Class 12 Biology - Chapter Evolution NCERT Solutions | Explain antibiotic resistance observed i
Explain antibiotic resistance observed in bacteria in light of Darwinian selection theory.
Darwinian selection theory states that individuals with favourable variations are better adapted than individuals with less favourable variation. It means that nature selects the individuals with useful variation as these individuals are better evolved to survive in the existing environment. An example of such selection is antibiotic resistance in bacteria. When bacterial population was grown on an agar plate containing antibiotic penicillin, the colonies that were sensitive to penicillin died, whereas one or few bacterial colonies that were resistant to penicillin survived. This is because these bacteria had undergone chance mutation, which resulted in the evolution of a gene that made them resistant to penicillin drug. Hence, the resistant bacteria multiplied quickly as compared to non-resistant (sensitive) bacteria, thereby increasing their number. Hence, the advantage of an individual over other helps in the struggle for existence.
More Questions From Class 12 Biology - Chapter Evolution
- Q:- Describe one example of adaptive radiation.
- Q:- Can we call human evolution as adaptive radiation?
- Q:- Try to trace the various components of human evolution (hint: brain size and function, skeletal structure, dietary preference, etc.)
- Q:-
Practise drawing various animals and plants.
- Q:- Using various resources such as your school library or the internet and discussions with your teacher, trace the evolutionary stages of any one animal say horse.
- Q:- Attempt giving a clear definition of the term species
- Q:- List 10 modern-day animals and using the internet resources link it to a corresponding ancient fossil. Name both.
- Q:- Find out from newspapers and popular science articles any new fossil discoveries or controversies about evolution.
- Q:- Find out through internet and popular science articles whether animals other than man have self-consciousness.
Popular Questions of Class 12 Biology
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Fill in the blanks:
(a) Humans reproduce __________. (asexually/sexually)
(b) Humans are__________. (oviparous/viviparous/ovoviviparous)
(c) Fertilization is __________ in humans. (external/internal)
(d) Male and female gametes are __________. (diploid/haploid)
(e) Zygote is __________. (diploid/haploid)
(f) The process of release of the ovum from a mature follicle is called__________.
(g) Ovulation is induced by a hormone called the __________.
(h) The fusion of male and female gametes is called _____________.
(i) Fertilisation takes place in _____________.
(j) Zygote divides to form _____________which is implanted in uterus.
(k) The structure which provides vascular connection between fetus and uterus is called ____________. - Q:- What do you think is the significance of reproductive health in a society?
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Adenine, Cytidine, Thymine, Guanosine, Uracil and Cytosine. - Q:- What are the various public health measures, which you would suggest as safeguard against infectious diseases?
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- Q:- Can you list 10 recombinant proteins which are used in medical practice? Find out where they are used as therapeutics (use the internet).
Recently Viewed Questions of Class 12 Biology
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(a) One organism is benefited.
(b) Both the organisms are benefited.
(c) One organism is benefited, other is not affected.
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- Q:-
Fill in the blanks:
(a) Humans reproduce __________. (asexually/sexually)
(b) Humans are__________. (oviparous/viviparous/ovoviviparous)
(c) Fertilization is __________ in humans. (external/internal)
(d) Male and female gametes are __________. (diploid/haploid)
(e) Zygote is __________. (diploid/haploid)
(f) The process of release of the ovum from a mature follicle is called__________.
(g) Ovulation is induced by a hormone called the __________.
(h) The fusion of male and female gametes is called _____________.
(i) Fertilisation takes place in _____________.
(j) Zygote divides to form _____________which is implanted in uterus.
(k) The structure which provides vascular connection between fetus and uterus is called ____________.
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