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Question: 1
Give length of cell cycle during mitosis in human cell.
Answer: 1
1-47In human average cell cycle is about is 24 hours Mitosis takes 30 minutes, G1phase takes 9 hours, S-phase takes 10 hours, and G2 phase takes 4.5 hours.
Question: 2
Write about the stage of telophase of mitosis.
Answer: 2
2-47During telophase of mitosis,nuclear membrane and nucleolus reappear,mitotic apparatus disappears and two nucleoli are formed in one cell.
Question: 3
Give two disadvantages of cloning..
Answer: 3
3-47Disadvantages of cloning are.
Question: 4
What events occur in anaphase of mitosis?
Answer: 4
4-47During anaphase of mitosis spindle contract and centromere divides and two sets chromosomes are formed.Each set of chromosomes moves toward opposite poles.So that each pole receive one set of chromosomes.
Question: 5
Distinguish between karyokinesis and cytokinesis.
Answer: 5
5-47Karyokinesis: Division of nucleus is called karyokinesis.
Cytokinesis: Division of cytoplasm is called cytokinesis.
Cytokinesis: Division of cytoplasm is called cytokinesis.
Question: 6
How chromatin differs from chromosomes.
Answer: 6
6-47Chromatin is thread like network,it is formed when chromosomes becomes uncoiled.
Chromosomes are composed of DNA and protenis. When chromatin is highly coiled it changes in to chromosomes.
Chromosomes are composed of DNA and protenis. When chromatin is highly coiled it changes in to chromosomes.
Question: 7
how and when the phragmoplast originates?
Answer: 7
7-47Phragmoplast originates from the Golgi vesicles or Golgi apparatus.Vesicles cuts of from the Golgi apparatus and arranged at the equator to from phragmoplast. Phragmoplast originate at the time of cytokinesis in plant cells.
Question: 8
Characterize pachytene stage of meiosis.
Answer: 8
8-47Pairing of homologous chromosomes is completed,chromosomes become further thick and short and crossing over takes places by chiasmata formation.
Question: 9
What is interphase? Write the name of its sub stages
Answer: 9
9-47The period of life cycle between two consecutive division is termed as the interphase,or misleadingly termed as the resting phase:\its sub stage are:
i) G1 phase ii) S-phase iii) G2 phase
i) G1 phase ii) S-phase iii) G2 phase
Question: 10
Define cell cycle.
Answer: 10
10-47The cell undergoes a sequence of changes,which involves period of growth,replication of DNA,followed by cell division.This sequence of changes is called cell cycle.
Question: 11
What is importance of kinetochore in the allignment of chromosomes during mitosis?
Answer: 11
11-47Spindle fibers attaches at kinetochore of chromosomes and they help to align chromosomes at the center of cell to from equatorial plate or metaphase plate.
Question: 12
Describe changes occur in during G1phase.
Answer: 12
12-47It is period of extensive metabolic activities,in which cell normal grows in size,specific enzymes are synthesized and DNA base units are accumulated for the DNA synthesis
Question: 13
What change occurs in dividing cell during zygotene?
Answer: 13
13-47Pairing of chromosomes takes place during the zygetene stage of the meiosis.
Pairing may start from center to towards end or may start from one end to another end.
Pairing may start from center to towards end or may start from one end to another end.
Question: 14
Define cell cycle.Give its phase.
Answer: 14
14-47Events or changes occur during the division of a cell is called cell cycle.It has two phase
i) Interphase ii) Mitotic phase.
i) Interphase ii) Mitotic phase.
Question: 15
Define crossing over.Give its significance.
Answer: 15
15-47It is exchange of segments of chromosomes between non sister chromatids. Its significance is that,it provides raw material for evolution and also from new recombination of genes.
Question: 16
Define mitotic apparatus. Or Give its functions.
Answer: 16
16-47Mitotic apparatus composed of spindle fibers,centriols and asters.Mitotic apparatus plays an important role in cell division and equal distribution of chromosomes during cell division.
Question: 17
Give four important functions of mitosis.
Answer: 17
17-47Four functions of mitosis are
Question: 18
How cytokinesis differ in plant and animal cell?
Answer: 18
18-47Cytokinesis in plants: In plants cytokinesis occur by phragmoplast formation.Golgi vesicles arrange in the center and fuse with each other forming cell wall between two daughter nuclei which in turn divides into two daughter cells.
Question: 19
Differentiate between cancer cell and normal cell or Write a least three characters of cancer cells.
Answer: 19
19-47Cancer cell can be distinguished from normal cells because they are less differentiated than normal cells,exhibit the characteristics of rapidly growing cell,i.e,is high nucleus to cytoplasmic ratio,prominent nucleoli and many mitosis.
Question: 20
Define non-disjunction of chromosomes. Or Define chromosomal non-disjunction.
Answer: 20
20-47It is chromosomal non disjunction,during which spindle fibers fail to attach with chromosomes and resulting unequal distribution of chromosomes occur.
Question: 21
Cancer is uncontrolled cell division. Explain.
Answer: 21
21-47It is called so because genes controlling the cell division lose their control over cell division and cell divides without any control,so it is called uncontrolled cell division.
Question: 22
Define metastasis. Or what is metastasis?
Answer: 22
22-47The cell composing a malignant tumor or cancer,divide more rapidly,mostly invade surrounding tissues,get into the body's circulatory system,and set up areas of proliferation away from their site of original appearance.This spread of tumor cells and establishment of secondary area of growth is called metastasis.
Question: 23
Name only stages of prophase I of meiosis.
Answer: 23
23-47Following are the sub stages of prophase I of meiosis
Question: 24
Give four importance of mitosis.
Answer: 24
24-47i) It transfers unchanged genetic information to the daughter cells
ii) It helps in all types of asexual reproduction like cloning,tissue culture etc
iii) It helps in healing of wounds
iv) It maintains the chromosomes number constant.
ii) It helps in all types of asexual reproduction like cloning,tissue culture etc
iii) It helps in healing of wounds
iv) It maintains the chromosomes number constant.
Question: 25
What are three sets of microtubules which originate from each pair of centriole during mitosis?
Answer: 25
25-47Three sets microtubules originate from centrioles are asteral microtubules radiate outward and from aster while other two sets of microtubules compose the spindle i.e the kinetochore microtubules and polar microtubules.
Question: 26
Give affect of XYY Klinefelter syndrome.
Answer: 26
26-47The affected persons are phenotypically male but have frequently enlarged breast,tendency to tallness,Obesity,small testes with no sperms at ejaculation and under development of secondary sex characters.
Question: 27
Write symptoms of Turner's syndrome.
Answer: 27
27-47Individuals with this condition do not survive pregnancy and aborted.Those who survive have female appearance with short stature webbed neck,without ovaries and complete absence of germ cells.
Question: 28
Give only cause of Down's syndrome and Klinefelter syndrome.
Answer: 28
28-47These are meiotic errors due to non disjunction and due to unequal distribution of chromosomes.
Question: 29
What changes in cell take place during diplotene?
Answer: 29
29-47The paired chromosomes repel each other and begins to separate.Separation however,is not complete,because homologous chromosomes remain united by their point of interchange.Each bivalent has at least one such point,the chromatids other wise separated.
Question: 30
Give causes and symptoms of Down's syndrome. Or Write symptoms of Down's syndrome.
Answer: 30
30-47The cause of Down's syndrome is the missing of 21stchromosomes due to non disjunction. The affected individuals have a flat,broad face,squint eyes with folds in the inner corner and protruding tongue,mental retardation and defective development of central nervous system.
Question: 31
Differentiate between malignent and benign tumor.
Answer: 31
31-47Maligent tumor: Malignant tumor or cancer divides more rapidly,mostly invade surrounding tissues get enter in circulatory system for spreading into other body parts.
Question: 32
How cytokinesis occur in plants?
Answer: 32
32-47At cytokinesis,in place of contractile ring a membrane structure,phragmoplast informed from vesicle,which originates from Golgi complex.These vesicles lined up in the center of the dividing cell,where they fuse to form phragmoplast. The membrane of vesicles become the plasma membrane of daughter cells.
Question: 33
Give main feature of metaphase of Meiosis-1.
Answer: 33
33-47Nuclear membrane disorganizes.Spindle fibers originate and attached with kinetochore of homologous chromosomes from each pole and arrange bivalent at equator.
Question: 34
Discuss diakinesis in meiosis.
Answer: 34
34-47During this phase the condensation of chromosomes reaches to its maximum.At the same time separation of homologous chromosomes is completed,but still they are united at one point,more oftenly at ends.Nucleoli disappear.
Question: 35
Differentiate between necrosis and apoptosis.
Answer: 35
35-47Necrosis: Cell death due to tissue damage is called necrosis
Question: 36
What events occur in anaphase-I in meiosis?
Answer: 36
36-47During the anaphase of meiosis -1.The spindle fibers contract and each member of homologous chromosomes moves towards each pole.In this way half chromosomes reaches to one pole and other half reaches to another pole.
Question: 37
What is importance of bivalent formation?
Answer: 37
37-47Due to bivalent formation of homologous chromosomes,the non sister chromatids exchange their segment during the crossing over resulting in new recombination.
Question: 38
Write a brief note on turner's syndrome.
Answer: 38
38-47These infected individuals have one missing X chromosomes with only 45 chromosomes(44 autosomes + X).Individuals with this condition often do not survive pregnancy and are aborted.Those who survive have female appearance with short stature,webbed neck,without ovaries and complete absence of germs cells.
Question: 39
Write down the two functions of programmed death of a cell.
Answer: 39
39-47Programmed cell death helps in proper control of multicellular development which lead to deletion of entire structure (e.g, the tail of developing human embryos) or part of structure (e.g tissue between developing digits.)
Question: 40
Write down the events of metaphase of mitosis.
Answer: 40
40-47The Kinetochore fibers of spindles attach to the kinetochore region (specialized area in centromere) of chromosomes and align them at the equator of the spindle forming equatorial plate or metaphase plate.
Question: 41
What is Klinfelter's syndrome?
Answer: 41
41-47The individual have an additional sex chromosome i.e,47.(44+xxy).They are phenotypically male but have frequently enlarged breast,tendency to tallness,obesity,small testes with no sperms at ejaculation and under development of Secondary sex characters.
Question: 42
What are the events of S-Phase?
Answer: 42
42-47Following G1the S-Phase (synthesis phase) during which the DNA is synthesized and chromosomes number is doubled.
Question: 43
What changes occur in a cell during apoptosis?
Answer: 43
43-47During apoptosis the cell shrink and condensed ultimately split up thus release the small membrane bounded apoptotic bodies which are generally phagocytosed by other cells. Intracellular constituents are not released freely in extracellular environment which otherwise might have toxic effect.
Question: 44
How does cell death help in development of multicellular organisms?
Answer: 44
44-47Programmed cell death help in proper control of multicellular organisms development,which may lead to deletion of entire structure (e.g.,the tail of the developing human embryo) or a part of structure (e.g.,tissues between developing digits).Cell death even controls number of neurons because most of the neurons in human body die during development.
Question: 45
Give the chances of occurrence of Down's syndrome in teenage mothers and a forty years old mother's offspring.
Answer: 45
45-47The chances of teenage mother having down's syndrome child is one in many thousands of forty years old mother,one in hundred chance and by forty five the risk is three times greater.
Question: 46
What is apoptosis?
Answer: 46
46-47The internal programme of events and sequence of morphological changes by which all cell commits suicide is called apoptosis.
Question: 47
What are the events of zygotene of prophase -I of meiosis?
Answer: 47
47-47First essential phenomenon of meiosis i.e, pairing of homologous chromosomes called synapsis starts. Each paired but not fused,complex structure is called bivalent or tetrad.
