Chapter 10: Cell Cycle and Cell Division

Question 1

the sequence of events by which a cell duplicates its genome, synthesises the other constituents of the cell and eventulally divides ito two daughter cells is termed ______________

Answer 1

Cell Cycle

Question 2

A typical Eukaryotic cell cycle illustrated by human cells in culture, These cells divide one in approximately every ________ hours

Answer 2

24

Question 3

Yeast can progress through the cell cycle in only about _______ minutes.

Answer 3

90 minutes

Question 4

The cell cycle is divided into two basic phases named as

Answer 4

Interphase
M Phase (mitosis phase)

Question 5

The M Phase represents the phase when the actual cell division or **Mitosis occurs and the ____________ represents the phase between two successive M Phase

Answer 5

Interphase

Question 6

The interphase lasts more than ______% of the duration of Cell Cycle

Answer 6

95 %

Question 7

The M phase starts with the Nuclear Division, corresponding to the separation of daughter chromosome _______________

Answer 7

Karyokinesis

Question 8

The M phase usually ends with division of cytoplasm called _______

Answer 8

Cytokinesis

Question 9

The Interphase also called ____________

Answer 9

Resting Phase
The time during which the cell is preparing for division by undergoing both cell growth and DNA replication

Question 10

The interphase is divided into three further phases

Answer 10

G₁ phase (Gap 1)
S phase (Synthesis)
G₂ phase (Gap 2)

Question 11

___________ phase the cell is metabolically active and continuously grows but does not replicate its DNA

Answer 11

G₁ phase

Question 12

___________________ phase marks the period during which DNA synthesis or replication takes place.

Answer 12

S or Synthesis phase

During this time the amount of DNA per cell doubles,
if the initial amount of DNA is denoted as 2C then it increases to 4C

There is no increase in the Chromosome number

Question 13

During the G₂ phase ,____________ are synthesised in preparation for mitosis while cell growth continues

Answer 13

Proteins

Question 14

Some cells in the adult animals do no appear to exhibit division eg-___________

Answer 14

Heart Cells

Question 15

The cells that do not divide further exit G₁ phase to enter an inactive stage called __________________

Answer 15

Quiescent stage (G₀)

Question 16

In animal, mitotic cell division is only seen in the diploid somatic cell, there are few exceptions to this where haploid cells divide by mitosis example-

Answer 16

male honey bees

Question 17

The __________ can show mitotic division in both haploid and diploid cells

Answer 17

Plants

Question 18

In Mitosis the number of chromosomes in the parent and progeny cells is the same, it is also called as ________________

Answer 18

Equational division

Answer 19

4 (Four)

Prophase
Metaphase
Anaphase
Telophase

Question 20

How many chromosomes in onion root tip cells

Answer 20

16

Question 21

Prophase is marked by the Initiation of _______________ of chromosomal material.

Answer 21

condensation

Question 22

The Centrosome, which had undergone duplication during ________ phase of Interphase, begins to move towards opposite poles of the in in Prophase

Answer 22

S

Question 23

The completion of prophase can thus be marked as chromosomal material condenses to for compact mitotic chromosomes, which are composed of ________ attached together at the ___________

Answer 23

chromatids

Centromere

Question 23

Cells at the end of Prophase , when viewed under the microscope , do not show ____________, _______________ ,___________ and _____________

Answer 23

Golgi complex
endoplasmic reticulum
nucleolus
nuclear envelop

Question 24

Condensation of chromosomes is completed and they can be observed clearly under the microscope in _________________, in this stage at which morphology of chromosomes is most easily studied.

Answer 24

**Metaphase**

Question 24

In metaphase chromosome is made up of ________ chromatids.

Answer 24

**Two sister**

Question 25

The metaphase is charaterised by all the chromosomes coming to lie at the **Equator** , The plane of alignment of the chromosomes is referred as _______________________

Answer 25

**Metaphase Plate**

Question 26

Spindle fibers attached to **Kinetochores** of chromosomes are key feature of ____________ phase

Answer 26

**Metaphase**

Question 27

Centromere Split and chromatids separate , and movement of chromatids to opposite poles is happen in ______________ phase of mitosis

Answer 27

**Anaphase**

Question 28

Chromosomes cluster at opposite spindle poles and their identity is lost as discrete elements Nuclear envelop develops around the chromosome clusters at each pole forming two daughter nuclei nucleolus, golgi complex and ER reforms all these key events are happen in _____________ phase of mitosis

Answer 28

**Telophase**

Question 29

**Mitosis** accomplished by **segregation of duplicated chromosomes into daughter nuclei** called _______________ , and the cell itself is divided into two daughter cells by the **separation of cytoplasm** called __________________

Answer 29

**Karyokinesis** **Cytokinesis**

Question 30

In **plant Cells**, wall formation starts in the Centre of the cells and grows outward , the formation of **new cell wall** begins with the formation of a simple Precursor , called the _____________

Answer 30

**Cell Plate**

Question 31

In some Organisms **Karyokinesis** is **not** followed by **Cytokinesis** as a result of which **Multinucleate** condition arises leading to the formation of _______________

Answer 31

**Syncytium** eg:- Liquid endosperm of **Coconut**

Question 32

Mitosis or the equational division is usually restricted to the __________ cells only

Answer 32

**Deploid**

Question 33

__________ usually results in the production of diploid daughter cells with identical genetic complement

Answer 33

**Mitosis**

Question 34

**Epidermis**, cells of the **lining of the gut**, and **blood cells** are being constantly replaced as cell repair by ____________ division. **growth** of multicellular organisms is also due to this division

Answer 34

**Mitotic** The **Apical** and the **Lateral Cambium** result in a continuous growth of plants throughout their life

Question 35

The specialised kind of cell division that reduces the chromosome number by half results in the production of **Haploid** daughter cells, this kind of division in called _____________

Answer 35

**Meiosis**

Question 36

Meiosis ensures the production of haploid phase in the life cycle of **Sexually reproducing organisms** whereas ________________ restores the **diploid** phase.

Answer 36

**Fertilisation**

Question 37

**Meiosis** happens during ____________________ in **Plants** and **animals**, this leads to formation of **Haploid** Gametes

Answer 37

**Gametogenesis**

Question 38

Meiosis involves two sequential cycles of nuclear and cell division called ___________ and ____________ but only a **single** cycle of **DNA replication**

Answer 38

**Meiosis I** **Meiosis II**

Question 39

_________ haploid cells are formed at the end of **meiosis II**

Answer 39

**4 (four)**

Question 40

**Meiotic** events can be grouped in **Meiosis I** and **Meiosis II** , phases are :-

Answer 40

**Meiosis I** Prophase I Metaphase I Anaphase I Telophase I **Meiosis II** Prophase II Metaphase II Anaphase II Telophase II

Question 41

Prophase I is subdivided into the ________ phases based on **Chromosomal Behaviour**

Answer 41

**L**eptotene **Z**ygotene **P**achytene **D**iplotene **D**iakineses

Question 42

During _____ stage chromosomes become gradually visible , The **compaction** of chromosomes continues throughout this phase

Answer 42

**Leptotene**

Question 43

During ___________ stage the chromosomes start pairing together and this process of association is called **Synapsis**

Answer 43

**Zygotene**

Question 44

Such paired chromosomes in **Zygotene** phase are called __________

Answer 44

**Homologous Chromosomes**

Question 45

Zygotene stage indicate that **chromosome synapsis** is accompanied by the formation of **Complex structure** called _____________

Answer 45

**Synaptonemal complex**

Question 46

The complex formed in **Zygotene phase** by a pair of synapsed **homologous** chromosome is called a __________ or __________

Answer 46

**Bivalent** **Tetrad** (these are more clearly visible at the next stage- **Pachytene**)

Question 47

During ________ stage, the **four** chromatids of each **Bivalent Chromosomes** becomes distinct and clearly appears as **Tetrad**

Answer 47

**Pachytene**

Question 48

_____________ stage is characterised by the appearance of **Recombination nodules**, the sites at which **Crossing over** occurs between **non-sister** chromatids of the homologous chromosomes

Answer 48

**Pachytene**

Question 49

**Crossing Over** is also an enzyme- mediated process and the enzyme involved is called____________

Answer 49

**Recombinase** crossing over leads to **recombination** of genetic material on the two chromosomes.

Question 50

____________ stage is recognised by the dissolution of the **Synaptonemal complex** and the tendency of the recombined homologous chromosomes of the bivalents to separate from each other **except** at the sites of crossovers. These **X-Shaped** structures are called ___________

Answer 50

**Diplotene** **Chiasmata** In **oocytes of some vertebrates**, diplotene can lasts for months or years

Question 51

The final stage of meiotic **prophase I** is ________________, This is marked by terminalisation of Chiasmata.

Answer 51

**Diakinesis**

Question 52

The bivalent chromosomes align on the **equatorial plate** and microtubules from the opposite poles of the spindle attach to the **kinetochore** of homologous chromosomes in _______________ stage of meiosis -I

Answer 52

**Metaphase I**

Question 53

The homologous chromosomes separate , while **Sister Chromatids** remain associated at their centromeres in ___________ phase

Answer 53

**Anaphase I**

Question 54

In _____________ The nuclear membrane and nucleolus reappear, **cytokinesis** follows ant this is called as **Dyad of cells**

Answer 54

**Telophase I**

Question 55

The stage between two meiotic division is called ___________________ and is generally short

Answer 55

**Interkinesis**

Question 56

Meiosis II resembles a normal ____________

Answer 56

**Mitosis**

Question 57

_____________ increases the genetic variability in the population of organisms from one generation to the next.

Answer 57

**Meiosis**

Question 58

Any sexually reproducing organism starts its life cycle from a single-celled______________

Answer 58

**Zygote**

Question 59

____________ is **Equational division** in which the chromosome number of the parent is conserved in the daughter cell, and ______________ is called the **Reduction division** since it reduces the chromosome number by half while making the **Gamete**

Answer 59

**Mitosis** **Meiosis**

Question 60

In **Anaphase I** __________________ separate and move to the opposite poles with both their chromatids but in Anaphase II the _______________ separate.

Answer 60

**Homologous Chromosome* **Sister chromatids**