1. The primary effluent is passed into large aeration tanks; it is constantly agitated mechanically and air is pumped into it.
2. The useful aerobic microbes grow vigorously to form floes, which are the mesh-like structures formed by masses of bacteria in association with fungal hyphae.
3. During their growth, these microbes consume a major part of the organic matter and hence, there is a significant reduction in the BOD of the effluent.

Yes.
Many animals other than human have self-consciousness. For example, dolphins are highly intelligent. They have a sense of self and they also recognise others among themselves. They can communicate with each other by whistles, tail slapping, and other body movements. Besides dolphins some other animals such as parrots, chimpanzees, orangutans, gorilla, etc. are also found to have self-consciousness.

Codominant Alleles
1. The alleles which are able to express themselves independently when present together are called codominant allele. As a result of the heterozygous condition, the phenotype different from either of a homozygous condition.
2. The joint character may appear to be intermediate between the ones produced by two homozygous genotypes.
3. It is different from incomplete dominance where one is more pronounced but in this case both characters are present.
4. In case of ABO blood group A and B, genes are present and shown as \({ I }^{ A }{ I }^{ B }\). Their erythrocyte coatings contain two glycoproteins are antigens, A and B.
5. In cattle, if a cattle with black coat is crossed with white coat, \({ F }_{ 1 }\) heterozygotes are found to possess roan coat, black and white patches appear separately but no hair has intermediate colour of black and white.

Bacterium Thermus aquaticus is a source of enzyme Tag polymerase. As it is a thermostable enzyme and work at high temperature, it is used to amplify DNA in vitro by PCR. The amplified fragment of desired DNA can be used to ligate with the vector for further cloning.

Counseling should be provided to students about reproduction related problems as
(i) Students are experiencing physical, physiological and psychological changes during adolescence.
(ii) Students should be guided about harms of early sex, hygiene of reproductive organs and STDs.

There is an adaptation in angiospermic plants to provide assured nutrition to the developing embryo. Most zygotes divide only after certain amount of endosperm is formed. Therefore, zygote remains dormant for sometime in a fertilised ovule.

The Ig monomer is a "Y"-shaped molecule that consists of four polypeptide chains, two identical heavy chains and two identical light chains connected by disulphide bonds.

Tapetum is the innermost layer of the microsporangium. It produces the exine layer of the pollen grains, which is composed of the sporopollenin, the most resistant organic material. During microsporogenesis, the cells of tapetum produce various enzymes, hormones, amino acids and other nutritious materials required for the development of pollen grains.

Human evolution cannot be called adaptive radiation because parent species of Homo sapiens have evolved by progressive evolution from homo habilis to homo erectus lineage.

(a) Single Cell Protein (SCP) are basically produced from the microbes, for example Candida utilis, Chlorella, Spirulina, Saccharomyces. SCP may be used directly as human food supplement or else it can be used in animal feed as protein-rich supplement.
(b) Soil It is a unique habitat which harbours a variety of microflora and fauna, and gives mechanical and nutritional support to higher plants on which human civilization is based.
Examples The rhizosphere micro-organisms have beneficial effects on the development of plant. The microorganisms catalyze the reactions in the rhizosphere and produce \({ CO }_{ 2 }\) and form organic acids that in turn solubilize the inorganic nutrients of plants. Some of the rhizosphere micro-organisms also produce growth stimulating substances.

Introduction of rDNA into host cell
(i) Microinjection
In this method, the recombinant DNA is directly injected into the nucleus of an animal cell.
(ii) Gene gun/Biolistics
In this method, used for plant cells, the cells are bombarded with high velocity microparticles of gold or tungsten coated with DNA.
(iii) Heat shock method In this method, the rDNA is forced into the competent cell by incubating the cell with rDNA on ice followed by placing them briefly at \({ 42 }^{ ° }C\) ( (heat shock) and then putting them back on ice.

(i) DNA-dependent DNA polymerase
 It catalyses the polymerisation of approximately 2000 bps in a second into DNA, with high degree of accuracy.
(ii) DNA-dependent RNA polymerase
It catalyses the formation of RNA from DNA.
(iii) In eukaryotes, there are three types of DNA
dependent RNA polymerase as follows
(a) RNA Polymerase-l Transcribes rRNAs.
(b) RNA Polymerase-II Transcribes precursor of mRNA, i.e. hnRNA.
(c) RNA Polymernse-lII Transcribes tRNA, srRNA and snRNAs.
(iv) Reverse transcriptase is used for the synthesis of complementary DNA over RNA template.

The male accessory ducts are rete testis, vasa efferentia, epididymis and vas deferens.These ducts store and transport the sperms from the testes to the outside through the urethra. The male accessory glands are paired seminal vesicles, prostate gland and paired Bulbourethral glands. The secretion of these glands forms seminal plasma, which is rich in fructose, calcium and certain enzymes. The secretion of Bulbourethral glands lubricates the glans penis.

Fertilisation can be prevented by barrier methods.
(i) Condoms are the barriers made of thin rubber/latex sheath, that covers the penis in males and the vagina and cervix in females.
(ii) Diaphragms, cervical caps and vaults are the barriers used by females.
(iii) Spermicidal creams are used to kill / incapaciate the sperms.

The diagram of 7- celled 8- nucleate embryo sac of plants is as follows:

The female gametophyte of plants is formed from a single functional megaspore with the help of four unequal mitotic divisions. These mitotic divisions give rise to 8 nuclei. Later, these nuclei assemble into 7 cells. To both chalazal and micropylar end three cells each move. The three cells at chalaza are called antipodal cells while those at micropylar end constitute egg apparatus. The egg apparatus includes two larger cells called synergid while the egg is the smallest cell that acts as a female gamete.  Two nuclei migrate to the centre and together they form a single cell called the central cell. This central cell consists of two nuclei called polar nuclei. Thus, the mature embryo sac possesses 7 cells ( 3 antipodal cells, 2 synergid cells, 1 egg cell and 1 central cell) and 8 nuclei ( 3 of antipodal cell, 2 of synergid cells, 1 of egg cell and 2 of central cell). 

Harmful effects of drugs like LSD, barbiturates, etc., are:
(i) Anxiety, shakiness, nausea and sweating, loss of mind control.
(ii) Reckless behaviour, vandalism and violence.
(iii) Lack of interest in personal hygiene, fluctuations in weight and appetite.
(iv) Social adjustment problems.
(v) Withdrawal, isolation, depression, fatigue, aggressive behaviour .
(vi) Withdrawal symptoms can be severe and life threatening.
(vii) Excessive doses of drugs may lead to coma and death due to respiratory failure, heart failure or cerebral haemorrhage.

(i) It is branch of biology which deals with mapping, sequencing and analysing genome
(ii) It will help in basic understanding of human genetics, disorders revealing the genes responsible for various ailments such as cardiovascular ailments, Alzheimer, cancer etc.and treatment of such disorders.

Population Control
Population explosion can be checked by two methods-population education and birth control.
Population Education 
The knowledge about the relationship between population size and the availability of resources for the welfare of the society is called population education.
1. The students should be convinced about the relationship of overpopulation and unemployment.
2. The citizens should be told how the large size of population is eating away the resources of the state and the reasons for limited availability of health care, education facilities, and other welfare schemes.
3. People should be made aware how large number of children eat away the meager resources of the family with nothing left for bad days, how large families rely on indebtedness to meet emergencies.How child bread earners do not improve the conditions of the family, how uneducated children remain burden on the society, etc. They should be convinced that a small family can live comfortably even with meager resources.
4. Mass Media of Communication.  Radio, television, newspapers, magazines, hoardings and posters should be employed to spread the message of family planning and birth control and its advantages.
The future of mankind depends on stabilisation of human population at a level that ensures basic necessities of life, employment, and happiness.
5. Law about marriageable age should be widely published and strictly enforced 921 years for boys and 18 years for girls).In developed countries, women marry at the age of 25-35 years.
6. As far as possible, stress should be laid on raising the social status of the women.Women having higher social status prefer smaller families. Such women generally marry late,
7. Remove the superstitions and wrong beliefs in the society about higher number of children being God's gift connected with the earthly or heavenly prosperity. 

(a) Genotype of:
A - Tt, B - TT, C - tt, D - Tt
(b) The phenotypic ratio is
3 Tall : I Dwarf
(c) It is a monohybrid cross.

(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
Explanation:
Innate immunity refers to nonspecific defense mechanisms that come into play immediately or within hours of an antigen’s appearance in the body. Four barriers are physical, physiological, cellular and cytokine barriers.

(c) If A is true, but R is false

(a): It has been shown, for instance that the same tRNA can recognise more than one codons differing only at the third position. This pairing is not very stable and is allowed due to wobbling in base pairing at this third position. This kind of wobbling allows economy of the number of tRNA molecules, since several codons meant for same amino acid are recognised by same tRNA. For instance, anticodon CGC can recognise codons GCU, GCC and GCA.