•  
    +91-22 - 43484479
    +91-22 - 43484480

Toppers' Discussion Forum

All questions answered by Topper experts.
Question By

Wed Apr 23, 2014 3:31 pm  

Ans: Mitosis cannot occur without the replication of DNA in S phase. Two important events take place during S phase: 1. Synthesis or duplication of DNA 2. Duplication of centriole DNA duplication is important as it maintains the chromosome number in the daughter cells. Since mitosis is an equational division, DNA replication is an important step of mitosis. There can be DNA replication without cell division. During cell division, the parent cell gets divided into two daughter cells. If there is repeated replication of DNA without cell division, the DNA so formed will keep accumulating inside the cell. This would increase the volume of the cell nucleus, thereby causing cell expansion. Example: DNA replication without cell division is observed in the salivary glands of Drosophila. The chromosome undergoes repeated DNA duplication resulting in the formation of polytene chromosome.

Wed Apr 23, 2014 3:14 pm  

Ans: No, there is no any colour for electric current.

Wed Apr 23, 2014 11:30 am  

Ans: Hexaploid wheat implies that it has six sets of chromosomes. The somatic cells are hexaploid, with six sets of chromosomes, 2n = 42 while the gametes are haploid , n = 21. Endosperm is triploid (3n) while the egg cell is haploid (n). So, the number of chromosomes in endosperm and egg cell will be 63 (3n=21×3=63) and 21 (n=21) respectively. 

Tue Apr 22, 2014 10:06 pm  

Ans: the

Tue Apr 22, 2014 10:05 pm  

Ans: java.lang.Exception: The input exceeds the limit of 3072 characters of length.

Tue Apr 22, 2014 10:01 pm  

Ans: C o n s i d e r space t h e space f o l l o w i n g space s e t space A equals open curly brackets x : x equals 2 n comma space n element of N comma n less than 6 close curly brackets : F o r space n equals 1 comma 2 comma 3 comma 4 comma 5 comma space w e space h a v e 2 n equals 2 comma 4 comma 6 comma 8 comma 10 T h u s comma space A equals open curly brackets 2 comma 4 comma 6 comma 8 comma 10 close curly brackets N o w space l e t space u s space w r i t e space t h e space s e t space open curly brackets 2 comma 4 comma 8 comma 16 comma 32 close curly brackets space i n space s e t space b u i l d e r space f o r m : L e t space B space b e space t h e space s e t space B equals space open curly brackets 2 comma 4 comma 8 comma 16 comma 32 close curly brackets S i n c e space 2 to the power of 1 equals 2 comma 2 squared equals 4 2 cubed equals 8 2 to the power of 4 equals 16 2 to the power of 5 equals 32 comma w e space c a n space w r i t e comma space t h e space s e t space B space a s comma B equals open curly brackets x : x equals 2 to the power of n comma n element of N comma n less than 6 close curly brackets

Tue Apr 22, 2014 9:17 pm  

Ans: Consider the following table:   java.lang.Exception: The input exceeds the limit of 3072 characters of length. Thus the relation is an equivalence relation if it satisfies the conditions, reflexive, symmetry, and transitive.    

Tue Apr 22, 2014 8:11 pm  

Ans: Let the original length of wire be L, cross sectional area be A Then resistance, Now length of wire L in increased 4 times by pulling i.e L'=4L .It means its cross sectional area will become A/4 i.e A'=A/4 Then new resistance will be

Tue Apr 22, 2014 8:11 pm  

Ans: Let the original length of wire be L, cross sectional area be A Then resistance, Now length of wire L in increased 4 times by pulling i.e L'=4L .It means its cross sectional area will become A/4 i.e A'=A/4 Then new resistance will be

Tue Apr 22, 2014 7:24 pm  

Ans: Embryo sac is a different concept. It is a megaspore of seed bearing plants which contains the fertilised ovum and the other nuclei which give rise to embryo and endosperm. In humans, the process of embryo development is different than in plants. The embryo is surrounded by the extra-embryonic membrane. A yolk sac is present ventral to the embryo. Yolk sac provides the early nourishment to the embryo.

Tue Apr 22, 2014 5:12 pm  

Ans: The ground state electronic configuration of silver is  is [Kr]4d105s1.

Tue Apr 22, 2014 3:14 pm  

Ans: Electric power is the rate at which electrical energy is produced or consumed in an electric circuit.   P = VI = I 2 R = V 2 /R   Hence, power is inversely proportional to the resistance. Therefore, higher is  the power rating smaller is the resistance.   Example:        

Tue Apr 22, 2014 2:11 pm  

Ans: Anisotropic solids have different arrangement of particles in all directions. It is the property of being directionally dependent, as opposed to isotropy. Anisotropic solids are those solids, in which due to different arrangement of particles in different directions, the values of physical properties such as refractive index, conductivity, thermal expansion etc. are different in different directions. It is characteristics of crystalline solids.

Tue Apr 22, 2014 11:12 am  

Ans: Dear Ram Benzoic acid is a weak acid (pKa ~ 4.2) will dissolve in sodium bicarbonate which is  a weak base (pKa ~ 6.4). There is no ppt because the products of an acid/base reaction is an ionic salt.   Regards

Topperlearning Team.

Tue Apr 22, 2014 11:10 am  

Ans: Aqueous KOH results into substitution reaction. Cl 3 C−CH 2 −CH 3 +3KOH(aq)→(OH) 3 C−CH 2 −CH 3 +3KCl It may be noted that more than one OH group cannot be present on the same carbon atom. In such a case, the compound will be extremely unstable and will readily lose a water molecule to form more stable propionic acid. (OH) 3 C−CH 2 −CH 3 ⟶HOOC−CH 2 −CH 3 +H 2 O Thus, propionic acid is the major product along with water molecule. Hence, the corrrect option is propionic acid (option 2).

Tue Apr 22, 2014 11:09 am  

Ans: Aqueous KOH results into substitution reaction. Cl 3 C−CH 2 −CH 3 +3KOH(aq)→(OH) 3 C−CH 2 −CH 3 +3KCl It may be noted that more than one OH group cannot be present on the same carbon atom. In such a case, the compound will be extremely unstable and will readily lose a water molecule to form more stable propionic acid. (OH) 3 C−CH 2 −CH 3 ⟶HOOC−CH 2 −CH 3 +H 2 O Thus, propionic acid is the major product along with water molecule. Thus the major product is propionic acid (option 2)

Tue Apr 22, 2014 11:04 am  

Ans:

Tue Apr 22, 2014 11:01 am  

Ans:

Tue Apr 22, 2014 10:59 am  

Ans:

Tue Apr 22, 2014 10:58 am  

Ans: Answer --Option 1  
Top Contributors this Month
#1
71 Comments 145 Likes
#2
45 Comments 161 Likes
#3
31 Comments 55 Likes
#4
27 Comments 36 Likes

Go Back to the Old Site