1. Write a note on the effect of protein synthesis on Mutation.
Ans. It is clear from the mechanism of protein synthesis that various genetic information are carried to mRNA through DNA which is in the form of Genetic code. Genetic code is infact the triplet of three nitrogenous bases which determines the sequence of amino acids in Protein. Due to Mutation, there is substitution of another purine or pyrimidine in place of a purine. It results into change in the sequence of Polynucleotide code. Hence, unwanted amino acids due to mutated codon are attaced in the chain. Hence, variation causes in the structure and function of protein.
The effect of mutation on protein-synthesis can be divided into two groups-
I. Effect of Frame-shift mutation-It is due to deletion or insertion of any nitrogenous base of DNA molecule. Gene mutation takes place which results into change in sequence of nitrogenous base. Due to this there will be change in codon of m-RNA, thus it results into complete change in sequence of Amino acid, resulting into change in conformation of protein.
II. Effect of Base shift mutation-In such type of mutation, one nitrogenous base is substituted by nitrogenous base by various factors. It results into change in codon and Amino acid of polypeptide. In Human beings, many diseases like Thalassemia and sickle-cell Anemia take place due to gene mutation.
2. What is Principle of Natural selection? Explain it with reference to moths of England.
Ans.-Natural selection plays a key role in the field of Darwinian Evolution. It is the main guiding force of Evolution. During his voyage on Galpagos island by a Naval ship HMS Beagle, Charles Darwin observed a wide range of variations among organisms but the main focus was on small finchies birds. After returning from voyage, he wrote a book “origin of species” to explain the process of evolution based on the principle of natural selection. The principle of natural selection is based on certain observations.
For example, organisms possess enormous potentiality of reproduction resulting into struggle among them for limited natural resources. Members of a population differ from each other in specialities and most variations are hereditary and well-adapted for new environment. In the long run, thus formation of new species due to numerous variations from their ancestors takes place.
Changing pattern of Moths in England provides a good example of natural selection. Before industrialisation in 1850, white winged moths (= Biston bitularia) were more in number than the dark winged moths (= Biston carbonaria). After industrialisation in 1920, dark moths increase in number to cope with predators and match with blackish depostion of smokes of factories on plants/lichens. In this way, in a mixed population, those adapted well survived more their number increased and so enjoyed their natural selection.
3.Give an account of various stages of origin and evolution whof Man.
Ans. Various stages of origin and evolution of Man are given below-
About 15 million years. ago, primates called Dryopithecus and Ramapithecus were existing. They were hairy and walked like gorillas and chimpanzees. Ramapithecus was more man-like while Dryopithecus was more ape-like.
The million years ago, Australopithecus probably lived in East African grasslands. This creature was called the first human- like being the hominid and was called Homo habilis. The Neanderthal man with a brain size of 1400 c.c. lived in near east and central Asia between 1 lakh to 40000 years ago. They used hides to protect their body and buried their dead. Homo sapiens arose in Africa and moved across continents and developed into distinct areas.
4. Enlist hazardous effect of misuse of Alcohol/Drugs.
Ans. The use of alcohol during adolescence may have long- term effects. The chronic use of drugs and alcohols damages nervous system and liver (Cirrhosis). Excessive doses of drugs may lead to coma and death due to respiratory failure, heart failure or cerebral haemorrhage. A combination of drugs or their intake alongwith alcohol generally results in over dosing and even deaths.
The most common warning signs of drugs and alcohol abuse among youth include drop in academic performance, unexplained absence from school/college, lack of interest in personal hygiene, depression, etc.
5. What do you mean by breeding experiment? How can we develop a disease resistant variety with its help?
Ans.-Breeding experiment is a device to produce by high quality progeny which is disease resistant against many infections. For diseases such as Malaria, Filaria & Dengue which are transmitted through insect vectors, the most important measure is to control or eliminate the vector and their breeding places. This can be achieved by avoiding stagnant water surrounding houses. This can be done by cultivation of insectivorous fishes like Gambusia and Heteropheustis. This can also be done by spraying chemicals like Kerosene oil on stagnant water to kill larva and pupa of Mosquitoes. [2%] –
In modern days there is some advancement to overcome these infections by vaccination & immunisation programmes for the eradication of Polio, diptheria, pneumonia and tetanus like dreadful diseases.
Discoveries of Antibiotics and various other drugs are also helpful in the treatment of various infections.
6. Write an essay on Tissue Culture.
Ans. The technique of tissue culture was first suggested by Haberlandt (1902). The plant tissue culture is the technique of in vitro maintenance and growth of plant cells, tissues and organs on a suitable artificial culture medium under controlled environmental conditions. An excised fragment of tissue or plant part used for raising a culture is called explant. The explant should be pathogen free. It is treated with antimicrobial ☐ chemicals like dilute hypochlorite. Culture medium contains nutrients required for growth and development of explants. The medium has inorganic salts, certain vitamins, 2-4% sucrose, Amino acid glycine, growth regulators with or without the use of
