Immune response by vaccine is different frorn that by antitoxin in humans in two ways
(i) Vaccines give long term protection unlike antitoxins.
(ii) Vaccines can either destroy, kill or render a pathogen inactive, whereas antitoxins render a toxic substance harmless.

i) AIDS caused by HIV
ii) T - lymphocytes

(1) Insulin is made up of two short polypeptide chains; A and chain B which are linked together bydisulphide bridges. (2) It is synthesised in inactive form called proinsulin.

(2) Insulin is synthesised as pro-hormone called proinsulin (i.e. which is to be processed before becoming functional) contains an extra stretch called C-peptide which is usually removed during maturation of insulin.

 Vertebrates like bear undergo hibernation, to escape in time.
Angiosperms produce seeds and certain other vegetative structures to tide over unfavourable conditions in the habitat.

Australopithecus lived in the East-African grassland.
1. They were probably not taller than four feet.
2. They walked upright.
3. They hunted with stone weapons and essentially ate fruits.

(i) Effect on kidney It reduces ADH secretion, which results in rapid dehydration.
(ii) Effect on brain Reduced self control, judgement, loss of muscle coordination, in coherent speech, etc.
(iii) Effect on heart Increased blood pressure which affects the activity of heart.
(iv) Effect on liver Alcohol consumption cause liver, cirrhosis.
(v) Effect on immunity Alcoholism decreases the resistance to infection.

1. Industrial Melanism : Before industrialisation started in England it was observed, there were more white -winged peppered moth, on trees than dark winged moth, but after industrialisation, there were more dark - winged moths in the same area,
2. predators spot a moth against a contrasting background, post industrialisation the tree trunks became dark due to industrial smoke and soot, Under this condition the white- winged moth did not survive, due to predators, but the dark-winged moth managed to survive. II or any other example explained under the following heads in the text book - fitness, selection and adaptation.

(i) He consumed uncovered food products and drinks which got contaminated by pathogenic microbes.
(ii) This practice helps in preventing spread of infectious diseases.

Natural Selection: In modern term natural selection is differential reproduction. Natural selection is main evolutionary process which causes the change of allele frequencies or in other words selection is the consistent differences in contribution of various genotypes to the next generation.
In in a population both small and largest individuals contribute relatively fewer offspring to the next generation then those closer to the averages do, stabilizing selection is operating.
If centre of population contributes more then equilibrium is maintained while if extremes of population work then two peaks in the distribution of a trait produced, while former is disruptive selection.

Bacillus thuringiens· :
(a) This bacterium produces a protein, which is toxic to he larvae of insects like bollworm, budworm, flies, bettles,etc.
 Bt-toxin gene has been cloned from the bacteria and been expressed in plants to provide resistance to insects without the need for chemical insecticides.
(b) The gene (cry) coding for the protein has been isolated using restriction enzymes.
They are cloned in the vectors and then introduced into a number of crop plants like cotton, tomato, corn, rice, etc.
There are a number of different forms of the gene, that code for insect-specific Cry proteins, e.g., crylAc and cryllAb control cotton bollworm.
crylAb controls corn borer.
The transgenic plants (called as Bt corn, Bt rice, Bt cotton, etc.) produce the protein in their cells and express the insect/pest resistance.

Nematode-resistant tobacco plants are produced through RNA interference. The process RNA interference (RNAi) involves silencing of a specific mRNA.
A complementary double-stranded RNA binds to the mRNA and prevents its translation.
The complementary! RNA for making the double stranded RNA comes either from an infection by RNA viruses or  mobile genetic elements, called transposons, which replicate through an RNA-intermediate.
The nematode-specific genes were introduced into the host plant by the use. of Agrobacterium vectors.
The introduction of DNA is such that it produced both sense and anti-sense RNA in the host cells.
These two RNAs are complementary to each other and hence form a double-strandedd RNA, which initiates the RNA interference and silencing of mRNA.
The parasite could not live in such a transgenic host that expresses the specific interfering double-stranded RNA;   so, the transgenic plant is protected from the nematode.

The chemical compound given is morphine. It is an effective sedative, analgesic and painkiller.
Morphine is obtained from latex of poppy plant. It is crystalline white in appearance and is odourless.

(i) There are several methods for the diagnosis of HIV infection like Enzyme Linked Immuno Sorbent Assay (ELISA), PCR test, Western blotting, etc. Out of these, ELISA and Western blotting are widely used. ELISA is based on the principle of antigen-antibody interaction Infection by pathogen can be detected by the presence of antigens like proteins and glycoproteins or by detecting the antibodies produced against the pathogen
(ii) Genetic material present in AIDS causing pathogen is RNA.

Deletion/mutation of the gene which forms the enzyme - adenosine deaminase.
1.Lymphocytes from the blood of the patient, can be grown in a culture outside the body, ADA cDNA gene can be inserted into the lymphocyte using retroviral vector, then lymphocytes can be returned to the patient. (They can start producing ADA).

Yes,a natural disaster can be cause for extinction of species.As new species evolved to fit ever changing ecological niches,older species fade away.
But,the rate of extinction is far constant.In last 500 million years,50-90% or more of all species on earth have disappeared in a geological blinks.the most studied mass extinction between the cretaceous and palaeocene peroid about 65 million years the cause is suspected to be volcanic eruptions and impacts of large asteroids or comets striking the earth.

Malaria is transmitted by anopheles mosquito, which is insect vector for the Plasmodium falciparum parasite.
This parasite needs warm conditions with temperatures above to 20°C complete its life cycle in the mosquito. Therefore, mosquitoes breed in warm conditions of tropics and in area of stagnant water.

(i) c, h
(ii) a, f
(iii) b
(vi) e
(v) d

The animal is a connecting link between reptiles and birds. The presence of scales and teeth in the beak are reptilian characters, whereas the beak itself is an avian character.

(i) (b) : The genetically modified crop called Btcotton contains Bt toxin genes. The gene cry 1 Ac and cry II Ab control cotton bollworms. Similarly, cry I Ab has been introduced in Bt corn to protect the same from corn borer.
(ii) (d) : cry I Ab has been introduced to Bt corn to protect them from corn borer. cry I Ac and cry II Ab control cotton bollworms.
(iii) (d) : Gene transfer to non-target plant species is a major disadvantageous concern of GM plants. It can even cause to produce 'superweeds'
(iv) (b)
(v) (a): The Bt toxin proteins exist as inactive protoxins but once an insect ingests the inactive toxin it is converted into an active form of toxin due to the alkaline pH of the alimentary canal that solublises the crystals. The activated toxin binds to the surface of midgut epithelial cells and create pores which cause cell swelling and lysis and finally cause death of the insect.

(i) (b): Initial contact with an antigen causes primary immune response. In primary immune response, no antibodies are present initially. Then, a slow rise in the antibody titer occurs, first IgM and then IgG, followed by a gradual decline in antibody titer. In secondary immune response, the antibody formation is accelerated and more intense. This is also called booster response. It mainly consists of IgG antibodies.
(ii) (b) : Vaccine is a preparation or extract of an inactivated/attenuated (weakened) pathogen of a disease which on inoculation into a healthy person provides immunity by inducing antibodies production.
(iii) (c) : IgG is the only class of antibody to cross the placenta from mother to foetus.
(iv) (d)
(v) (a)

(b) If both A and R are true, but R is not the correct explanation of A

(a): Predation and parasitism are considered to be negative interactions, because in both of these interactions one species gains and the other suffers. Predation is the interaction between species involving killing and consumption of prey. The species which eats the other is called the predator, and the one consumed by other is termed as prey. Predation is commonly illustrated by the herbivore-carnivore interaction.
Parasitism is the interaction in which the species smaller in size (the parasite) lives in or on the larger species (the host) from which it obtains food and shelter. Parasites like leeches, tick, lice, mites feed on the body fluids of the hosts. Parasites, like the predators limit the population of the host species. Parasites are generally host- specific, and do not have choice or alternatives like predators. Parasites are smaller in size and have higher biotic/reproductive potential compared to the predators. Parasites have poor means of dispersal and require specialised structures to reach or invade the host. Predators, on the other hand, are quite mobile and capable of capturing the prey.