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MCQ - Events in the Mitotic cycle

MCQ - Events in the Mitotic cycle


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The following question confused me at first

However, I presumed that it must be in comparison to meiosis. In that case D would be correct.

However, the correct answer is A.

How can this be? I know that in mitosis it is the chromatids that are 'pulled away' to opposite poles. In meiosis, this is whole chromatids but anaphase still occurs.

I suspect I don't understand the question. Where have I gone wrong in my reasoning?


Cell cycle can be divided into two phases:

1. Interphase

2. M-phase(Mitotic phase)

Note: M-phase can also mean Meiotic phase but it is not the full form of the acronym.

So M-phase in mitosis has four phases:

  • Prophase
  • Metaphase
  • Anaphase(your answer)
  • Telophase

A mitotic cycle:

The rest of the options:

B. Cytokinesis

Cytoplasmic division begins during or after the late stages of nuclear division in mitosis and meiosis.

Your question doesn't seem to consider cytokinesis as a part of M-phase (i.e to be occurring during the late karyokinesis). So it has to be ruled out.(Making some assumptions as this is a key to reaching the single correct answer in MCQs, if not this would have had two right answers.)

C. DNA replication - happens in S-phase of interphase

D. Interphase (certainly not the one)

Source: ncert


Solving the Reproduction in Organisms Multiple Choice Questions of Class 12 Biology Chapter 1 MCQ can be of extreme help as you will be aware of all the concepts. These MCQ Questions on Reproduction in Organisms Class 12 with answers pave for a quick revision of the Chapter thereby helping you to enhance subject knowledge. Have a glance at the MCQ of Chapter 1 Biology Class 12 and cross-check your answers during preparation.

Select the correct answer

Question 1.
A few statements describing certain features of reproduction are given below:
(i) Gametic fusion takes place
(ii) Transfer of genetic material takes place
(iii) Reduction division takes place
(iv) Progeny have some resemblance with parents
Select the options that are true for both asexual and sexual reproduction from the options given below:
(a) i and iii
(b) ii and iii
(c) ii and iv
(d) i and iii

Question 2.
The term ‘clone’ cannot be applied to offspring formed by sexual reproduction because:
(a) Offspring do not possess exact copies of parental DNA.
(b) DNA of only one parent is copied and passed on to the offspring.
(c) Offspring are formed at different times
(d) DNA of parent and DNA of offspring are completely different.

Answer: (a) Offspring do not possess exact copies of parental DNA.

Question 3.
Amoeba and Yeast reproduce asexually by fission and budding respectively, because they are:
(a) Microscopic organisms
(b) Heterotrophic organisms
(c) Unicellular organisms
(d) Uninucleate organisms.

Answer: (c) Unicellular organisms

Question 4.
A few statements with regard to sexual reproduction are given below:
(i) Sexual reproduction does not always require two individuals.
(ii) Sexual reproduction generally involves gametic fusion.
(iii) Meiosis never occurs during sexual reproduction
(Iv) External fertilisation is a rule during sexual reproduction.
Choose the correct statements from the options below:
(a) i and iv
(b) i and ii
(c) ii and iii
(d) i and iv

Question 5.
A multicellular, filamentous alga exhibits a type of sexual life cycle in which the meiotic division occurs after the formation of zygote. The adult filament of this alga has
(a) Haploid vegetative cells and diploid gametangia
(b) Diploid vegetative cells and diploid gametangia
(c) Diploid vegetative cells and haploid gametangia
(d) Haploid vegetative cells and haploid gametangia.

Answer: (d) Haploid vegetative cells and haploid gametangia.

Question 6.
The male gametes of rice plant have 12 chromosomes in their nucleus. The chromosome number in the female gamete, zygote and the cells of the seedling will be respectively
(a) 12, 24, 12
(b) 24, 12, 12
(c) 12, 24, 24
(d) 24, 12, 24

Question 7.
Given below are a few statements related to external fertilisation. Choose the correct statements.
(i) The male and female gametes are formed and released simultaneously.
(ii) Only a few gametes are released into the medium.
(iii) Water is the medium in a majority of organisms exhibiting external fertilisation.
(iv) Offspring formed as a result of external fertilisation have better chance of survival than those formed inside an organism.
(a) iii and iv
(b) i and iii
(c) ii and iv
(d) i and iv

Question 8.
The statements given below describe certain features that are observed in the pistil of flowers.
(i) Pistil may have many carpels
(ii) Each carpel may have more than one ovule
(iii) Each carpel has only one ovule
(iv) Pistil has only one carprel
Choose the statements that are true from the options below:
(a) i and ii
(b) i and iii
(c) ii and iv
(d) iii and iv

Question 9.
Which of the following situations correctly describe the similarity between an angiosperm egg and a human egg?
(i) Eggs of both are formed only once in a lifetime
(ii) Both the angiosperm egg and human egg are stationary
(iii) Both the angiosperm egg and human egg are motile.
(iv) Syngamy in both results in the formation of zygote
Choose the correct answer from the options given below:
(a) ii and iv
(b) iv only
(c) iii and iv
(d) i and iv

Question 10.
Appearance of vegetative propagules from the nodes of plants such as surgarcane and ginger is mainly because:
(a) Nodes are shorter than internodes
(b) Nodes have meristematic cells
(c) Nodes are located near the soil
(d) Nodes have non-photosynthetic cells

Answer: (b) Nodes have meristematic cells

Question 11.
Which of the following statements supports the view that elaborate sexual reproductive process appeared much later in the organic evolution?
(i) Lower groups of organisms have simpler body design
(ii) Asexual reproduction is common in lower groups
(iii) Asexual reproduction is common in higher groups of organisms
(iv) There is high incidence of sexual reproduction in angiosperms and vertebrates.
Choose the correct answer from the options given below:
(a) i and ii
(b) i and iii
(c) ii and iv
(d) ii and iii

Question 12.
Offspring formed by sexual reproduction exhibit more variations than those formed by asexual reproduction because:
(a) Sexual reproduction is a lengthy process
(b) Gametes of parents have qualitatively different genetic composition
(c) Genetic material comes from parents of two different species
(d) Greater amount of DNA is involved in sexual reproduction.

Answer: (b) Gametes of parents have qualitatively different genetic composition

Question 13.
Choose the correct statement from amongst the following:
(a) Dioecious (hermaphrodite) organisms are seen only in animals
(b) Dioecious organisms are seen only in plants
(c) Dioecious organisms are seen in both plants and animals
(d) Dioecious organisms are seen only in vertebrates.

Answer: (c) Dioecious organisms are seen in both plants and animals

Question 14.
There is no natural death in single celled organisms like Amoeba and bacteria because:
(a) They cannot reproduce sexually
(b) They reproduce by binary fission
(c) Parental body is distributed among the offspring
(d) They are microscopic.

Answer: (c) Parental body is distributed among the offspring

Question 15.
There are various types of reproduction. The type of reproduction adopted by an organism depends on:
(a) The habitat and morphology of the organism
(b) Morphology of the organism
(c) Morphology and physiology of the organisms
(d) The organism’s habitat, physiology and genetic makeup

Answer: (d) The organism’s habitat, physiology and genetic makeup

Question 16.
Identify the incorrect statement.
(a) In asexual reproduction, the offspring produced are morphologically and genetically identical to the parent
(b) Zoospores are sexual reproductive structures
(c) In asexual reproduction, a single parent produces offspring with or without the formation of gametes
(d) Conidia are asexual structures in Penicillium

Answer: (b) Zoospores are sexual reproductive structures

Question 17.
Which of the following is a postfertilisation event in flowering plants?
(a) Transfer of pollen grains
(b) Embryo development
(c) Formation of flower
(d) Formation of pollen grains

Answer: (b) Embryo development

Question 18.
The number of chromosomes in the shoot tip cells of a maize plant is 20. The number of chromosomes in the microspore mother cells of the same plant shall be :
(a) 20
(b) 10
(c) 40
(d) 15

Assertion and Reason Type Questions

These questions consist of two statements each, printed as Assertion and Reason. While answering these questions you are required to choose any one of the following four responses.
(a) If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.
(b) If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion.
(c) If Assertion is true but the Reason is false.
(d) If both Assertion and Reason are false.
Question 19.
Assertion: Sexual reproduction is
advantageous than asexual reproduction. Reason: Sexual reproduction is rapid mode of reproduction, while asexual reproduction is slow mode of reproduction.

Answer: (c) If Assertion is true but the Reason is false.

Question 20.
Assertion: Individuals produced by asexual reproduction are genetically similar to parents.
Reason: Asexual reproduction involves only mitotic divisions.

Answer: (a) If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.

Question 21.
Assertion: Stigma of pistil receives the pollen during pollination.
Reason: Pollen grains are produced in ovary of gynoecium.

Answer: (c) If Assertion is true but the Reason is false.

Question 22.
Assertion: In wheat and sugarcane, pollination takes place by water.
Reason: Water is not required for irrigation of wheat and sugarcane.

Answer: (d) If both Assertion and Reason are false.

Question 23.
Assertion: Continued self-pollination generation after generation results in pure line formation.
Reason: By continued self-pollination, plant becomes pure or homozygous for its characters.

Answer: (a) If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.

Question 24.
Assertion: Many single-celled organisms reproduce by binary fission.
Reason: In binary fission a cell divides into two halves and each rapidly grows into an adult.

Answer: (b) If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion.

Question 25.
Assertion: In viviparous animals, the zygote develops into a young one inside the body of the female organism.
Reason: Because of proper embryonic care and protection, the chances of survival of young ones are greater in viviparous organisms.

Answer: (b) If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion.

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Test: Mitosis

What is the proper sequence in mitosis?

Anaphase, metaphase, telophase and prophase

Telophase, anaphase, metaphase and prophase

Metaphase, telophase, prophase and anaphase

Prophase, metaphase, anaphase and telophase

Mitosis consists of four basic phases: prophase, metaphase, anaphase, and telophase. These phases occur in this strict sequential order, and cytokinesis - the process of dividing the cell contents to make two new cells - starts in anaphase or telophase.

1. Prophase - During prophase, chromosomes get visible (chromatids), the centrioles migrate to the poles, nuclear membrane and nucleolus disappear and spindle formation is seen. Prophase in mitosis is longer than any other phases of mitosis because the cell has to prepare for the actual division that takes place from early through late prophase.

2. Metaphase - During this, chromosomes lineup around the centre (Cells in metaphase have the chromosomes, which appear as long thin strands under the microscope).

3. Anaphase - here, chromatids separate and move to opposite poles by spindle fibers. This allows each daughter cell to have an identical copy of each of the original cell&rsquos chromosomes.

4.Telophase - During this phase, chromosomes disappear (become chromatin), nuclear membrane reforms, nucleoli reappears, spindle disappears and centrioles duplicate.


MCQs on Cell Cycle Phases

1. The division of cytoplasm is known as
(a) Mitosis
(b) Synapsis
(c) Cytokinesis
(d) Karyokinesis

2. The stage in which chromosomes align on the equator of spindle fiber is
(a) Telophase
(b) Anaphase
(c) Metaphase
(d) Prophase

3. The best stage at which the total number of chromosomes can be counted in any species is
(a) Telophase
(b) Metaphase
(c) Late anaphase
(d) Late prophase

4. Balbiani rings are found in
(a) Heterosome
(b) Lampbrush chromosome
(c) Autosome
(d) Polytene chromsome

5. This structure tends to vanish always during meiosis and mitosis
(a) Plastids
(b) Plasma membrane
(c) Nucleolus and nuclear membrane
(d) All of these

6. Centrosome duplication takes place in this phase
(a) S phase
(b) G1 phase
(c) G0 phase
(d) M phase

7. The __________ checkpoint is also known as restriction point
(a) G1 checkpoint
(b) G2 checkpoint
(c) M checkpoint
(d) None of these

8. The characteristic of this stage of mitosis is the separation of the sister chromatids
(a) Telophase
(b) Metaphase
(c) Prometaphase
(d) Anaphase

9. This condition is necessary for a cell to qualify through the G2 checkpoint
(a) Cell should be of a size sufficient enough
(b) Complete and accurate DNA replication
(c) Sufficient stockpile of nucleotides
(d) Complete attachment of mitotic spindle fibers to kinetochores

10. Individual chromosomes become distinct through a light microscope during this mitotic stage
(a) Prometaphase
(b) Prophase
(c) Anaphase
(d) Metaphase


Mitosis

Initially mitosis and karyokinesis was considered to be the same and cytokinesis was a separate process. But later both of karyokinesis and cytokinesis were considered as the two phase of mitosis. In somatic cells of higher organisms mitosis takes place. The daughter cells formed due to mitosis are identical in all respect to the parent cell. The daughter nuclei are not formed directly from the parent nucleus but via the formation of chromosomes hence it is also called Indirect cell division .

Occurrence of Mitosis: -

In the following cases the Mitosis occurs.
i) In the somatic cell of all eukaryotes.
ii) In the meristematic tissues of plants.
iii) In the lower animals during rege3narative growth.
iv) In the damaged plant parts for the purpose of wound healing.
v) In the development and differentiation of embryos.

Factors Including Mitosis: -

i) Greater amount of cytoplasm in comparison to that of nucleus.
ii) The increase in the metabolic process which liberate more energy in the form of ATP molecules.
iii) The increase in the amount of RNA in comparison to DNA.
iv) Synthesis of specific proteins required during mitosis.
v) Availability of adequate substrate.

Mechanism of Mitosis :

Mitosis is the process in which the chromosomes of the parent nucleus are distributed equaly into the two daughter cells. The entire process consists of two major phases:
i) KARYOKINESIS: The division of the nucleus.
ii) CYTOKINESIS: The division of the cytoplasm.

What is Miotic Cycle or Cell Cycle?

The Mitotic Cycle or Cell Cycle is the entire sequence of events happening from the end of one nuclear division to the beginning of the next of the mitosis process of cell division.

Control of Cell Cycle:

The cell cycle is controlled by different proteins in the cytoplasm, those are include:
a) Cyclins:
i) Cyclin D or G1 helping in synthesis of RNA.
ii) Cyclin E and A or, S phase Cyclins helping in the DNA replication.
iii) Mitotic Cyclin in Cyclin B are helping in the divisional stages.

b) Cyclin dependent kinases (Cdks): - Cyclin activated these enzymes and only get activated by binding with specific Cyclin belonging to a particular stage of cell division and add phosphate groups to different protein substrates.

c) Anaphase promoting complex: The group of protein molecules helps in the destruction of cohesive protein compounds and as a result the chromosomes can easily separated during anaphase.

Cell cycle checkpoints: -

The check points include the DNA damage checkpoints and spindle checkpoints operating during the Interphase and Metaphase, which stops cell division and initiate apoptosis.

Time taken for Mitotic cell division: -

in every organism when the current phases of mitosis are going on, maximum time is necessary for the Interphase and little time is necessary for the rest part of the cell division.

What is the importance of Interphase?

Interphase is a stage between two mitotic cycles in an eukaryotic cell, during which various physical and chemical changes for the preparation of cell division takes place. It is the cell division of longest period and called Inter-mitotic phase. The chromosomes appear as long and thin and forms diffused chromatin net. Due to highly hydrated condition it is quite less visible. There have three sub-phases of interface those are: -

i) Post mitotic Gap phase (G1): -this phase occupies 30 to 50% of the cell cycle and being the early stage of Interphase, it may call the past first Growth Phase. In this phase RNA and various regulatory proteins are synthesised. Enzymes required for DNA synthesis like DNA polymerase are synthesised. No synthesis of DNA takes place in this phase of mitosis. Accumulation of tubulin occur which causes elongation of the nucleus.
ii) Synthetic phase (S-phase): – this phase constitutes 35 to 45% of the cell cycle. It is the mid-interphase stage in which all the major metabolic activities of the findings cell take in place. In this phase of mitosis the DNA is synthesised. Volume of the nucleus becomes double due to DNA replication. Histone proteins are also synthesised. This single chromatid of the chromosome gets duplicated to form two identical Chromatids.
iii) Premitotic Gap phase(G2): – 10 to 20% of cell cycle is constitutes by this phase and also referred to as the second growth phase and actually is the gap between S-phase and prophase. In this phase of mitosis in major events include synthesis of specific RNA and protein, and stopping of DNA synthesis.

Major characteristics of interphase: –

i) The replication of DNA.
ii) Nuclear membrane remains intact and distinct.
iii) Due to accumulation of RNA and ribosome protein enlargement of nucleus.
iv) Synthesis of energy rich ATP molecules and microtubules take place.
v) Due to accumulation of cytoplasm the cell increases in size.
vi) A new centrosome is formed in animals cell from the existing one with a pair of centrioles placed at right angles to each other.
vii) In the cells of animal the net membrane biosynthesis increases and it remains stored at the cell surface in the form of blebs and helps the sale is to divide.
Click for MCQ on Cell Division


Question 1.
Ovulation in the human female normally takes place during the menstrual cycle
(a) at the mind secretory phase
(b) just before the end of the secretory phase
(c) at the beginning of the proliferative phase
(d) at the end of the proliferative phase.
Answer:
(d) at the end of the proliferative phase.

Question 2.
After ovulation Graafian follicle regresses into
(a) corpus atresia
(b) corpus callosum
(c) corpus luteum
(d) corpus albicans
Answer:
(c) corpus luteum

Question 3.
Immediately after ovulation, the mammalian egg is covered by a membrane known as
(a) chorion
(b) zona pellucida
(c) corona radiata
(d) vitelline membrane.
Answer:
(c) corona radiata

Question 4.
Which one of the following events is correctly matched with the time period in a normal menstrual cycle ?
(a) Release of egg : 5 th day
(b) Endometrium regenerates : 5 – 10 days
(c) Endometrium secretes nutrients for implantation: 11 – 18 days
(d) Rise in progesterone level : 1 – 15 days
Answer:
(b) Endometrium regenerates : 5 – 10 days

Question 5.
If mammalian ovum fails to get fertilised, which one of the following is unlikely ?
(a) Corpus luteum will distintegrate.
(b) Progesterone secretion rapidly declines.
(c) Estrogen secretion increases.
(d) Primary follicle starts developing.
Answer:
(c) Estrogen secretion increases.

Question 6.
A human female reaches menopause aroung the age of
(a) 50 years
(b) 15 years
(c) 70 years
(d) 25 years.
Answer:
(a) 50 years

Question 7.
A reaction of granules content which harden the zona pellucida and ensures sure block to polyspermy is
(a) acrosomal reaction
(b) cortical reaction
(c) acrosin reaction
(d) bindin reaction.
Answer:
(b) cortical reaction

Question 8.
Which part of the sperm plays an important role in penetrating the egg membrane ?
(a) Allosome
(b) Tail
(c) Autosome
(d) Acrosome
Answer:
(d) Acrosome

Question 9.
In oocyte secondary maturation occurs in
(a) ovary
(b) abdominal cavity
(c) Fallopian tube
(d) uterus.
Answer:
(c) Fallopian tube

Question 10.
Besides activating the egg another role of a sperm is to carry to egg
(a) RNA
(b) mitochondria
(c) DNA
(d) ribosomes.
Answer:
(c) DNA

Question 11.
Preparation of sperm before penetration of ovum is
(a) spermiation
(b) cortical reaction
(c) spermiogenesis
(d) capacitation.
Answer:
(a) spermiation

Question 12
Spermiation is the process of the release of sperms from
(a) seminiferous
(b) vas deferens
(c) epididymis
(d) prostate gland
Answer:
(a) seminiferous

Question 13.
Mature Graafian follicle is generally present in the ovary of a healthy human female around
(a) 5-8 day of menstrual cycle
(b) 11-17 day of menstrual cycle
(c) 18-23 day of menstrual cycle
(d) 24-28 day of menstrual cycle.
Answer:
(b) 11-17 day of menstrual cycle

Question 14.
Acrosomal reaction of the sperm occurs due to
(a) its contact with zona pellucida of the ova
(b) reactions within the uterine environment of the female
(c) reactions within the epididymal environment of the male
(d) androgens produced in the uterus.
Answer:
(a) its contact with zona pellucida of the ova

Question 15.
Which one of the following is not a male accessory gland ?
(a) Seminal vesicle
(b) Ampulla
(c) Prostate
(d) Bulbourethral gland
Answer:
(b) Ampulla

Question 16.
Which among the following has 23 chromosomes ?
(a) Spermatogonia
(b) Zygote
(c) Secondary oocyte
(d) Oogonia
Answer:
(c) Secondary oocyte

Question 17.
Which of the following hormones is not secreted by human placenta ?
(a) hCG
(b) Estrogens
(c) Progesterone
(d) LH
Answer:
(d) LH

Question 18.
The vas deferens receives duct from the seminal vesicle and opens into urethra as
(a) epididymis
(b) ejaculatory duct
(c) efferent ductule
(d) ureter
Answer:
(b) ejaculatory duct

Question 19.
Urethral meatus refers to the
(a) urinogenital duct
(b) opening of vas deferens into urethra
(c) external opening of the urinogenital duct
(d) muscles surrounding the urinogenial duct.
Answer:
(c) external opening of the urinogenital duct

Question 20.
Morula is a developmental stage
(a) between the zygote and blastocyst
(b) between the blastocyst and gastrula
(c) after the implantation
(d) between implantation and parturition.
Answer:
(a) between the zygote and blastocyst

Question 21.
The membranous cover of the ovum at ovulation is
(a) corona radiata
(b) zona radiata
(c) zona pellucida
(d) chorion.
Answer:
(a) corona radiata

Question 22.
Identify the odd one from the following
(a) Labia minora
(b) Fimbriae
(c) Infundibulum
(d) Isthmus
Answer:
(a) Labia minora

Question 23.
Temperature of the scrotum which is necessary for the functioning of testis is always ________ around below body temperature.
(a) 2°C
(b) 4°C
(c) 6°C
(d) 8°C
Answer:
(a) 2°C

Question 24.
Which of the following is correct about mammalian testes ?
(a) Graafian follicles, Sertoli cells, Leydig’s cells
(b) Graafian follicles, Sertoli cells, Seminiferous tubules
(c) Sertoli cells, Seminiferous tubules, Leyding’s cells
(d) Graafian follicle, leyding’s cells, Seminiferous tubule
Answer:
(c) Sertoli cells, Seminiferous tubules, Leyding’s cells

Question 25.
The nutritive cells found in seminiferous tubules are
(a) Leydig’s cells
(b) atretic follicular cells
(c) Sertoli cells
(d) chromaffin cells.
Answer:
(c) Sertoli cells

Question 26.
Sertoli cells are regulated by the pituitary hormone known as
(a) LH
(b) FSH
(c) GH
(d) prolactin.
Answer:
(b) FSH

Question 27.
The head of the epididymis at the head of the testis is called
(a) cauda epididymis
(b) vas deferens
(c) caput epididymis
(d) gubernaculum.
Answer:
(c) caput epididymis

Question 28.
Seminal plasma in humans is rich in
(a) fructose and calcium but has no enzymes
(b) glucose and certain enzymes but has no calcium
(c) fructose and certain enzymes but poor in calcium
(d) fructose, calcium and certain enzymes.
Answer:
(d) fructose, calcium and certain enzymes.

Question 29.
Prostate glands are located below
(a) gubernaculum
(b) seminal vesicles
(c) epididymis
(d) bulbourethral glands
Answer:
(b) seminal vesicles

Question 30.
The function of the secretion of prostate gland is to
(a) inhibit sperm activity
(b) attract sperms
(c) stimulate sperm activity
(d) none of these.
Answer:
(c) stimulate sperm activity

Question 31.
Lower narrow end of uterus is called
(a) urethra
(b) cervix
(c) clitoris
(d) vulva.
Answer:
(b) cervix

Question 32.
Bartholin’s glands are situated
(a) on the either side of vagina in humans
(b) on either side of vas deferens in humans
(c) on either side of penis in humans
(d) on either side of Fallopian tube in humans.
Answer:
(a) on the either side of vagina in humans

Question 33.
In human adult females oxytocin
(a) stimulates pituitary to secrete vasopressin
(b) causes strong uterine contractions during parturition
(c) is secreted by anterior pituitary
(d) stimulates growth of mammary glands.
Answer:
(b) causes strong uterine contractions during parturition

Question 34.
The third stage of parturition is called “after-birth”. In this stage
(a) excessive bleeding occurs
(b) fetus is bom and cervix and vagina contraction to normal condition happens
(c) fetus is bom and contraction of uterine wall prevents excessive bleeding
(d) placenta is expelled out.
Answer:
(d) placenta is expelled out.

Question 35.
After birth, colostrum is released from mammary glands which is rich in
(a) fat and low in proteins
(b) proteins and low in fat
(c) proteins, antibodies and low in fat
(d) proteins, fat and low in antibodies.
Answer:
(c) proteins, antibodies and low in fat

Question 36.
Spot the odd one out from the following structures with reference to the male reproductive system.
(a) Rate testis
(b) Epididymis
(c) Vasa efferentia
(d) Isthmus
Answer:
(d) Isthmus

Question 37.
Seminal plasma, the fluid part of semen, is contributed by
(i) seminal vesicle
(ii) prostate
(iii) urethra
(iv) bulbourethral gland
(a) (i) and (ii)
(b) (i), (ii) and (iv)
(c) (ii), (iii) and (iv)
(d) (i) and (iv)
Answer:
(b) (i), (ii) and (iv)

Question 38.
In humans, at the end of the first meiotic division, the male germ cells differentiate into the
(a) spermatids
(b) spermatogonia
(c) primary spermatocytes
(d) secondary spermatocytes.
Answer:
(d) secondary spermatocytes.

Question 39.
How many sperms are formed from a secondary spermatocyte ?
(a) 4
(b) 8
(c) 2
(d) 1
Answer:
(c) 2

Question 40.
How many sperms are formed from 4 primary spermatocytes ?
(a) 4
(b) 1
(c) 16
(d) 32
Answer:
(c) 16

Question 41.
In spermatogenesis, reduction division of chromosome occurs during conversion of
(a) spermatogonia to primary spermatocytes
(b) primary spermatocytes to secondary spermatocytes
(c) secondary spermatocytes to spermatids
(d) spermatids to sperms.
Answer:
(b) primary spermatocytes to secondary spermatocytes

Question 42.
Which of the following groups of cells in the male gonad, represent haploid cells ?
(a) Spermatogonial cells
(b) Germinal epithelial cells
(c) Secondary spermatocytes
(d) Primary spermatocytes
Answer:
(c) Secondary spermatocytes

Question 43.
The process of release of spermatozoa from Sertoli cells into cavity of the seminiferous tubules is called
(a) spermiogenesis
(b) spermatogenesis
(c) spermatocytogenesis
(d) spermiation.
Answer:
(d) spermiation.

Question 44.
The principal tail piece of human sperm shows the microtubular arrangement of
(a) 7 + 2
(b) 9 + 2
(c) 11 + 2
(d) 13 + 2
Answer:
(c) 11 + 2

Question 45.
Acrosome is a type of
(a) lysosome
(b) flagellum
(c) ribosome
(d) basal body.
Answer:
(a) lysosome

Question 46.
Which of the following contains the actual genetic part of a sperm ?
(a) Whole of it
(b) Tail
(c) Middle piece
(d) Head
Answer:
(d) Head

Question 47.
The sperms undergo physiological maturation, acquiring increased motility and fertilising capacity in
(a) seminiferous tubules
(b) vasa efferentia
(c) epididymis
(d) vagina.
Answer:
(c) epididymis

Question 48.
At what stage of life is oogenesis initiated in a human female ?
(a) At puberty
(b) During menarch
(c) During menopause
(d) During embryonic development
Answer:
(d) During embryonic development

Question 49.
1st polar body is formed at which stage of oogenesis ?
(a) 1st meiosis
(b) 2nd mitosis
(c) 1st mitosis
(d) Differentiation
Answer:
(a) 1st meiosis

Question 50.
Which one is released from the ovary ?
(a) Primary oocyte
(b) Secondary oocyte
(c) Graafian follicle
(d) Oogonium
Answer:
(b) Secondary oocyte

Question 51.
During oogenesis, each diploid cell produces
(a) four functional eggs
(b) two functional eggs and two polar bodies
(c) one functional egg and three polar bodies
(d) four functional polar bodies.
Answer:
(c) one functional egg and three polar bodies

Question 52.
In oogenesis haploid egg is fertilised by sperm at which stage ?
(a) Primary oocyte
(b) Secondary oocyte
(c) Oogonium
(d) Ovum
Answer:
(b) Secondary oocyte

Question 53.
Layers of an ovum from outside to inside is
(a) corona radiata, zona pellucida and vitelline membrane
(b) zona pellucida, corona rodiata and vitelline membrane
(c) vitelline membrane, zona pellucida and corona radiata
(d) zona pellucida, vitelline membrane and corona radiata.
Answer:
(a) corona radiata, zona pellucida and vitelline membrane

Question 54.
Which part of ovary in mammals acts as an endocrine gland after ovulation ?
(a) Stroma
(b) Germinal epithelium
(c) Vitelline membrane
(d) Graafian follicle
Answer:
(d) Graafian follicle

Question 55.
The sex of the fetus will be decided at
(a) fertilisation by male gamete
(b) implantation
(c) fertilisation by female gamete
(d) the start of cleavage.
Answer:
(a) fertilisation by male gamete

Question 56.
What is true about cleavage in the fertilised egg in humans ?
(a) It starts while the egg is in Fallopian tube.
(b) It starts when the egg reaches uterus.
(c) It is meroblastic
(d) It is identical to the normal mitosis.
Answer:
(a) It starts while the egg is in Fallopian tube.

Question 57.
Cleavage differs from mitosis in lacking
(a) synthetic phase
(b) growth phase
(c) both (a) and (b)
(d) none of these.
Answer:
(b) growth phase

Question 58.
The solid mass of 8-16 cells formed from zygote after successive mitotic divisions is called
(a) blastula
(b) gastrula
(c) morula
(d) none of these.
Answer:
(c) morula

Question 59.
Implantation takes place after __________ of fertilisation.
(a) 5 days
(b) 6 days
(c) 7 days
(d) 8 days
Answer:
(c) 7 days

Question 60.
Structure connecting the fetus to placenta is
(a) umbilical cord
(b) amnion
(c) yolk sac
(d) chorion.
Answer:
(a) umbilical cord

Question 61.
Which of the following hormones is not a secretory product of human placenta ?
(a) Human chorionic gonadotropin
(b) Prolactin
(c) Estrogen
(d) Progesterone
Answer:
(b) Prolactin

Question 62.
Urine test during pregnancy determines the presence of
(a) human chorionic gonadotropin hormone
(b) estrogen
(c) progesterone
(d) luteinising hormone.
Answer:
(a) human chorionic gonadotropin hormone

Question 63.
In the event of pregnancy, the corpus luteum persists under the influence of
(a) LH
(b) FSH
(c) chorionic gonadotropin
(d) progesterone.
Answer:
(c) chorionic gonadotropin

Question 64.
During the development of embryo, which of the following occurs first?
(a) Differentiation of organ
(b) Differentiation of tissue
(c) Differentiation of organ system
(d) Differentiation of cells
Answer:
(d) Differentiation of cells

Question 65.
The structures derived from ectoderm are
(i) pituitary gland
(ii) cornea
(iii) kidneys
(iv) notochord
(a) (i) and (iii)
(b) (ii) and (iii)
(c) (i) and (ii)
(d) (ii) and (iv).
Answer:
(c) (i) and (ii)

Question 66.
Gastrula is the embryonic stage in which
(a) cleavage occurs
(b) blastocoel form
(c) germinal layers form
(d) villi form.
Answer:
(c) germinal layers form

Question 67.
In the development of the human body, the ectoderm is responsible for the formation of
(a) lens of the eye
(b) nervous system
(c) sweat glands
(d) all of these.
Answer:
(d) all of these.

Question 68.
The first movements of the fetus and appearance of hair on its head are usually observed during which month of pregnancy ?
(a) Fourth month
(b) Fifth month
(c) Sixth month
(d) Third month
Answer:
(b) Fifth month

Question 69.
The early stage human embryo distinctly possesses
(a) gills
(b) gill slits
(c) external ear (pinna)
(d) eyebrows.
Answer:
(b) gill slits

Question 70.
Delivery of developed fetus is scientifically called
(a) parturition
(b) oviposition
(c) abortion
(d) ovulation.
Answer:
(a) parturition

We hope the given Biology MCQs for Class 12 with Answers Chapter 3 Human Reproduction will help you. If you have any query regarding CBSE Class 12 Biology Human Reproduction MCQs Pdf, drop a comment below and we will get back to you at the earliest.


Cell cycle and cell division NEET questions Answer Key

Answer key –
1 (1) 2 (3) 3 (2) 4 (1) 5 (4)
6 (4) 7 (2) 8 (2) 9 (1) 10 (3)
11 (1) 12 (4) 13 (3) 14 (3) 15 (3)
16 (2) 17 (2) 18 (4) 19 (2) 20 (1)
21 (1) 22 (3) 23 (3) 24 (3) 25 (3)
26 (1) 27 (3) 28 (1) 29 (2) 30 (2)
31 (4) 32 (2) 33 (1) 34 (4) 35 (3)
36 (1) 37 (1) 38 (1) 39 (4) 40 (2)
41 (3) 42 (1) 43 (2) 44 (3) 45 (4)
46 (3) 47 (1) 48 (4)


Class 11th Biology – 10 Cell Cycle and Cell Division MCQs

Meiosis I is reductional division as it reduces chromosomes to half (involves separation of homologous chromosomes) whereas Meisois II is equational division(involves separation of chromatids just like mitosis).Hence the correct option is B

Best material for the study of mitosis in laboratory is

Anther cells are used to study mitosis.

The endosperm of coconut is an example of

The endosperm of the coconut is formed as cytokinesis does not follow karyokinesis.It is an example of a multinucleate cell.

In meiosis, the daughter cells differ from parent cell as well as amongst themselves due to

Due to segregation, independent assortment and crossing over at the time of meiosis, daughter cells exhibit variation.

In cell cycle, DNA replication takes place in

G1 phase, also called Gap I phase is characterized by increase in cell size. In the S phase or synthetic phase, DNA molecules replicate. G2 is the second growth phase, also called Gap II where there is intensive formation of RNAs and proteins. In the mitotic metaphase, the chromosome are arranged at the equatorial plate.

Replication of centriole occurs during

It occurs during S phase of Interphase.

The phase between Meiosis I and Meiosis II is called

The phase between Meiosis I and Meiosis II is called Interkinesis.There are no phases like Interphase I and Interphase II.Interkinesis is followed by prophase II I.Hence the sequence is Meiosis I-Interkinesis-Meiosis II.

Recombination of genes occur at

The crossing over of homologous chromosome occurs in pachytene of prophase first of meiosis. It is known as recombination.

Which of the following statement is incorrect about meiosis?

Meiosis is reductional division. The other options are all true for meiosis.

The cell plate formed during cytokinesis in plants forms

The cell plate goes on to form the middle lamellae of the new plant cell. The cell wall and the secondary cell wall form over this lamella .The cell membrane is internal to the middle lamella.

Meiosis is evolutionary significant because it results in

Meiosis provides a chance for new combinations of chromosomes mainly by the phenomenon of crossing over and random distribution of homologous chromosomes between daughter cells.

Recombinant nodules are found during which of the following

Knot like structure 'Chromosomes' found in the stage leptotene of prophase first of meiosis.

Synaptonemal complex is formed during

Synaptonemal complex is formed during meiotic prophase first.

Amitosis is characteristic of -

Amitosis is characteristic of lower organisms.

Which of the following occurs only in meiosis?

Pairing of homologous chromosomes occurs only in meiosis. The other processes are common to both mitosis and meiosis.

Nuclear membrane reappears in

The nuclear envelope reappears during Telophase.

Necessity of Meiosis II is

As a result of meiosis, 4 haploid gametes are produced. meiosis I results in segregation of homologus chromosomes. meiosis II is similar to normal mitosis, it results in formation of tetrad of cells i.e., four haploid daughter cells.It does not increase the number of chromosomes or cells in an organism . It produces haploid and not diploid cells.

At which stage of the cell cycle are histone proteins synthesized in a eukaryotic cell?

Histone proteins are synthesized during S-phase of cell cycle.

Meiosis I is reductional division. Meiosis II is equational division due to

Meiosis II is an equational division which is meant for maintaining the haploid number, separating the two chromatids of a chromosome.

During cell division, the spindle fibres attatch to the chromosome at a region called

Kinetochore is the proteinaceous covering of centriole, to which spindle fibres attatch.

Which part of the cell disappears during mitosis?

The nucleolus along with the nuclear membrane disappears.

In plant cells cytokinesis takes place by

In plants cytokinesis takes place by cell plate formation which is laid down at the middle and then grows to the sides.Furrow formation is seen in animals.The furrow deepens and meets in the centre dividing the cell cytoplasm into two.

Mitotic anaphase differs from metaphase in possessing

In mitotic anaphase, the sister chromatids separate from each other and begin to move towards the opposite poles.

Microtubule is involved in the

The spindle fibres involved in cell division is made of microtubules.

Synapsis is seen during

The characteristic events of each stage is as follows Leptotene-compaction of chromosomes. Pachytene-crossing over. Zygotene-synapsis. Diplotene-formation of chiasmata. Diakinesis-Terminalisation of chaismata.

The exchange of genetic material between chromatids of paired homologous chromosomes during first meiotic division is called

The points of attachment between homologous chromosomes after their separation in diplotene are called chiasmata. The process of pairing of homologous chromosomes is called synapsis, transformation is process of gene trasfer in bacteria ,where exogenous genetic material is transferred from one bacrerial cell to another bacterial cell.

Best stage to observe shape, size and number of chromosomes is

During metaphase, the centromeres of the chromosome lie on the equatorial plate according to their size and spatial arrangement. So it is the best time to count the number and study the morphology of chromosomes.

In which stage of the cell cycle will RNA polymerase enzyme be most active ?

RNA polymerase is needed for protein synthesis which occurs during G2 phase

Cytokinesis refers to

The process of division of cytoplasm is called Cytokinesis.

Bivalents in meiosis are

Bivalent formation occurs in pachytene stage of meiosis. In this stage, two chromatids of homologous chromosome (Bivalent) later on forms a cross and now showing a tetravalent or tetrad stage.


1. The terms homothallic and monoecious are used to denote
(a) unisexual condition
(b) bisexual condition
(c) staminate flowers
(d) pistillate flowers.

2. The most significant feature of vegetative propagation is that
(a) it is a method of producing a large number of individuals genetically identical to the parent.
(b) it is a method of producing a large number of individuals genetically different from the parent.
(c) it ensures that the progeny individuals are resistant to diseases and pests.
(d) it is an age old practice.

3. In animals, juvenile phase is followed by,
(a) reproductive phase
(b) senescent phase
(c) old age
(d) vegetative phase.

4. External fertilisation occurs in majority of
(a) fungi
(b) liverworts
(c) algae
(d) mosses

5. Vegetative propagation in Pistia occurs by
(a) sucker
(b) offset
(c) runner
(d) rhizome

6. Sugarcane is propagated by
(a) stem cutting
(b) leaf buds
(c) root cutting
(d) seeds

7. A multicellular, filamentous alga exhibits a type of sexual life cycle in which the meiotic division occurs after the formation of zygote. The adult filament of this alga has [NCERT Exemplar]
(a) haploid vegetative cells and diploid gametangia
(b) diploid vegetative cells and diploid gametangia
(c) diploid vegetative cells and haploid gametangia
(d) haploid vegetative cells and haploid gametangia

8. Offspring formed by sexual reproduction exhibit more variation than those formed by Asexual reproduction because [NCERT Exemplar]
(a) sexual reproduction is a lengthy process
(b) gametes of parents have qualitatively different genetic composition
(c) genetic material comes from parents of two different species
(d) greater amount of DNA is involved in sexual reproduction.

9. There is no natural death in single celled organisms like Amoeba and bacteria because [NCERT Exemplar]
(a) they cannot reproduce sexually
(b) they reproduce by binary fission
(c) parental body is distributed among the offspring
(d) they are microscopic

10. There are various types of reproduction. The type of reproduction adopted by an organism depends on [NCERT Exemplar]
(a) the habitat and morphology of the organism
(b) morphology of the organism
(c) morphology and physiology of the organism
(d) the organism’s habitat, physiology, and genetic makeup

11. Appearance of vegetative propagules from the nodes of plants such as sugarcane and ginger is mainly because [NCERT Exemplar]
(a) nodes are shorter than intemodes
(b) nodes have meristematic cells
(c) nodes are located near the soil
(d) nodes have non-photosynthetic cells

12. Identify the correct sequence of events.
(a) Gametogenesis → Syngamy Embryogenesis → Zygote
(b) Gametogenesis → Zygote → Syngamy → Embryogenesis
(c) Gametogenesis → Embryogenesis → Zygote → Syngamy
(d) Gametogenesis → Syngamy → Zygote

13. Development of unfertilised ovum into a new individual is called ____ .

Answer/Explanation

Answer:
Explaination: Parthenogenesis.

14. Earthworms and sponges are _____ animals.

Answer/Explanation

Answer:
Explaination: Bisexual/Hermaphrodite.

15. Gametogenesis and gamete transfer are _____ events.

Answer/Explanation

Answer:
Explaination: Pre-fertilisation.

16. ____ cycle occurs in non-primate mammals like cows and dogs.

Answer/Explanation

Answer:
Explaination: Oestrous.

17. _____ are the motile microscopic structures produced by many algal species.

Answer/Explanation

Answer:
Explaination: Zoospores.

18. Vegetative reproduction in plants is a method of _____ reproduction.

Answer/Explanation

Answer:
Explaination: Asexual.

19. ____ results in the formation of zygote.

Answer/Explanation

Answer:
Explaination: Syngamy.

20. In oviparous animals like reptiles and birds, the fertilised egg is covered by a _____ shell and laid in a safe place.

Answer/Explanation

Answer:
Explaination: Calcareous.

21. _____ is the vital link that ensures continuity between one generation to the next.

Answer/Explanation

Answer:
Explaination: Zygote.

22. The offspring of ____ animals are vulnerable to predators.

Answer/Explanation

Answer:
Explaination: Oviparous.

23. Match the asexual reproductive structures in Column I with the organisms in Column II.

Column I Column II
A. Conidia 1. Chiamydomonas
B. Gemmules 2. Hydra
C. Zoospores 3. Penicillium
D. Buds 4. Sponges
5. Banana
Answer/Explanation

Answer:
Explaination: A – 3, B – 4, C – 1, D – 2

24. Match the terms in Column I with the organisms in Column II.

Column I Column II
A. Fragmentation 1. Pistia
B. Binary fission 2. Spirogyra
C. Bulbils 3. Saccharomyces
D. Budding 4. Paramoecium
5. Agave
Answer/Explanation

Answer:
Explaination: A – 2, B – 4, C – 5, D – 3

25. In papaya and date palm, both male and female flowers are present on the same plant. [True/False]

Answer/Explanation

Answer:
Explaination: False.

26. Mitotic cell divisions occur during embryo-genesis. [True/False]

Answer/Explanation

27. Plants produced through vegetative propagation are called clones. [True/False]

Answer/Explanation

28. Bony fishes, bryophytes and pteridophytes show internal fertilisation. [True/False]

Answer/Explanation

Answer:
Explaination: False.

29. Gametes are always haploid and gametogenesis always involves meiosis. [True/False]

Answer/Explanation

Answer:
Explaination: False.

Directions (Q30 to Q34): Mark the odd one in each of the following groups.

30. Earthworms, Sponges, Cockroaches, Tapeworms.

Answer/Explanation

Answer:
Explaination: Cockroaches.

31. FUCHS, Cladophora, Funaria, Homo sapiens

Answer/Explanation

Answer:
Explaination: Cladophora.

32. Turkey, Honey bees, Camels, Rotifers

Answer/Explanation

Answer:
Explaination: Camels.

33. Bony fishes, Reptiles, Birds, Bryophytes

Answer/Explanation

Answer:
Explaination: Bony fishes.

34. Reptiles, Monkeys, Birds, Frogs

Answer/Explanation

Answer:
Explaination: Frogs.

35. Name the biological process that enables continuity of species. [Delhi 2012C]

Answer/Explanation

Answer:
Explaination: Reproduction.

Answer/Explanation

Answer:
Explaination: Reproduction is defined as the biological process, in which an organism gives rise to young ones similar to itself.

37. Name the mode of reproduction that helps in producing genetically identical offspring. [Delhi 2012C]

Answer/Explanation

Answer:
Explaination: Asexual reproduction.

38. Offspring derived by asexual reproduction are called clones. Justify giving two reasons. [AI 2010 HOTS]

Answer/Explanation

Answer:
Explaination: (i) They are genetically and morphologically identical among themselves.
(ii) They are also genetically and morphologically identical to the parent.

39. Name an organism where cell division in itself is a mode of reproduction. [AI 2013 Foreign 2010]

Answer/Explanation

Answer:
Explaination: Amoeba, Paramoecium (any one)

40. Name the type of asexual reproduction, where the parent cell ceases to exist. [Delhi 2017C]

Answer/Explanation

Answer:
Explaination: Binary fission.

41. Which ones of the following organisms exhibit binary fission?
Bacillus, Penicillium, Yeast, Amoeba. [AI 2012C]

Answer/Explanation

Answer:
Explaination: Bacillus and Amoeba

42. Provide an example of each of single-celled organisms, which reproduce by:
(i) binary fission, (ii) budding. [Delhli 2017C]

Answer/Explanation

Answer:
Explaination: (i) Amoeba/Paramoecium
(ii) Yeast.

43. Which of the following statements is true of yeast?
(a) The cell divides by binary fission. One of them develops into a bud.
(b) The cell divides unequally. The smaller cell develops into a bud.
(c) The cell produces conidia, which develop into a bud. [Delhi 2013C]

Answer/Explanation

Answer: b
Explaination: (b) is true of yeast.

44. Name the organism and the mode of reproduction represented in the diagram given below. [AI 2010C]

Answer/Explanation

Answer:
Explaination: – Yeast
– Budding.

45. In yeast and Amoeba, the parent cell divides to give rise to two new individual cells. How does the cell division differ in these two organisms? [Foreign 2010 HOTS]

Answer/Explanation

Answer:
Explaination: – In yeast, the cell division is unequal the small cell grows into a bud, which remains attached to the large cell in the initial stages, but gets separated later.
– In Amoeba, the cell reproduces by binary fission, where the cell divides into two halves and each one grows rapidly into an adult.

46. Write one difference between binary fission and budding. [Delhi 2017C]

Answer/Explanation

47. Under unfavourable conditions, Amoeba shows encystation. What does it mean?

Answer/Explanation

Answer:
Explaination: Under unfavourable conditions, Amoeba withdraws its pseudopodia and develops a three-layered thick wall called cyst around it this process is called encystation.

48. Give one example each of a fungus, which reproduces by: [AI 2014C]
(a) budding
(b) conidia

Answer/Explanation

Answer:
Explaination: (a) Yeast
(b) Penicillium

49. Name an alga that reproduces asexually through zoospores. Why are these reproductive units so called? [AI 2013]

Answer/Explanation

Answer:
Explaination: Chlamydomonas. The zoospores are motile (like animals).

50. Identify the reproductive structure and name the organism they are being released from. [Delhi 2010C]

Answer/Explanation

Answer:
Explaination: – Zoospores
– Chlamydomonas

51. Mention a characteristic feature and a function of zoospores in some algae. [AI 2010]

Answer/Explanation

Answer:
Explaination: – Zoospores are microscopic, thin-walled and motile with flagella.
– They are meant for asexual reproduction.

52. How does Penicillium reproduce asexually? [Delhi 2011]

Answer/Explanation

Answer:
Explaination: Penicillium reproduces asexually by forming conidia.

53. Name the respective asexual reproductive structures of Yeast and Sponge. [AI 2012C]

Answer/Explanation

Answer:
Explaination: Yeast – Buds
Sponge – Gemmules

54. Which of the following statements is true of Hydra? [AI 2013C]
(a) It produces asexual gemmules.
(b) It produces unicellular bud.
(c) It produces multicellular bud.

Answer/Explanation

Answer: c
Explaination: (c) is true of Hydra

55. How is the phenomenon regeneration useful to a lizard?

Answer/Explanation

Answer:
Explaination: A lizard can discard a part of its tail, when in danger and it is regenerated later.

56. Name the vegetative propagules in the following: [AI 2014]
(a) Agave
(b) Bryopbyllum

Answer/Explanation

Answer:
Explaination: (a) Bulbils
(b) Leaf buds.

57. Give one example each of a plant that reproduces by
(a) runner
(b) offset

Answer/Explanation

Answer:
Explaination: (a) Grasses
(b) Water hyacinth.

58. Write the name of the organism that is referred to as the ‘Terror of Bengal’ [Delhi 2014]

Answer/Explanation

Answer:
Explaination: Water hyacinth.

59. Identify the picture and mention the vegetative part that helps it to propagate. [AI 2015C]

Answer/Explanation

Answer:
Explaination: – It is rhizome (modified stem) of ginger.
– Rhizome is the vegetative propagule, the buds in it help it to propagate.

60. Identify ‘A’ in the given diagram and state its function [Delhi 2016C]

Answer/Explanation

Answer:
Explaination: – ‘A’ shows the nodes of the rhizome of ginger.
– The buds arising from the nodes produce new plants, i.e., vegetative propagation.

61. Which of the following statements is true of ginger? [AI 2013C]
(a) Germinating bud appears from the eye of the stem tuber.
(b) Germinating bud appears from the node of the rhizome.
(c) Germinating bud appears from the notch of the leaf margin.

Answer/Explanation

Answer: b
Explaination: (b) is true of Ginger

62. Why do intemodal segments of sugarcane fail to propagate vegetatively, even when they are in contact with damp soil? [CBSE Sample Paper 2010 HOTS]

Answer/Explanation

Answer:
Explaination: The plantlets arise from the buds present on the nodes only when the nodes come in contact with the damp soil, will they produce roots and shoots and not from internodal segments.

63. Name the vegetative propagules in [Foreign 2017]
(i) Potato and
(ii) Pistia.

Answer/Explanation

Answer:
Explaination: (i) ‘Eyes’ (buds) in the tuber
(ii) Offset.

64. Name the units of vegetative propagation in grasses and water hyacinth. [AI 2012C]

Answer/Explanation

Answer:
Explaination: Grasses – Runner
Water hyacinth – Offset

65. Identify ‘A’ in the diagram and mention its function. [Delhi 2016 C]

Answer/Explanation

Answer:
Explaination: – ‘A’ is the offset of water hyacinth.
– It is the vegetative propagule that helps it to propagate.

66. Which of the following statements is true of Bryophyllum? [Delhi 2013C]
(a) Germinating bud appears from the eye of the stem tuber.
(b) Germinating bud appears from the node of the rhizome.
(c) Geminating bud appears from the notch at the leaf margin.

Answer/Explanation

Answer: c
Explaination: (c) is true of Bryophyllum.

67. Identify ‘A’ in the diagram and mention its function. [Delhi 2016C]

Answer/Explanation

Answer:
Explaination: – ‘A’ represents the leaf buds on a leaf of Bryophyllum.
– The leaf buds produce plantlets when the leaf falls and comes in contact with damp soil.

68. Name the mode of reproduction that ensures the creation of new variants, [Delhi 2012C]

Answer/Explanation

Answer:
Explaination: Sexual reproduction.

69. Name the phase, all organisms have to pass through before they can reproduce sexually. [AI 2011]

Answer/Explanation

Answer:
Explaination: Juvenile phase (vegetative phase in plants)

70. What marks the end of juvenile phase in flowering plants?

Answer/Explanation

Answer:
Explaination: Initiation of floral buds marks the end of juvenile phase in flowering plants.

71. Name the two groups of plants which show clear cut vegetative, reproductive and senescent phases.

Answer/Explanation

Answer:
Explaination: Annual and biennial plants.

72. Mention the unique flowering phenomenon exhibited by Strobilanthus kunthiana (neelakurinji). [Delhi 2012]

Answer/Explanation

Answer:
Explaination: This plant flowers once in twelve years.

73. Mention the unique feature with respect to flowering and fruiting in bamboo species. [Delhi 2012]

Answer/Explanation

Answer:
Explaination: Bamboo flowers only once in its life time, generally after 50-100 years. It produces a large number of fruits and seeds and dies.

74. Name two animals that exhibit oestrous cycle. [Foreign 2016]
Or
Give an example of an animal that exhibits oestrous cycle. [AI 2014C]

Answer/Explanation

Answer:
Explaination: Cows/Sheep/Rats/Dogs/Deers/Tiger.

75. Write the two pre-fertilisation events from the list given below: Syngamy, Gametogenesis, Embryogenesis, Pollination. [Delhi 2014C]

Answer/Explanation

Answer:
Explaination: Gametogenesis and pollination.

76 Which one of the following statements is true of Cucurbits?
(a) It is monoecious producing both staminate and pistillate flowers in the same plant.
(b) It is monoecious producing staminate and pistillate flowers in two different plants.
(c) It is dioecious producing staminate flowers in one plant and pistillate flowers in another. [Delhi 2013C]

Answer/Explanation

Answer: a
Explaination: (a) is true of Cucurbits.

77. Which of the following statements is true of date palm? [AI 2013C]
(a) It is monoecious producing both staminate flowers and pistillate flowers in the same plant.
(b) It is monoecious producing staminate flowers in one tree and pistillate flowers in another tree.
(c) It is dioecious producing staminate flowers in one tree and pistillate flowers in another tree.

Answer/Explanation

Answer: c
Explaination: (c) is true of date palms.

78. Cucurbits and papaya plants bear staminate and pistillate flowers. Mention the categories they are put under separately on the basis of the type of flowers they bear. [Delhi 2012 HOTS]
Or
How are Cucurbita plants different from papaya plants with reference to the flowers they bear? [AI 2011C HOTS]

Answer/Explanation

Answer:
Explaination: – Cucurbits are monoecious, as staminate and pistillate flowers are found in the same individual plant.
– Papaya plants are dioecious as an individual plant bears exclusively either staminate flowers or pistillate flowers.

79. All papaya plants bear flowers, but fruits are seen only in some. Explain. [AI 2011C HOTS]
Or
All date palm plants bear flowers, but fruits are seen in some. Explain. [AI 2011C]

Answer/Explanation

Answer:
Explaination: Papaya/date palm is dioecious the plants which produce only male flowers, do not bear fruits, while the plants which produce female flowers, bear fruits.

80. Label the male and female sex organs writh their technical terms in the figure of Chara, given below.

Answer/Explanation

Answer:
Explaination:

81. Meiosis is an essential event in the sexual cycle of any organism. Give two reasons.? [Foreign 2015 HOTS]

Answer/Explanation

Answer:
Explaination: (i) It creates genetic variation in the offspring and help in survival of species.
(ii) It is necessary to maintain the characteristic chromosome number through generations.

82. Name the group of organisms that produces non-motile male gametes. How do they reach the female gamete for fertilisation? [Foreign 2011]

Answer/Explanation

Answer:
Explaination: – Seed plants (gymnosperms and angiosperms) produce non-motile male gametes.
– They are carried in the pollen tube to the female gametes.

83. Name the phenomenon and one bird where the female gamete directly develops into a new organism. [AI 2013]

Answer/Explanation

Answer:
Explaination: Parthenogenesis is the phenomenon. Turkey shows it.

84. Name the common phenomenon with reference to reproduction in rotifers, honey bees and turkey. [Delhi 2013C]

Answer/Explanation

Answer:
Explaination: They all show parthenogenesis.

85. Name the phenomenon and the cell, responsible for the development of a new individual without fertilisation as seen in honeybees. [Foreign 2011]

Answer/Explanation

Answer:
Explaination: – Parthenogenesis is the phenomenon.
– Female gamete (ovum) is the cell.

86. In the whiptail lizards, only females are bom generation after generation. There are no males. How is this possible? [CBSE Sample Paper 2010 HOTS]
Or
The turkey usually produces females for several generations. How is this possible? [CBSE Sample Paper 2010 HOTS]

Answer/Explanation

Answer:
Explaination: The whiptail lizard/turkey shows parthe-nogenesis, the phenomenon in which the female gamete undergoes development without fertilisation into a new individual in these animals it develops into a female individual.

87. Mention the site where syngamy occurs in amphibians and reptiles, respectively. [AI 2010]

Answer/Explanation

Answer:
Explaination: – In amphibians, it occurs in the medium of water, i.e. external fertilisation.
– In reptiles, it occurs inside the body of female animals, i.e. internal fertilisation.

88. In which two of the following organisms is fertilisation external?
Bony fishes, Ferns, Frogs, Birds [Delhi 2014C]

Answer/Explanation

Answer:
Explaination: Bony fishes and frogs.

89. Name the type of cell division that takes place in the zygote of an organism exhibiting haplontic life cycle. [Delhi 2011]

Answer/Explanation

Answer:
Explaination: Meiosis.

90. At what stage does meiosis occur in an organism exhibiting haploidic life cycle and mention the fate of the products thus produced. [Delhi 2019]

Answer/Explanation

Answer:
Explaination: – Meiosis occurs during the germination of zygote.
– The haploid spores formed develop into haploid individuals.

We hope the given Biology MCQs for Class 12 with Answers Chapter 1 Reproduction in Organisms will help you. If you have any query regarding CBSE Class 12 Biology Reproduction in Organisms MCQs Pdf, drop a comment below and we will get back to you at the earliest.


Cell Cycle

In asexually reproducing eukaryotic cells, one &ldquoturn&rdquo of the cell cycle consists of two general phases: interphase, followed by mitosis and cytokinesis. Most of the cells in a fully-developed multicellular organisms are typically found in interphase. Mitosis is the the point in the cell cycle associated with division or distribution of replicated genetic material to two daughter cells. During mitosis the cell nucleus breaks down and two new, fully functional, nuclei are formed. After mitosis is finished, Cytokinesis is the process that divides the cytoplasm into two distinctive cells.

Interphase

G1 Phase

The first stage of interphase is called the G1 phase, or first "gap". During G1, the cell is quite active at the biochemical level. The cell is accumulating the building blocks of all cellular components, as well as accumulating enough energy reserves to complete the task of replicating each chromosome in the nucleus.

A cell moves through a series of phases in an orderly manner. During interphase, G1 involves cell growth and protein synthesis, the S phase involves DNA replication and the replication of the centrosome, and G2 involves further growth and protein synthesis. The mitotic phase follows interphase. Mitosis is nuclear division during which duplicated chromosomes are segregated and distributed into daughter nuclei. Usually the cell will divide after mitosis in a process called cytokinesis in which the cytoplasm is divided and two daughter cells are formed.

S Phase

Throughout interphase, nuclear DNA remains in a semi-condensed chromatin configuration. In (synthesis phase), DNA replication results in the formation of two identical copies of each chromosome&mdashsister chromatids&mdashthat are connected to each other along their length by proteins called cohesins. At the end of this stage, each chromosome has been replicated.

Eukaryotic cells include various microtubule organizing centers (MTOCs) the most relevant ones here are the centrosomes. The centrosomes are often duplicated during S phase (although they will move to opposite poles of the cell only during M phase). The two resulting centrosomes will give rise to the mitotic spindle, the apparatus that orchestrates the movement of chromosomes later during mitosis. MTOCs perform other functions in the organization of the microtubules, including the growth and localization of flagella. In some organisms (notably animals) centrosomes include of a pair of rod-like centrioles composed of tubulin and other proteins that sit at right angles to one another other. These structures are also often found at the sites of organization of cilia or flagella. However, centrioles are not observed in many fungi or higher plants.

G2 Phase

G2 phase, or second gap, is defined as the stage in which cells appear to have twice the amount of DNA observed in G1, while the chromosomes still appear to be diffuse (as they are throughout interphase). However, G2 cells are often dealing with issues encountered during replication (including replication forks stalled by DNA damage) and these issues must be resolved prior to entry into M phase. Some cell organelles are duplicated, and the cytoskeleton is dismantled to provide resources for the mitotic spindle. The final preparations for the mitotic phase must be completed before the cell is able to enter the first stage of mitosis. As discussed below, this a critical juncture for the cell, and the site of a cell cycle "checkpoint". Problems observed by the cell at this point will lead to an arrest of the cell cycle in G2 until these problems are resolved.

G0 Phase

Cells in the G0 phase are not actively preparing to divide. The cell is in a quiescent (mitotically inactive) stage, having exited the cell cycle. Some cells enter G0 temporarily until an external signal triggers the onset of G1. Other cells that never or rarely divide, such as mature cardiac muscle and nerve cells, remain in G0 permanently. These cells generally exit the cell cycle immediately after cytokinesis.

A Quick Aside: Structure of Chromosomes During the Cell Cycle

If the DNA from all 46 chromosomes in a human cell nucleus was laid out end to end, it would measure approximately two meters however, its diameter would be only 2 nm. Considering that the size of a typical human cell is about 10 µm, DNA must be tightly packaged to fit in the cell&rsquos nucleus. At the same time, it must also be readily accessible for the genes to be expressed. During some stages of the cell cycle, the long strands of DNA are condensed into compact chromosomes. There are a number of ways that chromosomes are compacted.

When should we expect to see highly condensed DNA in the cell (which phases of the cell cycle)? When would the DNA remain un-compacted (during which phases of the cell cycle)?

Double-stranded DNA wraps around histone proteins to form nucleosomes that have the appearance of &ldquobeads on a string.&rdquo The nucleosomes are coiled into a 30-nm chromatin fiber. When a cell undergoes mitosis, the chromosomes condense even further.

Mitosis and Cytokinesis

During cell division a cell undergoes two major processes. First, it completes mitosis, during which the duplicated information enclosed in the nucleus is distributed between two daughter nuclei. Cytokinesis then occurs, dividing the cytoplasm and cell body into two new cells.

The major phases of Mitosis are visually distinct from one another and were originally characterized by what could be seen by viewing dividing cells under a microscope. Some instructors may ask you be able to distinguish each phase be looking at images of cells or more commonly by inspection of cartoon depiction of mitosis. Dr. Britt will employ these vocabulary words, so you should learn them.

DNA is stained blue, microtubules are green. The stages of cell division oversee the separation of identical genetic material into two new nuclei, followed by the division of the cytoplasm. Mitosis is divided into five stages&mdashprophase, prometaphase, metaphase, anaphase, and telophase&mdashvisualized here by light microscopy with fluorescence. Mitosis is usually followed by cytokinesis, shown here by a transmission electron microscope. (credit "diagrams": modification of work by Mariana Ruiz Villareal credit "mitosis micrographs": modification of work by Roy van Heesbeen credit "cytokinesis micrograph": modification of work by the Wadsworth Center, NY State Department of Health donated to the Wikimedia foundation scale-bar data from Matt Russell)

Prophase is the first phase of mitosis, during which the loosely packed chromatin coils and condenses into visible chromosomes. During prophase, each chromosome becomes visible with its identical partner (sister chromatid) attached, forming the familiar X-shape of sister chromatids. The nucleolus disappears early during this phase, and the nuclear envelope also disintegrates. The centrosome begins to migrate to each pole of the cell, and microtubules begin to emanate from this region. This marks the beginning of formation of the mitotic spindle.

Near the end of prophase there is an invasion of the nuclear area by microtubules from the mitotic spindle. The nuclear membrane has disintegrated. The kinetochore is a protein structure on the centromere that is the point of attachment between the mitotic spindle and the sister chromatids. This attachment results from the massive accumulation of motor proteins on each kinetochore- their cargo is the kinetochore itself, and they travel along the microtubules. This stage is referred to as late prophase or alternatively &ldquoprometaphase&rdquo to indicate the transition between prophase and metaphase.

What is the kinetochore?

You may recall that we have discussed that larger objects diffuse very slowly in the cell, and are assisted in their diffusion, and provided some directionality, by motor proteins (dyneins and kinesins) that propel their cargo along microtubules. A chromosome is certainly the most massive structure that has to be moved by motor proteins. For most eukaryotes, each sister chromatid carries a centromere at a single, unique position. (That position is replicated at each round of DNA replication.) Some proteins bind at the centromere throughout the cell cycle. Other additional proteins only load onto this position in prophase, and the entire assemblage (protein new and old, at this position) is now called the kinetochore. The kinetochore includes several hundred regulatory, structural, and motor proteins. The kinetochore has several sequential jobs: to pull chromosomes to the metaphase plate, to establish tension by pulling each sister tin opposite directions, to detect the presence or absence of tension, to trigger the release of the sister chromatids from one another once tension is established at all kinetochores simultaneously, and finally to pull the sisters to opposite poles.

Why is tension important? From the discussion and diagram shown above, can you determine why the establishment of tension is critical for ensuring that sister chromatids move to opposite poles?

Metaphase is the second stage of mitosis. During this stage, the sister chromatids, with their attached microtubules, line up along a linear plane in the middle of the cell. A metaphase plate forms between the centrosomes that are now located at either end of the cell. The metaphase plate is the name for the plane through the center of the spindle on which the sister chromatids are positioned. The microtubules are now poised to pull apart the sister chromatids and bring one from each pair to each side of the cell. Establishment of tension at every sister chromatid will result in the severing of cohesin proteins that bind the two sisters together, allowing the now properly aligned kinetochores to haul each sister to opposite poles. This migration is known as.

. Anaphase. Anaphase takes place over a few minutes, when the pairs of sister chromatids are separated from one another. These chromosomes are pulled to opposite ends of the cell by their kinetochores, as the microtubules shorten. Each end of the cell receives one partner from each pair of sister chromatids, ensuring that the two new daughter cells will contain identical genetic material. The genome has now been successfully replicated (in S phase) and evenly distributed!

Telophase is the final stage of mitosis. Telophase is characterized by the formation of two new daughter nuclei at either end of the dividing cell. These newly formed nuclear membranes surround the genetic material, which uncoils such that the chromosomes return to loosely packed chromatin. Nucleoli also reappear within the new nuclei, and the mitotic spindle breaks apart, each new cell receiving its own complement of DNA, organelles, membranes, and centrioles (if it's a species that has this feature). At this point, the cell is already beginning to split in half as cytokinesis begins.

A cell accidentally produces 4 MTOCs, instead of 2. What might be the consequences for mitosis and the genetic content of the daughter cells?

Cytokinesis

Cytokinesis is the second part of the mitotic phase during which cell division is completed by the physical separation of the cytoplasmic components into two daughter cells. Although the stages of mitosis are similar for most eukaryotes, the process of cytokinesis is quite different for eukaryotes that have cell walls, such as plant cells.

In cells such as animal cells that lack cell walls, cytokinesis begins following the onset of anaphase. A contractile ring composed of actin filaments forms just inside the plasma membrane at the former metaphase plate. The actin filaments pull the equator of the cell inward, forming a fissure. This fissure, or &ldquocrack,&rdquo is called the cleavage furrow. The furrow deepens as the actin ring contracts, and eventually the membrane and cell are cleaved in two (see the figure below).

In plant cells, a cleavage furrow is not possible because of the rigid cell walls surrounding the plasma membrane. A new cell wall must form between the daughter cells. During interphase, the Golgi apparatus accumulates enzymes, structural proteins, and glucose molecules prior to breaking up into vesicles and dispersing throughout the dividing cell. During telophase, these Golgi vesicles move on microtubules to collect at the metaphase plate. There, the vesicles fuse from the center toward the cell walls this structure is called a cell plate. As more vesicles fuse, the cell plate enlarges until it merges with the cell wall at the periphery of the cell. Enzymes use the glucose that has accumulated between the membrane layers to build a new cell wall of cellulose. The Golgi membranes become the plasma membrane on either side of the new cell wall (see panel b in the figure below).

In part (a), a cleavage furrow forms at the former metaphase plate in the animal cell. The plasma membrane is drawn in by a ring of actin fibers contracting just inside the membrane. The cleavage furrow deepens until the cells are pinched in two. In part (b), vesicles coalesce at the former metaphase plate in a plant cell. The vesicles fuse and form the cell plate. The cell plate grows from the center toward the cell walls. New cell walls are made from the vesicle contents.

Cell Cycle Check Points

It is essential that daughter cells be nearly exact duplicates of the parent cell. Mistakes in the duplication or distribution of the chromosomes lead to mutations that may be passed forward to every new cell produced from the abnormal cell. To prevent a compromised cell from continuing to divide, there are internal control mechanisms that operate at three main cell cycle checkpoints at which the cell cycle can be stopped until conditions are favorable. These checkpoints occur near the end of G1, at the G2&ndashM transition, and during metaphase (see figure below).

The cell cycle is controlled at three checkpoints. Integrity of the DNA is assessed at the G1 checkpoint. Proper chromosome duplication is assessed at the G2 checkpoint. Attachment of each kinetochore to a spindle fiber is assessed at the M checkpoint.

G1 Checkpoint

The G1 checkpoint determines whether all conditions are favorable for cell division to proceed into S phase where DNA replication occurs. The G1 checkpoint, also called the restriction point, is the point at which the cell irreversibly commits to the cell-division process. In addition to adequate reserves and cell size, there is a check for damage to the genomic DNA at the G1 checkpoint. A cell that does not meet all the requirements will not be released into the S phase.

G2 Checkpoint

The G2 checkpoint bars the entry to the mitotic phase if certain conditions are not met. As in the G1 checkpoint, cell size and protein reserves are assessed. However, the most important role of the G2 checkpoint is to ensure that all of the chromosomes have been replicated and that the replicated DNA is not damaged.

M Checkpoint

The M checkpoint occurs near the end of the metaphase stage of mitosis. The M checkpoint is also known as the spindle checkpoint because it determines if all the sister chromatids are correctly attached to the spindle microtubules. Because the separation of the sister chromatids during anaphase is a critical step, the cycle will not proceed until the kinetochores of each pair of sister chromatids are firmly anchored to spindle fibers arising from opposite poles of the cell.

Watch what occurs at the G1, G2, and M checkpoints by visiting this animation of the cell cycle.

When the Cell Cycle gets out of Control

Most people understand that cancer or tumors are caused by abnormal cells that multiply continuously. If the abnormal cells continue to divide unstopped, they can damage the tissues around them, spread to other parts of the body, and eventually result in death. In healthy cells, the tight regulation mechanisms of the cell cycle prevent this from happening, while failures of cell cycle control can cause unwanted and excessive cell division. Failures of control may be caused by inherited genetic abnormalities that compromise the function of certain &ldquostop&rdquo and &ldquogo&rdquo signals. Environmental insult that damages DNA can also cause dysfunction in those signals. Often, a combination of both genetic predisposition and environmental factors lead to cancer.

The process of a cell escaping its normal control system and becoming cancerous may actually happen throughout the body quite frequently. Fortunately, certain cells of the immune system are capable of recognizing cells that have become cancerous and destroying them. However, in certain cases the cancerous cells remain undetected and continue to proliferate. If the resulting tumor does not pose a threat to surrounding tissues, it is said to be benign and can usually be easily removed. If capable of damage, the tumor is considered malignant and the patient is diagnosed with cancer.

Homeostatic Imbalances:

Cancer Arises from Homeostatic Imbalances

Cancer is an extremely complex condition, capable of arising from a wide variety of genetic and environmental causes. Typically, mutations or aberrations in a cell&rsquos DNA that compromise normal cell cycle control systems lead to cancerous tumors. Cell cycle control is an example of a homeostatic mechanism that maintains proper cell function and health. While progressing through the phases of the cell cycle, a large variety of intracellular molecules provide stop and go signals to regulate movement forward to the next phase. These signals are maintained in an intricate balance so that the cell only proceeds to the next phase when it is ready. This homeostatic control of the cell cycle can be thought of like a car&rsquos cruise control. Cruise control will continually apply just the right amount of acceleration to maintain a desired speed, unless the driver hits the brakes, in which case the car will slow down. Similarly, the cell includes molecular messengers, such as cyclins, that push the cell forward in its cycle.

In addition to cyclins, a class of proteins that are encoded by genes called proto-oncogenes provide important signals that regulate the cell cycle and move it forward. Examples of proto-oncogene products include cell-surface receptors for growth factors, or cell-signaling molecules, two classes of molecules that can promote DNA replication and cell division. In contrast, a second class of genes known as tumor suppressor genes sends stop signals during a cell cycle. For example, certain protein products of tumor suppressor genes signal potential problems with the DNA and thus stop the cell from dividing, while other proteins signal the cell to die if it is damaged beyond repair. Some tumor suppressor proteins also signal a sufficient surrounding cellular density, which indicates that the cell need not presently divide. The latter function is uniquely important in preventing tumor growth: normal cells exhibit a phenomenon called &ldquocontact inhibition&rdquo thus, extensive cellular contact with neighboring cells causes a signal that stops further cell division.

These two contrasting classes of genes, proto-oncogenes and tumor suppressor genes, are like the accelerator and brake pedal of the cell&rsquos own &ldquocruise control system,&rdquo respectively. Under normal conditions, these stop and go signals are maintained in a homeostatic balance. Generally speaking, there are two ways that the cell&rsquos cruise control can lose control: a malfunctioning (overactive) accelerator, or a malfunctioning (underactive) brake. When compromised through a mutation, or otherwise altered, proto-oncogenes can be converted to oncogenes, which produce oncoproteins that push a cell forward in its cycle and stimulate cell division even when it is undesirable to do so. For example, a cell that should be programmed to self-destruct (a process called apoptosis) due to extensive DNA damage might instead be triggered to proliferate by an oncoprotein. On the other hand, a dysfunctional tumor suppressor gene may fail to provide the cell with a necessary stop signal, also resulting in unwanted cell division and proliferation.

A delicate homeostatic balance between the many proto-oncogenes and tumor suppressor genes delicately controls the cell cycle and ensures that only healthy cells replicate. Therefore, a disruption of this homeostatic balance can cause aberrant cell division and cancerous growths.


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