PYQ Analysis: What NEET Actually Tests from CB-03
Most Frequently Tested (High Priority):
Topic 1: S Phase — DNA Content vs. Chromosome Number NEET question pattern: "After S phase / at G2, DNA content is 4C. What is the chromosome number?" Correct answer: Still 2n (not 4n) because sister chromatids are joined at the centromere. Trap answer students choose: 4n (confusing DNA content with chromosome number) Frequency: Appears almost every year in some form.
Topic 2: Prophase I Substage — Crossing Over vs. Chiasmata Pattern 1: "Crossing over occurs in which substage?" → Pachytene (NOT Zygotene) Pattern 2: "Chiasmata are visible in which substage?" → Diplotene (NOT Pachytene) Most common student errors: Selecting Zygotene for crossing over, or Pachytene for chiasmata visibility. Frequency: 1 question almost every NEET year.
Topic 3: Anaphase I vs. Anaphase of Mitosis Pattern: "What separates during anaphase I?" → Homologous chromosomes (NOT sister chromatids) Trap: Students answer "sister chromatids" because they generalise from mitosis knowledge. Frequency: High — directly or indirectly tested multiple times.
Medium Priority (Asked Every 2–3 Years):
- Number of cells produced by meiosis → 4 haploid
- Identification of G0 cells → neurons, mature RBCs
- Direction of cytokinesis → centripetal (animal), centrifugal (plant)
- Duration/percentage of interphase vs. M phase
Low Priority (Background Understanding):
- Recombination nodules in pachytene
- Shugoshin protecting centromeric cohesins
- Terminalization of chiasmata in diakinesis
Exam Strategy:
- Always check: "Is the question asking about DNA content (C) or chromosome number (n)?" — they are different
- For prophase I questions: use LZPDD and the rule "Pair in Z, Cross in P, See in D"
- For anaphase questions: "Meiosis I = homologues; everything else = sister chromatids"