Life Science(Biology)

     The permanent alteration in  sequences of nitrogen bases in the DNA by   (i) deletion ,  (ii) insertion ,   (iii) inversion and  (iv) substitution (transition / transversion) is called as mutation .      If a purine of a DNA is substituted by another purine   or a pyrimidine by another pyrimidine , then the phenomenon is then termed as transition .   e.g. AT is replaced by GC and vice versa.     When a purine  of a DNA is substituted by a pyrimidine  and vice versa is called as transversion.     e.g. GC is replaced by CG and vice versa.                                 and             AT  is replaced by TA and vice versa.     Note :  Transitions are more frequent than Transversion . UV as a Physical Mutagen: Though UV is non-ionising , it is a kind of Mutagen.  (1) Thymine dimerisation: .  Fig.1.  Thymine (T) Fig.2 Formation of Thymine dimers due to uv ray absorption . (1)If a T  base absorbs UV-rays then a bond of C=C breaks ; electrons of 4 no and 5 no C

PARAMECIUM Systematic position: Phylum:.          Protozoa Subphylum.    Cilliophora Class.              Ciliata Subclass.        Holotrichia Order.              Hymenostomatida Genus.            Paramecium  Species.          caudatum                          aurelia                           multimicronucleatum                          bursaria                          calkinsi                          woodruffi                          trichium                          polycaryum The first three species belong to aurelia group as these are elongated ,circular in TS and cytoproct is lateral.Remaining species come under bursaria group as these are short ,broad , flat in TS ,posterior end is broad and cytoproct is subterminal. Structure: P.caudatum is described in detail: Size: 170 to 290 microns(0.17 to 0.29mm) Shape: Slipper-like or sole of shoe-like , so known as slipper animalcule. (i) It's slender anteriorly with blunt/round end and pointed / cone-shaped posteriorly

TDP(General)1st Semester Exam.,2015                         Full Marks: 40                         Time :2 hours Candidates are required to give their answers in their own words as far as      practicable 1.(a) (i) Classify cytoskeleton.  (ii) Describe the structure of mitochondria. (iii) What is osteoporosis?          4+5+1=10                            Or (b) (I) What is apoptosis? (ii) Discuss active transport mechanism with example. (iii) Differentiate between smooth muscle and skeletal muscle.                    2+5+3=10 2.(a) (I) What is viscosity? State it's physiological significance. (ii) What is protective colloids? (iii) Explain Henderson-Hasselbalch equation.                                (1+2)+2+5=10                          Or (b) (I)What is pH ? Name two physiological buffers of blood. (ii) Discuss the basic principle of electrophoresis. (iii) What is ultrafiltration? Give an example .                                        2+5+3=10 3.(a) (i) Define thalassaemia. (i