Tips and Tricks of The Day

Record Limit : 

Ex: A body of mass 5 kg falls from a height of 30 metre. If its all mechanical energy is changed into heat, then heat produced will be:
A) 350 cal                                    
B) 150 cal
C) 60 cal                                       
D) 6 cal
W = JQ 
mgh = J×H
Q = mgh /J = 5×9.8×30 / 4.2 = 350cal
Ex: Thirty percent of the bases in a sample of DNA extracted from eukaryotic cells is adenine. What percentage of cytosine is present in this DNA?
A) 10%                                         
B) 20%
C) 30%                                         
D) 40%
Explanation: If 30 percent of DNA is adenine, then by Chargaff's rule 30 percent will be thymine. The remaining 40 percent of the DNA is cytosine and guanine. Since the ratio of cytosine to guanine must be equal, then each accounts for 20 percent of the bases.
Ex: Symbiotic nitrogen fixation in non-leguminous plant is carried out by:
A) Azotobacter
B) Brodyrhizobiun
C) Clostridium
D) Frankia
Explanation: Frankia is symbiont in root nodules of several nonlegume plants like Casuarina and Alnus (Alder).
Ex: Enzymes which are slightly different in molecular structure but can perform identical activity are called:
A) Isoenzymes
B) Holoenzymes
C) Apoenzymes
D) Coenzymes
Explanation: Isoenzymes : A few enzymes are isomerically equal to others and are only differing in their molecular structure.
Ex: Which one of these carbohydrates is a monosaccharide?
A) Starch                          
B) Glucose
C) Sucrose                        
D) Cellulose
Explanation: Starch-Polysaccharide, Sucrose-disaccharide, and Cellulose-Polysaccharide.
Ex: The plants in which vascular tissues are absent and well developed aerenchyma is present, are
A) Xerophytes
B) Halophytes
C) Hydrophytes
D) Mesophytes
Explanation: Aerenchyma helps in floating of hydrophyte plants.
Ex:  A catalyst is a substance which:
A) Increases the equilibrium concentration of the product
B) Changes the equilibrium constant of the reaction
C) Shortens the time to reach equilibrium
D) Supplies energy to the reaction
Explanation: A catalyst is a substance which alters the rate of reaction and shortens the time to reach equilibrium.
Ex: Sickle cell aneamia is more common in South Africa. This is due to:
A) Change in beta-chain of haemoglobin
B) More population of house flies
C) Change in alpha-chain of haemoglobin
D) Change in gamma-chain of haemoglobin
Explanation: Sickle cell aneamia is caused by a single gene mutation in the sixth place of β−chain of haemoglobin where glutamic acid is replaced by valine.
Ex: What is the value of RQ if 192 gms of O2 is consumed and  264 gms of CO2 is produced:
A) Less than one
B) More than one
C) Zero
D) Unity
R.Q.  = CO2 volume / O2 volume =126/44 / 192/32 = 6/ 6 = 1
Ex: The process in which viruses are involved in sexual reproduction of bacteria is called:
A) Transduction
B) Transcription
C) Transformation
D) Translation
Explanation: In the process of transduction, virus is used as a carrier in the transfer of DNA from one bacterial cell to other.