Aneuploidy is the condition used to describe a chromosomal aberration or alteration that is caused by an addition or deletion of one or a few chromosomes. It results in genetic disorders. It differs from polyploidy which is the addition of one or more complete sets of chromosome in the genome.  Individuals having following chromosomal abnormalities are defmed as
(i) Trisomy of 21st chromosome It is also known as Down's syndrome. In this, a person is born with three chromosomesat 21st position rather than normal pair.
(ii) XXX It is also known as triple X-syndrome or Klinefelter's syndrome. This condition can occur only in females where they have three X-chromosomes instead of two. 
(iii) XO It is also known as Turner's syndrome. It always affects the females in which one of the two chromosomes are defective or completely absent. The individuals with this syndrome are born with 45 chromosomes in each cell rather than 46. 

Replacement of the normal sexual reproduction by asexual reproduction without fertilisation is called apomixis, e.g. replacement of the flower by bulbils and replacement of the seed by a plant. Apomictically produced offsprings are genetically identical to the parent plant. In flowering plants, apomixis is used in a restricted sense to mean angiosperm, i.e. asexual reproduction through seeds. In some plant species, it is common, e.g. Asteraceae and Poaceae. In some species, the diploid egg cell is formed without reduction division and develops into embryo without fertilisation. It is an asexual reproduction in the absence of pollinators such as in extreme environments.
In some species like Citrus, some of the nucellar cells surrounding the embryo sac start dividing and develop into embryo. It occurs in the megaspore mother cell and does not undergo meiosis, thus produces diploid embryo sac through mitotic divisions. Thus, it explains that, embryo sacs of some apomictic species appear normal but produce diploid cells.

ii) Difference between i) oviparity and ii) vivipary are as follows:

Ecological pyramids are diagrammatic illustrations of connection between different trophic levels in terms of energy, biomass and number of organisms.
Pyramids of biomass can be both upright and inverted. This can be understood from the examples given below:
(i) The pyramid of biomass in a pond ecosystem is inverted. Because, the sum total of the weight of phytoplankton (produce) is far less than a few fishes feeding on them, at higher tropic levels.

(ii) Pyramid of biomass in a forest ecosystem is upright because producers are more in biomass than primary consumers.Primary consumers are more than secondary consumers and secondary consumers are more than tertiary consumers (top). Pyramid of energy is never inverted, (i.e. it is always upright).Because, when energy flows from a particular trophic level to the next trophic level, some energy is always lost as heat at each step. Each bar in the energy pyramid indicates the amount of energy present at each trophic level in a given time.

(a) Difference between repetitive DNA and satellite DNA.

(b) Difference between mRNA and tRNA 

(c) Difference between Template strand and Coding strand

(i) Regulatory gene in this operon is as follows:
Role of regulatory gene in switching off operon is as follows:
(a) It codes for the repressor protein of the operon, which is synthesised constitutively.
(b) The repressor has affinity for the operator gene.It binds to operator and prevents the RNA polymerase from transcribing the structural genes.
(ii) When repressor binds to the operator, the operon is switched off and transcription is stopped.So it is called a negative regulation.
(iii) Lactose is an inducer molecule.
gene 'z' codes for \(\beta \)-galactosidase, which is responsible for the hydrolysis of lactose galactose and glucose.'y' gene codes for permease.It increase the permeability of the cell to lactose.

(i) He occupies three trophic levels in three different food chains.
(ii) (a)Plants(vegetables) ->Pragyan
(b)Plants->Insects->Hen->Egg->Pragyan
(c)Plants->Hen->Egg->Pragyan.
(iii) Food chain (a) gives him maximum energy. This is because plants are autotrophs, i.e. they produce food through the process of photosynthesis and according to 10% law only 10% energy is passed on to next trophic level.
(iv) Pragyan is a sincere child, who possess scientific attitude towards his daily life.

(ii) Griffith was not able to find the chemical nature of transforming agent.It was finally Hershey and Chase who proved that DNA is the genetic material.They proved it by using radio labelled elements, such as ³⁵S and ³²P. Radioactivity was detected in the cell which was due to the presence of  ³²P in DNA.

Plants require sunlight for photosynthesis. Therefore, light is an important factor that affects the distribution of plants, e.g.,
(i) Many species of small plants (herbs and shrubs) growing in forests are adapted to photosynthesis optimally under very low light conditions so they are seen distributed in shady areas under tall, canopied trees.
(ii) Many plants in the shade will grow vertically to gain access to light. These plants will appear to have maller4 leafs than others of the same species of the same age found in conditions with better sunlight.
(iii) Large sized trees will be present in areas that get abundant sunlight.
(iv) Plants dependent on sunlight to meet their photoperiodic requirements of flowering, will try to be distributed in area where this requirement is being met for their reproductive success.

Genetic engineering is a manipulation of genetic material in vitro. It involves the techniques to alter the chemistry of genetic material (DNA and RNA), to introduce the host organisms and thereby change the phenotype of the host organism.
Steps of rDNA technology are:
(i) Isolation of DNA.
(ii) Fragmentation of DNA by restriction endonucleases.
(iii) Isolation of the desired DNA fragments.
(iv) Amplification of the gene of interest.
(v) Ligation of the DNA fragment into the victor using DNA ligase.
(vi) Transfer of the recombinant DNA into the host.
(vii) Culturing the host cell on a suitable medium on a large scale.
(viii) Extraction of the desired product.
(ix) Downstream processing of the products as finished products.

(i) Single target site is present for particular restriction enzyme. If more than one site is present, then more cuts would fragment the plasmid.
(ii) 

(iii) (a) Now a days antibiotic resistance gene as markers are not used as they create more risk of plasmids to resistant gene to other bacteria.
It may spread the antibiotic resistance in many bacteria.
(b) Reporter genes are used now a days instead of antibiotic resistance genes. These genes have an ability to produce color in the presence of chromogenic substrate.

The arguments that can be put forward to justify the topic are:
(i) Reduce misconceptions and increase accurate knowledge Students have various wrong and inaccurate information about sex-related and pubertal issues. Accurate knowledge will help them cope up with their bodily changes and hormonal effects easily.
(ii) Clarify and strengthen positive values and attitude It is only through healthy discussions that students can realize that women are not the weaker sex because of their body structure. Such discussions will inculcate a feeling of equality amongst both sexes.
(iii) Increase communication with parents or other trusted elders These seminars open up students to consult their elders in case of confusion and doubt. It will make them understand that reproduction is a normal phenomenon and there is nothing inappropriate in discussing it with elders.
(iv) Increase the skills and thinking needed to make informed decisions and act upon them Out of curiosity, students are often seen getting involved in drug use, unhygienic and unsafe sexual activities, etc. increasing the risk of STDs and other diseases. making them well informed through such seminars well help them to take correct decisions.

Fig 1. represents  interaction between individuals of a single population.
Fig 2. represents  interaction between individuals of 3species (A,B,C) in a community.
Fig 3. represents a biome having 3 communities at different stages of development

(i) Analgesic;
(ii) Stimulation;
(iii) Opium
(iv) Cannabis sativa;
(v) Alcohol;
(vi) Lysergic acid diethylamide;
(vii) Mescaline;
(viiii) Viruses;
(ix) Penicillin;
(x) Chlesterol.

In an ecological succession, there is a tendency towards an increase in biodiversity (i.e. species diversity) from pioneer to climax stage due to following reasons:
(i) Environmental conditions become more and less hostile.
(ii) More and more ecological niches become available.
(iii) There is a change in types of plant and animal species towards a state of stability.
(iv) There is an increase in organic matter and biomass supported by available energy.

(a) Two examples of man-made ecosystems are: Gardens and parks, crop fields and fishery tanks.
(b) Salient features of man-made ecosystems:
(i) These are simple and highly efficient.
(ii) These are generally monoculture (e.g. field crops) with low biodiversity.
(iii) These are generally unstable
(iv) These are more vulnerable to sudden changes because of low biodiversity, stability and self-regulation.

Three above statements do not mean one and the same thing because:
(i) Statement (a) indicates total productivity of wheat but does not indicate the extent of area.
(ii) Statement (b) indicates productivity of wheat/acre on a specific day.
(iii) Statement (c) indicates productivity of wheat/acre/specific period.

The growth curve shown aboveis logistic growth curve or S-shaped curve.
Logistic growth curve is considered more realistic because unlimited resources are not available in an ecosystem or in a habital, where
K-stands for carrying capacity.
N-indicates population density, which is the number of species of a population per unit area. r-is for intrinsic rate of natural increase.

This phenomenon indicated in the questions is convergent evolution where by organisms, not closely related, evolve similar environment e.g.,
(i) Streamlined shape of sharks and dolphins. The former is a fish, while dolphin is a mammal, but both of them depend on swift movement through the water so a streamlined shape is essential. Thus, it is the similar habitat that resulted in selection of similar adaptive features in different groups of organisms, but toward the same funcion.
(ii) Spines and thorns, both look similar and provide protection to the plant, but the plants to which they belong are distantly related.

In the population of pepper moth two variants exist the dark and the light coloured. Before industrialisation, the light coloured moths were covered bark of the trees.
The predators were unable to spot them and hence, their population were more in number. With industrialisation, the barks got covered with soot. The growth of lichens reduced, the light coloured moths were thus, spotted by the predators and their number decreased.
However, the black variants were camouflased better on soot covered barks and their number increased drastically.
If the industries were removed, the population of black moths would have declined because as stated before, they would not be able to camouflage against a light background. Also the growth of lichens would increase. Therefore, the dark variants would be spotted better bu predators and be eaten more frequently.

Amniocentesis is a foetal sex determination test based upon the chromosomal pattern in the amniotic fluid surrounding the developing embryo. It should be legally banned throughout the country as such a ban shall check increasing female foeticide cases and maintain a normal sex rJtio in the country.

(i) Mode of Action.     Oestrogen inhibits ovulation by preventing FSH production.
(ii) Advantages.   Hormonal contraceptives are super devices to prevent conception.
(iii) Disadvantages.   They disturb the menstrual cycles.