Zoology
The first step in the biosynthesis of polypeptides is catalysed by:
A.
Initiation factors (Ifs)
B.
Aminoacyl tRNA synthetase
C.
Peptidyl transferase
D.
Terminal transferase
Kappa particles are the:
A.
Submicroscopic granules formed by the folding of the naked DNA
B.
Endosymbionts representing the gram negative bacterial species
C.
Viral particles capable of self perpetuation in the host cytoplasm
D.
Protozoans parasites whose multiplication is controlled by the host metabolites
During cell division, mitochondria:
A.
Accumulate near the spindle
B.
Arrange themselves at the equator
C.
Migrate to terminal poles
D.
Disappear
The enzyme aminoacyl synthetase facilitates:
A.
Joining of two neighbouring amino acids on ribosomes
B.
Adoption of amino acid by a t-RNA molecule of its type
C.
Insertion of aminoacyl-tRNA into the ribosomal A-sites
D.
Transfer of aminoacyl-tRNA from the ribosomal A site to P site
The segment of DNA molecule determining the amino acid sequence of a protein is known as:
A.
Operator gene
B.
Regulator gene
C.
Modifier gene
D.
Structural gene
If replication of DNA does not occur in the nucleus, then the nucleus:
A.
Keeps on growing in size
B.
Grows to a certain size and thereafter remains at that size
C.
Does not grow at all
D.
Reduces in size
Colchicine arrests any mitotically dividing cell at metaphase by:
A.
Preventing the polymerisation of tubulin into microtubules of spindle
B.
Preventing the movement of spindle fibres as a result of which chromosomes fail to go to the opposite poles
C.
Destroying the contractile property of the spindle protein which eventually coagulates
D.
Dislodging chromosomes from the fibrous elements of the spindle and consequently the chromosomes remain confined to the equatorial plane
During meiotic cell division, genetic recombination between two homologous chromosomes are facilitated by:
A.
Movement of centromere
B.
Extrusion of polar bodies
C.
Movement of centrioles
D.
Formation of synaptonemal complex
Spermiogenesis is the transformation of:
A.
Spermatogonium into primary spermatocyte
B.
spermatogonium into functional spermatozoa
C.
Primary spermatocytes into secondary spermatocytes
D.
Spermatids into spermatozoa
In Telophase-I of meiosis the endoplasmic reticulum forms the:
A.
Nucleolus
B.
Spindle
C.
Nuclear envelope
D.
Daughter chromosomes
The number of the chiasma, formed during pachytene, depends on:
A.
Number of chromatids
B.
Chromatin material
C.
Size of chromosomes
D.
None of these
The broken chromatid segments are united with the chromatids during pachytene due to the presence of an enzyme:
A.
Endonuclease
B.
Ligase
C.
Polymerase
D.
Ecdyses
Down's syndrome occurs due to:
A.
Sex-chromosomes abnormality
B.
Gene mutation
C.
Autosomal abnormality
D.
Entrochromosomal abnormality
The two daughter-cells formed during mitosis contain:
A.
The same amount of DNA, but a set of chromosomes different from those of the parent cell
B.
The same amount of DNA and the same set of chromosomes as those of the parent cell
C.
Half the amount of DNA and the same set of chromosomes as those of the parent cell
D.
Double the amount of DNA and a set of chromosomes different from those of the parent cell
Which of the following disappears during cell division?
A.
Plasma membrane
B.
Mitochondria
C.
Nuclear membrane
D.
Ribosomes
Terminalization of chiasma takes place at:
A.
Diplotene stage
B.
Diakinesis stage
C.
Pachytene stage
D.
Zygotene stage
In ________ the pairing in homologous chromosomes starts from the end and continues towards their centromeres.
A.
Tandom synapsis
B.
Procentric synapsis
C.
Proterminal synapsis
D.
None of these
The bouquet stage during prophase of meiosis occurs in:
A.
Leptotene
B.
Zygotene
C.
Pachytene
D.
Diplotene
In meiosis the correct sequence of prophase is:
A.
Leptotene => Zygotene => Pachytene => Diplotene => Diakinesis
B.
Leptotene => Pachytene => Zygotene => Diplotene => Diakinesis
C.
Diplotene => Leptotene => Pachytene => Zygotene => Diakinesis
D.
Zygotene => Leptotene => Pachytene => Diakinesis
The amount of DNA becomes double during _______ phase of meiosis.
A.
Prophase - I
B.
Anaphase - I
C.
Telophase - I
D.
Metaphase - I
The point of contact between two chromatids during crossing over is known as:
A.
Desmosome
B.
Synapsis
C.
Chiasma
D.
Terminalization
The number of crossing over depends on the:
A.
Length of chromosomes
B.
Width of chromosomes
C.
Both (a) and (b)
D.
Number of genes
Crossing over occurs in the homologous chromosomes during the:
A.
Bivalent stage
B.
Tetrad stage
C.
Both (a) and (b)
D.
None of these
The enzyme found in chromosome is a:
A.
DNA polymerase
B.
RNA polymerase
C.
DPN - pyrophosphorylase and nucleoside triphosphate
D.
All of these
When both the breaks during inversion, occur on the same side of centromere, it is called _________ inversion.
A.
Paracentric
B.
Pericentric
C.
Both (a) and (b)
D.
None of these