Questions in this category will check not only your memory but also your understanding in the topic.
The chance of picking the wrong one is very high. If you pick the right one and you have a solid justification for the selection, then you are right on the track. This right answer will definitely boost your confidence regarding your capability to solve problems in your subject. Let us take questions one by one.
1. Which of the following pair is responsible for site specific recombination?
a) DNA pol III and ligaseb) DNA pol I and ligasec) DNA pol II and ligased) Restriction endonuclease and ligase
First and foremost read and reread the question. Here the keyword in the question is site specific recombination. Take the term into your think tank. Site specific recombination! Recombination exchange of segments . DNA pol in all 3 options. DNA pol is meant for addition of nucleotides in a growing strand and you are close to it. For recombination there should be a nick or cut, Which enzyme can cause cleavage? Once cleaved it should be recombined and joined. Which enzyme is responsible for sealing the nick or single stranded breaks?. I hope you have the answer. And most importantly, the real confidence to work out more. For successful in MCQs, you have to bring that pace and just move on.
2. B-DNA is stabilised by the
a) Hydrogen bondb) Ionic interactionc) Vander wall interactionsd) Covalent linkage
To answer this question we should know the major interaction involved in the formation of B-DNA.
The interaction between nucleotides in a DNA molecule is the phopho diester linkage which is co-valent interaction. The major second interaction is the formation of H-bonds between the nitrogenous bases of two strands making the structure double stranded. Now you have the answer the major interaction involved in the formation of double stranded helical structure is undoubtedly ……..
Type III: descriptive interactive questions with lot of options. These questions are framed on the basis of some basic concepts or processes in biology. These types of questions will check the level of understanding in the matter than memory.
Let us get into the question directly
3. Which among the following will have a higher transpiration rate?
A: plant in still air
B: plant in turbulent air
C: plant in still air but night
a. A>B>Cb. B>C>Ac. B>A>Cd. C>A>B
To answer this question, we should know the basics of transpiration. The question is what are the factors that affects transpiration rate? Specifically how wind influences transpiration rate.
Here we know that transpiration rate is higher in windy condition as transpired vapour on the aerial plant parts are continuously displaced by wind favouring more transpiration. Now we have only two options b. and C. with case B as first. Now we have to pick from option b. and c. At night, transpiration rate is low as stomata is closed at night. Now we have the answer c. B>A>C.
Remember read the case/ situations and options carefully before picking one.
4. Match the following
A. Azolla 1.nostoc
B. Casurina 2. Bradyrhizhibium
C. Guneria 3. Anabena
D. Soyabean 4. Frankia
a) A-3, B-2, C-3, D-1b) A-4, B-3, C-2, D-1c) A-3, B-1, C-4, D-2d) A-1, B-2, C-3, D-4
To answer this type of question, you need to be sure of at least one matching pair. The question is from the topic biologic N2 fixation. Let us take the above example. Here I am damn sure that, Azolla is related to anabena. Anabena is an algae, a N2 fixer that resided in the leaf pockets of Azolla. Set. Check option with this pair A-3.
Two options. Option a) and c). now you have 50:50 chance of picking the right one.
A-3 is set. Now I know Soyabean is alegume and Bradyrhizobium is the species involved in N2 fixation. I think now I have the answer. Option c which is A-3 and D-2.
This is time consuming, but you should try and find an answer.
We will be discussing more and more in the coming posts.
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Your innovative ways to tackle MCQs are always Welcome.