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Q. No.| Assertion (A): | Meiosis leads to recombinations of genes. |
| Reason (R): | Crossing over occurs in pachytene sub-stage of prophase I of meiosis. |
| 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. |
| Assertion (A): | Tendency of parental combinations to remain together is called crossing over. |
| Reason(R): | Crossing over provides proof in favour of the linear arrangement of genes on chromosomes. |
| 1. | Both (A) & (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) & (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. |
Match each item in Column I with one item in Column II and chose your answer from the codes given below.
|
Column I (stage of prophase I) |
Column II (event) |
|
I. Zygotene II. Pachytene III. Diplotene IV. Diakinesis |
1. Crossing over 2. Chiasmata formation 3. Bivalent formation 4. Terminalization of chiasmata |
Codes:
I II III IV
1. 1 2 3 4
2. 2 1 4 3
3. 3 1 2 4
4. 3 2 1 3
Match the following Column-I with Column-II.
| Column-I | Column-II | ||
| A. | Synapsis aligns homologous chromosomes | (i) | Anaphase II |
| B. | Synthesis of RNA and protein | (ii) | Zygotene |
| C. | Action of enzyme recombinase | (iii) | G2 - phase |
| D. | Centromeres do not separate, but chromatids move towards opposite poles | (iv) | Anaphase I |
| (v) | Pachytene |
1. A-(ii), B-(i), C-(iii), D-(iv)
2. A-(ii), B-(iii), C-(v), D-(iv)
3. A-(i), B-(ii), C-(v), D-(iv)
4. A-(ii), B-(iii), C-(iv), D-(v)
| List-I | List-II | ||
| A. | Pairing of homologous chromosomes | I. | Chiasmata |
| B. | Actual interchange of segments between two homologous chromosomes | II. | Synaptonemal complex |
| C. | Protein body formed between paired homologs | III. | Synapsis |
| D. | The cross shaped configuration visible between homologs | IV. | Crossing over |
1. A - (IV); B - (III); C- (I); D - (II)
2. A - (III); B - (IV); C- (I); D - (II)
3. A - (III); B - (IV); C- (II); D - (I)
4. A - (IV); B - (III); C- (II); D - (I)
Read the four statements (a-d) and choose the correct option.
| a. | Spindle fibers attach to kinetochores of chromosomes during metaphase. |
| b. | Cell growth results in disturbing the ratio between the nucleus and the cytoplasm. |
| c. | Pachytene stage is relatively short-lived compared to the leptotene. |
| d. | Interkinesis is a short-lived stage characterized by duplication of DNA. |
1. a, b & c are correct
2. Only c is incorrect
3. b & d are correct
4. a & b are correct
| Statement I: | In mitosis, chromosomal number in the progeny as well as in parents remains the same |
| Statement II: | Mitosis takes place in gametes |
| 1. | Both statement I and statement II are correct |
| 2. | Both statement I and statement II are incorrect |
| 3. | Statement I is correct but statement II is incorrect |
| 4. | Statement I is incorrect but statement II is correct |
| Assertion(A): | Meiosis reduces the chromosome number by half in gametes. |
| Reason(R): | Meiosis is called the reductional division. |
| 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. | (A) is false, but (R) is true. |
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Q. No.
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