a/r test 10

in each of the following questions, a statement of assertion is given and a corresponding statement of reason is given just below it. of the statements, mark the correct answer as

a) both A and R are true and R is the correct explanation of A
b) both A and R are true and R is not the correct explanation of A
c) A is true and R is false
d) both A and R are false

zoology: evolution 3
1.
A: there was a sudden increase in population of Biston carbonaria over a pre favoured Biston betularia during industrial revolution in britain
R: it occured due to industrial melanism

2.
A: sickle cell anaemia show stabilizing selection
R: harmful alleles persists in a population and heterozygotes have better survival value

3.
A: the random change in frequency of alleles occurring by chance are called genetic drift
R: tsunami lead to bottleneck effect in mangroves

4.
A: in an experiment, two toad species living in same habitat and physiologically, mechanically and genetically compatible, were found to be reproductively isolated
R: members of first toad species show mating in early part of rainy season and members of second toad species show mating in later part of rainy season

5.
A: gradual speciation occurs in both allopatric and sympatric conditions
R: geography determines speciation in both allopatric and sympatric conditions

botany: cell division

1.
A: RBCs occur in G0 phase
R: erythroblasts produce RBCs

2.
A: the generation time in nerve cells is infinity
R: they always remain in intermitosis

3.
A: heterotypical division occur in meiosis II
R: in meiosis II, separating chromatids are similar

4.
A: when cytokinesis I is absent and both cytokinetic divisions occur after karyokinesis II, it is called simultaneous type cytokinesis
R: it occurs in monocots

5.
A: 100 meiosis are required to produce the pollens to produce 100 fruits on a Cyperus tree
R: 1 meiosis produce 1 pollen in Cyperus

chemistry: atomic structure 2

1.
A: energy and angular momentum are quantized in bohr model of atom
R: bohr model successfully explain Li 2+ line spectrum

2.
A: the splitting of spectral lines in magnetic field is known as zeeman effect
R: bohr model explained it

3.
A: humphrey series lie in far infrared region
R: it is produced when electron in outer shell jumps to 6th shell in hydrogen

4.
A: an orbital cannot have more than two electrons
R: the electrons in the orbital creates opposite magnetic field

5.
A: number of spherical nodes in an orbital is given by n-l-1
R: number of nodes in an orbital is n-1

physics: kinematics 3

1.
A: angular displacement is an axial vector
R: rotational effects are represented by axial vectors

2.
A: an ant moves clockwise on this screen. it's angular momentum is perpendicular to the plane of screen away from you
R: direction of axial vectors is given by right hand screw rule

3.
A: if n vectors of equal magnitude makes angle of equal value with each other, resultant is a null vector
R: a vector with zero magnitude having no specific direction is zero vector

4.
A: if three forces acting at a point are in equilibrium then each force is proportional to sine of the angle between the other two
R: lami's theorem states that:


5.
A: minimum number of equal forces required to make the resultant zero is two
R: minimum number of unequal forces required to make resultant zero is three


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