Heredity And Evolution Test - 1

Colour blindness usually involves the inability to distinguish between colours. Cone cells, or cones, are one of three types of photoreceptor cells in the retina of mammalian eyes (e.g. the human eye). They are responsible for colour vision.

Colour blindness is a sex linked trait that affects males much more often than females because the genes of this trait are on X chromosome.

Males only have one X chromosome, while females have two X chromosomes, so even one defective gene present on X chromosome will be expressed in males.

In nucleus of each cell, the DNA molecule is packaged into thread like structure called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones, that support its structure.

Recessive trait can be expressed only under homozygous condition whereas dominant trait can be expressed in both heterozygous and homozygous conditions.

Darwin published his theory of evolution with compelling evidence in his 1859 book 'Origin of Species', overcoming scientific rejection of earlier concepts of transmutation of species.

Inheritable traits are the traits that get passed down from generation to the next generation. Seed colour in plants is an example of inherited trait. All others are examples of acquired traits.

The organs which do not perform any function in the organism, but were once functional in the ancestors of that organism are known as vestigial organs. Toe nail is not a vestigial organ. It protects the toes from injury.

Feathers initially served the function of providing insulation in cold weather [as in some dinosaurs (reptiles)]. But with time, these feathers evolved and got adapted to be used for flight (as in birds). This shows that birds are closely related to reptiles (dinosaurs).