Meiosis

Q. You have studied mitosis in onion root tip cells. It has 16 chromosomes in each cell. Can you tell:
(i) How many chromosomes will the cell have at the $G_1$ phase, after S phase, and after M phase?

Q. What is protoplast fusion?

Q. Terminalisation of chiasmata occurs during:

1. Diplotene
2. Diakinesis
3. Pachytene
4. Zygotene

Q.

Does DNA replication occur in meiosis?

Q. Primary endosperm nucleus (PEN) is formed by the fusion of

1. 2 antipodal cell nuclei + 1 male gamete nucleus
2. 2 polar nuclei + 1 synergid cell nucleus
3. 2 polar nuclei + 1 male gamete nucleus
4. 1 polar nucleus + 1 antipodal cell nucleus + 1 synergid cell nucleus

Q.

Does DNA replicate in both mitosis and meiosis?

Q.

What is the shortest phase of mitosis?

Q. Which of the following statements about the four cells formed after meiosis is true?
(i) All of the four cells are haploid
(ii) Two of the four cells are haploid and the other two are diploid
(iii) They are genetically identical
(iv) They are genetically dissimilar

1. Only (i)
2. Both (ii) and (iv)
3. Both (i) and (iv)
4. Both (i) and (ii)

Q. If there are 30 chromosomes in G1 phase then what will be number of bivalents in zygotene stage?

1. 15
2. 30
3. 45
4. 60

Q. If 2n = 8, what shall be the number of chromatids in each daughter cell after meiosis I?

1. 4
2. 16
3. 2
4. 8

Q. In diploid organism, gametes are produced by meiosis division but in haploid organism gametes are produced by

1. Reduction division
2. Amitosis
3. Both a and b
4. Mitosis

Q. Percentage of crossing over is more when

1. genes are present at different locations on the same cell
2. genes are located on non-homologous chromosomes
3. genes are located close to each other on the same chromosome
4. genes are located far apart from each other on the same chromosome

Q. If there are 30 chromosome in G 1 phase then what will be the no of bivalent in zygotene phase?

Q. If a diploid species has a primary spermatocyte containing 60 chromosomes, what shall be the number of chromatids in each of the secondary spermatocyte produced after the completion of meiosis I?

1. 30
2. 15
3. 60
4. 120

Q.

How are trisomics classified?

Q. At the end of meiosis-II, number of haploid cells formed are:

1. Two
2. Four
3. Eight
4. One

Q. At which stage does segregation of alleles take place?

1. During mitosis
2. During meiosis
3. During fertilization

4. During embryo formation

Q. The first meiotic division is called _______ while the second one is called _______.

1. equational; reduction
2. reduction; equational
3. multiplication; reduction
4. multiplication; equational

Q. Which of the following is incorrect with respect to meiosis?

1. It involves two cycles of DNA replication, one before meiosis-I and another before meiosis-II
2. It involves crossing over that leads to recombination
3. Sister chromatids separate during anaphase-II
4. Nuclear membrane disappears during prophase

Q. The number of chromosomes is reduced to half in _____.

1. Meiosis
2. Mitosis
3. Meiosis I

4. Meiosis II

Q.

Write in brief about the exchange of genes between Homologous Chromosomes.

Q.

Find examples where the four daughter cells from meiosis are equal in size and where they are found unequal in size.

Q. Assertion: Though the chromosome content of the daughter cells is halved by the end of meiosis I, meiosis II is essential for generation of haploid cells.

Reason: During meiosis II, the duplicated sister chromatids separate from each other and are distributed into the haploid daughter cells.

1. Both the assertion and reason are true and the reason is the correct explanation of the assertion
2. Both the assertion and reason are true but the reason is not the correct explanation for the assertion
3. The assertion is true but the reason is false
4. Both assertion and the reason are false

Q. Which of the following sequences shows the correct life cycle for humans?

1. diploid egg + diploid sperm --> haploid zygote --> mitosis --> haploid adult --> meiosis --> diploid gametes
2. 
   diploid egg + diploid sperm --> haploid zygote --> meiosis --> haploid adult --> mitosis --> diploid gametes
3. 
   haploid egg + haploid sperm --> diploid zygote --> mitosis --> diploid adult --> meiosis --> haploid gametes
4. 
   haploid egg + haploid sperm --> diploid zygote --> meiosis --> diploid adult --> mitosis --> haploid gametes

Q. A triploid nucleus cannot undergo meiosis because:

1. Crossing over does not occur
2. Karyokinesis can not occur
3. Chromosomes do not replicate
4. Not all of the chromosomes can form homologous pairs

Q.

Question 14
Which tissue of animals and plants exhibits meiosis?

Q. The second meiotic division leads to:

1. Separation of sex chromosomes
2. Fresh DNA synthesis
3. Separation of chromatids and centromere
4. Separation of homologous chromosomes

Q.

Question 1
Meiosis in diploid organisms results in
(a) production of gametes
(b) reduction in the number of chromosomes
(c) introduction of variation
(d) All of the above

Q.

Question 9
Identify the wrong statement about meiosis
(a) Pairing of homologous chromosomes
(b) Four haploid cells are formed
(c) At the end of meiosis the number of chromosomes are reduced to half
(d) Two cycle of DNA replication occurs

Q. Meiosis is characterised by

1. None of the above
2. Reduction division
3. Equal division
4. Both reduction and equal division