UPSC Prelims Practice Questions — Sex systems boost mitochondrial evolution in many kinds of insects
Q1. In many haplodiploid Hymenoptera, the developmental switch that produces a diploid female rather than a haploid male is governed primarily by which of the following?
- A. Heterozygosity at the complementary sex determination (CSD) locus
- B. Presence of a Y chromosome inherited from the father
- C. A ZW sex-chromosome pair in the female
- D. An XO chromosome configuration in the male
Q2. With reference to haplodiploid and diplodiploid sex-determination systems in insects, consider the following statements:
1. In a haplodiploid system males develop from unfertilised eggs and are haploid, whereas in a diplodiploid system both sexes are diploid.
2. Haplodiploidy is also referred to as arrhenotoky.
3. Under haplodiploidy, females develop from unfertilised eggs while males develop from fertilised eggs.
Which of the statements given above is/are correct?
- In a haplodiploid system males develop from unfertilised eggs and are haploid, whereas in a diplodiploid system both sexes are diploid.
- Haplodiploidy is also referred to as arrhenotoky.
- Under haplodiploidy, females develop from unfertilised eggs while males develop from fertilised eggs.
- A. 1 only
- B. 1 and 2 only
- C. 2 and 3 only
- D. 1, 2 and 3
Q3. Consider the following insect groups often cited in discussions of sex-determination systems:
1. Hymenoptera (ants, bees and wasps)
2. Thysanoptera (thrips)
3. Lepidoptera (butterflies and moths)
4. Some mites and whiteflies
Which of the above is/are NOT correctly identified as exhibiting haplodiploidy?
- Hymenoptera (ants, bees and wasps)
- Thysanoptera (thrips)
- Lepidoptera (butterflies and moths)
- Some mites and whiteflies
- A. 1 and 3
- B. 3 only
- C. 2 and 4
- D. 1 and 4
Q4. In the context of insect reproduction, the term 'arrhenotoky' refers to:
- A. The production of haploid males from unfertilised eggs
- B. The production of diploid females from unfertilised eggs
- C. The production of males from fertilised eggs
- D. The production of offspring without the formation of eggs
Q5. The universally adopted marker used to identify animal species through DNA barcoding is a short region of which gene?
- A. Cytochrome c oxidase subunit I (COI)
- B. Cytochrome b (cytb)
- C. 16S ribosomal RNA gene
- D. NADH dehydrogenase subunit 1 (ND1)
Q6. The standard COI 'barcode region' used for animal species identification is approximately how many base pairs long?
- A. 658 base pairs
- B. 158 base pairs
- C. 1,658 base pairs
- D. 16,500 base pairs
Q7. With reference to the 2025 study 'Haplodiploidy accelerates mitogenome evolution in insects', consider the following statements comparing haplodiploid and diplodiploid insect lineages:
1. Haplodiploid lineages showed roughly 1.7 times higher amino-acid substitution rates than diplodiploid taxa.
2. Haplodiploid lineages showed about 3.5 times higher Ka/Ks ratios than diplodiploid taxa.
3. Insertion–deletion mutations (indels) in the COI region were far more common in diplodiploid families than in haplodiploid families.
Which of the statements given above is/are correct?
- Haplodiploid lineages showed roughly 1.7 times higher amino-acid substitution rates than diplodiploid taxa.
- Haplodiploid lineages showed about 3.5 times higher Ka/Ks ratios than diplodiploid taxa.
- Insertion–deletion mutations (indels) in the COI region were far more common in diplodiploid families than in haplodiploid families.
- A. 1 and 2 only
- B. 2 and 3 only
- C. 1 and 3 only
- D. 1, 2 and 3
Q8. In the 2025 study, insect species were approximated by 'BINs'. A Barcode Index Number (BIN) is best described as:
- A. A cluster of similar COI barcode sequences that serves as an operational species proxy
- B. The complete mitochondrial genome sequence of a single species
- C. A unique nuclear-genome accession number assigned to each specimen
- D. A conservation status code assigned by the IUCN Red List
Q9. The global effort to build a reference library of DNA barcodes for species identification and biodiversity monitoring is coordinated primarily by which of the following?
- A. International Barcode of Life (iBOL)
- B. International Union for Conservation of Nature (IUCN)
- C. Convention on International Trade in Endangered Species (CITES)
- D. Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES)
Q10. In DNA-barcoding-based biodiversity surveys, the term 'cryptic species' refers to:
- A. Genetically distinct lineages that are morphologically almost indistinguishable from one another
- B. Visibly distinct species that turn out to be genetically identical
- C. Extinct species known only from fossil evidence
- D. Species that live exclusively underground or in caves
Q11. Consider the following pairings of a sex-determination system with an animal group:
1. XY system — mammals, including humans
2. ZW system — birds, in which females are the heterogametic sex
3. XX-XO system — crickets and grasshoppers
4. Haplodiploidy — a system in which males are diploid and females are haploid
Which of the above is/are correctly identified?
- XY system — mammals, including humans
- ZW system — birds, in which females are the heterogametic sex
- XX-XO system — crickets and grasshoppers
- Haplodiploidy — a system in which males are diploid and females are haploid
- A. 1 and 3 only
- B. 1, 2 and 3 only
- C. 2 and 4 only
- D. 1, 2, 3 and 4
Q12. With reference to global DNA-barcoding infrastructure, consider the following statements:
1. The Centre for Biodiversity Genomics is based at the University of Guelph, Canada.
2. The Barcode of Life Data System (BOLD) is developed and hosted under the International Barcode of Life (iBOL) project.
3. iBOL was first formally proposed as a concept by Paul Hebert in 2013.
Which of the statements given above is/are correct?
- The Centre for Biodiversity Genomics is based at the University of Guelph, Canada.
- The Barcode of Life Data System (BOLD) is developed and hosted under the International Barcode of Life (iBOL) project.
- iBOL was first formally proposed as a concept by Paul Hebert in 2013.
- A. 1 and 2 only
- B. 2 and 3 only
- C. 1 and 3 only
- D. 1, 2 and 3