Home
Class 12
BIOLOGY
Diagrammatic representation of the opera...

Diagrammatic representation of the operation of natural selection two peaks are formed. This condition shows effect of ...... (A) Disruptive (B) Directional (C) Stabilizing (D) Distractive

A

Disruptive

B

Directional

C

Stabilising

D

Distractive

Text Solution

Verified by Experts

The correct Answer is:
A
Promotional Banner

Topper's Solved these Questions

  • BOARD QUESTION PAPER MARCH -2020

    KUMAR PRAKASHAN|Exercise Part-B (Section-A)|10 Videos
  • BOARD QUESTION PAPER MARCH -2020

    KUMAR PRAKASHAN|Exercise Part-B (Section-B)|8 Videos
  • BIOTECHNOLOGY AND ITS APPLICATIONS

    KUMAR PRAKASHAN|Exercise Section - F (Multiple Choice Questions (MCQs ASKED IN COMPETITIVE EXAM))|90 Videos
  • ECOSYSTEM

    KUMAR PRAKASHAN|Exercise SECTION - F (MCQs ASKED IN COMPETTIVE EXAM)|84 Videos

Similar Questions

Explore conceptually related problems

To avoid self-pollination and provide contrivance for cross pollination, the pollen grains of some flowers have no fertilizing effect on the stigma of the same flower but causes death. What is this condition called? (A) Homogamy (B) Dicliny (C) Self sterility (D) dichogamy

Thin films, including soap bubbles and oil slicks, show patterns of alternating dark and bright regions resulting from interference among the reflected light waves. If two waves are in phase their crest and troughs will coincide. The interference will be constructive and the aplitude of the resultant wave will be greater than the amplitude of either constituent wave. if the two waves are out of phase, the crests of one wave will coincide with the troughs of the other wave. The interference will be destructive and the amplitude of the resultant wave will be less than that of either constituent wave. at the interface between two transparent media some light is reflected and some light is refracted. * When incident light, reaches the surface at point a, some of the light is reflected as ray R_(a) and and some is refracted following the path ab to the back of the film. *At point b some of the light is refracted out of the film and part is reflected back refracted out of the fiml as ray R_(c) . R_(a) and R_(c) are parallel. However, R_(c) has travelled the extra distance within the film of abc. if the angle of incidence is small then abc is approximately twice the film's thickness. if R_(a) and R_(c) are in phase they will undergo constructive interference and the region ac will be bright if R_(a) and R_(c) are out of phase, they will undergo destructive interference. * Refraction at an interface never changes the phase of the wave. * For reflection at the interface between two media 1 and 2, if n_(1)ltn_(2) the reflected wave will change phase by pi . if n_(1)gtn_(2) the reflected wave will not undergo a phase change. for reference n_(air)=1.00 * if the waves are in phase after refection at all interfaces, then the effects of path length in the film are Constructive interference occur when (n= refractive index) 2t=mlamda//n" "m=0,1,2,3... .. Destructive interference occurs when 2t=(m+1//2)lamda//n" "m=0,1,2,3... Q. A 600 nm light is perpendicularly incident on a soap film suspended in air. The film is 1.00 mum thick with n=1.35. Which statement most accurately describes the interference of the light reflected by the two surfaces of the film?

Thin films, including soap bubbles and oil slicks, show patterns of alternating dark and bright regions resulting from interference among the reflected light waves. If two waves are in phase their crest and troughs will coincide. The interference will be constructive and the aplitude of the resultant wave will be greater than the amplitude of either constituent wave. if the two waves are out of phase, the crests of one wave will coincide with the troughs of the other wave. The interference will be destructive and the amplitude of the resultant wave will be less than that of either constituent wave. at the interface between two transparent media some light is reflected and some light is refracted. * When incident light, reaches the surface at point a, some of the light is reflected as ray R_(a) and and some is refracted following the path ab to the back of the film. *At point b some of the light is refracted out of the film and part is reflected back refracted out of the fiml as ray R_(c) . R_(a) and R_(c) are parallel. However, R_(c) has travelled the extra distance within the film of abc. if the angle of incidence is small then abc is approximately twice the film's thickness. if R_(a) and R_(c) are in phase they will undergo constructive interference and the region ac will be bright if R_(a) and R_(c) are out of phase, they will undergo destructive interference. * Refraction at an interface never changes the phase of the wave. * For reflection at the interface between two media 1 and 2, if n_(1)ltn_(2) the reflected wave will change phase by pi . if n_(1)gtn_(2) the reflected wave will not undergo a phase change. for reference n_(air)=1.00 * if the waves are in phase after refection at all interfaces, then the effects of path length in the film are Constructive interference occur when (n= refractive index) 2t=mlamda//n" "m=0,1,2,3... .. Destructive interference occurs when 2t=(m+1//2)lamda//n" "m=0,1,2,3... Q. The average human eye sees colors with wavelengths between 430 nm to 680 nm. For what visible wavelength will a 350 nm thick n=1.35 soap film produce maximum destructive interference?

Consider following speed time graphs describing motion of two bodies A and B on straight line paths. Form these graphs which of the following information can certainly be obtained? (A) Distance travelled for the body A (B) Distance travelled for the body B (C) Displacement for the body A (D) Didplacement for the body B

The displacement of the medium in a sound wave is given by the equation y_(1) = A cos(ax + bt) where A , a and b are positive constants. The wave is reflected by an obstacle situated at x = 0 . The intensity of the reflected wave is 0.64 times that of the incident wave. (a) What are the wavelength and frequency of incident wave? (b) Write the equation for the reflected wave. ( c ) In the resultant wave formed after reflection, find the maximum and minimum values of the particle speeds in the medium. (d) Express the resultant wave as a superposition of a standing wave and a travelling wave. What are the positions of the antinodes of the standing wave ? What is the direction of propagation of travelling wave?

Figure shows a metal rod PQ resting on the smooth rails AB and positioned between the poles of a permanent magnet. The rails, the rod, and the magnetic field are in three mutual perpendicular directions. A galvanometer G connects the rails through a switch K. Length of the rod =15 cm, B =0.50 T, resistance of the closed loop containing the rod 9.0 m Omega . Assume the field to be uniform. (a) Suppose K is open and the rod is moved with a speed of 12 "cm s"^(-1) in the direction shown. Give the polarity and magnitude of the induced emf. (b) Is there an excess charge built up at the ends of the rods when K is open ? What if K is closed ? (c) With K open and the rod moving uniformly, there is no net force on the electrons in the rod PQ even though they do experience magnetic force due to the motion of the rod. Explain. (d) What is the retarding force on the rod when K is closed ? How much power is required (by an external agent) to keep the rod moving at the same speed (= 12 cm s^(-1) ) when K is closed ? How much power is required when K is open? (f)How much power is dissipated as heat in the closed circuit ? What is the source of this power ? (g) What is the induced emf in the moving rod if the magnetic field is parallel to the rails instead of being perpendicular ?

A transverse harmonic wave on a string is described by y(x,t) = 3.0 sin (36 t + 0.018x + pi//4) where x and y are in cm and t in s. The positive direction of x is from left to right (a) Is this a travelling wave or a stationary wave? If it is travelling what are the speed and direction of its propagation? (b) What are its amplitude and frequency? (c ) What is the initial phase at the origin ? (d) What is the least distance between two successive crests in the wave?

A disc of radius R is rotating with an angular omega_(0) about a horizontal axis. It is placed on a horizontal table. The coefficient of kinetic friction is mu_(k) . (a) What was the velocity of its centre of mass before being brought in contact with the table? (b) What happens to the linear velocity of a point on its rim when placed in contact with the table? (c) What happens to the linear speed of the centre of mass when disc is placed in contact with the table? (d) Which force is responsible for the effects in (b) and (c )? (e) What condition should be satisfied for rolling to being? (f) Calculate the time taken for the rolling to begin.

Of the following statements , which are true for S_(N)2 reaction. (a) Tertiar alkyl halides reacts faster than secondary. (b) The absolute configuration of product is opposite to that of the reactant when an optically active substrate is used. (c) The used shows first order kinetics. (d) The rate of the reaction depends markedly on the nucleophilicity of the attacking reagent. (e) The mechanism is one step. (f) Carbocations are intermediate. (g) Rate prop [Alkyl][halides] (h) The rate of the reaction depends on the nature of the leaving group.