Worth-Remembering
40. Assertion (A) : All the various genes of a population make up its
gene pool.
Reason (R) : The Hardy-
Weinberg equilibrium is a cons- tancy of gene pool.
(A) (B) (C) (D) (E)
ANSWERS WITH HINTS
Physics
1. When a silicon semiconductor is doped with a boron atom, it behaves as P-type semiconductor.
—T/F
2. The difference between the length of a certain brass rod and that of a steel rod is claimed to be constant at all temperatures.
—T/F
3. By applying magnetic field γ-rays can be deviated.
—T/F
4. The efficiency of a Carnot engine is given by η =
(
1 – Q2)
Q1 =
(
1 –)
T2 T1—T/F
5. If an ideal gas expands adiabatically, it does positive work and its internal energy decreases.
—T/F
6. The root mean square speeds of the molecules of different ideal gases, maintained at the same temperature are the same.
—T/F
7. Sun radiation is warm because it contains ultraviolet rays.
—T/F
8. Two rods A and B are of equal length. Each rod has its ends at temperature T1 and T2. Then rate of flow of heat through the rods A and B is equal.
—T/F
9. Kinetic energy of photoelectrons emitted from any surface varies linearly with the frequency of the light incident on the surface.
—T/F
10. The focal length of a lens is the same for lights of all colours.
—T/F
11. When electric current flows through a metallic wire, electric charge flows through the wire at a speed of the order of a few millimeters per second.
—T/F
12. A converging lens in one medium can be diverging in another medium.
—T/F
13. Emission of β-particle from a radioactive atom changes its atomic number.
—T/F
14. For a diode the variation of its anode current (Ia) with the anode voltage (Va) at two different cathode
temperatures T1 and T2 is shown in the figure. The temperature T2 is greater than T1.
V T I a a 1 T2 ⎯→ ↑ —T/F
15. Green glass when heated to high temperature emits red light.
—T/F
Chemistry
16. The decreasing order of electron affinity of F, Cl, Br is F > Cl > Br
—T/F
17. Squashes are ‘stored in bottles after adding’ sodium metabisulphite.
—T/F
18. Photobromination of 2-methyl propane gives a mixture of 1-bromo-2-methyl propane and 2-bromo-2- methyl propane in the ratio 9 : 1.
—T/F
19. Ferrous sulphate (FeSO4.7 H2O) is known as blue vitriol or Mohr’s salt.
—T/F
20. The tendency of catenation is much higher in case of carbon than silicon.
—T/F
21. The green colour of chromic hydroxide becomes yellow on reacting with NaOH in presence of H2O2.
—T/F
22. The enol form of CH3COCH2COCH3 is stabilized through intramolecular hydrogen bonding.
—T/F
23. Homologues can never be isomeric.
—T/F
24. The formula of deep red gas formed on warming potassium dichromate with KCl in conc. H2SO4 is H2Cr2O7.HCl.
—T/F
25. Formic acid is weaker acid as compared to acetic acid.
—T/F
26. The major role of fluorspar (CaF2) which is added in small quantities in electrolytic reduction of alumina
dissolved in fused cryolite is to lower the temperature of the melt.
—T/F
27. F—F bond is less stronger than Cl—Cl bond.
—T/F
28. Caesium (Cs) is an important material used in solar cells.
—T/F
29. Carbon atom in – CHO group is sp3 hybridised. —T/F
30. The aqueous solution ferric ion (Fe3+(aq)) is fairly basic because it acts as a source of hydroxide ions (OH–).
—T/F
Zoology
31. The hippocampus of human brain consolidates short- term memories into long-term memories.
—T/F
32. The parathyroid glands release parathyroid hormone which decreases calcium levels in blood.
—T/F
33. Encephalins and endorphins are natural painkillers.
—T/F
34. Genetic drift is random change in the gene pool of small populations resulting from death, migration, or isolation.
—T/F
35. Genes coding for proteins are regulatory genes, and genes controlling regulatory genes are structural genes.
—T/F
36. Individuals affected by Klinefelter's syndrome are males only.
—T/F
37. Polygenic inheritance occurs when several separate genes control a single phenotypic trait.
—T/F
38. Human karyotype can be best prepared at metaphase stage of cell division.
—T/F
39. The phenotype includes traits which can be obser- ved, measured, or analyzed. The genotype includes the genes for the traits of the phenotype.
—T/F
40. Prosmian is a group of primates that includes apes and humans.
—T/F
41. Connective tissues bind organs together, support and insulate the body, and store energy.
—T/F
42. A conserved DNA sequence of 180 base pairs encodes a protein domain in many proteins.
—T/F
43. Tissue membranes include serous (closed cavities), mucous (open passage ways), cutaneous (body sur- face) and synovial (joint cavities) membranes.
—T/F
44. Epitope is an antibody determinant.
—T/F
45. First-degree burns are limited to the epidermis and second-degree burns injure the epidermis, dermis and penetrate to the hypodermis and below.
—T/F
Botany
46. In the year 1928-29 the Dutch plant physiologist Went finally proved the existence of a chemical transmitter.
—T/F
47. ‘Lock and Key’ hypothesis can be misleading when applied to the question of enzymatic catalysis.
—T/F
48. A mycorrhiza is a mutualistic association between green algae and fungi.
—T/F
49. Eolian landforms are topographic features generated by the wind.
—T/F
50. The fruit of cereals is mostly referred to as caryopsis.
—T/F
51. The family of Leguminosae is divided into three sub- families on the basis of calyx and gynoecium arrangements.
—T/F
52. The point of contact where crossing over occurs is called a chiasma.
—T/F
53. Ca and Mg are microelements because they are required only in extreme small quantities by plants.
—T/F
54. A cover providing protection to root cap is called tunica.
—T/F
55. Chemiosmotic theory does not provide the intellectual framework for understanding many biological energy transductions.
—T/F
56. In eukaryotes nucleus stores genetic information.
—T/F
57. Germplasm protection at a very low temperature is known as cryopreservation.
—T/F
58. A normal human karyotype shows 22 pairs of autosomes and one pair of sex chromosomes.
—T/F
59. The plasma membrane is followed by the colloidal fluid of called endoplasm.
—T/F
60. The lytic cycle is not divided into any stages.
Physics
Q. Why does the glow of lamps