F1 stands for first filial (daughter) generation
<span>F2 stands for second filial (daughter) generation</span>
A punnet square predict the traits of offspring genetic crosses and test crosses.
<u>Explanation:</u>
In pea plants, the traits or characteristics inheritance is been observed and studies by Gregor Mendel. A model was proposed by him, in which the characteristics or traits are specified from genes. Genes can take different alleles or versions. The appearance of an organism can be determined by the dominant alleles. These hides the characteristics of recessive alleles.
The law of segregation is, When gametes are made by an organism the copy of one gene is passed to each gametes. The combinations of allele which is genotype, and the phenotypes which are the characteristics that are observable can be predicted by a Punnett square. This is done by genetic crosses.
In order to predict whether the organism is heterozygous or homozygous can be determined by a test crosses.
Biological systems do not contradict the second law of thermodynamics. Even in this case, entropy is still always increasing. Biological systems can only decrease their own entropy by using copious amounts of energy and by increasing entropy in their surrounding environment. Also, unfavorable anabolism reactions are always paired with more favorable reactions, such as the use of ATP in order to make the overall Gibb's free energy of the reaction negative.
They are used to define periods Geological time.
