$XX$ and $XO$ chromosome.

$XY$ and $XY$ type sex determination seen in many insect and mammals including humans. Males have $X$ and $Y$ chromosome along with autosome and females have pair of ' $X$ ' chromosome along with autosome

Parents Phenotypes Male Female

Genotypes $44 A + XY 44 A + XX$

Gametes $22 A + X 22 A + Y 22 A + A 22 A + X$

$22 A + X 22 A + X$

Children $22 A + X 44 A + XX 44 A + XY$ Female

$22 A + Y 44 A + XY 44 A + XY \text { Male }$

Sex ratio Female : Male = $1: 1$

In plants The flowering plants are mostly bisexual and lack sex chromosomes. The unisexual flowering plants tent to have $XX-XY$ type of sex chromosomal mechanism for sex determination. The female plants are $XX$ and male plants are $XY.$

$XX$ and $XO$ Type of Sex Determination

Found in insect like grasshopper, cockroaches and bugs. Males have only $X$ sex-chromosome and autosomes, female have pair of $X$ chromosome and autosome

Parents Phenotypes Male Female

Genotypes $A A+X O\; A A+X X$

Gametes $A+X, A+O\; A+X, A+Y$

$F_{1}$-generation

$XX-XO$ type of sex determination