NEET · Biology —

Principles of Inheritance and Variation appeared 7 times across 1 year — 7.8% of Biology. This question is from ABO Blood Group Crosses and Probability.

Year 2024 Total
Questions 7 7
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What is the probability of having children with 'O' blood group, where both mother and father are heterozygous for 'A' and 'B' blood group, respectively?

Solution & Explanation

Related Formula
Parent Genotypes: I^A i × I^B i Offspring Genotypes: I^A I^B (AB), I^A i (A), I^B i (B), ii (O)
Core Logic

Mother's genotype (heterozygous A) = I^A i Father's genotype (heterozygous B) = I^B i

Crossing these parents yields four possible genotypes in equal proportions (1 : 1 : 1 : 1):

  • I^A I^B (Blood group AB)
  • I^A i (Blood group A)
  • I^B i (Blood group B)
  • i i (Blood group O)
Step 1: Calculation of Probability
Probability of 'O' blood group (i i) = (1)/(4) = 25%
Pattern Recognition

Sees: "heterozygous A and B parents blood group O probability". Shortcut: Cross I^A i × I^B i gives 1/4 = 25% for each blood group (A, B, AB, O).

Chapter Mix

Class 12 Biology: Principles of Inheritance and Variation

Reference Study Guides

Principles Of Inheritance And Variation

More Principles of Inheritance and Variation Previous-Year Questions — Page 2

Q154 neet_2024_05_may_morning Sex Determination in Grasshopper (XX-XO Type)
In a population of a grasshopper species, the chromosome number of some members is 23 and some other members possess 24 chromosomes. The 23 and 24 chromosome-bearing members in this species are:
  • A. all males
  • B. all females
  • C. females and males, respectively
  • D. males and females, respectively

Solution

Related Formula

Grasshopper Sex Determination (XX-XO): aligned Male &= 22 Autosomes + X = 23 chromosomes (XO) Female &= 22 Autosomes + XX = 24 chromosomes (XX) aligned

Core Logic

In grasshoppers, sex determination is of the XX-XO type. Males have only one X chromosome in addition to autosomes (XO), giving them an odd total chromosome number (23). Females have a pair of X chromosomes (XX), giving them an even total chromosome number (24).

Step 1: Match

23 chromosomes = males; 24 chromosomes = females.

Pattern Recognition

Sees: "grasshopper 23 and 24 chromosomes". Shortcut: XX-XO type arrow XO male has 1 less chromosome (23) than XX female (24).

Chapter Mix

Class 12 Biology: Principles of Inheritance and Variation

Q159 neet_2024_05_may_morning Gametogenesis in Haploid Organisms
In which animal do haploid cells divide mitotically to produce gametes?
  • A. Male honeybees
  • B. Male grasshoppers
  • C. Male earthworms
  • D. Male frogs

Solution

Related Formula

Haplodiploidy in Honeybees: Male (Drone, n = 16) Mitosis Sperm ( n = 16)

Core Logic

Male honeybees (drones) develop parthenogenetically from unfertilised haploid eggs (n = 16). Because their body cells are already haploid, they produce gametes (sperms) via mitosis rather than meiosis.

Step 1: Evaluation of Other Options

Male grasshoppers, earthworms, and frogs are diploid organisms (2n) and produce gametes through meiotic division.

Pattern Recognition

Sees: "haploid cells divide mitotically to produce gametes". Shortcut: Male honeybees (drones).

Chapter Mix

Class 12 Biology: Principles of Inheritance and Variation

More Principles of Inheritance and Variation Questions — neet_2024_05_may_morning

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JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)