Plant Biotechnology

Step 1: Understanding Taq Polymerase

- Taq polymerase is a thermostable enzyme used in PCR (Polymerase Chain Reaction).
- It was isolated from the bacterium Thermus aquaticus, which thrives in hot springs.

Step 1: Understanding the Restriction Sites in pBR322

- The pBR322 plasmid contains two antibiotic resistance genes:
- Ampicillin resistance (bla gene).
- Tetracycline resistance gene.
- The BamHI restriction site is present in the tetracycline resistance gene, which allows for gene insertion.

Step 1: Classification of Diatoms:
Diatoms (Bacillariophyceae) are broadly classified into two orders based on symmetry:

• Centrales (Centric diatoms): These are circular, discoid, or cylindrical in shape. They exhibit Radial symmetry.
• Pennales (Pennate diatoms): These are elongated, boat-shaped, or needle-like (e.g., \Pinnularia, \Navicula). They exhibit Bilateral symmetry.

Step 2: Match Variables:
X (Centrale) = Radial.
Y (Pennales) = Bilateral.
Step 3: Final Answer:
Option (B) matches this sequence.

1. pBR322 map: Hind I → site A, EcoRI → site B, ampR → antibiotic resistance, Ori → origin of replication.
2. BamHI & KanR are different sites/genes.
3. Correct identification is (1) A-Hind I, B-ECoR1, C-ampR, D-Ori.

Step 1: Analyze the Diagram:

• D (Complex I): Accepts electrons from NADH ( ). This is NADH dehydrogenase.
• B (Complex II): Feeds electrons into the Ubiquinone pool but does not pump protons. This is Succinic dehydrogenase.
• C (Complex III): Receives electrons from Ubiquinone and passes them to Cytochrome c. This is the Cytochrome complex or Cytochrome c reductase.
• A (Complex IV): Receives electrons from Cytochrome c and reduces Oxygen to Water ( ). This is Cytochrome c oxidase.

Step 2: Match with Options:
A = Cyt C oxidase, B = Succinic dehydrogenase, C = Cyt C reductase, D = NADH dehydrogenase. This sequence corresponds to Option (D).

Lyases are enzymes that catalyze the cleavage of C–C, C–O, C–N bonds by means other than hydrolysis or oxidation, often forming a double bond or a new ring structure. Dehydrogenases remove hydrogen atoms; hydrolases catalyze hydrolysis; isomerases rearrange atoms within a molecule. Therefore, Lyases is correct.

- Codominance shows a phenotypic ratio 1:2:1 in F2 (e.g., AB blood group) with the same genotypic ratio 1:2:1.
- Incomplete dominance shows a phenotypic ratio equal to the genotypic ratio 1:2:1 (e.g., red × white → pink). Here statement II is wrong in the phenotypic ratio 3:1.
- Monohybrid test cross produces phenotypic and genotypic ratios 1:1.
- Dihybrid test cross (heterozygous × homozygous recessive) produces phenotypic 1:1:1:1, not 9:3:3:1.
Hence, correct combinations are I & III.

1. Sturtevant constructed the first genetic linkage map using Drosophila melanogaster.
2. Sutton and Boveri → chromosome theory, Morgan → experimental genetics, Bateson & Punnett → early Mendelian work.
3. Correct answer is (2) Sturtevant.

Cry proteins produced by genetically modified Bt crops target specific pests. CryIIAb targets Lepidopteran pests like cotton bollworms. CryIAb targets corn borers. They bind to midgut receptors and form pores leading to cell lysis. Other pests like nematodes and tobacco budworms are not primarily affected.

1. pBR322 map: Hind I → site A, EcoRI → site B, ampR → antibiotic resistance, Ori → origin of replication.
2. BamHI & KanR are different sites/genes.
3. Correct identification is (1) A-Hind I, B-ECoR1, C-ampR, D-Ori.

1. Zinc → required for enzyme activation, not directly ABA synthesis.
2. Molybdenum → cofactor for nitrate reductase, not carbohydrate translocation.
3. Boron and Nickel pairs are correct.
4. Hence incorrect pairs: I & IV → (3) I & IV.