COMPETITIVE EXAM MCQs SERIES of LIFE SCIENCES for CSIR-UGC NET/JRF, SLET, GATE, and other entrance tests: DEVELOPMENTAL BIOLOGY – Ageing and Related Molecular Mechanisms.
Syllabus Outline
- Theories of ageing: free radical theory, mitochondrial dysfunction, and DNA damage.
- Longevity regulation.
- Genetic and environmental factors influencing lifespan.
- Model organisms in ageing research and experimental techniques.
This quiz contains 25 concept-based, most frequently asked MCQs on “DEVELOPMENTAL BIOLOGY – Ageing and Related Molecular Mechanisms”. Each question has a single correct/most appropriate answer.
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1. Age-related decline in mitochondrial function is primarily associated with:
A) Decrease ATP production
B) Increased protein folding efficiency
C) Accumulation of mitochondrial DNA mutations
D) Reduced reactive oxygen species
2. What is the primary consequence of progressive telomere shortening in somatic cells?
A) Increased mutation repair
B) Cellular senescence
C) Enhanced protein synthesis
D) Increased mitochondrial activity
3. The “vicious cycle” hypothesis of the mitochondrial free radical theory of ageing has been re-evaluated using polymerase gamma mutator mice. Which observation most strongly challenges the traditional reactive oxygen species-centric view?
A) Mutator mice show a mosaic pattern of respiratory chain deficiency in cardiac tissue.
B) Accelerated accumulation of mitochondrial DNA mutations occurs without a corresponding increase in oxidative damage markers.
C) Overexpression of mitochondrial-targeted catalase does not rescue the premature ageing phenotype.
D) Clonal expansion of pre-existing mitochondrial DNA mutations is faster in metabolically active tissues.
4. A 50-year-old individual has a DNA methylation age of 62 years based on Horvath’s epigenetic clock. What is the correct interpretation?
A) Reduced risk of age-related diseases
B) Age acceleration associated with increased mortality risk
C) Age acceleration associated with decreased mortality risk
D) Early attainment of replicative senescence
5. Why do symptoms of mitochondrial dysfunction often appear suddenly later in life in the context of heteroplasmy?
A) Mutant mDNA is degraded in the cytoplasm before dysfunction appears
B) Mitochondrial fusion prevents early expression of mutations
C) Nuclear genes fully compensate until late life
D) Mutant mDNA must exceed a threshold before dysfunction appears
6. Rapamycin extends lifespan by inhibiting the mechanistic target of rapamycin complex 1. What happens if autophagy-related genes are deleted?
A) Lifespan still increases due to improved DNA repair
B) Mitochondrial biogenesis increases immediately
C) Lifespan increases further via mechanistic target of rapamycin complex 2 activation
D) Lifespan extension is largely abolished
7. When plasma from aged humans is injected into young mice, what is the expected effect?
A) Increased neurogenesis and improved cognition
B) Reduced neural stem cell numbers and impaired cognition
C) Reversal of epigenetic ageing
D) Restoration of antioxidant metabolism
8. The concept of mitohormesis suggests that:
A) Mild mitochondrial stress activates protective pathways that extend lifespan
B) Any mitochondrial stress deactivates protective pathways that extend lifespan
C) High antioxidant intake activates protective pathways that extend lifespan
D) High mitochondrial stress activates protective pathways that extend lifespan
9. Why is Drosophila melanogaster a useful model for studying ageing in the heart and nervous system?
A) High regenerative capacity in adult tissues
B) Absence of sirtuins in the brain
C) Lack of a circulatory system simplifies studies
D) Age-related physiological changes resemble those in humans
10. Which mutation type accumulates most frequently in polymerase gamma mutator mice?
A) Guanine to thymine transversions
B) Transition mutations
C) Large deletions
D) Double-strand breaks
11. Which gene category yielded the most longevity candidates?
A) Flagellar assembly genes
B) Cuticle synthesis genes
C) Protein turnover genes
D) Non-coding RNA genes
12. Which marker is commonly used to identify senescent cells?
A) Alkaline phosphatase
B) β-galactosidase
C) Telomerase reverse transcriptase
D) Green fluorescent protein
13. Which molecules initiate Senescence-Associated Secretory Phenotype (SASP)?
A) Histones
B) Chaperones
C) tRNA synthetases
D) microRNAs
14. Which statement is correct about the Hayflick Limit Across Species?
A) Same division limit in all mammals
B) Longer-lived species have higher division limits
C) Worm cells divide indefinitely
D) Only embryonic cells have limits
15. Senescent cells in adipose tissue secrete Senescence-Associated Secretory Phenotype (SASP) factors that inhibit the differentiation of adipocytes. This effect directly contributes to which age-related metabolic condition?
A) Type 1 Diabetes
B) Insulin Resistance
C) Hyperthyroidism
D) Osteoporosis
16. In selection experiments for longevity in Drosophila, what is the “cost of reproduction” observed in long-lived lines?
A) Long-lived flies have higher fertility in early life but die suddenly after the first week.
B) Long-lived flies selected for late-life fertility often show reduced early-life fecundity.
C) Long-lived flies require 10 times more food than wild-type flies.
D) Long-lived flies are unable to fly due to muscle atrophy.
17. Which amino acids are most strongly linked to the activation of mTORC1, and whose restriction is sufficient to extend lifespan?
A) Methionine and Leucine
B) Glycine and Proline
C) Aspartate and Glutamate
D) Tryptophan and Tyrosine
18. According to the “unified theory of life course” proposed by Horvath and Raj, which two processes are linked to biological ageing?
A) Puberty and Menopause
B) Mitosis and Meiosis
C) Translation and Transcription
D) Development and Maintenance
19. Which statement is true regarding the relationship between the Hayflick limit and organismal lifespan?
A) The Hayflick limit is identical for all mammalian species.
B) Species with longer lifespans have higher Hayflick limits in their fibroblasts.
C) Fibroblasts from C. elegans have an infinite Hayflick limit.
D) The Hayflick limit only applies to embryonic cells, not adult cells.
20. Based on Horvath’s clock research, which of the following is most likely to result in a lower biological age than chronological age?
A) Chronic obesity and high-fat diet.
B) Healthy diet and regular physical exercise.
C) Habitual smoking of more than 20 cigarettes a day.
D) Exposure to high levels of environmental pollutants.
21. Which of the following demonstrates the principle of hormesis?
I – Low doses of radiation increase the lifespan of Drosophila.
II – Mild heat stress-inducing chaperones that protect against later, severe stress.
III – Complete deprivation of food for 30 days leading to death in mice.
IV – Low ROS activates antioxidant response
A) I, II, and IV
B) I and III
C) II and IV
D) I, II, III, and IV
22. Which demonstrates hormesis?
I – Low-dose radiation increases lifespan
II – Mild heat stress induces protection
III – Starvation causes death
IV – Low ROS activates antioxidant response
A) I, II, and IV
B) I and III
C) II and IV
D) I, II, III, and IV
23. Which statements align with the disposable soma and antagonistic pleiotropy theories?
I – Energy is preferentially allocated to germline over somatic maintenance
II – Genes beneficial early in life may be harmful later
III – Ageing is a programmed process for species turnover
IV – Caloric restriction shifts energy toward maintenance and extends lifespan
A) I, II, and IV
B) II and III only
C) I and III only
D) I, II, III, and IV
24. Assertion (A): The biological age of blood, as measured by Horvath’s epigenetic clock, can predict all-cause mortality even after adjusting for chronological age and smoking.
Reason (R): The clock tracks the accumulation of stochastic mutations in the nuclear DNA that occur at a constant rate throughout life.
A) Both (A) and (R) are true, and (R) is the correct explanation of (A).
B) Both (A) and (R) are true, but (R) is not the correct explanation of (A).
C) (A) is true, but (R) is false.
D) (A) is false, but (R) is true.
25. Assertion (A): Somatic cells have a limited number of divisions (Hayflick limit), whereas embryonic stem cells can divide indefinitely.
Reason (R): Telomere shortening acts as a molecular clock, and the lack of telomerase in most somatic cells triggers a p53-mediated DNA damage response.
A) Both A and R are true, and R correctly explains A
B) Both A and R are true, but R does not explain A
C) A is true, but R is false
D) A is false, but R is true
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References
- Michael Barresi and Scott Gilbert (2023). Developmental Biology, Oxford University Press, 13th Edition.
- Lincoln Taiz, Ian Max Møller, Angus Murphy, and Eduardo Zeiger (2022). Plant Physiology and Development, Oxford University Press, 7th Edition.
- Geoffrey Cooper and Kenneth Adams (2022). The Cell: A Molecular Approach, Oxford University Press, 9th Edition.
- Alberts, B., Johnson, A., Lewis, J., Morgan, D., Raff, M., Roberts, K., & Walter, P. (2014). Molecular Biology of the Cell, Garland Science, 4th Edition.
- Robert A Weinberg, Robert A. Weinberg (2006). The Biology of Cancer, Taylor & Francis, 1st Edition.
- Gupta, P.K. (2022). Cell and Molecular Biology, Rastogi Publications, 5th Edition.
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