161.

Which one of the following pairs of features is a good example of polygenic inheritance

• Human height and skin colour

• ABO blood group in humans and flower colour of Mirabilis jalapa

• Hair pigment of mouse and tongue rolling in humans

• Human eye colour and sickle cell anaemia

Mating of an organism to a double recessive in order to determine whether it is homozygous or heterozygous for a character under consideration is called

• reciprocal cross

• dihybrid crossn

• test cross

• back cross

In which one of the following sets of three items each belong to the category mentioned against them

• Lysine, glycine, thiamine - amino acids

• Myosin, oxytocin and gastrin - hormones

• Rennin, helicase and hyaluronidase - enzymes

• Optic nerve, oculomotor, vagus - sensory nerves

Given below is a highly simplified representation of the human sex chromosomes from a karyotype

• The gene a and b could be of

  colour blindness and body height

• attached ear lobe and Rhesus blood group

• haemophilia and red-green colour blindness

• phenylketonuria and haemophilia

Genes present in the cytoplasm of eukaryotic cells are found in

• mitochondria and inherited via egg cytoplasm

• lysosomes and peroxisomes

• Golgi bodies and smooth endoplasmic reticulum

• plastids and inherited via male gamete

Given below is a pedigree chart showing the inheritance ofa certain sex-linked trait in humans

The trait traced in the above pedigree chart is

• dominant X- linked

• recessive X- linked

• dominant Y- linked

• recessive Y- linked

The "cri-du-chat" syndrome is caused by change in chromosome structure involving

• deletion

• duplication

• inversion

• translocation

Grain colour in wheat is determined by three pairs of polygenes. Following the cross AABBCC (dark colour) x aabbcc (light colour), in F₂ generation what proportion of the progeny is likely to resemble either parent?

• None

• Less than 5 percent

• One third

• Half

Primary source of allelic variation is

• independent assortment

• recombination

• mutation

• polyploidy

Assertion: Polytene chromosomes have a high amount of DNA.

Reason: Polytene chromosomes are formed by repeated replication of chromosomal DNA without separation of chromatids.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.