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B1 ILTS – 09

Evolution

Zoology · Class 12 Chapter 7 · error and blank review

Test date 06-09-2026Marks obtained 526NEET 2027 · Gr 12 Live Full Course
1questions in this chapter
1answered wrong
0left blank

Weak areas from this paper

The straight-down option was chosen againrecurring

Q151 — and Chemistry Q84 on the same paper

Both match-the-column questions on this paper were answered A-I, B-II, C-III, D-IV. In both, the middle rows were right and the outer rows were crossed. In Q84 it was A and C; here it is A and D.

Two questions, two subjects, the same tidy sequential option. That is a procedure fault, not a content gap: the matching is being abandoned partway and the neatest-looking option taken. Setters include that option precisely because it attracts an unfinished answer.

Fix to drill. Cover List-II with your hand. Write all four of your own answers in the margin. Only then uncover and match. If the option you arrive at is A-I, B-II, C-III, D-IV, treat that as a warning and re-derive two rows before you commit.

Definitions in population geneticswatch

Q151

The two terms that got crossed — gene pool and gene frequency — are the two that sound most alike and mean the most different things. One is a total; the other is a proportion.

Only one Evolution question appeared on this paper, so there is no wider pattern to read from. It is worth a short revision pass rather than a full chapter re-study.

Fix to drill. Write the five Hardy–Weinberg disturbing factors and the four terms from this question on a single card, each with a five-word definition. Recite it before Evolution practice sets.
Question by question
Q151Marked wrongMatch the column · population genetics terms

Match List-I with List-II. A. Gene pool   B. Genetic drift   C. Gene flow   D. Gene frequency   |   I. Stable within a generation   II. Change in gene frequency by chance   III. Transfer of genes into or out of population   IV. Total number of genes and their alleles

  • A-III, B-II, C-I, D-IV
  • A-IV, B-II, C-III, D-I
  • A-I, B-II, C-III, D-IV
  • A-II, B-III, C-IV, D-I
Given
Four population-genetics terms and four descriptions.
Asked
The correct pairing.
Concepts

Define each term in your own words before reading List-II. Four definitions, four one-line answers:

Gene pool — every allele of every gene present in the whole population. It is a total, an inventory. That maps to IV, “total number of genes and their alleles”.

Genetic drift — allele frequencies shifting by pure chance, with no selective advantage involved, most visible in small populations. That is II.

Gene flow — alleles moving between populations by migration and interbreeding. “Transfer of genes into or out of population” is III, almost word for word.

Gene frequency — how common one allele is at a given moment. Under Hardy–Weinberg equilibrium it does not change from one generation to the next, so it is “stable within a generation”, which is I.

Formula
Hardy–Weinberg: p + q = 1
  p² + 2pq + q² = 1

factors that disturb equilibrium:
  gene flow, genetic drift, mutation,
  genetic recombination, natural selection
Baby steps
  1. Cover List-II. Write your own definition of each of A, B, C and D in the margin.
  2. Now uncover List-II and find the description that matches each definition you wrote — not the other way round.
  3. A is an inventory of alleles → IV. B is chance → II. C is movement between populations → III. D is a value that holds steady → I.
  4. A-IV, B-II, C-III, D-I. Notice that the wrong answer chosen was the sequential A-I, B-II, C-III, D-IV option — the same option that was wrongly chosen in Chemistry Q84 on this paper.
Answer — A-IV, B-II, C-III, D-I
You marked: A-I, B-II, C-III, D-IV — B and C were correct, and A and D were swapped. Gene pool is the total collection of alleles (IV); gene frequency is what stays stable within a generation (I).
define each term first, then look for its definitionAgene poolevery allele in the whole populationIVtotal number of genes and their allelesBgenetic driftrandom change, no selection involvedIIchange in gene frequency by chanceCgene flowalleles crossing a population boundaryIIItransfer of genes into or out of populationDgene frequencyhow common one allele is right nowIstable within a generationA–IV, B–II, C–III, D–Irows A and D were swapped — B and C were already right

Each term defined independently, then matched.

Shortcut
“Pool” means a total, and “frequency” means a proportion. Those two English words alone separate A from D without any biology — and A and D are exactly the pair that got crossed.