Question

1. Name the following
(a) The shortest stage of mitosis.
(b) The structure which initiates cell division in animal
cell.
(c) The tip of the chromosome which are rounded
and sealed.
(d) The type of chromosome whose centromere is
in the middle.
(e) The stage of mitosis during which nuclear
membrane and nucleolus reappears.
(A membrane that disappears during late
prophase.
(9) A pair of chromosomes carrying dissimilar
alleles for a particular character.
(h) Acts as bearer of heredity units. ICSE 2002]
() Two animals which have nineteen pairs of
ICSE 2004)
) A region of plant body where cell division occurs
ICSE 1995)
chromosomes.
very actively.
(k) Structure that initiates cell division. [ICSE 2007)
() Chromosomes appear thread like. [IcSE 2009
(m) The type of cell division which occurs in the cells
of the reproductive organs. [ICSE 2010]
(n) The exchange of chromatid parts between the
maternal and paternal chromatids of a pair of
homologous chromosomes during meiosis.
ICSE 2016]
(o) The number of chromosomes present in a nerve
cell of a human being. [ICSE 2018]
2. Find the odd one out
()Growth of cell, synthesis of DNA, synapsis and
synthesis of proteins.
(i) Synapsis, crossing over, chiasma formation and
interkinesis.
(in) Aster formation, spindle formation
disappearance of nucleolus and formation of
equatorial plate
(iv) Splitting of centromere, formation of daughter
chromosomes, reappearance of nucleolus.
(v) Phosphate, RNA, Sugar, Nitrogenous base.
[ICSE 2017]
(vi) Centrosome, Cll wall, Cell membrane, Large
vacuoles. ICSE 2018]

Answer 1

• the shortest stage of mitosis is METAPHASE. this is so because in metaphase the duplicated chromosomes lie on the equatorial plane.
• CENTRIOLE is the structure in the animal cell which initiates mitosis.
• CHROMATIDS are the tip of the chromosome
• sister chromatids
• TELOPHASE is the stage when nuclear membrane reappears.
• after crossing over HOMEO LOGOS PAIR OF CHROMOSOMES are seen
• genes .. chromosome
• k) centriole
• chromatin fibres
• meiosis
• crossing over is the exchange of chromatid material
• 23 pairs of chromosome
• synapse
• formation of equatorial plane
• interkinesis
• formation of daughter chromosome
• RNA
• cell wall