Top 25+ Cell Cycle and Cell Division - Biology Questions and Answers For NEET 2024 Exam Preparation

Q1. Our cell can divide itself once approximately in

1. 24 minutes
2. 24 hours
3. 24 seconds
4. 24 days

Answer: (b)

---

Q2. Ribosomes are produced in

1. cytoplasm
2. nucleolus
3. mitochondria
4. Golgibody

Answer: (b)

---

Q3. Which statement best explains the evolutionary advantage of meiosis?

1. Genetic recombinations are possible from generation to generation
2. Meiosis alternates with mitosis from generation to generation
3. Meiosis is necessary for sexual reproduction.
4. The same genetic system is passed on from generation to generation.

Answer: (a)

Meiosis involves exchange of genes between homologous chromosomes. So the gametes produced are genetically different from each other. Offsprings produced by the fusion of gametes therefore also show recombinations or genetic variations. These variations in the offsprings make organisms more adaptable to the environment and these have a definite role in evolution.

---

Q4. Which stages of cell division do the following figures A and B represent respectively?

1. (b)
2. (d)
3. (a)
4. (d)

Answer: (b)

---

Q5. Anaphase Promoting Complex (APC) is a protein degradation machinery necessary for proper mitosis of animal cells. If APC is defective in a human cell, which of the following is expected to occur?

1. Chromosomes will not segregate
2. Chromosomes will be fragmented
3. Recombination of chromosome arms will occur
4. Chromosomes will not condense

Answer: (a)

During anaphase, Anaphase Promoting Complex (APC) is a protein necessary for separation of daughter chromosomes. A defective APC will cause the chromosomes fail to segregate during anaphase.

---

Q6. Replication of centriole occurs during

1. Mid metaphase
2. Late metaphase
3. Early anaphase
4. Interphase

Answer: (d)

During the S-period, the centrioles separate and undergo duplication which produces two pairs of centrioles still contained within the radiating masses of microtubules.

---

Q7. The correct sequence of stages in cell cycle is

1. $G_1$ , $G_2$ , S, M
2. $G_1$ , S, $G_2$ , M
3. M, S, $G_1$ , $G_2$
4. $G_2$ , $G_1$ , M, S

Answer: (b)

---

Q8. At metaphase, chromosomes are attached to the spindle fibres by their

1. Satellites
2. Centromere
3. Secondary constrictions
4. Kinetochores

Answer: (d)

---

Q9. Which one of the following precedes re- formation of the nuclear envelope during M phase of the cell cycle?

1. Transcription from chromosomes, and reassembly of the nuclear lamina
2. Formation of the contractile ring, and formation of the phragmoplast
3. Decondensation from chromosomes, and reassembly of the nuclear lamina
4. Formation of the contractile ring, and transcription from chromosomes

Answer: (b)

M phase or mitotic phase is the actual division phase and formation of contractile ring and formation phragmoplast precedes reformation of nuclear envelope. Contractile ring is belt-like bundle of actin and myosin that appears during cell division immediately below the plasma membrane. Contraction of this ring leads to the separation of the two daughter cells.

Phragmoplast is the region of plant cell cytoplasm that becomes evident in the latter stages of mitosis. It forms from the residual microtubules of the polar mitotic spindle and appears to function in transporting materials to the new cell plate forming between the daughter cells.

Once the cell plate is complete, the phragmoplast is divided and gradually disappears, the cell plate finally becoming transformed into the middle lamella lying between the new cell walls.

---

Q10. The synaptonemal complex appears

1. in zygotene stage.
2. between homologous chromosomes.
3. composed of DNA + protein.
4. All of the above

Answer: (d)

The synaptonemal complex is formed at the region of synapsis. It is a protein structure that forms between homologous chromosomes (two pairs of sister chromatids) during meiosis and is thought to mediate chromosome pairing, synapsis, and recombination. This stage appears in zygotene stage of prophase I of meiosis I.

---

Q11. Assertion: The crossing over is an enzyme-mediated process.

Reason: The enzyme involved in crossing over is lyase.

1. If both Assertion and Reason are true but the Reason is not the correct explanation of the Assertion.
2. If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
3. If Assertion is true but Reason is false.
4. If both Assertion and Reason are false.

Answer: (c)

Crossing over is the exchange of genetic material between two homologous pair of chromosomes. Crossing over is also an enzyme-mediated process and the enzyme involved is called recombinase.

---

Q12. In meiosis, the daughter cells differ from parent cell as well as amongst themselves due to

1. segregation and crossing over
2. independent assortment and crossing over
3. segregation, independent assortment and crossing over
4. segregation and independent assortment.

Answer: (c)

In meiosis, the daughter cells differ from parent cell as well as amongst themselves due to segregation, independent assortment and crossing over. Daughter cells inhibit variations.

Meiosis leads to recombinations or new combinations of genes or characters as a result of crossing over. Due to these recombinations, variations are created, which have role in process of evolution.

---

Q13. Meiosis takes place in –

1. Intercalary meristem
2. Apical meristem
3. Reproductive cells
4. Vegetative cells

Answer: (c)

Meiosis takes place in reproductive cells.

---

Q14. Diakinesis is characterized by

1. Assemblage of spindle
2. Condensation of chromosome
3. Disappearance of nucleous and nuclear membrane
4. All the above

Answer: (d)

---

Q15. Significance of meiosis lies in

1. maintaining consistency of chromosome number during sexual reproduction.
2. reduction of chromosome number to one half.
3. production of genetic variability.
4. all of the above.

Answer: (d)

Meiosis results in four daughter cells and each with having half the number of chromosomes of the parent cell. Meiosis begins with a parent cell that is diploid, i.e it has two copies of each chromosome. The parent cell undergoes one round of DNA replication followed by two separate cycles of nuclear division. The process leads to production of four daughter cells that are haploid, which means that they contain half the number of chromosomes of the diploid parent cell. The significance of meiosis are:

1. It maintains the same chromosome number in the sexually reproducing organisms. From a diploid cell, haploid gametes are produced which in turn fuse to form a diploid cell.
2. It restricts the multiplication of chromosome number and maintains the stability of the species.
3. Maternal and paternal genes get exchanged during crossing over which results in variations among the offspring.
4. All the four chromatids of a homologous pair of chromosomes segregate and go over separately to four different daughter cells. This leads to variation in the daughter cells genetically.

---

Q16. How many mitotic divisions are needed for a single cell to make 128 cells?

1. 32
2. 7
3. 28
4. 14

Answer: (b)

Mitosis is an equational division where after division each cell produces two daughter cells, therefore after 7 divisions one cell will give 128 cells in case of mitosis.

---

Q17. During cell cycle, the DNA replication occurs in

1. S-phase
2. M-phase
3. $G_{1}$ -phase
4. $G_{2}$ –phase

Answer: (a)

---

Q18. The separation of daughter chromosomes occurs in

1. Metaphase
2. The beginning of anaphase
3. Late prophase
4. Early prophase

Answer: (b)

---

Q19. The two chromatids of a metaphase chromosome represent

1. homologous chromosomes of a diploid set
2. non-homologous chromosomes joined at the centromere
3. replicated chromosomes to be separated at anaphase
4. maternal and paternal chromosomes joined at the centromere

Answer: (c)

---

Q20. Number of chromosomes in a zygote may be indicated by

1. x
2. 4x
3. 3x
4. 2x

Answer: (d)

---

Q21. Synapsis occurs between

1. spindle fibres and centromere
2. two homologous chromosomes
3. mRNA and ribosomes
4. a male and a female gamete.

Answer: (b)

---

Q22. Crossing over that results in genetic recombination in higher organisms occur between

1. non-sister chromatids of a bivalent
2. sister chromatids of bivalent
3. two daughter nuclei
4. two different bivalents

Answer: (a)

---

Q23. At what stage of the cell cycle are histone proteins synthesized in a eukaryotic cell?

1. During S-phase
2. During entire prophase
3. During $G_2$ stage of prophase
4. During telophase

Answer: (a)

During S phase or synthetic phase the replication of DNA takes place. For replication of DNA histone proteins are required so they are also synthesized during this phase. It takes about 30%- 50% of the total cell cycle.

Prophase and telophase are stages involved in mitosis or meiosis. During $G_2$ phase division of centrioles, mitochondria and chloroplasts occurs.

---

Q24. The complex formed by a pair of synapsed homologous chromosomes is called

1. axoneme
2. equatorial plate
3. bivalent
4. kinetochore.

Answer: (c)

During zygotene stage chromosomes start pairing together and this process of association is called synapsis. Such paired chromosomes are called homologous chromosomes.

Electron micrographs of this stage indicate that chromosome synapsis is accompanied by the formation of complex structure called synaptonemal complex.

The complex formed by a pair of synapsed homologous chromosomes is called a bivalent or a tetrad.

---

Q25. Best stage to observe shape, size and number of chromosomes is

1. metaphase
2. interphase
3. prophase
4. telophase

Answer: (a)

---