenomena (e.g., climate change, deforestation, habitat loss, global warming). These are Noun Phrases. To connect them as reasons, you must use Because of (or Due to / Owing to).
- Example: Many species are endangered because of climate change.
- BECAUSE + Clause (Subject + Verb):
- Use “because” when you are explaining the mechanics of a problem using a full sentence. It MUST be followed by a Subject and a conjugated Verb.
- Example: Animals are dying because [humans] [are destroying] their habitats.
- The “V-ing / Participle” Trap in Academic Writing:
- Be extremely careful with structures like: “The forest is disappearing ________ companies cutting down trees.”
- Many B1 learners see “cutting” and think it is a verb, so they use Because. However, “cutting” is just a participle describing the “companies”. The entire phrase is technically a Noun Phrase. Therefore, you must use Because of.
- Correct: The forest is disappearing because of companies cutting down trees.