Q. No.The fruit fly has 8 chromosomes (2n) in each cell. During the interphase of mitosis, if the number of chromosomes at G1 phase is 8, what would be the number of chromosomes after the S phase?
1.
4
2.
32
3.
8
4.
16
Crossing over that results in genetic recombination in higher organisms occurs between:-
1. Non-sister chromatids of a bivalent
2. Two daughter nuclei
3. Two different bivalents
4. Sister chromatids of a bivalent
The stage during which separation of the paired homologous chromosomes begins is
| 1. | Pachytene | 2. | Diplotene |
| 3. | Diakinesis | 4. | Zygotene |
Spindle fibres attach on to
1. kinetochore of the chromosome
2. centromere of the chromosome
3. kinetosome of the chromosome
4. telomere of the chromosome
| 1. | Complete disintegration of nuclear envelope takes place. |
| 2. | Chromosomes are highly condensed. |
| 3. | Metaphase chromosomes are made up of four sister chromatids held together by centromere. |
| 4. | Chromosomes lie at the equator of the cell. |
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| COLUMN I | COLUMN II | ||
| A. | Zygotene | P. | Crossing over |
| B. | Pachytene | Q. | Synapsis |
| C. | Diplotene | R. | Terminalization of chiasmata |
| D. | Diakinesis | S. | Appearance of chiasmata |
| A | B | C | D | |
| 1. | Q | P | S | R |
| 2. | P | Q | S | R |
| 3. | P | Q | R | S |
| 4. | Q | P | R | S |
| 1. | The chromosome number and DNA content remain 2N and 2C respectively |
| 2. | The chromosome number and DNA content are 4N and 2C respectively |
| 3. | The chromosome number and DNA content are 2N and 4C respectively |
| 4. | The chromosome number and DNA content are 4N and 4C respectively |
| 1. | the cell plate that represents the middle lamella |
| 2. | the cell plate that represents the primary cell wall |
| 3. | the cleavage furrow that represents the middle lamella |
| 4. | the contractile ring that represents the primary cell wall |
| 1. | Metaphase I | Bivalent align on the equatorial plate |
| 2. | Anaphase I | Splitting of centromere |
| 3. | Prophase II | Nuclear membrane disappears by the end |
| 4. | Metaphase II | Microtubules from the opposite poles of the spindle get attached to the kinetochores of sister chromatids |
| Assertion (A): | Meiosis conserves specific chromosome number of each species across generations in sexually reproducing organisms. |
| Reason (R): | Meiosis, per se, results in reduction of chromosome number by half. |
In the light of the above statements choose the correct answer from the options given below:
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | Both (A) and (R) are False. |
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