Model Question Paper

• Microsporogenesis is the process of formation of microspores in anther.

•

• Ampulla is a part of female reproductive accessory duct. (Fallopian tube)

• It is the site for the fertilisation.

• Surgical method involves cutting and tying up the ducts i.e. fallopian tube in females and vas deference in males.

• This only blocks the transportation of gametes.

• This occurs due to the addition of the deoxyribonucleotides to the free 3’ end of the template strand.

• Thus the replication on 5' → 3' is discontinuous.

• However the discontinuous strands synthesised are joined using DNA ligase enzyme.

• The method used for the determination of the genotype of an organism is called test cross.

• In this type of cross, organism with unknown genotype is crossed with the recessive trait parents.

• If the all the progenies obtained are of same type then it is said that the organism with unknown genotype is homozygous.

• It is concluded that the genotype of unknown organism is heterozygous, if 50-50% result is obtained.

It was suggested by Heldane and Oparin, and experimentally proved by Urey and Miller that in the very starting atmosphere was reducing in nature.

It consisted of NH_3, H_2, CH_{4 ,}the temperature was very high.

Due to absence of vascular supply, meristems remain free from pathogens.

• When a DNA or RNA is tagged with radio labelled tag, and then allowed to hybridise with complementary DNA strand.

• These tagged probes are then seen by technique of autoradiography.

In aquatic system, biomass of primary producers i.e. phytoplankton is less than that of zooplanktons; biomass of fishes is much more than zooplankton. Hence, pyramid of biomass appears inverted.

• Green evolution is related with the use of hybrid plants which were more efficient in uptaking nutrients and water, even from great depth sites.

• This lead to nutrients depletion, and led to barren soils.

• Moreover use of fertilizers and pesticides also contributed in soil infertility. And led to soil erosion and desertification.

Two important conditions under which MTP can be performed are:

• If the pregnancy could prove to be fatal either for mother or the child in future.

• In case of unwanted pregnancy.

a. Wing of bat and butterfly __A_______

b. Wing of bat and flipper of whale __H______

c. Wing of butterfly and flipper of whale ____H______

d. Flipper of whale and wing of bird _____H ______

Codominance: when both the alleles are dominant, and express equally to produce traits.

Incomplete dominance: in this case two alleles combine to produce a new trait. Example RR (red flower) when crossed with rr( white flowers) gives a new phenotype to form pink flowers of Rr genotype.

• Colostrums is rich in antibody IgA.

• It is the example of Passive Immunity.

A. Single cell protein

The protein produced by culturing single celled organism is called Single cell protein.

Yeast , Spirulina and a bacterium Methylophilus methylotropus are used for the culturing to obtain SCP.

b. Orgamic farming

• Involves use of natural ways for the farming.

• Instead of using fertilizers, microbes are used to enrich soil with nutrients e.g. cyanobacteria like Nostoc and Anabena are known to fix nitrogen. Hence used to supplement soil with N element.

• Use of biocontrol agents: instead of using inorganic insecticides or fungicides naturally occurring organisms are used.

E.g. strain of Bacillus thuringensis is known to encode for insecticidal proteins. And protects the cotton farm from insects.

a.

b. Proto-oncogenes. These are normal genes that on activation due to mutation may change into oncogenes.

Viral-oncogenes, these are the cancer causing genes present inside the virus.

Propionibacterium shermanii is used to produce Swiss cheese.

Steps involved in insulin production using rDNA technology:

a. The gene which are known to synthesise A and B poly peptide chains are isolated.

b. It is inserted in the plasmid of the E. Coli bacteria, at a site where gene for beta- glactosidase synthesis is present, using a DNA ligase enzyme.

c. Now as the plasmid synthesise beta galactosidase, it produces A & B polypeptide chains.

d. These A&B polypeptide chains are isolated and combined by disulphide bonds.

Selectable markers are the sites present in the vectors plasmid, used to distinguish between tranformant and non transformant cell. E.g.

• Antibiotic resistance gene like BaH MI-provides tetracycline resistance.

• Chromogenic genes.

a.

b.

GPP – Respiratory losses = NPP

Following is the correct sequence:

• Fragmentation

• Leaching

• Catabolism

• Humification

• Mineralisation

Recycling of e-waste under friendly biological condition is the best way for its disposal.

• In Angiosperms and Vertebrates, sexual mode of reproduction is pronounced.

• Sexual mode of reproduction allows gradual changes in genetic pool, due to recombination.

• It allows the variation and helps the organism to adapt well according to the changing environment.

• In asexual reproduction, no variations are allowed exact copies of parents are produced. It leads to poor adaptability. Hence the organisms with such increased complexity, chose to reproduce sexually.

• Ruptured Grafian follicles form the Corpus luteum.

• Corpus luteum produces progesterone and helps to maintain the endometrium lining, required for the implantation of embryo.

• However if fertilisation doesn’t happen then there is no need of endometrium lining.

• As in absence of fertilisation, endometerium is not required and the corpus luteum degenerates in 10-12 days.

• Colour blindness is a sex linked(X-linked) recessive disorder.

• X linked disorder expresses themselves in males more frequently, because they have only one copy of X chromosome.

• Whereas, females have two copies of X chromosomes. They will get affected by this disorder only when they have both the copies of affected alleles.

Due to following reasons DNA is considered to be more stable as a genetic material then RNA:

• DNA is chemically more stable than RNA.

 In DNA instead of Uracil, Thymine is present.

 2’-OH group is present in RNA, which makes it more reactive and less stable.

• DNA being double stranded is more stable structurally than single stranded RNA.

• Cannabinoids are drugs, which binds with the brain and suppresses feeling of pain.

• These are obtained from a plant Cannabis sativa.

• Effects:

A. It increases heart beats thereby increasing blood pressure.

B. Reduces inflammation

C. Reduces muscle spasm and relieves pain and anxiety.

• Bt toxins are the protein crystals produced by Bacillus thruingensis.

• These toxins are insecticidal in nature.

• When an insect ingest bt toxin, the protoxin converts into active form due to the alkaline nature of gut, the Bt toxin binds with the lining of gut, creates pore, causing death of insect.

• This insecticidal property is used by mankind by taking out the cry gene which is known to encode for Bt toxin.

• And this Cry gene is introduced into the plants. So that whenever an insect ingest, the cotton plants would die.

• A nematode called the Meliodygyne incognitia is known to cause root knots in tobacco plant.

• Scientists developed a method called RNAi to kill this nematode.

• A host specific double stranded DNA was introduced, such that it produced both sense and antisense sequences.

• Both these sense ad antisense sequences undergo transcription and form two complementary RNA strands.

• Both the strands combine to form double helix.

• Which is chopped off, hence the gene expression of nematode inactivates.

Role of synergid:

Synergids consist of filliform apparatus which directs the growth of pollen tube into the embryo sac by secreting some chemical substances.

As the pollen tube enters the synergid, it starts to degenerate.

OR

a) Children need to be prepared mentally for the upcoming body changes due to arrival of adolescence.

b) Sex related issues like STDs, unwanted pregnancies, MTP must be taught.

c) Students are needed to be given classes on sex education, in order to break the taboo related with reproductive health.

d) School students need to be counselled about different aspects of adolescences i.e. related problems and its solutions.

e) Children are needed to be made aware of the importance of habit of cleanliness and hygiene.

(a) • Birds are the best examples of female heterogamety.

• Females decide the sex of the off springs.

Female bird – ZW, Male bird- ZZ

(b) • Organisms with male heterogametes like humans, males are the deciding factor in the sex determination of the off spring.

• Whereas in birds, where female are heterogametic, sex is determined by the mother.

• In some of the organisms like crocodiles sex determination depends on temperature.

• In crocodiles it is observed above 32⁰C males are formed and below it the females are produced.

OR

1. Splicing- primary transcripts contain exons and inrons.

Introns are the sequences which don’t code for any protein. Hence, they need to be removed. The intron sequences form loops and then are cleaved.

2. Capping and tailing: as in eukaryotes RNA is transported from nucleus to the cytoplasm, it needs some protection in order to avoid degradation of DNA.

Hence, at the 3’ end poly adenylate chain, and at the 5’ end methyl gaunosine triphosphate residues are added.

a. Tropical Rain forest

b. Grasslands

c. 0⁰-10⁰C

d. 50-200cm

e. Arctic and Alpine Tundra

OR

a. Natality rate= [600/1200]*100

=50%

b.Mortality rate= [200/1200]*100

=16.7%

c. No. Of cranes immigrated= 700

d. No. Crane emigrated=800

e. Population of crane=1500