Why can the wings of a bird and the wings of a bat not considered homologous?

The wings of a bird and bat are not homologous organs but analogous organs. Analogous organs are defined as organs having different evolutionary origins but are evolved to perform the same function. Such organs bring about convergent evolution. For flight, bats use the forelimbs that are modified into wings, and the skin between finger bones is stretched to form a membranous wing, while the wings of the bird are made up of feathers extending all along the arm for flight. This dissimilarity in the structure of their wings shows that the wings of the bird and bat are not inherited from a common ancestor.

How are acquired traits different from inherited traits? (Give any two points.)

The traits acquired are the ones a person develops during his lifetime. Those aren't passed from generation to generation. On the other hand, hereditary characteristics have been present in the individual since birth and are passed on from one generation to the next. Acquired traits do not result in changes in the DNA of the germ cell but somatic cells when genes with inherited traits are found in the germ cell DNA.

Write down the differences between the dominant gene and the recessive gene.

Characteristics Dominant gene Recessive gene Definition The trait which can express its effect over a contrasting trait is called a dominant trait. The trait that cannot express its effect over contrasting traits or gets suppressed by the contrasting trait is called a recessive trait. Expression It is expressed even in the presence of one copy of an allele for a particular character in the gene, i.e., it is expressed in the heterozygous condition. It is expressed only when two copies of an allele for a particular character in the gene are present, i.e., it is expressed in the homozygous condition and the absence of the corresponding dominant trait.

Differentiate between homologous and analogous organs.

Characteristics Homologous organs Analogous organs Definition Homologous organs are referred to as the organs of different animals having similar basic structures and origins. Homologous structures represent divergent evolution. Analogous organs are referred to the organs having different basic structures and origins. Analogous structures represent convergent evolution. Examples Examples of these organs include the arms of humans and the flippers of the whale. Examples of these organs include the wings of birds, bats and insects.

The term heredity refers to the study of the transmission of the genetic material from parents to their offspring and the laws governing such a transmission. This transmission is carried out by chromosomes which pass on the information from one generation to the next.