biology MCQs - 12th class Chapter 07 Mcqs

1

The sequence of changes involving a period of growth, replication of DNA, and cell division is called?

A

Mitosis

B

Meiosis

C

Cell Cycle

D

Interphase

2

Interphase is a period between two consecutive divisions and is also misleadingly called?

A

Prophase

B

Resting phase

C

M-phase

D

S-phase

3

In the human cell cycle, which phase is the longest, lasting about 10 hours?

A

G1 phase

B

G2 phase

C

Mitosis

D

S-phase

4

Which phase is characterized by extensive metabolic activity, cell growth, and synthesis of specific enzymes?

A

S-phase

B

G2 phase

C

G1 phase

D

G0 phase

5

Cells like nerve cells can exit the cell cycle and enter a non-dividing state called?

A

G1 phase

B

S-phase

C

G0 phase

D

G2 phase

6

The total duration for a full cell cycle in yeast cells is approximately?

A

24 hours

B

90 minutes

C

30 minutes

D

4.5 hours

7

The division of the nucleus during mitosis is known as?

A

Cytokinesis

B

Karyokinesis

C

Interkinesis

D

Apoptosis

8

During which phase of mitosis do chromosomes become visible as thin threads and condense?

A

Metaphase

B

Anaphase

C

Telophase

D

Prophase

9

The specialized microtubule structure including the aster and spindle is called the?

A

Centrosome

B

Kinetochore

C

Mitotic apparatus

D

Chromatin

10

The kinetochore fibers of the spindle attach to what specific area on the centromere?

A

Primary constriction

B

Kinetochore

C

Sister chromatid

D

Telomere

11

In which phase of mitosis do chromosomes align at the cell's equator to form a plate?

A

Prophase

B

Metaphase

C

Anaphase

D

Telophase

12

The separation of sister chromatids occurs during which phase of mitosis?

A

Metaphase

B

Anaphase

C

Telophase

D

Prophase

13

Which phase of mitosis is considered the most critical for ensuring equal distribution of chromatids?

A

Prophase

B

Metaphase

C

Anaphase

D

Telophase

14

The reformation of the nuclear envelope and decondensation of chromosomes occurs during?

A

Anaphase

B

Prophase

C

Metaphase

D

Telophase

15

In animal cells, cytokinesis is achieved by the formation of a?

A

Cell plate

B

Phragmoplast

C

Contractile ring

D

Cell wall

16

In plant cells, cytokinesis involves the formation of a structure called the?

A

Cleavage furrow

B

Contractile ring

C

Phragmoplast

D

Aster

17

The vesicles that form the phragmoplast in plant cells originate from the?

A

Endoplasmic reticulum

B

Ribosomes

C

Golgi complex

D

Mitochondria

18

Uncontrolled and unregulated cell division can lead to a disease called?

A

Necrosis

B

Apoptosis

C

Cancer

D

Down's syndrome

19

A tumor that is of small size and localized, not spreading to other parts, is known as?

A

Malignant

B

Metastatic

C

Benign

D

Carcinogenic

20

The spread of tumor cells to other parts of the body is called?

A

Metastasis

B

Malignancy

C

Proliferation

D

Invasion

21

Which type of cell division reduces the chromosome number to half?

A

Mitosis

B

Budding

C

Amitosis

D

Meiosis

22

Meiosis involves how many consecutive divisions after a single DNA replication?

A

One

B

Two

C

Three

D

Four

23

The interphase of meiosis is stated to lack which stage?

A

G1 stage

B

S stage

C

G2 stage

D

G0 stage

24

The pairing of homologous chromosomes during meiosis is called?

A

Crossing over

B

Synapsis

C

Chiasmata

D

Bivalent

25

In which sub-stage of Prophase I does synapsis begin?

A

Leptotene

B

Zygotene

C

Pachytene

D

Diplotene

26

The exchange of segments between non-sister chromatids of homologous chromosomes is known as?

A

Synapsis

B

Disjunction

C

Crossing over

D

Segregation

27

Crossing over occurs during which sub-stage of Prophase I?

A

Leptotene

B

Zygotene

C

Pachytene

D

Diplotene

28

The points of interchange where homologous chromosomes remain united after starting to separate are called?

A

Centromeres

B

Kinetochores

C

Telomeres

D

Chiasmata

29

In which stage do chiasmata become visible as homologous chromosomes separate?

A

Pachytene

B

Zygotene

C

Diplotene

D

Diakinesis

30

During which phase of meiosis do homologous chromosomes separate, while sister chromatids remain together?

A

Anaphase of mitosis

B

Anaphase I

C

Anaphase II

D

Metaphase I

31

After Telophase I and cytokinesis, the two daughter cells are?

A

Diploid

B

Haploid

C

Tetraploid

D

Aneuploid

32

Meiosis II is a division that is similar to?

A

Mitosis

B

Meiosis I

C

Interphase

D

Amitosis

33

The final result of meiosis is the formation of?

A

Two diploid cells

B

Two haploid cells

C

Four diploid cells

D

Four haploid cells

34

The failure of chromosomes to segregate properly during anaphase is called?

A

Synapsis

B

Crossing over

C

Non-disjunction

D

Cytokinesis

35

Down's syndrome is caused by non-disjunction of which chromosome pair?

A

18th

B

13th

C

21st

D

Sex chromosomes

36

An individual with Klinefelter's syndrome has which chromosome composition?

A

44 + X

B

44 + XXY

C

44 + XYY

D

Trisomy 21

37

An individual with Turner's syndrome is characterized by which chromosome composition?

A

44 + X

B

44 + XXY

C

44 + XXX

D

44 + Y

38

Programmed cell death, a process of cellular suicide, is called?

A

Necrosis

B

Apoptosis

C

Cancer

D

Lysis

39

Cell death due to tissue damage, which causes swelling and bursting of cells, is known as?

A

Apoptosis

B

Necrosis

C

Phagocytosis

D

Metastasis

40

During apoptosis, dying cells shrink and release small membrane-bounded structures called?

A

Lysosomes

B

Vesicles

C

Apoptotic bodies

D

Vacuoles

41

In animal cells, the contractile ring is formed by which proteins?

A

Tubulin and dynein

B

Actin and myosin

C

Collagen and elastin

D

Keratin and vimentin

42

Which of the following is an importance of mitosis?

A

Producing gametes

B

Causing variation

C

Asexual reproduction

D

Reducing chromosome number

43

The genetic information in daughter cells after mitosis is _______ the parent cell.

A

different from

B

half of

C

double

D

unchanged from

44

The phase where condensation of chromosomes reaches its maximum during Prophase I is?

A

Leptotene

B

Pachytene

C

Diplotene

D

Diakinesis

45

According to the text, cancer is caused mainly by mutations in?

A

Germ cells

B

Somatic cells

C

Gametes

D

Zygotic cells

46

The term 'apoptosis' is a Greek word that means?

A

To build up

B

To divide

C

Dropping off or falling off

D

To swell and burst

47

The two significant happenings of meiosis that cause variation are crossing over and ?

A

Random assortment of chromosomes

B

DNA replication

C

Cytokinesis

D

Spindle formation

48

In which cells do astral microtubules form an aster?

A

Plant cells

B

Bacterial cells

C

Fungal cells

D

Animal cells

49

The frequency of births for Down's Syndrome is approximately?

A

1/15,000

B

1/6,000

C

1/700

D

1/1,000

50

What is the chromosomal condition for Patau Syndrome as listed in the table?

A

Trisomy 21

B

Trisomy 18

C

Trisomy 13

D

XO