1. Genetic code was discovered by
A. Khorana and Matthaei
B. Flemming and Methaei
C. Holley, Nirenberg and Khorana (Correct)
D. Holley and Nirenberg
Solution:
The deciphering of the genetic code was a cumulative effort. Marshall W. Nirenberg and Heinrich Matthaei performed the pioneering experiment in 1961 that decoded the first codon (UUU → phenylalanine), and later Holley, Khorana, and Nirenberg collectively identified and interpreted the full genetic code (Wikipedia). For this collective scientific achievement, they were jointly awarded the Nobel Prize in Physiology or Medicine in 1968 (Wikipedia).
2. Progeny of breeder seed is referred to as:
A. Breeder seed
B. Nucleus seed
C. Foundation seed (Correct)
D. Certified seed
Solution:
- Nucleus seed: Original pure seed from the breeder.
- Breeder seed: Produced from nucleus seed under breeder supervision.
- Foundation seed: Progeny of breeder seed, used for further certified multiplication.
- Hence, the correct answer is C. Foundation seed.
3. Molecular basis of organ differentiation depends on the modulation in transcription by:
A. RNA pol
B. Transcription factor (Correct)
C. Anticodon
D. All of the above
Solution:
Organ differentiation is largely directed by spatial and temporal regulation of gene expression. This regulation is mediated by transcription factors, which bind to DNA regulatory elements to enable or inhibit transcription by RNA polymerase.
4. The phenomenon of linkage was first observed by:
A. Bateson and Punnett (Correct)
B. Nilson
C. Hugo de Vries
D. Mendel
Solution:
The concept of linkage, where genetic traits tend to be inherited together, was first reported by William Bateson and Reginald Punnett in the early 20th century and predates formal mapping efforts by Sturtevant and others.
5. Examples of transposons in human genome are:
A. LINE (Correct)
B. SINE (Correct)
C. Both A and B (Correct)
D. IS elements
Solution:
Human genomes contain mobile genetic elements such as LINEs (Long Interspersed Nuclear Elements) and SINEs (Short Interspersed Nuclear Elements). These are examples of retrotransposons. IS elements, in contrast, are typically found in bacteria.
6. Cell cycle is regulated by:
A. Cyclins
B. Cyclin‑dependent kinases (CDKs)
C. Inhibitory proteins
D. All of the above (Correct)
Solution:
Cell-cycle progression is tightly controlled by a network of:
- Cyclins (regulatory proteins whose levels fluctuate cyclically),
- CDKs, which are activated by cyclins,
- CDK inhibitors, which act as brakes on the cycle.
7. Exosmosis takes place when a plant cell is placed in:
A. Hypotonic solution
B. Isotonic solution
C. Hypertonic solution (Correct)
D. Non‑ionic solution
Solution:
In a hypertonic solution, water exits the plant cell (exosmosis), causing it to shrink or plasmolyze.
8. Match the following columns (Allopolyploid species):
| Column I (Parental species) | Column II (Resulting species) |
|---|---|
| a. Raphanus sativus × Brassica oleracea | 2. Raphanobrassica |
| b. Nicotiana tabacum × Nicotiana glutinosa | 1. Nicotiana digluta |
| c. Triticum aestivum × Secale cereale | 4. Triticale |
| d. Gossypium herbaceum × Gossypium raimondii | 3. Gossypium hirsutum |
Options:
A. a‑2, b‑1, c‑4, d‑3 (Correct)
B. a‑1, b‑2, c‑3, d‑4
C. a‑4, b‑3, c‑2, d‑1
D. a‑3, b‑4, c‑2, d‑1
Solution:
This precise matching is a well-established classification of synthetic or naturally occurring allopolyploid species in plant genetics and breeding.
9. The concept of multiline cultivar was developed by:
A. Jensen (1952) (Correct)
B. Allard (1960)
C. Simmonds (1979)
D. Johannsen (1903)
Solution:
The multiline cultivar—a mixture of genetically similar lines differing in some resistance genes but agronomically uniform—was first conceptualized by Ole Jensen in 1952.
10. Of the total water uptake by a plant, passive absorption of water accounts for:
A. 20%
B. 60%
C. 98%
D. 10% (Correct)
Solution:
Passive absorption (e.g., via root pressure and diffusion) contributes only a small fraction—around 10%—of the total water uptake. The remainder is driven by transpiration pull.
%20(2).png)
0 Comments