Multiple Choice QuestionsAssertion : A gamete may carry either of the traits but not both.
Reason : This is Mendel's second law or law of independent assortment.
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
The distance between two genes in a chromosome is measured in cross-over units which represent
ratio of crossing over between them
percentage of crossing over between them
number of crossing over between them
none of these.
Assertion: Persons suffering from haemophilia fail to produce blood clotting factor VIII.
Reason: Prothrombin producing platelets in such persons are found in very low concentration.
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.
XO-chromosomal abnormality in human beings causes
Turner's syndrome
Down's syndrome
Klinefelter's syndrome
None of these
A.
Turner's syndrome
Turner's syndrome is characterised by the monosomy of XO type. It is characterized by a lack of ovaries and menstrual cycle. Affected women are sterile and lack secondary sexual characteristics, although the external genitalia are present. The syndrome is named after the US endocrinologist H. H. Turner (1892- 1970).
Down's syndrome is a congential form of mental retardation due to a chromosome defect in which there are three copies of chromosome no. 21 instead of the usual two (XXX). The affected individual has a short broad face and slanted eyes (as in the Mongolian races), short fingers, and weak muscles. It can be detected before birth by amniocentesis. It is named after the British physician John Down ( 1828- 96).
Klinefelter's syndrome is characterised by trisomy (XXY). These are male individuals, who are phenotypically fairly normal but have a fairly low sperm count and are therefore sterile.
If a homozygous red-flowered plant is crossed with a homozygous white-flowered plant, the offsprings will be
half- white flowered
half- red flowered
all white flowered
all red flowered
Gene which suppresses other gene's activity but does not lie on the same locus is called as
epistatic
supplementary
hypostatic
codominant
Pure line breed refers to
heterozygosity only
heterozygosity and linkage
homozygosity only
homozygosity and self assortment
Assertion : Haemophilia is a recessive sex linked disease.
Reason : Haemophilia occurs due to mutation of a structural gene on chromosome 15.
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
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
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