A fully developed embryo sac
A fully-developed and mature embryo sac is shown above.
(a) Name the cell from which it has developed.
(b) What is the ploidy level of its nuclei?
(c) What is filiform apparatus? Mention its significance.

A farmer has been cultivating paddy in his field season after season. Of late, the yield has been decreasing though there is no occurrence of pests or disease. He has been advised to use Nostoe by the local centre of the Agricultural department. To his surprise, the yield started increasing.
(a) How does Nostoe help to increase the yield of paddy crops?
(b) Name two other organisms ofthe same category that can serve this purpose.

A pond is a shallow water body, which is fairly a self-sustainable unit that explains the complex interactions in an aquatic ecosystem. The water with all the dissolved inorganic and organic nutrients is the major abiotic component.
Name the three groups of biotic components in the pond and give an example for each.

Organisms occupy a specific place in their natural surroundings or in a community according to their feeding relationship with the other organisms. Based on the source of nutrition of food organisms occupy a particular place, called trophic level, in a food chain.
(a) What technical term is given to the organisms occupying the first, second and third trophic levels in a food chain?
(b) Choose an example for each of the above trophic levels, from the following list of organisms: Rabbit, Wolf, phytoplanktons, frog, snail, Hydrilla, jackal.

Read the following and answer any four questions from (i) to (v) given below :
Translation is the process of polymerisation of amino acids to form a polypeptide. The order and sequence of amino acids are defined by the sequence bases in the mRNA. The amino acids are joined by a bond called peptide bond. Ribosome is the site of protein synthesis.
(i) Which ion is essential for association of both units of ribosome at the time of protein formation ?

(ii) During translation, how many initiation factors are required in eukaryotes for initiation reactions?

(iii) Which part of mRNA contains untranslated regions (UTR)?

(iv) Name the enzyme that helps in combining amino acid to its particular tRNA.

(v) From the given list, select the translation machinery.
1. mRNA
2. Ribosomes
3. Amino acids
4. tRNAs
5. Peptidyl transferase
6. Amino acyl tRNA synthetase
7. Pyrophosphatase

Read the following and answer any four questions from (i) to (v) given below:
Transgenic animals can serve as factories that in some cases, may produce large amount of proteins more efficiently. Transgenic mice have been engineered to express human antibodies by introducing large segment of human DNA encoding human immunoglobulin genes. In transgenic large animals such as cow or sheep proteins of pharmaceutical value can be produced in large quantities in milk which is later purified. Transgenesis can be used to alter many phenotypic properties including growth rate, fat composition, milk production, hair texture, etc.
(i) The production of transgenic animals includes

(ii) In transgenic animals, i.e., cow and sheep proteins of pharmaceutical value are produced in large quantities in the

(iii) Mouse is mostly preferred animal for studies on gene transfer because
A. short oestrous cycle
B.long gestation period
C.Short generation time
D.Production of one or two offspring per pregnancy

(iv) Transgenic genes alter many phenotypic properties including

(v) Assertion : Transgenic mice have been engineered to express human antibodies.
Reason : Large segment of human DNA encoding human immunoglobulin have been transferred to mice.

Read the following and answer any four questions from (i) to (v) given below:
Insulin used to cure diabetes was earlier extracted from pancreas of slaughtered cattle and pigs. Insulin extracted from an animal source, though caused some patients to develop allergy or other types of reactions to the foreign protein. Human insulin consists of two short polypeptide chains: chain A and chain B, that are linked together by disulphide bridges. In mammals including humans, insulin is synthesised as a pro-hormone which contains an extra stretch called the C-peptide. This C peptide is not present in mature insulin and is removed during maturation into insulin.
(i) Identify A in the given figure.
 
 

(ii) The following is a list of some stages involved in producing human insulin from genetically engineered bacteria.
1. The bacteria are cultured in a fermenter for large scale production.
2. Recombinant insulin is extracted from the bacterial cells that expresses insulin gene.
3. The same restriction enzyme is used again to cut the bacterial plasmid for insertion of the human insulin gene.
4. Bacteria take up the plasmid carrying the insulin gene.
5. A restriction enzyme is used to cut human DNA to extract the insulin gene.
Select the correct order of these stages.

(iii) To insert the insulin gene into bacterial DNA, both the bacterial plasmid and the human chromosome containing the insulin gene are treated with the same restriction enzyme. Using the same restriction enzyme ensures that

(iv) Why is the fermentor important for the production of human insulin by transgenic bacteria

(v) A bacteriologist carries out his first attempt at engineering E.coli with the gene for human insulin. During the process, he realises that his stock of DNA ligase has depleted but decides to continue anyway. What is a likely consequence of his decision?

Read the following passage and answer the questions given below .
During the unfortunate corona virus lockdown, Kavita started cursing the existence of microbes on earth. On hearing this, Deepak told Kavita that not all the microbes are harmful for us. Many microbes are useful in producing medicines, bioactive molecules and household products .
(i) Antibiotics are produced by a living organism. What relationship do these hare with target and non-target organisms?
(ii) Mention the source and functions of cyclosporin-A and statins.
(iii) Beside making curd, mention the household function of bacterial microbe Lactobacillus.
(iv) Mention any two functions of fungal microbe Saccharomyces cerevisiae.
(v) Swiss cheese is characterised by large holes. What causes such a condition in it ?

Rama lives in a society where a robbery occurred last night. Robbers came into the flat and murdered the old lady residing there. Police came and restricted entry into the flat. They took samples from the room, where the dead body was found. While examining, they found that there is some blood and tissue in the nails of an old lady. According to their observation, police filtered out their inspection to three suspects viz. servant, cook, and milkman. Finally, after two days of robbery, the police caught the criminal. It was the old lady’s cook. Rama was amazed to see how quickly the police completed and shut the case. She asked the inspector how they did it. The policeman told her that it become possible due to the sample collected from the victim, which lead them to the criminal. The sample taken from nail scraping was amplified using PCR and then tested.
1.What technique was used by the police to identify the criminal?
(a) DNA fingerprinting
(b) Gel electrophoresis
(c) Molecular diagnosis
(d) Cloning
2.In PCR, the temperature used to denature the DNA is about
(a) 76°C
(b) 25°C
(c) 95°C
(d) 40°C
3.Which of the following statements regarding PCR is correct?
(a) Taq polymerase, which is isolated from the bacterium Thermus aquaticus is stable at low temperature only.
(b) With the help of D N A ligase, t h e complementary sticky ends of the DNA are joined to produce an rDNA.
(c) Since the sequence of primers is complementary to the 5′ end of the template DNA, they anneal to it.
(d) DNA purified from the cell is precipitated by adding hot ethanol.
4.Taq polymerase synthesizes DNA region between the primers using
(a) Mg²⁺ 
(b) dNTPs
(c) DNA ligase
(d) both (a) and (b)
5.Given below are the steps of the polymerase chain reaction

Select the option that correctly mentions the sequence in which they occur.
(a) (ii) → (iii) → (i)
(b) (i) → (ii) → (iii)
(c) (iii) → (i) → (ii)
(d) (ii) → (i) → (iii)