ISC Class 12 Biology Question Paper Solution 2018

The ISC Class 12 Biology – Paper I (Theory) was conducted on 21st March 2018. The exam started at 2 PM, and students were given 3 hours to finish the paper. The maximum marks allocated to paper was 70. Here, we have provided the ISC Class 12 Biology Question Paper Solution 2018. Solving the 2018 paper and then going through the solution pdf will help students in assessing their current level of exam preparation. They will get to know their strong and weak areas in Biology and accordingly they can study to improve their overall performance in the board exam. Students can download, both the ISC Class 12 Biology Question Paper and Solution pdf 2018 from the link below.

Students can also access the Solved ISC Class 12 Biology Previous Year Question Papers for more practice. They can have a look at the ISC Class 12 Biology Question Paper Solution 2018 below.

Difficult Topics of ISC Class 12 Biology Paper 2018

Topics which students found difficult during the exam are:

• Bio patent

• Ecosystem (Food chain)

• Acronyms BOD, PAR, PCR, SCID

• Human evolution

• Gene therapy / SCID

• Role of microbes in human welfare

• Industrial melanism

• Ramsar sites

• Blue-white method of selection of recombinants

• Oestrous cycle

• Structure of DNA

• Punnett square

Confusing ISC Class 12 Biology Questions 2018

Biology concepts in which students got confused are:

• Source of opium (Papaver / Cannabis)

• Avery, McCleod, McCarty’s experiment / Griffith’s experiment

• Abiogenesis / Biogenesis

• Bio patent /Bio piracy

• Parthenocarpy / Parthenogenesis /Apomixis

• Global warming / Ozone hole

• Types of immunity

• Tissue culture technique / Plant hybridization

• Spermiogenesis / Spermatogenesis

• Hotspots /Biosphere reserves

• Amenorrhea / Lactation

ISC Class 12 Biology Question Paper Solution 2018

Question 1:

(a) Answer the following questions briefly and to the point:

(i) Give a significant point of difference between Oestrous and Menstrual cycle.

(ii) Give the biological name of the organism causing typhoid.

(iii) If the haploid number of chromosomes in a plant species is 20, how many chromosomes will be present in the cells of the shoot tip?

(iv) Name a plant which flowers every twelve years.

(v) Name the diagnostic test for AIDS.

(vi) Name the terminal stage of ageing in the life cycle of plants.

(vii) Which organisms constitute the last trophic level?

(viii) What is emasculation?

(b) Each of the following questions has four choices. Choose the best option in each

case:

(i) Length of the DNA with 23 base pairs is:

1. 78.4 Å
2. 78.2 Å
3. 78 Å
4. 74.8 Å

(ii) Opium is obtained from:

1. Papaver somniferum
2. Cannabis sativa
3. Erythroxylum coca
4. Datura metel

(iii) According to Abiogenesis, life originated from:

1. Non-living matter
2. Pre-existing life
3. Oxygen
4. Extra-terrestrial matter

(iv) The largest unit in which gene flow is possible is:

1. Organism
2. Population
3. Species
4. Genes

(c) Give one significant contribution of each of the following scientists:

(i) P. Maheshwari

(ii) E. Wilson

(iii) M. S. Swaminathan

(iv) H. Boyer

(d) Define the following:

(i) Bio patent

(ii) Parthenocarpy

(e) Give a reason for each of the following:

(i) Pollen grains of wind pollinated flowers are produced in large quantities.

(ii) Equilibrium of a forest ecosystem can be disturbed by uncontrolled hunting of big predators.

Answer: (a) (i)

(ii) Salmonella typhi

(iii) 40 chromosomes/diploid/2n/double/20 pairs

(iv) Strobilanthes kunthiana/ S. kunthiana/ Neelakurunji/ Kurunji

(v) ELISA test/Western Blot/PCR

(vi) Senescence

(vii) Decomposers / Top carnivores/ apex predator

(viii) Emasculation is the removal of anthers from bisexual flower before maturing for cross fertilisation.

(b) (i) (4) or 74.8

(ii) (1) or Papaver somniferum

(iii) (1) or Non-living matter

(iv) (3) or Species/ (2) or Population

(c) (i) P. Maheshwari: Plant tissue culture/Plant embryology/Production of haploid

(ii) E. Wilson: (Coined the term) Biodiversity

(iii) M. S. Swaminathan: Green Revolution in India

(iv) H. Boyer: Discovered Restriction Enzyme / Endonuclease

(d) (i) Biopatent: It is a legal right given to the owner for a biological discovery or biological product/ Intellectual Property Right.

(ii) Parthenocarpy: Production of seedless fruits / development of fruits without fertilisation.

(e) (i) Pollen grains of wind pollinated flowers are produced in large quantities because,

a large number of pollen grains may be wasted on the way / to ensure / to increase the chance of pollination.

(ii) Equilibrium of a forest ecosystem can be disturbed by uncontrolled hunting of big predators as population of herbivores will increase rapidly which will exhaust vegetation, causing herbivores to starve to death. /disturbs food chain/ intraspecific competition.

Question 2:

(a) A woman with blood group O married a man with blood group AB. Show the possible blood groups of the progeny. List the alleles involved in this inheritance.

OR

(b) If the mother is a carrier of colour blindness and the father is normal, show the possible genotype and phenotype of the offspring of the next generation, with the help of a punnet square.

Answer: (a)

(i) Possible blood groups of the progeny: A & B

(ii)

(b)

Question 3: Define life span. Give the life span of an elephant.

Answer: Life span is the time period from birth to natural death.

Life span of an elephant: 20 – 90 years.

Question 4: Give two characteristic features of each of the following:

(a) Ramapithecus

(b) Cro-Magnon man

Answer: Characteristic features:

(a) Ramapithecus:

• Approx 1.2 m
• Man, like feeding habits/Omnivore
• Bipedal/semi-erect/almost erect
• Canines small
• Short face
• Small brain
• Thickly enameled teeth
• They could bend their knuckles/knuckle walking
• Lived in late Miocene / early Pliocene
• Fossil collected from India and Africa
• 650 cranial capacity

(b) Cro-Magnon man:

• 1·8 m tall / 6 – 6·5 ft
• Head large/ Broad flat forehead
• Prominent supra – orbital ridges
• Erect posture/Bipedal
• Body less hairy/
• Chin prominent
• Nose narrow and elevated
• Face /orthognathus
• Cranial capacity 1650 – 1660 cc
• Cave dwellers and hunters
• Drawing and painting pictures
• Learnt to make tools
• Buried their dead
• Cooked food on fire/ Use of fire
• Domesticated animals
• Social life/lived in families
• Skill of talking/language/facial gesture/ Communication/expression
• Omnivorous

Question 5: (a) List any four effects of global warming.
OR
(b) State any four measures to control noise pollution.

Answer: (a) Effects of global warming:

1. Effects on weather and climate:

(i) Mean temperature increases by approximately 0.6% in the 20th century.

(ii) Frequency of extreme events like extreme cold/heat/drought and floods are expected to increase/coastal flood.

(iii) Increased moisture carrying capacity of air/affects rains.

(iv) Rise in mean sea-level.

(v) melting of ice caps, glaciers and Greenland ice sheets/polar caps/snow.

(vi) thermal expansion of ocean water.

(vii) Odd climatic conditions/El nino phenomenon.

2. Effects on animals and plants:

(i) Any temperature change affects the distribution pattern of plants.

(ii) Extinction of a large number of plant and animal species.

3. Effects on food production:

(i) Explosive growth of weeds.

(ii) Eruption of a number of plant diseases and pests.

(iii) Increased basal rate of respiration in plants.

(iv) Decrease in food production.

OR

(b) Measures to control noise pollution:

(i) Use of better designed, quieter machines industries.

(ii) Use of proper lubrication and better maintenance.

(iii) Sound proof jackets or filters can reduce noise from machines/use of acoustic material.

(iv) Workers should wear protective devices like ear muffs or cotton plugs.

(v) Noisy industries should be away from the residential areas.

(vi) Enforce restriction on the use of loudspeakers and amplifiers.

(vii) Plantation of coniferous trees on highways. /green mufflers

(viii) Strict laws to use better designed engines for aeroplanes.

(ix) No horn zones (schools/hospitals).

(x) Strict norms for vehicular horns/silencers.

(xi) Use of sound absorbent materials/ mufflers/use of curtains.

(xii) Machines with low sound emissions to be used.

(xiii) Ban on use of firecrackers.

Question 6: Define BOD. What is its significance in an aquatic ecosystem?

Answer: BOD: (Biochemical/biological oxygen demand) It is the amount of dissolved oxygen needed by aerobic organisms to breakdown organic material present in a given water sample, (at a certain temperature, over a specific time period)./oxygen content of water/dissolved oxygen in H₂O.

Its significance in an aquatic ecosystem: It indicates water pollution. Greater BOD more polluted/unfit for organisms to live/survive/measures organic matter in water/measures oxygen content/death of organisms/leads to Eutrophication /algal growth/microbial growth.

Question 7: Give one significant difference between each of the following pairs:

(a) Humoral immunity and cell mediated immunity.

(b) Benign tumour and malignant tumour

Answer: (a)

(b) Benign tumour and malignant tumour:

Question 8: Give four causes of infertility in males.

Answer: Causes of infertility in males:

(i) Cryptorchidism / azoospermia / oligospermia/low sperm count

(ii) Alcoholism/ Smoking

(iii) Thyroid dysfunction/ Hormonal imbalance/ Gonadotropin deficiency

(iv) Impotency/Incapacitation

(v) Under secretion of accessory glands

(vi) Y chromosome deletions /Genetic problem

(vii) Use of antihypertensive/ antipsychotic drugs/radiotherapy/surgery

(viii) Erectile dysfunction

(ix) Vas deferens blockage

(x) Acidity in urethra

(xi) Low sperm motility

(xii) Hyperthermia/high temp/tight undergarment

(xiii) Genetic problem

(xiv) Infection/Any STD

(xv) Deformities in sperm/abnormal shape, size

(xvi) Nutritional deficiency

(xvii) Age/Senility

(xviii) Mechanical damage/injury to reproductive part

Question 9:(a) Draw a labelled diagram of L.S. of human testis.
OR
(b) Draw a labelled diagram of the mature embryo sac of angiosperms.

Answer: (a) Draw a labelled diagram of L.S. of human testis:

(b) Diagram of the mature embryo sac of angiosperms:

Question 10: Explain gene therapy, with reference to treatment of SCID.

Answer: Gene therapy: Correction of genetic defect through genetic engineering /rDT.

(i) Deficiency of Adenosine Deaminase causes SCID (Severe combined immune deficiency)

(ii) Patient lacks T-cells and B-cells.

(iii) Cells from bone marrow of the patient are cultured outside the body.

(iv) The functional ADA gene is transferred into these cells through/ retrovirus vector/use of restrictions enzyme, ligase

(v) Transformed cells are transferred to the patient.

(vi) T cells and B cells appear in the blood.

(vii) After birth has to be done repeatedly

(viii) Effective in embryonic condition/before birth

Question 11: Study the table given below. Do not copy the table, but write the answers in the correct order.

Answer: (a) Streptococcus

(b) Clot dissolving/clot buster/treatment of myocardial infarction/Heart attack/Thrombolytic agent

(c) Statins

(d) Blood cholesterol lowering agent/acts as competitive inhibitor of enzyme involved in cholesterol

(e) Lactobacillus/Lactic Acid Bacteria

(f) Curd production

Question 12: Explain industrial melanism.

Answer: Variety

(i) Two varieties of peppered moth.

(ii) Biston betularia – white / dull gray

(iii) Biston carbonaria – black

(iv) Before industrialization – number of white variety was more

(v) After industrialization – the number of black varieties increased.

Effects

(vi) Due to pollution lichens disappeared

(vii) Trees became dark

(viii) Added advantage to black variety through camouflage

(ix) Selective feeding by the predator birds

(x) Directional selection/Natural selection

Question 13: Describe the tissue culture technique in plants.

Answer:

The tissue culture technique in plants:

1. Selection of explants/plant tissue
2. Sterilization of explant / culture medium / instruments
3. Inoculation in the culture medium
4. Incubation under ideal / sterile / aseptic conditions
5. Callus formation
6. Differentiation (by auxins / cytokinins
7. Generation of plantlets
8. Hardening
9. Transferred to fields
10. Organogenesis

Question 14: Define the following:

(a) Spermiogenesis

(b) Reproductive health

(c) Amenorrhea

Answer: (a) Spermiogenesis: Transformation of spermatid into sperm.

(b) Reproductive health: Ability of a person to produce healthy offspring / total well-being in all aspects of reproduction (physical, physiological, psychological and social)

(c) Amenorrhea: Stoppage of menstruation. /absence of menstrual cycle/absence of menstruation during lactation after birth of child.

Question 15:

(a) Define the following:

(i) Hotspots

(ii) Ramsar Sites

(iii) Red data book

OR

(b) Define the following:

(i) Biodiversity

(ii) Eutrophication

(iii) PAR

Answer: (a) (i) Hotspots: a region with high level of endemic species / an area rich in biodiversity/area of high level of species richness/under threat.

(ii) Ramsar Sites: wet land areas of biodiversity/conservation of wetlands.

(iii) Red data book: book containing list of endangered species/rare flora and fauna.

OR

(b) (i) Biodiversity: Degree of variation of life forms/variety of organisms in an area/richness

of organisms in an area/totality of genes, species and ecosystems of a given region.

(ii) Eutrophication: process of accumulation of inorganic nutrients in an aquatic ecosystem/nutrient enrichment/dumping of domestic and industrial wastes in water leading to depletion of oxygen/Deadening of water bodies/algal bloom.

(iii) PAR: it is the amount / wavelength of light available for photosynthesis.

Question 16:

(a) Describe post transcriptional processing of RNA in eukaryotes.

OR

(b) Describe Avery, McLeod and McCarty’s experiment. State its significance.

Answer: (a) Post transcriptional processing of RNA in eukaryotes:

Definition: Changes in primary transcript (hnRNA) to mature / functional mRNA.

• 5ʹ capping – with methylguanosine

• Poly –A tail – addition of adenylate residues at 3’ end

• Splicing of introns/removing introns

• Joining of Exons

Capping and tailing prevents degradation of mRNA

OR

(b) Avery, McLeod and McCarty’s experiment:

• Extracted and purified proteins, DNA, RNA, etc. from heat killed S-strain bacteria. /Pneumococci

• Treated the extract with protease, RNase and DNase

• DNase treated extract did not kill the mice

Protease, RNase killed the mice

• Proved DNA is the genetic material

Significance – Hereditary material can be extracted from one organism and introduced into

another (transformation)/DNA is a transforming principle

Question 17: (a) Write a short note on the Chipko Movement.
OR
(b) Write a short note on Joint forest management.

Answer: (a) Chipko movement:

• People lost their lives

• Related to forest conservation

• Villages in Garhwal started this movement

• To protect the trees from cutting /felling

• Gained momentum under the leadership of Sunderlal Bahuguna/Amrita Devi

• Trees were hugged by rural people/embraced the trees

• Chipko name given means embrace

• Prevented contractors from cutting the trees.

• This became a turning point in the history of eco-development.

• Movement encourages planting of trees for timber/food/shelter/making villages self sufficient.

• Amrita Devi Award instituted

OR

(b) Joint forest management:

• Established by the Government of India.

• Involves both, state forest department and local rural communities

• Currently 17.30 hectares forest area under them

• Rural communities protect the forest from fire/ grazing/ illegal harvesting/Poaching

• In return forest department provides non-timber forest products and share of revenue from the sale. / provides employment

• Products offered are gums, resins and medicines.

• Avoid urban tribal conflict.

Question 18: (a) What does PCR stand for? Describe the different steps of PCR.
OR
(b) Give an account of the Blue-White Method of selection of recombinants.

Answer: (a) Polymerase Chain Reaction: It is a method of making multiple copies of the gene of interest (gene amplification) in vitro using oligonucleotides and DNA polymerase.

Or

PCR technique is used for gene amplification.

Steps:

(i) Denaturation:

• Target DNA heated to a high temperature (94-96 ⁰C)
• results in the separation of two strands
• Each strand serves as a template for DNA synthesis.

(ii) Annealing:

• The two oligonucleotide primers are annealed (hybridized) to each single stranded DNA following rule of complementarity. (60 ⁰C)
• It is caused at low temperature (40⁰ – 60⁰)

(iii) Extension (Polymerisation):

• With the help of Taq DNA Polymerase DNA is synthesized between the primers using dNTPs and Magnesium ions (72 ⁰C).

(iv) The newly synthesized DNA is subjected to same procedure to double the DNA

content from the previous cycle.

Accept properly labelled diagram or flow chart

OR

(b) Blue-White Method of selection of recombinants:

1. Based on insertional inactivation
2. Foreign gene inserted or using restriction endonuclease/Ligase
3. Lac Z gene (coding for Beta – galactosidase enzyme)
4. Beta – galactosidase converts colourless substrate (chromogenic substrate) (X-gal) into blue coloured product.
5. In transformed hosts Lac Z inactivated due to insertion of foreign DNA.
6. Non-transformed colonies convert colourless X-gal into blue coloured product.
7. Transformed colonies remain white.
8. It helps to differentiate between transformant/recombinant and non-transformant/ nonrecombinant.

We hope students must have found ISC Class 12 Biology Question Paper Solution 2018 helpful for their exam preparation. We have also compiled ISC Class 12 Previous Year Question Papers for Physics, Biology, Maths and Biology at one place for students convenience. Happy Learning and stay tuned to BYJU’S for the latest update on ICSE/CBSE/State Boards/Competitive exams. Also, don’t forget to download the BYJU’S App.