A dihybrid test cross gives 1000 offspring, of which 160 are recombinant types. What is the distance between the two genes?
Correct answer D. 16 map units
Topic / 48 questions
Inheritance MCQs
Inheritance MCQs are multiple-choice questions on how traits pass from parents to offspring, covering Mendel's laws, monohybrid and dihybrid crosses, linkage, sex-linked inheritance and blood groups. Every question on MCQs360 shows the correct answer instantly, which makes it easy to check genetics calculations step by step.
- Biological Molecules 74
- Coordination and Control 72
- Biology Diagnostic 70
- Cell Structure and Function 67
- Biotechnology 65
- Reproduction 58
- Bioenergetics 55
- Circulation 50
- Inheritance 48
- Digestion 45
- Immunity 45
- Support and Movement 45
- Acellular Life (Viruses) 45
- Homeostasis 45
- Respiration and Gaseous Exchange 45
- Evolution 45
- Enzymes 45
- Cell Cycle 41
- Chromosome and DNA 40
- Biology Introduction 38
- Ecosystem 27
How do codominance and incomplete dominance differ in the heterozygote?
Correct answer B. In codominance both parental traits appear fully; in incomplete dominance an intermediate appears
The ABO blood group system is controlled by ____.
Correct answer C. three alleles of one gene, Iᴬ, Iᴮ and i
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How many genotypes and phenotypes are possible in the ABO blood group system?
Correct answer C. 6 genotypes and 4 phenotypes
A man of genotype Iᴬi marries a woman of genotype Iᴮi. What is the probability that their child has blood group O?
Correct answer A. 1/4
Both parents have blood group O. Which blood group can their children have?
Correct answer D. O only
A child has blood group AB. Which pair of parental blood groups is NOT possible?
Correct answer D. O and AB
Erythroblastosis foetalis is most likely when ____.
Correct answer B. an Rh-negative mother carries an Rh-positive foetus after an earlier Rh-positive pregnancy
Genes that lie close together on the same chromosome and tend to be inherited together are said to be ____.
Correct answer C. linked
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Gene linkage was first worked out in detail by T. H. Morgan using ____.
Correct answer D. Drosophila melanogaster
Crossing over takes place between ____.
Correct answer D. non-sister chromatids of homologous chromosomes in prophase I
The visible points where non-sister chromatids remain joined after crossing over are called ____.
Correct answer C. chiasmata
A person with blood group AB has both A and B antigens on the red cells. This illustrates ____.
Correct answer C. codominance
Genes A and B are linked 12 map units apart. What proportion of gametes from an AB/ab individual will be Ab?
Correct answer C. 6%
If two genes show complete linkage, a test cross of AB/ab × ab/ab gives ____.
Correct answer B. only two parental types in a 1 : 1 ratio
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The maximum recombination frequency observed between two genes is ____.
Correct answer D. 50%
The frequency of crossing over between two linked genes increases with ____.
Correct answer D. the distance between them on the chromosome
Why is a recessive X-linked trait such as colour blindness more common in men than in women?
Correct answer A. Men have only one X chromosome, so a single recessive allele is expressed
Haemophilia A is caused by a recessive X-linked allele that leads to a deficiency of ____.
Correct answer B. clotting factor VIII
A carrier woman (XᴴXʰ) marries a normal man (XᴴY). What proportion of their sons is expected to be haemophilic?
Correct answer D. 1/2
About Inheritance MCQs
The topic starts with Mendel's work on the garden pea and the laws of dominance, segregation and independent assortment. Many questions ask you to work out ratios and probabilities from monohybrid, dihybrid and test crosses, including problems on carriers of recessive conditions and multiple children. Further questions cover gene linkage and how it counters independent assortment, crossing over and recombination frequency, and sex determination. Sex-linked inheritance is tested through haemophilia and red-green colour blindness. The topic also includes the ABO and Rh blood group systems, codominance and multiple alleles, and erythroblastosis foetalis.
Key facts to remember
- A monohybrid cross between two heterozygotes gives a 3:1 phenotypic ratio and a 1:2:1 genotypic ratio.
- A dihybrid cross between two double heterozygotes gives a 9:3:3:1 phenotypic ratio when the genes are unlinked.
- Recombination frequency between two linked genes cannot exceed 50%.
- Haemophilia and red-green colour blindness are X-linked recessive traits.
- The ABO blood group is controlled by three alleles, with the A and B alleles codominant and both dominant over O.
- Erythroblastosis foetalis can occur when an Rh-negative mother carries an Rh-positive foetus.
Exams that include Inheritance MCQs
Pakistan
- MDCAT
- NUMS
- AKU
- FSc boards
India
- NEET
Bangladesh
- HSC
- Medical Admission Test
How to prepare for Inheritance MCQs
- Draw a Punnett square for every cross until you can predict common ratios without one.
- Use the product rule for independent events to solve dihybrid probability questions quickly.
- Always write sex-linked genotypes with the X and Y chromosomes so you do not lose track of carriers.
- Remember that a son receives his X chromosome from his mother, which explains criss-cross inheritance.
Frequently asked questions
Which exams ask Inheritance MCQs?
In Pakistan, Inheritance questions appear in MDCAT, the NUMS and AKU entry tests and FSc board papers. Students in India meet the same content in NEET, and in Bangladesh it is tested in HSC Biology and the Medical Admission Test.
Why is haemophilia more common in males?
The haemophilia gene is recessive and lies on the X chromosome. A male has only one X chromosome, so a single faulty allele causes the disorder. A female needs two faulty alleles to be affected, so most females with one copy are unaffected carriers.
How does linkage affect Mendel's law of independent assortment?
Genes that lie close together on the same chromosome tend to be inherited together, so they do not assort independently. Crossing over during meiosis can separate them, producing recombinant offspring, and the further apart the genes are, the more often this happens.
Last reviewed October 2026