A test cross involves the cross between offspring of \({ F }_{ 1 }\) with a homozygous recessive parent to determine the genotype of \({ F }_{ 1 }\) offspring, whereas, reciprocal cross involves the study of same character with reversed sexes.It is made to determine if sex has any role on dominance-recessive relationship.

Yes, aquarium is a man-made ecosystem (artificial). If an ecosystenm possesses all physical and biological components,then it issaid to be complete.
Since, aquarium has both biotic components (plants and fishes) and abiotic components (air and water), so it is a complete ecosystem.

It is a case of mutualism because both the fig tree and the wasp are benefitted by this interaction.
The female wasp uses the ovary as a site for oviposition and the developing seeds within the fruit for nourishing the larvae.
The fig inflorescence is pollinated while the wasp is searching for the suitable place for egg-laying.

1. When one of the termination codons (UAA, UAG, UGA) comes at the A-site, it does not code for any amino acid and there is no tRNA molecule for it.
2. As a result, the polypeptide synthesis (or elongation of polypeptide) stops.
3. The polypeptide synthesised is released from the ribosome, catalysed by a 'release factor'.

(ii) There are four major factors that results in loss of bidiversity and these are
(a) Habitat loss and fragmentation
(b) Over-exploitation.
(c) Alien species invasion
(d) Co-extinction 
(iii) No, Alok was a brave and courteous boy. He expressed his love for animals, commitment towards natural resources and their conservation.

The formula for calculating population density is D_p= N/A. In this equation, D_p is the density of population, N is the total population as a number of people, and A is the land area covered by that population.

Phenotypes                               Smooth seeded X and red flowered                              Smooth seeded and
Parents                                          SsRr                                                                                          White flowered SsRr
Genotype

RNA is more liable and prone to degradation (owing to the presence of 2'OH group in its ribose) Hence, heat-killed S-strain may not have retained its ability to transform the R-strain into virulent form if RNA was its genetic material.

1. In England, before industrial revolution, there were more white-winged or dull-grey moths on the tree trunks, than the dark-winged or melanic moths.
2. In the collection of moths, carried out in the same area after industrial revolution, there were more dark-winged moths.
3. The explanation given for this observation was that predators will spot a month against a contrasting background.
4. During the post-industrialisation period, the trunks became dark with the industrial smoke and soot.
5. Under this condition, white-winged moths did not survive as predators could easily spot these, while dark-winged or melanic moths survived better.
6. Before industrialisation, there used to be a thick growth of the almost white coloured lichens on the tree trunks and in that background, the white-winged moths survived better; the dark coloured moths were easily spotted and picked up by their predators.
7. In this case,the moths which were able to camouflage and hide in the background survived and increased their population size through reproduction.

RNA is the first genetic material because:
(i) RNA can directly code for the synthesis of proteins and hence can easily express the character; it is the genetic material in many viruses.
(ii) RNA can also act as a catalyst; there are some important biochemical reactions in living systems that are catalysed by RNAs and not proteins.
(iil) Many essential life processes like splicing, translation, etc. have evolved around RNA.

(a) Central dogma:

given by Francis Crick.
(b) Messelsont & stanl experiment:

(Same value points to be awarded in an  explanation).

Ecologist Paul Ehrlich gave 'rivet popper hypothesis' to understand the contribution of the species richness. He compared each species with rivet in the body of an airplane.
(i) This hypothesis explain that ecosystem to be an airplane and the species to be the rivets joining all parts together.
(ii) If every passenger traveling in the airplane start taking rivets home(causing a species to become extinct), initially it may not affect flight safety (proper functioning of ecosystem), but over a period of time the plane become weak and dangerous (Species become endangered and then extinct).

(a) The gene controlling ABO blood group in human exists in three allelic forms, \(I^{ \wedge }I^{ B }\) and i, i.e. multiple alleles.
(b) Mother-homozygous A group -\(I^{ \wedge }I^{ \wedge }\)  Father-homozygous B group \(I^{ \wedge }I^{ \wedge }\)The progeny will be as follows:

(a) The advanced ex-situ techniques.
(i) Cryopreservation of gametes of threatened species
(ii) In vitro fertilisation of eggs.
(iii) Tissue culture methods of plant propagation.
(iv) Seed banks to store seeds of commercially important plants for long periods.
(b) The International Conventions
(i) Convention on Biological Diversity (Earth Summit), 1992, held in Rio de Janeiro.
(ii) World Summit on Sustainable Development, 2002, held in Johannesberg, South Africa.

(B) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(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.

(a) : Back cross is a cross which is performed between hybrid and one of its parents. In plant breeding, back cross is performed a few times in order to increase the traits of that parent. For example, a crop plant is crossed with a wild variety in order to obtain its disease resistance. In the process, most good traits of the crop plant get diluted. The hybrid is, therefore, repeatedly crossed with parent crop plant in order to transfer the good traits back into it.

(a): B-DNA is a helical structure with diameter of 20 Â. If pairing occurs between two purines, it would need too much space and if pairing occurs between two pyrimidines, it would occupy too little space. The constancy of DNA diameter is maintained only when a pyrimidine always pairs with a purine