Class 12 Biology Chapter 21 – Genetics MCQs | FBISE | Grade 12 Biology

Class 12 Biology Chapter 21 – Genetics MCQs | FBISE | Grade 12 Biology

Description: Practice 50 exam-oriented MCQs from Class 12 Biology Chapter 21 – Genetics, covering Mendelian inheritance, alleles, genetic crosses, linkage, recombination, sex-linked inheritance, mutations, and genetic variation.

1. Genetics is the study of

A) heredity and variation
B) cell respiration only
C) ecosystems only
D) digestion only
2. The transmission of characteristics from parents to offspring is called

A) variation
B) heredity
C) mutation
D) adaptation
3. The basic unit of heredity is the

A) ribosome
B) chromosome pair
C) gene
D) cell membrane
4. Alternative forms of the same gene are called

A) enzymes
B) codons
C) chromatids
D) alleles
5. An individual with two identical alleles for a gene is

A) homozygous
B) heterozygous
C) hemizygous
D) polyploid
6. An individual with two different alleles for a gene is

A) homozygous
B) heterozygous
C) haploid
D) monoploid
7. The genetic makeup of an organism is its

A) karyotype
B) phenotype
C) genotype
D) ecotype
8. The observable characteristics of an organism are its

A) alleles
B) genotype
C) genome
D) phenotype
9. Gregor Mendel performed his classic inheritance experiments mainly using

A) pea plants
B) fruit flies
C) mice
D) maize
10. Mendel selected pea plants partly because they have

A) only asexual reproduction
B) clear contrasting traits
C) no visible traits
D) no genetic variation
11. A cross involving one pair of contrasting traits is a

A) test cross
B) dihybrid cross
C) monohybrid cross
D) back cross only
12. A cross involving two pairs of contrasting traits is a

A) single-factor cross
B) monohybrid cross
C) reciprocal cross
D) dihybrid cross
13. The principle stating that allele pairs separate during gamete formation is the law of

A) segregation
B) dominance
C) independent assortment
D) linkage
14. The principle stating that different gene pairs can assort independently is the law of

A) segregation
B) independent assortment
C) dominance
D) recombination
15. In a heterozygous individual, the allele expressed in the phenotype under complete dominance is the

A) mutant allele
B) recessive allele
C) dominant allele
D) linked allele
16. A recessive trait is expressed when the genotype is

A) polygenic
B) heterozygous dominant
C) homozygous dominant
D) homozygous recessive
17. The genotype Aa is

A) heterozygous
B) homozygous dominant
C) homozygous recessive
D) haploid
18. The genotype AA is

A) heterozygous
B) homozygous dominant
C) homozygous recessive
D) hemizygous
19. The genotype aa is

A) heterozygous
B) homozygous dominant
C) homozygous recessive
D) polygenic
20. A test cross is usually performed between an individual of unknown genotype and a

A) haploid individual
B) homozygous dominant individual
C) heterozygous individual only
D) homozygous recessive individual
21. The typical phenotypic ratio in an F2 monohybrid cross under complete dominance is

A) 3:1
B) 1:1
C) 9:3:3:1
D) 1:2:1
22. The typical genotypic ratio in an F2 monohybrid cross is

A) 3:1
B) 1:2:1
C) 9:3:3:1
D) 1:1
23. The typical phenotypic ratio in a Mendelian dihybrid F2 cross is

A) 1:2:1
B) 3:1
C) 9:3:3:1
D) 1:1:1:1
24. A cross between an organism and one of its parents is called a

A) reciprocal cross
B) test cross
C) dihybrid cross
D) back cross
25. A cross between two heterozygous individuals Aa × Aa can produce

A) AA, Aa and aa
B) only AA
C) only aa
D) only Aa
26. Incomplete dominance occurs when the heterozygote has

A) the dominant phenotype only
B) an intermediate phenotype
C) the recessive phenotype only
D) no phenotype
27. Codominance occurs when

A) neither allele is expressed
B) one allele completely masks the other
C) both alleles are expressed in the heterozygote
D) only recessive alleles are expressed
28. The ABO blood group system is an example involving

A) polyploidy
B) only complete dominance
C) only incomplete dominance
D) multiple alleles and codominance
29. In the ABO system, the IA and IB alleles are

A) codominant
B) recessive to each other
C) always lethal
D) linked to the Y chromosome
30. The O blood group genotype is

A) IAIA
B) ii
C) IBIB
D) IAIB
31. A trait controlled by many genes is described as

A) haploid
B) monogenic
C) polygenic
D) codominant only
32. Human skin colour is commonly used as an example of

A) cytoplasmic inheritance
B) complete dominance only
C) Y-linked inheritance
D) polygenic inheritance
33. Genes located on the same chromosome are said to be

A) linked
B) independent
C) recessive
D) polygenic
34. Linkage tends to cause genes to

A) assort completely independently
B) be inherited together
C) mutate together
D) become alleles
35. Crossing over can produce

A) new chromosomes without DNA
B) identical clones
C) recombinant chromosomes
D) only parental combinations
36. The frequency of recombination between two linked genes is related to their

A) allele frequency only
B) dominance only
C) protein size
D) distance apart on the chromosome
37. Genes farther apart on the same chromosome generally show

A) higher recombination frequency
B) lower recombination frequency always
C) no crossing over
D) complete linkage
38. Sex-linked genes are located on

A) autosomes only
B) sex chromosomes
C) ribosomes
D) mitochondrial membranes
39. In humans, the X chromosome is generally larger than the

A) mitochondrial chromosome
B) autosome 1
C) Y chromosome
D) chromatid
40. X-linked recessive traits are often more common in males because males

A) have no genes
B) have two X chromosomes
C) lack autosomes
D) have only one X chromosome
41. A male inherits his X chromosome from his

A) mother
B) father
C) both parents equally
D) grandfather only
42. A male inherits his Y chromosome from his

A) mother
B) father
C) both parents equally
D) maternal grandfather only
43. A mutation is a

A) change in diet
B) change in body temperature
C) change in genetic material
D) change in habitat only
44. A mutation involving a single nucleotide pair is commonly called a

A) genomic imprint
B) polyploid mutation
C) chromosome number mutation only
D) point mutation
45. Insertion or deletion of nucleotides can cause a

A) frameshift mutation
B) silent gene only
C) codominant allele
D) test cross
46. A mutation that changes a codon into a stop codon is a

A) missense mutation
B) nonsense mutation
C) silent mutation
D) neutral chromosome
47. A mutation that changes a codon so that a different amino acid is specified is a

A) silent mutation
B) nonsense mutation
C) missense mutation
D) frameshift only
48. A mutation that does not change the amino acid encoded may be

A) frameshift
B) nonsense
C) missense
D) silent
49. Genetic variation in populations can result from mutation, recombination and

A) independent assortment
B) digestion
C) respiration
D) transpiration
50. The study of inheritance patterns helps explain

A) only ecosystem energy flow
B) transmission of traits between generations
C) only cellular respiration
D) only muscle contraction


Class 12 Biology Chapters

Syllabus and SLO Alignment

Syllabus: This chapter covers Mendelian inheritance, alleles, genetic crosses, linkage, recombination, sex-linked inheritance, mutations, and genetic variation as prescribed for FBISE Grade 12 Biology.

SLO Alignment: These MCQs are designed to assess the relevant FBISE Student Learning Outcomes (SLOs) through knowledge, understanding, and application of the concepts covered in this chapter.

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