Heredity and Evolution Test - 7

The voyage of the Beagle (1831-1836) was one of the most important scientific expeditions in history. On board was the young naturalist Charles Darwin.

Darwin made an extensive study of the flora and fauna in coastal islands of south America.

Genetic recombination is the production of offspring with combinations of traits that differ from those found in either parent.

Natural selection leads to evolutionary change when individuals with certain characteristics have a greater survival or reproductive rate than other individuals in a population and pass on these inheritable genetic characteristics to their offspring.

Archaeopteryx is an iconic fossil, often thought of as the 'missing-link' between dinosaurs and birds. It was first described in 1861 by the German palaeontologist Hermann von Meyer (1801-1869). Since then Archaeopteryx has been the focus of controversy surrounding the origin of birds and their links with dinosaurs.

An alternative form of a gene is known as an allele. Alleles vary in their sequence which may or may not result in a variant phenotype of a particular trait. Alleles represent variations of a gene that is responsible for a particular trait.

The billions of human beings living today all belong to one species: Homo sapiens. As in all species, there is variation among individual human beings, from size and shape to skin tone and eye color. But we are much more alike than we are different.

Gregor Mendel is called the father of genetics because he was the first person in the world to observe the fact that characteristics were passed on from the parents to the children.

Since roundness and yellow colour are shown by capital letters in the genotype so they are dominant traits. We know that only dominant traits are expressed in F1 generation.

The genotype  is the part (DNA sequence) of the genetic makeup of a cell, and therefore of an organism or individual, which determines a specific characteristic  of that cell/organism/individual.

As during fertilisation, sperm only gives nucleus, but ova gives nucleus as well as cytoplasm. Therefore, the mitochondrial DNA and other cytoplasmic factors are inherited directly from mother. there are some traits which are exclusively linked with Y- chromosome and they are inherited by the male child directly from father.