Q.21 Number of chromosomes present in Arabidopsis thaliana is-
1.8
2. 10
3. 12
4. 14
Answer: None of the options are correct. Arabidopsis thaliana has 5 chromosomes (2n=10).
Arabidopsis thaliana, the model plant organism in plant biology, has a haploid chromosome number of n=5 (diploid 2n=10). The options provided (8, 10, 12, 14) likely test confusion between haploid/diploid numbers or other plant species.
Option Analysis
-
1. 8: Incorrect. May confuse with ancestral Brassicaceae karyotype (n=8 in Arabidopsis lyrata) from which A. thaliana evolved via chromosome fusions.
-
2. 10: Incorrect but closest. This represents diploid number (2n=10), not haploid. Questions often specify “n=” vs “2n=”.
-
3. 12: Incorrect. No relation to Arabidopsis; possibly rice (n=12) confusion.
-
4. 14: Incorrect. May confuse with some Solanaceae plants or misremembered data.
Correct Answer: n = 5 chromosomes (chromosomes 1, 2, 3, 4, 5; total ~135 Mb genome sequenced in Col-0 ecotype).
Arabidopsis thaliana chromosomes number is 5 (haploid n=5), making it the premier model organism in plant genetics and molecular biology for GATE Life Sciences exams.
Arabidopsis Genome Facts
-
Haploid: n = 5 chromosomes
-
Diploid: 2n = 10 chromosomes
-
Genome size: ~135 Mb (25,498 genes)
-
First plant genome sequenced: 2000 (Chromosome 1: 29 Mb)
-
Ecotype: Col-0 (Wassilewskija reference)
Why Options Wrong Table
| Option | Number | Reality | Common Confusion |
|---|---|---|---|
| 1 | 8 | Wrong | Ancestral karyotype |
| 2 | 10 | Diploid (2n) | Haploid questions specify n= |
| 3 | 12 | Wrong | Rice (Oryza sativa) |
| 4 | 14 | Wrong | Tomato/potato family |
Model Organism Superiority
| Feature | Arabidopsis | Other Plants |
|---|---|---|
| 5 chromosomes | Easy genetics | 12-42 typical |
| 6-week generation | Rapid experiments | 3-12 months |
| 135 Mb genome | Fully sequenced | Giga-base pairs |
GATE Life Sciences Strategy
Keyword pattern: “Number of chromosomes present in Arabidopsis thaliana” = 5. Options test haploid (n) vs diploid (2n) confusion. Links to your plant genetics series after molecular biology (PCR/colony hybridization).
Jaipur lab tip: Arabidopsis seeds from local agri universities; perfect for genetics practicals and GATE PYQ mastery.
