a - Small intestine.
b - Rhino viruses
c - Nose,respiratory passage
d - Alveoil of lungs

During flowering seasons, the honey-bees visit a number of flowers in search of edible pollen and nectar; since they collect nectar from a large number of flowers, honey collection improves during flowers seasons.

(a) Primary treatment
1. Physical removal of particles like debris, soil, sand or silt through filtration, sedimentation in stages.
2. Solids settle to form primary sludge, the supernatants form the primary effluent
(b) Secondary Treatment
It is the biological treatment
(i) Effluent passed into aeration tanks
(ii) Vigorous growth of useful aerobic microbes into flocs.
(iii) Significant reduction of BOD due to use of organic matter by microorganisms.
(iv) After fall in the level of BOD, the effluent is passed on to settling tanks where bacterial flocs settle to form activated sludge.
(v) Activated sludge is passed on to anaerobic sludge digester, where bacteria and fungi are anaerobically digested.

a) Bone marrow - blood cells-lymphocytes are produced and mature.
Thymus,- Large at the time of birth but keep reducing in size with age. T-Lymphocytes are produced and mature
Spleen - Acts as a filter for micro-organisms in blood and reservoir for RBCs.In foetus it producers all types all types to blood cells but in adults it produces only lymphocytes. Macrophages of spleen are phagocytic
Lymph nodes - Act as filters for lymph, trap micro-organisms or other antigens and activate lymphocytes and initiate immune system
(b) Primary lymphoid organs - bone marrow and thymus.
Immature lymphocytes differentiate into antigen sensitive lymphocytes
Secondary lymphoid organ - spleen and lymph nodes.
Provide the site for interaction of lymphocytes with antigen, which proliferate to become effector cell.

(a)
(b) The virus is called retro virus because its genetic material is RNA that is transcribed to DNA using enzyme reverse transciptase.
(c) Yes, the infected cell can survive, while viruses are being replicated and released.

(i) Animal breeding is a branch of animals husbandry that aims to increase the animal yield and improvement of desirable qualities of animal product.
(iii) New breed of cattle and poultry are Jersey and Leghorn respectively.

The various steps involved in plant breeding are discussed below:
1. Collection of variability. The entire collection (of plants I seeds) having all the diverse alleles for all genes in a given crop is called germplasm collection.
2. Evaluation and Selection of parents. The germplasm is evaluated to identify plants with desirable combination of useful characters. The selected plants are multiplied and used in the process of hybridization. Pure lines are created wherever desirable and possible.
3. Cross hybridization among the selected parents. Cross hybridizing the two parents to produce hybrids that genetically combine the desired characters in one plant.
4. Selection and testing of superior recombinants. This step consists of selecting, among the progeny of the hybrids, those plants that have the desired character combination. The selection process is crucial to the success of the breeding objective and requires careful scientific evaluation of the progeny. This step yields plants that are superior to both of the parents (very often more than one superior progeny plant may become available).
5. Testing, release, and commercialization of new cultivars. The newly selected lines are evaluated for their yield and other agronomic traits of quality, disease resistance etc. This evaluation is done by growing these in the research fields and recording their performance under ideal fertiliser application,irrigation and other crop management practices. The evaluation in research fields is followed by testing the materials in farmers fields, for at least three growing seasons, at several locations in the country, representing all the agroclimatic zones where the crop is usually grown. The material is evaluated in comparison to the best available local crop cultivar - a check or reference cultivar.

The process of breeding crops for higher level of vitamins and minerals, higher proteins, healthier fats, to improve public health is known as biofortification.
It helps to improve:
(i) Protein content and quality;
(ii) Oil content and quality;
(iii) Vitamin content: and
(iv) Micronu ient and mineral content. 
IARI has released several vegetable crops that are rich in vitamins and minerals. e.g. Vitamin A enriched carrots, spinach, pumpkin, vitamin C enriched bitter grourd, bathua, mustard, tomato, iron and calcium enriched spinach and bathua, protein enriched beans-lablab, broad, French and garden pea.

a - Antigen binding site
b - Light chain
c - Heavy chain
(i) They are chemically proteins
(ii) B-Iymphocytes
(iii) Humoral immune response

(i) Acetic acid - Acetobacter aceti
(ii) Butyric acid - Clostridium butylicum
(iii) Lacteric acid - Lactobacillus delbruekii