Question

Biologically what is the difference between male and female? Is sex a static state for all organisms give examples for your answer.

Answer 1

Sexual dimorphism: Beginning at the genetic level, we have 23 pairs of chromosomes. 22 pairs are same in both males and females and are called autosomes. The one pair left is called sex chromosome pair. The female has XX chromosomes and males have XY chromosomes. This distinguishes them by later coding for different reproductive organs and secondary sexual characters. Males develop testis as main reproductive organ and produce sperms whereas female develops ovaries which produce eggs.

As they reach puberty, the differences become more prominent due to change in activity of sex-specific hormones. Under the effect of testesterone, male develops body hair, facial hair. The voice deepens due to development of adam's apple. Muscle strength increases and bone structure becomes heavy. Shoulders broaden and height picks up. On the other hand, females under high levels of estrogen start menstruation. They develop breasts and wider lips. These characters help in future child-bearing. At the psycological level too, the differences become more noticeable.

Sex not a static state: Sex may change in some species depending on the external factors like temperature, body attachment, loss of a particular sex from a colony. For example- In a turtle species, temperature higher than 31 degrees changes testis development to ovaries whereas at 26 degrees,it diffrentiates into testis froming male.

In bonellia, an annelid, sex determination depends on contact with surface. If the larva settles on the floor of sea, it develops into a female and if it remains attached to proboscis of adult, it remains a male.