Practise 42 real Federal Board questions on Genetics from 2023 to 2026. See the answer and explanation as soon as you answer.
Genetics is one of the 15 main chapters in our Federal Board FSC Biology question bank (11th and 12th class), and about 8% of its real questions come from it. Tayyari Karo has 42 real questions on this chapter from 2023 to 2026; 14 are multiple choice and marked instantly, and the rest are short and long questions with a model answer. By difficulty: 37 medium, 4 easy, 1 hard.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
These are real past-paper questions. Think of your answer first, then open the explanation.
Polygenic inheritance results in:
Answer: B. Continuous variation
When multiple genes act additively on one trait (polygenic inheritance), the phenotype shows continuous variation (e.g. height, skin colour) rather than discrete classes.
Range of the data 10, 12, 15, 11, 13, is:
Answer: C. 5
Range = maximum − minimum = 15 − 10 = 5.
Identify the trait which is NOT controlled by polygenes:
Answer: D. Tongue rolling
Tongue rolling is a simple Mendelian (single-gene) trait, whereas height, skin colour and intelligence are polygenic, showing continuous variation.
A couple has a child with cystic fibrosis: An autosomal disorder. If both parents are carrier and do not show symptoms, what is the probability that their next child will have cystic fibrosis?
Answer: A. 25%
Cystic fibrosis is autosomal recessive; two carriers (Aa × Aa) give a 1/4 (25%) chance of an affected (aa) child.
Which of the following will be hemophilic?
Answer: B. X^h Y
Since hemophilia is X-linked recessive, a male with genotype X^h Y is hemizygous for the defective allele and will be hemophilic; X^h X^H is an unaffected carrier female and X^H Y is a normal male.
A heterozygote red eyed female drosophila is mated with white eye male drosophila. What would be the expected %age of red eyed female as a result of cross?
Answer: A. 25%
X^R X^r (red, heterozygous female) × X^r Y (white male) gives offspring in equal 1:1:1:1 proportions: X^R X^r (red female), X^r X^r (white female), X^R Y (red male), X^r Y (white male) — so red-eyed females make up 25% of total offspring.
Explain through a cross that incomplete dominance is a deviation from Mendel's law of segregation.
Mendel's law of segregation predicts that a cross between two heterozygotes (Rr × Rr) should give a 3:1 phenotypic ratio (dominant:recessive) because one allele completely dominates the other. In incomplete dominance, e.g. crossing red-flowered (RR) and white-flowered (rr) four o'clock plants, the F1 heterozygote (Rr) shows an intermediate pink phenotype instead of pure red. …
The full model answer is in the app.
Explain the XX-XY mechanism of sex determination in man. Why males are known to be heterogametic?
In humans, sex is determined by the sex chromosomes: females carry two X chromosomes (XX) and males carry one X and one Y chromosome (XY).
During meiosis, a female (XX) produces eggs that all carry a single X chromosome — she is homogametic (produces only one type of gamete). A male (XY) produces two types of sperm in equal numbers: half carry an X chromosome and half carry a Y chromosome — hence males are heterogametic (produce two different types of gametes with respect to sex chromosomes).
At fertilization, if an X-bearing sperm fertilizes the egg, the zygote is XX and develops as a female; if a Y-bearing sperm fertilizes the egg, the zygote is XY and develops as a male. …
The full model answer is in the app.
| Session | Questions |
|---|---|
| 2026 Annual | 6 |
| 2025 1st Annual | 12 |
| 2025 2nd Annual | 11 |
| 2024 Annual | 8 |
| 2023 Annual | 5 |
42 real Federal Board (FBISE) Biology questions on Genetics from 2023 to 2026, for 11th and 12th class. Each one shows the session it came from.
No. We could not find an official FBISE marking scheme for these papers, so the answers and explanations are written by Tayyari Karo for practice. Check anything important with your teacher or textbook.
You can start free with no signup. A small set of papers per subject is free, and Premium unlocks the full question bank.
