Latihan TOEFL Reading 17: Epigenetics and Gene Expression

1. What is the passage primarily about?

1. Arguing that genes have no influence on traits
2. Comparing neurons and muscle cells in detail
3. Describing the complete structure of DNA
4. Explaining epigenetics and how it resolves the paradox of cellular differentiation

2. The word 'paradox' in paragraph 1 is closest in meaning to

1. A simple, straightforward fact
2. An apparently contradictory situation
3. A chemical compound
4. A type of laboratory equipment

3. According to paragraph 1, what remains identical across nearly all of an organism's cells?

1. The cell's physical shape
2. The cell's specific function
3. The cell's location in the body
4. The DNA sequence

4. According to paragraph 2, what can methyl group additions to DNA do?

1. Create entirely new genes
2. Have no effect on gene activity
3. Completely delete genetic information
4. Switch genes on or off by altering their accessibility

5. It can be inferred from paragraph 2 that different cell types in the body arise because

1. Cells randomly select their function at birth
2. Different genes become active or silenced depending on the tissue
3. Each cell type has a completely different DNA sequence
4. Only skin cells contain functional DNA

6. Why does the author mention methyl group additions in paragraph 2?

1. To criticize current genetic research methods
2. To give a specific example of how epigenetic modification works mechanically
3. To compare neurons with skin cells directly
4. To argue that DNA sequences frequently change

7. The word 'acquired' in paragraph 3 is closest in meaning to

1. Completely artificial
2. Impossible to measure
3. Obtained through experience or environmental influence
4. Present from birth without any environmental influence

8. According to paragraph 3, what environmental factors can influence epigenetic patterns?

1. Only age
2. No environmental factors influence them
3. Diet, stress, and exposure to toxins
4. Only genetic mutations

9. It can be inferred from paragraph 3 that the nature versus nurture debate

1. Was completely resolved before epigenetics was discovered
2. Has been reopened by findings about environmentally influenced epigenetic inheritance
3. Only applies to physical traits, not behavior
4. Has no connection to epigenetics

10. What is the function of paragraph 3 in relation to paragraph 2?

1. It repeats paragraph 2's content
2. It shifts to a completely unrelated topic
3. It contradicts the mechanism described in paragraph 2
4. It expands the discussion from cellular mechanisms to environmental influence and inheritance

11. The word 'silenced' in paragraph 2 is closest in meaning to

1. Made permanently active
2. Duplicated multiple times
3. Physically removed from the cell
4. Made inactive or turned off

12. According to paragraph 1, what is epigenetics the study of?

1. Heritable changes in gene expression without alterations to the DNA sequence
2. The physical structure of chromosomes only
3. Changes to the DNA sequence itself
4. The history of genetic research

13. According to paragraph 3, may some epigenetic patterns be passed to subsequent generations?

1. Yes, some acquired patterns may be passed on
2. The passage does not address inheritance
3. Only in plants, not animals
4. No, epigenetic patterns can never be inherited

14. It can be inferred that before epigenetics was well understood, cellular differentiation might have seemed to

1. Only occur in single-celled organisms
2. Contradict the idea that all cells share identical DNA
3. Have no relationship to gene expression at all
4. Confirm that different cells have different DNA

15. What is paragraph 2 mainly about?

1. How epigenetic modifications mechanically control gene activity across cell types
2. The discovery of DNA's double helix structure
3. Environmental toxins and their sources
4. The history of epigenetics as a field