State two contrasting features each of sex determination, in humans, birds and honey bees.
Answers
Answer:
in humans- males_XY
females- XX
in birds-The female is homogametic (XX) and male is heterogametic (XY). The sex of the offspring is determined by the male gamete. Birds: ... - The female is heterogamous and the male is haploid, homogamous.
in honey bees- In honeybees, the drones (males) are entirely derived from the queen, their mother. The diploid queen has 32 chromosomes and the haploid drones have 16 chromosomes. ... Sex determination in honey bees is initially due to a single locus, called the complementary sex determiner (csd) gene.
Birds
Birds show the ZZ-ZW system of sex determination. In this system, the female is heterogametic (ZW), and the male is homogametic (ZZ). During gametogenesis, half of the eggs have a Z chromosome and the other half will have a W chromosome. For males, all sperm contains a single Z chromosome. On fertilization of Z egg with Z sperm, a male with ZZ genotype is produced. When W egg fertilizes with Z sperm, a female with ZW genotype is produced. Snakes, butterflies, some amphibians, and some fishes also exhibit this type of sex Determination
Humans
In human beings, the cells of males and females have the same number of chromosomes. In this type of sex-determination system, the male is the heterogametic sex (XY) and the female is homogametic (XX). During gametogenesis, half of the sperms have an X chromosome and the other half will have a Y chromosome. For females, all eggs contain a single X chromosome.
Bees
Sex determination in bees is dependent on the number of chromosomes they receive. A male bee is called a drone which has a haploid set of chromosomes (16) and the mother bee is called a queen bee which has a diploid set of chromosomes (32).
When sperm from a male and egg from a female fuse together, they form a female diploid offspring. However, when an unfertilised female egg undergoes parthenocarpy, it produces a haploid male bee or drones.