Cell Cycle and Cell Division NCERT

Consider the given statements:
Statement I: If the initial number of chromosomes in a cell at \(
G_1
\) phase is 2 N and DNA content is 2 C , the number of chromosomes and the content of DNA at the end of the S-phase will be 4 N and 4 C .
Statement II: The cell replicates its DNA and doubles its number of chromosomes during the S-phase of the cell cycle.

Identify the incorrect statement regarding the cell cycle of a typical eukaryotic cell:

\(
\begin{array}{|l|l|l|l|l|l|l|}
\hline
\text{} & \text{A} & \text{B} & \text{C} & \text{D} & \text{E} & \text{F} \\
\hline
\text{1.} & \text{P arm} & \text{Q arm} & \text{Telomere} & \text{Non-sister chromatids} & \text{Centrosome} & \text{Spindle microtubules} \\
\hline
\text{2.} & \text{Q arm} & \text{P} & \text{Secondary constriction} & \text{Sister chromatids} & \text{Kinetochore} & \text{Polar microtubules} \\
\hline
\text{3.} & \text{P arm} & \text{Q arm} & \text{Telomere} & \text{Sister chromatids} & \text{Kinetochore} & \text{Spindle microtubules} \\
\hline
\text{4.} & \text{Q arm} & \text{P arm} & \text{Primary constriction} & \text{Non-sister chromatids} & \text{Centromere} & \text{Spindle microfilaments} \\
\hline
\end{array}
\)

Consider the given two statements:
Statement I: In animals, mitotic cell division is only seen in the diploid somatic cells.
Statement II: Plants can show mitotic divisions in both haploid and diploid cells.

The correct chronology of stages of karyokinesis in mitosis is:

Mitosis is also called ‘equational division’ because:

Consider the given two statements:
I. Morphology of chromosomes is best studied at metaphase
II. At this stage, a chromosome is made up of two sister chromatids, held together at the centromere

At the metaphase plate:

Identify the correct statement amongst the following.

Consider the following two statements:
I. Plant cells undergo cytokinesis in a different manner than the animal cells.
II. Plant cells are enclosed by a relatively inextensible cell wall.

Identify the incorrect statement regarding cytokinesis:

Consider the given two statements:
Statement I: In animal cells, cytokinesis is achieved by the appearance of a furrow in the plasma membrane.
Statement II: During cytokinesis in plant cells, the formation of the new cell wall begins with the formation of a simple precursor called the cell plate that represents the middle lamella between the walls of the two adjacent cells.

The given diagram shows a slide with cells labeled as A , B , C and D at different stages of cell division. Identify the correct match:

\(
\begin{array}{|l|l|l|l|l|}
\hline
\text{} & \text{A} & \text{B} & \text{C} & \text{D} \\
\hline
\text{1.} & \text{Interphase} & \text{Telophase} & \text{Prophase} & \text{Anaphase} \\
\hline
\text{2.} & \text{Interkinesis} & \text{Anaphase} & \text{Prophase} & \text{Metaphase} \\
\hline
\text{3.} & \text{Interkinesis} & \text{Telophase} & \text{Metaphase} & \text{Anaphase} \\
\hline
\text{4.} & \text{Interphase} & \text{Prophase} & \text{Metaphase} & \text{Anaphase} \\
\hline
\end{array}
\)

In meiosis:

\(
\text { Match each item in Column I with one in Column II and select the correct answer from the codes given below: }
\)

\(
\begin{array}{|l|l|l|l|}
\hline
\text{} & \text{Column I} & \text{} & \text{Column II} \\
\hline
\text{A} & \text{Zygotene} & \text{a} & \text{Pairing of homologous chromosomes} \\
\hline
\text{B} & \text{Pachytene} & \text{b} & \text{Appearance of chiasma} \\
\hline
\text{C} & \text{Diplotene} & \text{c} & \text{Terminalization of chiasma} \\
\hline
\text{D} & \text{Diakinesis} & \text{d} & \text{Crossing over} \\
\hline
\end{array}
\)

Codes:

\(
\begin{array}{|c|c|c|c|c|}
\hline & \text { A } & \text { B } & \text { C } & \text { D } \\
\hline 1 . & \text { a } & \text { c } & \text { b } & \text { d } \\
\hline 2 . & \text { a } & \text { d } & \text { b } & \text { c } \\
\hline 3 . & \text { a } & \text { b } & \text { c } & \text { d } \\
\hline 4 . & \text { b } & \text { c } & \text { d } & \text { a } \\
\hline
\end{array}
\)

The cell shown in the given diagram is in which phase? 

The correct chronology of stages of Prophase I is:

Which of the following is not a feature of diakinesis stage of prophase I of meiosis I?

Crossing over or recombination can be defined as:

The beginning of diplotene is recognized by:
I. dissolution of the synaptonemal complex
II. the tendency of recombined homologues of bivalents to separate
III. tetrads becoming clearly visible

Consider the following statements regarding meiosis:
I. At metaphase I, the microtubules from the opposite poles of the spindle attach to the pair of homologous chromosomes.
II. At anaphase I, the homologous chromosomes separate, while sister chromatids remain associated with each other.
Of the two statements:

Match the following with respect to meiosis:0
\(
\begin{array}{|l|l|l|l|}
\hline \text { (a) } & \text { Zygotene } & \text { (i) } & \text { Terminalization } \\
\hline \text { (b) } & \text { Pachytene } & \text { (ii) } & \text { Chiasmata } \\
\hline \text { (c) } & \text { Diplotene } & \text { (iii) } & \text { Crossing over } \\
\hline \text { (d) } & \text { Diakinesis } & \text { (iv) } & \text { Synapsis } \\
\hline
\end{array}
\)
\(
\begin{array}{|l|l|l|l|l|}
\hline & \text { (a) } & \text { (b) } & \text { (c) } & \text { (d) } \\
\hline 1 . & \text { (iv) } & \text { (iii) } & \text { (ii) } & \text { (i) } \\
\hline 2 . & \text { (i) } & \text { (ii) } & \text { (iv) } & \text { (iii) } \\
\hline 3 . & \text { (ii) } & \text { (iv) } & \text { (iii) } & \text { (i) } \\
\hline 4 . & \text { (iii) } & \text { (iv) } & \text { (i) } & \text { (ii) } \\
\hline
\end{array}
\)

Consider the following two statements:
I. The growth of multi-cellular organisms is due to mitosis.
II. Mitosis results in the production of diploid daughter cells with identical genetic complement usually.

Of the two statements:

The cell shown in the given diagram is in which phase:-

Consider the following key events:
I. Chromosomes cluster at opposite spindle poles and their identity is lost as discrete elements.
II. Nucleolus, Golgi complex and ER reform.
The stage of mitosis characterized by these key events is:

During diakinesis of prophase I:
I. Terminalisation of chiasmata takes place.
II. Meiotic spindle is assembled.
III. Nucleolus disappears and the nuclear membrane breaks down.
The correct statements are:

The mechanisms that contribute to the genetic variation arising from sexual reproduction include:
I. Independent assortment of chromosomes
II. Crossing over
III. Random fertilization

Consider the given two statements:
I. The kinetochore is essential for the chromosome segregation that is classically associated with mitosis and meiosis.
II. The kinetochore assembles on the centromere and links the chromosome to microtubule polymers from the mitotic spindle during mitosis and meiosis.

The cell shown in the given diagram is in which phase:-

Organisms prefer sexual mode of reproduction in adverse conditions because:

The most important significance of meiosis is that:

Identify the correct statement regarding meiosis amongst the following:
I. Meiosis involves two sequential cycles of nuclear and cell divisions but only a single cycle of DNA replication.
II. Meiosis II is initiated after the parental chromosomes have replicated to produce identical sister chromatids at the S phase.
III. Meiosis involves pairing of bivalents and recombinations between them.

Cells at the end of prophase of mitosis, when viewed under the microscope, do not show:
I. Golgi complexes
II. Endoplasmic reticulum
III. Nucleolus
IV. Nuclear envelope

How many of the following statements with respect to this phase are not incorrect ?

1. Cell division proper lasts for only about an hour.
2. This Phase represents the phase when the
   actual cell division
3. In this phase Cell remains Metabolically inactive
4. This phase is divided into three further phases
5. This phase is also Known as Resting phase
6. In this phase the time during which the cell is preparing for division
   by undergoing only cell growth  in an orderly manner.

Arrange the following events of meiosis in correct
sequence
(a) Crossing over
(b) Synapsis
(c) Terminalisation of chiasmata
(d) Disappearance of nucleolus

Match the following events that occur in their respective phases of cell cycle and select the correct option

\(
\begin{array}{|l|l|l|l|}
\hline \text { (a) } & \text { G }_1 \text { phase } & \text { (i) } & \begin{array}{l}
\text { Cell grows and organelle } \\
\text { duplication }
\end{array} \\
\hline \text { (b) } & \text { S phase } & \text { (ii) } & \begin{array}{l}
\text { DNA replication and } \\
\text { chromosome duplication }
\end{array} \\
\hline \text { (c) } & \text { G }_2 \text { phase } & \text { (iii) } & \text { Cytoplasmic growth } \\
\hline \text { (d) } & \text { Metaphase } & \text { (iv) } & \text { Alignment of chromosomes } \\
\hline
\end{array}
\)
\(
\begin{array}{|l|l|l|l|l|}
\hline & \text { (a) } & \text { (b) } & \text { (c) } & \text { (d) } \\
\hline 1 . & \text { (ii) } & \text { (iii) } & \text { (iv) } & \text { (i) } \\
\hline 2 . & \text { (iii) } & \text { (iv) } & \text { (i) } & \text { (ii) } \\
\hline 3 . & \text { (iv) } & \text { (i) } & \text { (ii) } & \text { (iii) } \\
\hline 4 . & \text { (i) } & \text { (ii) } & \text { (iii) } & \text { (iv) } \\
\hline
\end{array}
\)

Consider the following events:
I. Centromere split and chromatids separate
II. Chromatids move to opposite poles
The stage of mitosis characterized by these two events is:

In meiosis, DNA replication occurs:

Match the stage of meiotic cell division in column I with corresponding event in Column II and select the correct option from the codes given:

\(
\begin{array}{|l|l|l|l|}
\hline
& \text{COLUMN I} & & \text{COLUMN II} \\
\hline
\text{A} & \text{Metaphase I} & \text{P} & \text{Homologous chromosomes separate, sister chromatids remain associated} \\
\hline
\text{B} & \text{Anaphase I} & \text{Q} & \text{Centromere splits} \\
\hline
\text{C} & \text{Metaphase II} & \text{R} & \text{Bivalents align at the equatorial plate} \\
\hline
\text{D} & \text{Anaphase II} & \text{S} & \text{Microtubules from the opposite poles get attached to kinetochores of sister chromatids} \\
\hline
\end{array}
\)

Codes:

\(
\begin{array}{|l|l|l|l|l|}
\hline & \mathrm{A} & \mathrm{~B} & \mathrm{C} & \mathrm{D} \\
\hline \text { 1. } & \mathrm{P} & \mathrm{R} & \mathrm{~S} & \mathrm{Q} \\
\hline \text { 2. } & \mathrm{P} & \mathrm{R} & \mathrm{Q} & \mathrm{~S} \\
\hline \text { 3. } & \mathrm{R} & \mathrm{P} & \mathrm{Q} & \mathrm{~S} \\
\hline \text { 4. } & \mathrm{R} & \mathrm{P} & \mathrm{~S} & \mathrm{Q} \\
\hline
\end{array}
\)

Read the following statements and identify them as
true (T) or false (F) and accordingly choose the
correct option.
A. The compaction of chromosomal material
continues throughout leptotene
B. Bivalent clearly appear as tetrad in zygotene.
C. Cells are haploid with double DNA content after
meiosis-I as compared to \(
G_2
\)
phase.
D. Daughter cell produced after equational division
differ from one another but identical to the parent
cell
\(
\begin{array}{lllll}
&\text { A } & \text { B } & \text { C } & \text { D } \\
\text { (1) } &\mathrm{T} & \mathrm{~T} & \mathrm{~T} & \mathrm{~T} \\
\text { (2) } &\mathrm{T} & \mathrm{~T} & \mathrm{~F} & \mathrm{~F} \\
\text { (3) } &\mathrm{F} & \mathrm{~F} & \mathrm{~T} & \mathrm{~T} \\
\text { (4) } &\mathrm{T} & \mathrm{~F} & \mathrm{~F} & \mathrm{~F}
\end{array}
\)

If there are \(
30
\) chromosomes in \(
G_1
\)
phase then the
number of chromosomes in prophase-I of meiosis
will be

A diploid organism has \(
24
\) chromosomes in each
cell. If the number of chromosomes at G1
phase is \(
24
\), then what would be the number of chromosomes
just after S phase?

How many homologous pairs of chromosomes will
be found in metaphase I of a diploid cell of an
angiospermic plant having \(
40
\) chromosomes in its
root meristematic cell?

Prophase is marked by