Q26 of 26 Page 1

Describe the experiment conducted by S.L. Miller and write its contribution towards origin of life on earth.

OR


Write any five salient features of genetic code.


S.L. Miller’s experiment –


• He created electric discharge in a closed flask containing CH4, H2, NH3 and water vapour at .


• The conditions were set similar to those of the primitive atmosphere in the laboratory.


• He observed formation of amino acids while in similar experiments performed by other scientists the presence of complex molecules like- sugar, pigments, nitrogen bases and fats in the flask were also observed.



OR


Salient features of genetic code –


i. The codon is triplet. 61 codons code for amino acids and 3 stop codons do not code for any amino acids, hence they function as stop codons.


ii. One codon codes for only one amino acid, hence, it is unambiguous and specific.


iii. Some amino acids are coded by more than one codon, hence the code is degenerate.


iv. The codon is read in mRNA in a contiguous fashion. There are no punctuations.


v. The code is nearly universal i.e. UUU codes for Phenylalanine from bacteria to humans.


vi. AUG has dual functions. It codes for Methionine (met) and it also acts as initiator codon.


More from this chapter

All 26 →
22

Describe the Secondary/Biological treatment given to the sewage water before it can be released into natural water bodies.

 23

Good air quality is one of the important factors for healthy life for young and old alike. Vehicular pollution is one of the major causes of deterioration of air quality in big cities.

(a) List any two ways in which you can try to bring in awareness amongst the students of your age group to reduce air pollution in your city.


(b) Why is the Government promoting use of CNG/unleaded Petrol as a fuel for public and private cars, and buses etc.? Explain.


 24

(a) Explain with the help of an example each, the following interactions that arise between the organisms living in a particular habitat.

(i) Predation


(ii) Competition


(b) “Evolution of ‘mutualists’ is tightly linked.” Justify with the help of an example.


OR


How does the primary succession occur and progress in a newly created pond? Give one example each of the plants appearing at different stages of succession. What would you call this type of succession?


 25

(a) “The female gametophyte of an angiosperm is a seven celled, eight nuclei containing structure. ” Justify.

(b) Explain double fertilization in angiosperms.


OR


(a) Differentiate between spermatogenesis and oogenesis in humans with respect to:


(i) time of their initiation; (ii) number of gametes produced by each primary spermatocyte or primary oocyte; (iii) size of the gametes produced.


(b) Write the role of F.S.H. and L.H. in regulation of spermatogenesis and oogenesis.