Q154 (2024)
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:
- all males
- all females
- females and males, respectively
- males and females, respectively
### Related Formula
$\text{Grasshopper Sex Determination (XX-XO):}
\begin{aligned}
\text{Male} &= 22 \text{ Autosomes} + \text{X} = 23 \text{ chromosomes (XO)}\\
\text{Female} &= 22 \text{ Autosomes} + \text{XX} = 24 \text{ chromosomes (XX)}
\end{aligned}$
### 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 $\rightarrow$ XO male has 1 less chromosome (23) than XX female (24).
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 12 Biology: Principles of Inheritance and Variation
