Immune System

Step 1: Understanding plaques.
Plaques are clear zones formed on a bacterial lawn when bacteriophages infect and destroy bacterial cells.

Step 2: Mechanism of plaque formation.
After infection, bacteriophages multiply inside bacterial cells and cause lysis of the host cell. Repeated cycles of infection and lysis produce clear patches called plaques.

Step 3: Option analysis.
New bacterial colonies form opaque regions, not plaques.
Bacteriophages initiate infection but plaques represent dead cells.
Virions alone do not form visible plaques.

Step 4: Conclusion.
Hence, plaques are formed due to lysed bacterial cells.

Step 1: Understanding critical elements.
Critical elements are nutrients required by crops in large amounts and are often deficient in agricultural soils.

Step 2: Identifying primary macronutrients.
Nitrogen (N), Phosphorus (P), and Potassium (K) are primary macronutrients essential for plant growth and yield.

Step 3: Conclusion.
Thus, the critical elements are N, P, and K.

Step 1: Understanding genome size.
Genome size refers to the total amount of DNA present in an organism.

Step 2: About {Methanococcus jannaschii. It is an archaean whose complete genome was one of the first to be sequenced.

Step 3: Genome measurement.
The genome size of {Methanococcus jannaschii} is approximately 1.66 megabases, i.e., 1660 kb.

Step 4: Conclusion.
Therefore, the correct genome size is 1660 kb.

Step 1: Understanding germ plasm.
Germ plasm refers to the total genetic resources of a crop species. It includes seeds or plants that possess all possible genetic variations found within that crop.
Step 2: Importance in plant breeding.
In conventional plant breeding, germ plasm is collected to identify desirable traits such as disease resistance, high yield, or stress tolerance. A wide genetic base increases the chances of developing improved crop varieties.
Step 3: Analysis of options.
(A) Collection of genes from a particular crop plant: Incorrect, as germ plasm includes many plants, not a single plant.
(B) Gene library of same variety: Too narrow and does not represent genetic diversity.
(C) Gene library of genomes: Germ plasm is not limited to laboratory gene libraries.
(D) Entire collection of plants/seeds with diverse alleles: Correct, as it represents the complete genetic diversity of a crop.
Step 4: Conclusion.
Germ plasm collection includes the entire genetic diversity of a crop species in the form of plants or seeds.

Step 1: Understanding Whittaker’s five-kingdom classification.
R. H. Whittaker proposed a five-kingdom classification system based on cell structure, body organization, mode of nutrition, and reproduction.
Step 2: Identifying multicellular heterotrophs.
In this system, multicellular heterotrophs are divided into two separate kingdoms based on mode of nutrition.
Plantae are autotrophs, while multicellular heterotrophs are grouped under Fungi (absorptive nutrition) and Animalia (ingestive nutrition).
Step 3: Analysis of options.
(A) 4: Incorrect — too many kingdoms.
(B) 3: Incorrect — not as per Whittaker’s system.
(C) 1: Incorrect — heterotrophs are not placed in a single kingdom.
(D) 2: Correct — Fungi and Animalia.
Step 4: Conclusion.
According to R. H. Whittaker, multicellular heterotrophs are placed in two kingdoms.

Step 1: Understanding poultry diseases.
Poultry birds can suffer from diseases caused by fungi, bacteria, viruses, and parasites. Identifying the causative agent helps in classification of diseases.
Step 2: Nature of fungal diseases.
Aspergillosis, thrush, and favus are fungal diseases caused by different fungal species affecting respiratory tract or skin of poultry birds.
Step 3: Explanation of Pullorum.
Pullorum disease is caused by the bacterium {Salmonella pullorum}. It is a bacterial disease and not a fungal infection.
Step 4: Analysis of options.
(A) Aspergillosis: Fungal disease caused by {Aspergillus}.
(B) Pullorum: Bacterial disease, hence not fungal.
(C) Thrush: Fungal infection caused by {Candida}.
(D) Favus: Fungal skin disease.
Step 5: Conclusion.
Pullorum is not a fungal disease of poultry and is the correct answer.

Step 1: Understanding Aspergillosis.
Aspergillosis is a fungal infection caused by the Aspergillus species. It commonly affects poultry and other animals, especially in confined or poorly ventilated environments.
Step 2: Analyzing the options.
(A) fungal: Correct — Aspergillosis is a fungal disease caused by the Aspergillus species.
(B) bacterial: Incorrect — Aspergillosis is not caused by bacteria.
(C) protozoan: Incorrect — Protozoan infections are caused by protozoa, not fungi.
(D) viral: Incorrect — Aspergillosis is a fungal disease, not viral.
Step 3: Conclusion.
The correct answer is (A) fungal, as Aspergillosis is caused by fungi.