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Maternal gametes always contain an X chromosome, so the sex of the animals' offspring depends on whether a sex chromosome is present in the male gamete. Its sperm normally contains either one X chromosome or no sex chromosomes at all. This system determines the sex of offspring among:
Some chromosomal sex determination systems in animals A sex-determination system is a biological system that determines the development of sexual characteristics in an organism . [ 1 ] Most organisms that create their offspring using sexual reproduction have two common sexes, males and females , and in other species, there are hermaphrodites ...
A deeper understanding of developmental biology shows that common morphology is, in fact, the product of shared genetic elements. [5] For example, although camera-like eyes are believed to have evolved independently on many separate occasions, [ 6 ] they share a common set of light-sensing proteins ( opsins ), suggesting a common point of ...
GCSE Bitesize was launched in January 1998, covering seven subjects. For each subject, a one- or two-hour long TV programme would be broadcast overnight in the BBC Learning Zone block, and supporting material was available in books and on the BBC website. At the time, only around 9% of UK households had access to the internet at home.
Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant males and females will sexually reproduce and have offspring together. Domesticated animals are known as ...
Each of these offspring contains numerous genes which have coding for specific tasks and properties. Males and females both contribute equally to the genotypes of their offspring, in which gametes fuse and form. An important aspect of the formation of the parent offspring is the chromosome, which is a structure of DNA which contains many genes. [1]
The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the full set of genes of their single parent and thus the newly created individual is genetically and physically similar to the parent or an exact clone of the parent.
The coefficient of inbreeding (COI) is a number measuring how inbred an individual is. Specifically, it is the probability that two alleles at any locus in an individual are identical by descent from a common ancestor of the two parents.