Chapter3(cell Division)

Question 1

What are the stages of cell cycle

Answer 1

GSM
1. Gap 1-Growth and preparation of the chromosome for replication
2.synthesis of DNA and replication of the chromosome
3.Preparation for Mitosis
4.Mitosis

Question 2

What’s the longest phase in the cell cycle

Answer 2

Interphase: Gap1,Synthesis and Gap 2

Question 3

What’s the short period of the cell cycle ?

Answer 3

Mitotic phase

Question 4

During interphase the cell grows by producing what?

Answer 4

Protein and cytoplasmic organelle

Question 5

The resting and the non dividing stage of cell cycle is called?

Answer 5

Interphase

Question 6

What happens during the interphase?

Answer 6

1. The period of synthesis and growth 2.The cell absorbs nutrients to build new cells
   3.DNA replication occurs
2. Chromatin(a long thread-like structure)are present in this phase instead of chromosomes.

Question 7

The DNA replication occur during what phase of the interphase?

Answer 7

during the S phase of the interphase.

Question 8

The cell consists of how many chromosomes and chromatid respectively

Answer 8

46&92 respectively

Question 9

What’s the longest phase of mitosis?

Answer 9

Prophase

Question 10

What occurs in the mitotic prophase?

Answer 10

1.Nucleolus and cell membrane disappears
2.condensation of chromatin to visible chromosomes
3.centrioles move to opposite side of the cell
4.spindle are formed

Question 11

Spindle are form by ?

Answer 11

Centromeres

Question 12

Short centrioles are called

Answer 12

Asters

Question 13

What’s the coordinating center for the cells microtubules?

Answer 13

Centrosome

Question 14

The cell inherits how many centrosome

Answer 14

A single

Question 15

What occurs in the metaphase;

Answer 15

1.Chromosome arrange themselves at the equator of the cells
2. Chromosome are attached to the spindle

Question 16

The point where chromosomes attach to spindle is called?

Answer 16

Kinetochore

Question 17

Spindle are form by

Answer 17

Centromere

Question 18

What’s occurs in mitotic anaphase ?

Answer 18

1.centromere split to form chromosomes( a pair of chromatid)
2.the chromosomes move to the poles of the cell

Question 19

What occurs in the mitotic telophase?

Answer 19

1.spindle fibres break down
2. centrioles replicate
3.nuclear membrane and nucleolus reappear
4. Chromosomes change to chromatin thread
5 division of cell membrane occur

Question 20

What are the phases in prophase I and what happened in each phase?

Answer 20

1.leptotene: chromosomes become visible and shortened i.e chromatin turns to chromosome
2.Zygotene:Homologous chromosome pairs to form bivalent i.e synapses
3.Pachytene:Bivalents shorten and thicken to become more physical
4.Diplotene :Bivalent pull slightly apart at the chiasma
5.Diakinesis:homologous centromere move apart and chromatid begins to shorten

Question 21

What’s a chiasma?

Answer 21

Point of attachment between 2 non- sister chromatid

Question 22

What occurs in metaphase I?

Answer 22

Homologous chromosome pairs(Bivalents) align along the equator

Question 23

What occurs in Anaphase I?

Answer 23

Homologous chromosomes separate and move to opposite poles.

Question 24

What is the cell that is produced in telophase I?

Answer 24

two haploid daughter cells, each with one set of chromosomes is formed

Question 25

Crossing over occurs at what phase ?

Answer 25

Prophase I, parchytene

Question 26

General recombination during meiosis is achieved by

Answer 26

1.Crossing over
2.independent assortment of chromosomes

Question 27

What are the significance of mitosis?

Answer 27

1.Genetic stability:daughter cells are genetically identical to parent cell and no variation
2.Growth:increase in number of cells is by mitosis
3.Regeneration: ability to regenerate a whole part of a body
4:Asexual reproduction

Question 28

What are the significance of meiosis ?

Answer 28

1.Sexual reproduction
2.Genetic Variation

Question 29

Nucleosome

Answer 29

A section of DNA wrapped around a core protein

Question 30

The presence of chiasma indicates that;

Answer 30

The 2 chromatids are in synaptonemal complex