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Biofertilizers are the organisms that enrich the nutrient quality of soil. Bacteria, cyanobacteria and fungi are the three groups of organisms used as biofertilizers. 

i) Bacteria 

a) symbiotic bacteria Rhizobium. 

b) Free living bacteria Azospirillum & Azotobactor. 

c) They fix the atmospheric nitrogen and enrich soil nutrients. 

ii) Cyanobacteria 

Cyanobacteria are autotrophic microbes widely distributed in aquatic and terrestrial environment. Many of them can fix atmospheric nitrogen and increase the organic matter of the soil through their photosynthetic activity. In paddy field cyanobacteria serves as important biofertilizers. Commercially farmers use these cyanobacteria in their fields to replenish soil nutrients and to reduce dependency on chemical fertilizers. 

Important examples are Anabaena, Nostoc and Oscillatoria. 

iii) Fungi/ Mycorrhiza 

Fungi are also known to develop symbiotic relationship with plant roots. Such a relationship is called mycorrhiza. Many members of the genus Glomus form mycorrhizae. The fungus absorbs phosphorus from the soil and passes it to the plant. Plants having such association show other benefits also

a) Resistance to root borne pathogens 

b) Tolerance to salinity. 

c) Tolerance to drought 

d) Overall increase in the plant growth and development.

A parasite that resides inside the body of host, will certainly cause discomfort to the host. But if the host dies, the parasite also will diminish. Therefore, Ideal parasite will not extract more benefits from the host. But ideal parasite cannot stay alive without association with host. They need host for various purposes like nutrition, food. Some need the host for completing their life cycle. So parasite will always harm the host in order to thrive.

1. Most of the parasites cause harm to the host.

2. Host is affected by reducing its survival, growth and reproduction. 

3. Some parasites can also be fatal to the host causing death of the host. 

4. The population density of host species is reduced by parasites. 

5. The host species become more vulnerable to predation by making it physically weak.

1. Host and parasitic relationship is most specific. This means that for a particular parasite there is specific host. 

2. Many parasites have evolved to be host-specific as they can parasitize only a single species of host. Therefore, during evolution, they both co-evolve together, against each other.

Biofertilisers are micro-organisms which increases soil fertility and enhances nutrients to crop plants.

• Nitrogen fixing bacteria and Cyano bacteria Converts free N₂ from atmosphere to salts of N₂.
• Phosphate bacteria – Secrete phosphatase that dissolves insoluble phosphate from soil for absorption by plants.
• Mycorrhiza – occurs in forest plants solubilizes and absorbs nutrients from organic matter

The malarial parasite is Plasmodium vivax which needs a vector anopheles mosquito.

Copepods are the ectoparasites which infest the marine fish.

1. Homeostasis keeps the body in equilibrium. 

2. All the internal functions are maintained due to homeostasis. 

3. Survival, growth and reproduction can be achieved due to this steady state. 

4. The external environment changes constantly but by homeostasis, organisms can cope up with this change. 

5. Thus homeostasis is a way of adaptation for survival.

(a) Natality balance mortality

Nicotine, caffeine, quinine, strychnine, opium, etc. are secondary metabolites which act as defensive substances produced by plants against grazers and browsers.

(a) Logistic growth 

(b)(a) N-population of size 

(b) r- intrinsic rate of natural increase 

(c) K-Carrying capacity

(a) Temperature is sub-zero level in polar areas and high altitude and increases to above 50°c in tropical desert in summer.

(a) Birth rate or total number of live births per 1,000 of a population in a year.

(b) Death rate or total number of death per 1,000 of a population in a year. 

(c) Emigration- movement of individuals out of the population 

(d) Immigration- movement of individuals into the population

Answer is  a, b.

Hibernation – winter sleeping 

Aestivation – Summer sleeping 

Migration – Moving into more suitable area 

Diapause – inactive in adverse condition

Correct answer is (a) It enables their stomata to remain closed during day time.

Aestivation.

Summer sleep – Aestivation

Winter sleep – Hibernation

(a) low stability and high resilience

(d) Mammals from colder climate generally have shorter ears and limbs.

(1) They have a thick cuticle on their leaf surfaces and have their stomata arranged in deep pits to minimise water loss through transpiration.

(2) They also have a special photosynthetic pathway (CAM) that enables their stomata to remain closed during day time

(3) The photosynthetic function is carried out by the flattened stems.

1. Thick cuticle on their leaf surfaces

2. Stomata arranged in deep pits to minimise water loss through transpiration.

3. They show CAM path way (they open stomata during night and closed during day time)

4. Opuntia, their leaves are reduced to spines and the flattened stems do photosynthesis.

(b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion

1.

• Conformers
• Regulators
• Partial regulators

2.

• Organism Cannot maintain constant internal environment.
• Organism can maintain constant internal environment through thermoregulation and osmoregulation.

(a) Mortality is the number of death of a population at a given period and Natality is the number of birth during a given period.

(b) Immigration is the number of individuals of the same species that have come into the habitat from elsewhere during the time period. Emigration is the number of individuals of the population who left the habitat and gone elsewhere during the time period.

Gause’s competitive exclusion principle states that two closely related species competing for the same resource cannot coexist indefinitely and the competitively inferior one will be eliminated eventually by the superior one. 

For example, after the introduction of goats in Galapagos Islands, the Abingdon tortoise became extinct within a decade due to greater browsing efficiency of the goats.

Plants have evolved a variety of morphological and chemical defences against their predators (herbi-vores).

1. Thorns in plants are morphological means of defence.

2. Plants produce and store chemicals that make the herbivore sick.

Eg: Glycosides, Quinine, Caffeine, Opuim etc.

Answer (d) I, II

(d) both a and b

1. competitive exclusion principle

2. resource partitioning

(a) Mutualism 

(b) Competition 

(c) Predation

(d) Parasitism

(e) Commensalism

(f) Amensalism

Temperature has a significant role in the kinetics of enzymes and thus influence the metabotic activities and physiological functions. Accordingly organisms can be classified into eurythermal (tolerate wide range of temperature) and Stenothermal (restricted to narrow range of temperature)

1. Competitive Exclusion Principle states that the closely related species competing for the same resources cannot co-exist indefinitely The competitively inferior one will be eliminated eventually.

2.  Abingdon tortoise compete with goats in galapagos island for same food source and tortoise became extinct.

1. 2 adaptations they developed:

• increase RBC production
• increase breathing rate

2. nausea, fatigue.

Yes

Their body surface area is large compared to body volume, hence they have to spend more energy to increase metabolic rate when cold outside for producing more heat.

Phenotypic adaptions are acquired non genetic changes in individuals such as physiological modification, acclimatization or behavioural changes.

For examples, if a person has ever been to any high altitude, on visiting such as place he or she must have altitude sickness because body does not get enough oxygen. But gradually he or she gets acclimatized and stop experiencing altitude sickness.

Organisms maintain internal environment as constant by sweating shivering deposition of fat layer below skin and hairy covering on body surface.

1. Yes.

2. In high altitudes there is low oxygen availability. The tribes having high RBC production since the binding capacity of RBC with 02 decreases and ultimately results in high breathing rate.

The microbes of high temperature area are known as thermoacidophiles. They are able to survive at high temperature through.

1. Reduction in amount of free water.

2. Occurrence of branched chain lipids that reduce fluidity of cell membranes.

N_t = N₀e^rt

Since N_t = 2; No = 1, e = 2.71828 ; t = 3

2 = (1 × 2.71828)^3r

Log 2 = 3 r log (2.71828)

0.3010 = 3 r × 0.4343

r = 0.2310

Intrinsic rate of increase = 23.1 %

• Population density.
• Natality or birth rate.
• Mortality or death rate.
• Population growth.
• Sex ratio.
• Age distribution.

The three phases of growth are phase of cell division, phase of cell enlargement and phase of cell maturation.

(a) Calcium: 

Role : Involved in selective permeability of cell membranes, activator of certain enzymes, required as calcium pectate in middle lamella of cell wall at root and stem apex (for cell division). 

Deficiency symptom : stunted growth.

(b) Boron: 

Role : Required for uptake and utilization of Calcium (Ca²⁺), pollen germination, cell differentiation, carbohydrate translocation. Deficiency symptom : Brown heart disease

(c) Chlorine: 

Role : Na⁺ and K⁺ help to determine solute concentration and anion – cation balance in cells, necessary for oxygen evolution in photosynthesis. Deficiency symptom : Poor growth of plant.

Attributes of population : Birth rate, death rate, sex ratio, age pyramids/age distribution.

1. The oesophagus and trachea lie side by side. 

2. There is possibility that food particles may enter respiratory passage at the time of gulping. 

3. However, the epiglottis prevents the entry of food into the respiratory passage by closing it temporarily. 

4. Thus, for preventing the entry of food particles into respiratory passage, the glottis is guarded by a flap called epiglottis.

1. The cyclic movement of nitrogen between the atmosphere, biosphere and geosphere in different forms is called nitrogen cycle. 

2. Nitrogen cycle is one of the most important biogeochemical cycles. 

3. The nitrogen cycle involves many processes such as cycling of nitrogen through the biosphere, atmosphere and geosphere, nitrogen fixation, nitrogen uptake, formation of biomass, ammonification, nitrification and denitrification, etc. 

4. Bacteria such as Nitrosomonas, Nitrosococcus and Nitrobacter are the nitrifying bacteria which play an important role in nitrification. 

5. Denitrification is carried out by the bacteria Pseudomonas denitrifficans. From this it is obvious that bacteria play a major role in nitrogen cycle. 

6. Nitrogen fixation occurs by physical, industrial and biological methods. Prokaryotic organism play an important role in biological nitrogen fixation.

Correct answer is (a) 3 lobes

Vestibule, respiratory part and sensory part are the three regions of nasal chamber.

(i) Fore gut, Mid gut and Hind gut 

(ii) Role of Gizzard, Hepatic caecae and Malpighian tubules are as follows: 

(a) Gizzard: The crop opens posteriorly into a small thick walled, muscular gizzard. They help in grinding the food. 

(b) Hepatic caecae: Hepatic caecae open at start of midgut and secrete many digestive enzymes-lipase, protease, peptidase, amylase, maltase, lactase, invertase and chitinase. 

(c) Malpighian tubules: The malpighian tubules help in removal of excretory products from the haemolymph. 

(iii) Three segments. 

(iv) Paurometabolous with reference to cockroach means a simple, gradual direct metamorphosis in which immature forms resemble the adult except in size and referred to as nymph. 

(v) Cockroach eyes are called compound eyes because they are made up of repeating units, the ommatidia, each of which function as a separate receptor.

Correct answer is (c) mesethmoid