Biology 12 Human Health and Disease Chapter 8 – Exercise

Q 1. What are the various health measures which you would suggest to safeguard us against infectious diseases? Ans 1. Preventive measures are precautionary steps taken to check the transmission of infectious diseases. Common preventive measures include education, isolation, vaccination, sanitation, and sterilization. Education: People should be educated about the communicable diseases so that they […]

Biology 11 Biotechnology Principles and Processes Chapter 11 – Exercise

Q 1. Can you list 10 recombinants which are used in medical practice? Find where they are used as therapeutics (use internet). Ans 1. Some of the important recombinant proteins and their therapeutic uses are listed below: Recombinant proteins Therapeutic uses 1.     Insulin 2.     DNase I 3.     Tissue Plasminogen activator (t-PA) 4.     Anti-thrombin III 5.     […]

Biology 12 Biodiversity and Conservation chapter 16 – Exercise

Biology 12 Biodiversity and Conservation chapter 16 – Exercise, Q 1. Name the three components of biodiversity. Ans 1. Three important components of biodiversity are: genetic diversity, species diversity and ecosystem diversity. Q 2. How do ecologists estimate the total numbers of species present in the world? Ans 2. Ecologists make a statistical comparison of […]

NCERT 12 Physics Nuclei Chapter 13 Exercise

Q.1.(a) Two stable isotopes of 3Li6 and 3Li7 have respective abundances of 7.5  and 92.5 . These isotopes have masses 6.01512 u and 7.01600 u respectively. Find the atomic weight of lithium.(b) Boron has two stable isotopes 5B10. Their respective masses are 10.01294 u and 11.00931 u, and the atomic weight of boron is 10.811 […]

Biology 12 Organism and Populations Chapter 13 – Exercise

Biology 12 Organism and Populations Chapter 13 – Exercise, Q 1. How is diapause different from hibernation? Ans 1. Hibernation is the phenomenon commonly depicted by ecothermal (cold-blooded) animals which escape cold by hiding them in shelters such as caves, burrows, cervices, hollow thee trunks, mud etc. revealing minimum physiological activity. This phenomenon is also […]

Biology Molecular Basis of Inheritance Chapter 6 – Exercise

Q.1 Group the following as nitrogenous bases and nucleosides: Adenine, Cytidine, Thymine, Guanosine, Uracil and Cytosine. Ans. Nitrogenous bases: Adenine, Thymine, Uracil, Cytosine Nucleosides: Cytidine, Guanosine Q.2 If a double stranded DNA has 20% of cytosines, calculate the percent of adenine in the DNA. Ans. In a DNA molecule, the number of cytosine molecules is equal to […]

NCERT 12 Chemistry General Principles and Processes Of Isolation of Elements Chapter 6 Exercise 1

Q.6.1. Suggest a condition under which magnesium could reduce alumina. Ans. The two redox reactions are : Q.6.2. Although thermodynamically feasible, in practice, magnesium metal is not used for the reduction of alumina in the metallurgy of aluminium. Why? Ans. Below the temperature (1623 K), corresponding to the point of intersection of Al2 O3 and […]

NCERT 12 Physics Semiconductor Electronics Materials, Devices And Simple Circuits Chapter 14 Exercise

Q.1. In n- type which of the following statement is true: (a) Electrons are majority carriers and trivalent atoms are the dopants (b) Electrons are minority carriers and pentavalent atoms are the dopants (c) Holes are minority carriers and pentavalent atoms are the dopants (d) Holes are majority carries and trivalent atoms are the dopants […]

Biology Reproduction in Organisms Chapter 1 – Exercise

Q-1  Why is reproduction essential for organisms? Ans. Reproduction is essential for organisms because the continuity of the species generation after generation. Q-2 Which is a better mode of reproduction sexual or asexual ? Why ? Ans. Sexual reproduction is a better mode of reproduction because is needs meiosis and fusion of male and female […]

NCERT 12 Physics Atoms Chapter 12 Exercise

Q.1. Choose the current alternative from the clues given at the end of each statement : (a) The size of the atom in Thomson’s model is ……. The atomic size in Rutherford’s modal (much greater than/no different from/much less than) (b) IN the ground state of………., electrons are in stable equilibrium, while in …….. electrons […]

Biology 12 Principles of Inheritance and Variation Chapter 5

Q.1. Mention the advantages of selecting pea plant for experiment by Mendel. Ans. Mendel selected pea plant because of the following special feature : Garden peas were found to differ in certain definite and easily detectable traits. The traits of each kind of pea plant were presented in generation after generation because the plants had […]