ISC Biology 2014 Class-12 Previous Year Question Papers

ISC Biology 2014 Class-12 Previous Year Question Paper Solved for practice. Step by step Solutions with Part-I, and II (Section-A,B and C). By the practice of ISC Biology 2014 Class-12 Solved Previous Year Question Paper you can get the idea of solving.

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ISC Biology 2014 Class-12 Previous Year Question Papers Solved


-: Select Your Topics :-

Part-I,

Sections-A, Part- II,

Sections-B, Part- II,

Sections-C, Part- II,


Maximum Marks: 70

Time allowed: Three hours

(Candidates are allowed additional 15 minutes for only reading the paper. They must NOT start writing during this time.)

  • Answer all questions in Part I and six questions in Part II, choosing two questions from each of the three sections A, B and C.
  • All working including rough work should be done on the same sheet as, and adjacent to, the rest of the answer.
  • The intended marks for questions or parts of questions are given in brackets [ ].

Part-I
(Attempt all questions)

ISC Biology 2014 Class-12 Previous Year Question Papers Solved

Question 1.
(a) Mention one significant difference between each of the following :
(i) Parenchyma and sclerenchyma.
(ii) Epistasis and dominance.
(iii) Hormones of ovulatory phase and hormones of luteal phase.
(iv) Symplastic movement and apoplastic movement.
(v) Phenotype and Genotype.

(b) Give reasons for the following :
(i) Testes descend into the scrotum before birth.
(ii) Secondary growth does not occur in monocot stems.
(iii) Nitrogenous fertilizers are not applied in fields where leguminous crops grow.
(iv) Genetic code is ‘universal’.
(v) At higher temperatures, green plants start evolving CO2 instead of 02.

(c) Each of the following questions/statements has four suggested answers. Rewrite the correct answer in each case. [5]
(i) Typhoid is classified as a :
(A) Viral disease
(B) Genetic disorder
(C) Bacterial disease
(D) Protozoan disease

(ii) Bt cotton is resistant to :
(A) Insects
(B) Herbicides
(C) Salt
(D) Drought

(iii) Roots and shoots lengthen through the activity of:
(A) Apical meristem
(B) Vascular cambium
(C) Lateral meristem
(D) Cork cambium

(iv) An antiviral protein released from infected and dying cells is :
(A) Antigen
(B) Antibody
(C) Antiserum
(D) Interferon

(v) Opening and closing of stomata is due to
(A) Ca2+
(B) Na+
(C) K+
(D) CL

(d) State the best-known contribution of: [3]
(i) Alec Jeffery
(ii) P.K. Sethi
(iii) Hugo de Vries

(e) Expand the following:
(i) SCID
(ii) ZIFT
Answer:
(a)

Parenchyma Sclerenchyma
(i) Fundamental soft plant tissue made-up of thin walled cells that forms the major part of leaves, roots, stem pith and fruit pulp. Mechanical strengthening or supportive plant tissue made-up of thick walled long cells or fibres and short cells sclereids.
Epistasis Dominance
(ii) In this two pairs of non-allelic genes are involved a gene pair inhibits the expression of another non-allelic gene. Out of a pair of alleomorphic genes, the one which appears in Fj generation, is called dominant and the phenomenon is called dominance.
Hormones of Ovulatory phase Hormones of Luteal phase
(iii) Estrogen and Luteinizing hormone bring about ovulation and causes a empty graafian follicle to develop into a corpus luteum which produces progesterone. Progesterone hormore stimulates the uterine lining development before implantation of a fertilized egg.
Symplastic movement Apoplastic movement
(iv) Water moves from cell to cell in the cytoplasm via the plasma membranes and plasmodesmata. Water moves from cell to cell via spaces in the outer cellulose cell walls.
Phenotype Genotype
(v) It is the externally observable charac­ters, controlled by genes It is the genetic constitution of an organism with regard to a character.

(b)

(i) Sperm formation requires a temperature which is few degree less than the normal body temperature. Scrotum has almost no fat insulation; so it keeps the testes at a cooler temperature. Also contraction or relaxation of muscles of scrotum moves the testes close to or far from heat of the body according to the environmental temperatures.

(ii) Secondary growth does not occur in monocot stem because it does not contain the meristematic tissue-cambium, which is responsible for secondary growth in plants. Vascular bundles are closed.

(iii) Nitrogenous fertilizers are not -needed in fields where leguminous crops grow because these plants have root nodules containing nitrogen fixing bacteria. They convert the nitrogen of soil air to nitrates which is used by these plants. The nitrates mix with the soil when these plants are ploughed under.

(iv) Genetic code is universal, triplet because it consist of three out of four nitrogenous bases-adenine, guanine, thymine and cytosine. These four bases in different triplet com-binations from all the various types of proteins, formed by genetic coding.

(v) At higher temperatures and high oxygen concentration, CO2 may be released by some plants instead of O2 because the main enzyme of photosynthesis -RuBP-carboxylase or Rubisco functions as RuBP-oxygenase. It splits RuBP into PGA and phosphoglycolic acid. The later is changed to glycolic acid and then to glycine. In the mitochondria, glycine forms serine and CO2, which is released. This process is called photorespiration. It undergoes photosynthesis.

(c)

(i) Bacterial disease.
(ii) Insects.
(iii) Apical meristems.
(v) K+
(iv) Interferon.

(d)

(i) DNA fingerprinting.
(iii) Gave the term mutation.
(ii) Developed “Jaipur foot.

(e) (i) Severe Combined Immune Deficiency.
(ii) Zygote Intrafallopian Transfer.


Section-A Part-II (50 Marks)
(Answer any two questions)

ISC Biology 2014 Class-12 Previous Year Question Papers Solved

Question 2.
(a) Describe the Miller and Urey experiment on the origin of life. [3]
(b) Define the following : [2]
(i) Frame shift mutations.
(ii) Genetic drift.
Answer:
(a) Oparin-Haldane’s concept of biochemical basis of origin of life was put to a test by Stanley Miller and Harold C. Urey (1953) in laboratory by creating the probable conditions of primitive earth. They designed their apparatus of glass tubes and flasks as shown in the figure and created an atmosphere containing hydrogen, ammonia, methane and water vapour in one chamber of the apparatus and allowed condensed liquids to accumulate in another chamber. Energy was supplied by heating the liquid containing chamber as well as by electric sparks from electrodes in the gaseous chamber. The experiment was run continuously for a week and then they analysed the chemical composition of the liquid inside the apparatus. They found that the liquid contained a large number of complex organic compounds including some amino acids such as glycine, adenine and asparatic acid.
They designed their apparatus of glass tubes and flasks as shown in the figure and created an atmosphere containing hydrogen,

However, from the result of this experiment, they suggested that the electrical discharge, produced during lightening in the primitive atmosphere of earth containing hydrogen, ammonia, nitrogen and water vapour might have resulted in the formation of amino acids and other essential organic building blocks (sugars, nucleotides, etc.) of living organisms and possibly these could thus have formed life on the primitive earth. Thus, the experiment of Miller and Urey provides support for the biochemical concept of origin of life of Oparin and Haldane.

(b)

(i) A frameshift mutation is a genetic mutation caused by a deletion or insertion of a single base in a DNA sequence (code) that shifts the way the sequence is read.
(ii) Genetic drift refers to the change in a type and ffequencey of genes in a population due to a random occurrence.

Question 3.    (ISC Biology 2014 Class-12 Solved Previous Year Question )
(a) Name and define the three types of natural selection. [3]
(b) State the following: [2]
(i) Hardy-Weinberg’s principle
(ii) Theory of recapitulation.
Answer:
(a) Three types of natural selection are f
(1) Stabilizing or Balancing Selection : It leads to the elimination of organisms having overspecialized characters and maintains homogenous population which is genetically constant. It favours the average or normal phenotypes while eliminates the individual with extreme expression, e.g., sickle cell anaemia in human beings.

(2) Direction or Progressive Selection : In this selection, the population changes towards one particular direction alongwith change in environment. As environment is undergoing, continuous change, the organism having acquired new characters survive, and others are eliminated e.g., Industrial melanism.

(3) Disruptive or Diversifying Selection : It is a type of natural selection which favours extreme expression of certain traits to increase variance in a population. It breaks a homogeneous population into many adapted forms and results in balanced polymorphism, e.g., Three types of snails in sea.

(b)

(i) The Hardy-Weinberg principles states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences.
(ii) It states that ontogeny recapitulates phytogeny. It means that embryos, in their development repeat the evolutionary history of their ancestors in a short, abbreviated form.

Question 4.
(a) Mention the important features of the Neanderthal man. [3]
(b) What are homologous organs? How do they help in providing evidence for organic evolution? [2]
Answer:
(a) A typical Neanderthal man had

  • Height less than 150 cm.
  • Heavily built with strong and outwardly curved thigh bones.
  • Cranial capacity of 1450 cm3.
  • Brow ridges prominent.
  • Skull thick-boned, depressed and protuded behind.
  • Forehead was low and sloping.
  • Devised and used flint tools.
  • Lived in caves and used animal skin to cover themselves.
  • Buried their dead with ceremonies.

(b) Organs having different functions but have similar embryogenic origin and development and having similar relationship with adjacent organs are called homologous organs.

They indicate close relationship between their possessors, e.g., the forelimbs Of human, wing of bird, leg of horse and flipper of a seal are all apparently different from one another in structure and function, yet they are all built on the same pentadactyl plan, having the same number of bones, muscles, blood vessels and nerves arranged in the same pattern and developed similarly. Therefore, the most reasonable explanation is that the forelimb of all of these animals were inherited long ago from a common ancestor.


Sections-B, Part- II,
(Answer any two questions)

ISC Biology 2014 Class-12 Previous Year Question Papers Solved

Question 5.
(a) Describe the different types of vascular bundles. [4]
(b) Give three anatomical differences between a monocot root and a dicot root. [3]
(c) Explain the effect of light and temperature on photosynthesis. [3]
Answers:
(a) There are mainly three types of vascular bundles :
(i) Radial: These are the vascular bundles in which the xylem and the phloem lie radially side-by-side (e.g., in roots of seed plants). This is found in roots.
in roots of seed plants

(ii) Conjoint : Those in which the two types of vascular tissues lie on same radius. Here xylem and phloem together form a bundle. They are of two sub-types :
(a) Collateral, and
(b) Bicollateral.

(a) Collateral: The xylem and phloem lie together on the same radius in the position that xylem lies inwards and the phloem outwards. In dicotyledonous stem, the cambium is found to be present in between xylem and phloem, such bundles are called open (e.g., in Helianthus), and in monocotyledonous stems, the cambium is absent, it is called closed {e.g., Maize).

(b) Bicollateral: In such vascular bundles, the phloem is found to be present on both sides of xylem. Simultaneously two cambium strips also occur. Various elements in a bundle are arranged in the following order – outer phloem, outer cambium, xylem, inner cambium and inner phloem. Such bundles are commonly found in the members of family Cucurbitaceae. Such bundles are always open.

(iii) Concentric : In this type, one type of vascular tissue surrounds the other. The concentric bundles may be of two subtypes, amphivasal and amphicribal. In amphivasal bundle, the xylem surrounds the phloem found in Dracaena, Yucca and other monocots and some dicots. If the phloem surrounds the xylem then it is called amphicribal as found in many ferns. Such concentric bundles are always closed.

(b)
Dicot Root:

  1. Cortex is comparatively narrow.
  2. Phloem parenchyma present.
  3. Endodermis is less thickened and casparian strips are more prominent.
  4. Number of vascular bundles is 2 to 3, 6 or rarely 8.
  5. Xylem elements are polygonal.
  6. Pith is mostly absent.

Monocot Root:

  1. Cortex is wide.
  2. Phloem parenchyma absent.
  3. Endodermis invisible only in young root.
  4. Vascular bundles are numerous.
  5. Xylem elements are oval or round.
  6. Pith is always present.

(c)

(i) Light : The intensity of light affects the rate of photosynthesis and thus controls the rate of production of ATP and NADPH2 . An increase in light intensity will increase the rate pf photosynthesis (if no other factor is limiting). Beyond the light saturation inten-sity, the increased intensity of light does not increase the rate of photosynthesis. That intensity of light at which the CO2 used in photosynthesis is equal to that of liberated during respiration is called the light compensation point. The rate of photosynthesis does not depends upon the duration of light but the amount of carbohydrate produced, depends upon the duration of light. The quality of light also affects the process as it occurs only in the visible part of spectrum i.e., 380 nm – 760 nm wavelengths. It usually does not take place in ultraviolet and infrared rays as these rays are injurious to proto-plasm. The highest rate of photosynthesis is in red light followed by blue light while green light is least effective in photosynthesis as most of it is reflected back.

(ii) Temperature : Temperature along with other environmental conditions affects photo-synthesis in a number of ways. At low temperature, the rate of photosynthesis is low because the enzymes are affected adversly. At high temperature also, the enzymes get denatured and the rate of photosynthesis declines. The optimum range of temperature for photosynthesis is 20°C – 35°C. Upto 35°C, the process shows a progressive increase with rise in temperature and this increase follow vant Hoff’s Law, according to which the rate of chemical reaction doubles for every 10°C rise of temperature of other factors are not limiting.

Question 6.    (ISC Biology 2014 Class-12 Solved Previous Year Question )
(a) Explain the transpiration pull theory for ascent of sap. [4]
(b) Explain the process of spermatogenesis in humans. [3]
(c) Define the following : [3]
(i) Placentation
(ii) Parthenocarpy
(iii) Diffusion
Answer:
(a) Cohesion and Transpiration Pull Theory : This theory was first proposed by Dixon and Jolly (1894) and is based on the following features :
(i) Cohesion and Adhesion : Mutual attraction between water molecules is called cohesion. The walls of tracheids and vessels of xylem are made-up of lignin and cellulose and have stomg affinity for water (adhesion).

(ii) Tension : Transpiration pull develops a negative pressure or tension in xylem sap which is transmitted down to the root.

The moist walls of mesophyll cells in leaf lose water vapour to the intercellular spaces. Sufficient quantity of water is transpired through intercellular spaces of the mesophyll cells through stomata. This is because, dry air outside the leaf has lower water potential than moist air of leaf, as a result water diffuses out of stomata and diffusion pressure deficit (DPD) increases. As a result, more water is sucked from adjoining inner mesophyll . cells and ultimately from xylem tissue. This tension is transmitted down to the roots.

The water column does not break because of cohesive and adhesive forces.

(b) The process of spermatogenesis occurs in the male gonads-testes. Testes are made-up of many seminiferous tubules lined by germinal epithelium. Cells of germinal layer divide to form spermatozoa in the following four steps :

(1) Spermatocytogenesis : The germinal epithelial cells which enter the process of spermatogenesis are called primary germ cells. Each primary cell by repeated mitotic divisions gives rise to a number of (unspecialized) cells called spermatogonia. They also keep dividing and enter the next phase.
Growth Phase : The spermatogonia increase in size and grows. Each spermatogonium divides mitotically to form two primary spermatocytes which are diploid and joined by their cytoplasm. The primary spermatocytes undergo meiosis.

(2) Meiosis I : The primary spermatocytes undergo the 1st meiotic or maturation division, each form two haploid (x) secondary spermatocytes.

(3) Meiosis II : The secondary spermatocytes undergo Ilnd meiotic division and produces two spermatids. A spermatid is a round cell with a spherical nucleus.

(4) Spermiogenesis : It is the process of transformation of circular spermatid to a spermatozoan. In this process, the nucleus of the spermatid becomes the head of the sperm, the golgi apparatus, containing proteolytic enzymes, becomes the acrosome cap, mitochondria form middle part and centrosome form the tail.
mitochondria form middle part and centrosome form the tail.

(c)

(i) Placentation : It is the arrangement of ovules inside the ovary.
(ii) Parthenocarpy : The formation of fruits without fertilization is called parthenocarpy e.g., Banana.
(iii) Diffusion : It is the movement of molecules or ions of solid, liquid or gas from their higher concentration to their lower concentration area.

Question 7.
(a) Why are xylem and phloem classified as complex tissues? Describe the structure of phloem. [4]
(b) Describe the ultra-structure of chloroplast. [3]
(c) State three functions of the placenta. [3]
Answer:
(a) Xylem and phloem are called as complex tissues because they are formed of more than one type of cells. Xylem is composed of tracheids, tracheae, xylem parenchyma and xylem fibres. Tracheids and tracheae (vessels) are called as conducting elements.

Phloem is made-up of four types of cells :

  • Sieve elements
  • Companion cells
  • Phloem parenchyma
  • Phloem fibres

(i) Sieve elements : In lower vascular plants, single celled structures called sieve cells are present while the Angiosperms have the multicellular sieve tube members. They are long tubular channels. They are formed of elongated living cells without nucleus and arranged end to end in vertical rows. The end walls of the individual sieve tubes are perforated by number of pores. The end walls of sieve cells are known as sieve plates. These plates connect the adjacent sieve cells to form a continuous long distance channel for the transport of food materials.

(ii) Companion cells : Sieve tube members of the Angiosperms are accompanied by highly specialised parenchyma cells called as companion cells. They are in contact with cytoplasm of the sieve tube members by plasmodesmata in their thin walls.

Companion cells have nucleus, richly granular cytoplasm and vacuoles. They control the activities of sieve tube members.
Companion cells have nucleus, richly granular cytoplasm and vacuoles. They control the activities of sieve tube members.

(iii) Phloem parenchyma : The phloem parenchyma cells are living, thin walled and the most simple ones. They contain starch, tannins and crystals. These cells perform the function of storage and lateral translocation of food substances.

(iv) Phloem fibres : The phloem fibres or sclerenchyma cells are the components of phloem. The fibres may be septate or non-septate and may be dead or non-living at maturity. They provide mechanical support to the plant body.

(b) Chloroplast is a oval structure surrounded by two unit membrane separated from one another by a space called periplastidial space. Internally the chloroplast is disc like structures the grana embedded in a colourless matrix called stroma.

Each granum is made-up of a stack of closed compartment called thylakoids. Each thylakoid consists of two parallel membranes joined at their margins. The membranes of thylakoids contain layer of paricles called quantasomes (photosynthesis units). Each quantasome has 230 molecules of chlorophyll. In stroma, there are many membranes running parallel to each other throughout the length of chloroplast which are called lamellae.
Different grana are connected with each other through tubular connection called stroma lamellae. Each chloroplast contains nearly 40-60 grana embedded in the stroma.
Different grana are connected with each other through tubular connection called stroma lamellae. Each chloroplast contains nearly 40-60 grana embedded in the stroma.

Grana are the sites for the light reaction and stroma is the site for dark reaction of photosynthesis.

(c) In mammals, placenta performs the following functions :

  1. It helps in the nutrition of embryo as the nutrients like amino acids, monosugars, vitamins, etc., diffuse from maternal blood into foetal blood through placenta.
  2. It helps in respiration of the embryo as 02 of the maternal blood and C02 of foetal blood diffuse through placenta.
  3. It also helps in excretion of the embryo as nitrogenous wastes of foetal blood like urea diffuse into maternal blood through placenta.
  4. It also acts as an endocrine gland as it secretes certain hormones like estrogen, relaxin, progesterone and Human Chorionic Gonadotropin (HCG).

Sections-C, Part- II,
(Answer any two questions}

ISC Biology 2014 Class-12 Previous Year Question Papers Solved

Question 8.
(a) Describe the experiment performed by Griffith. What conclusions did he infer from his observations? [4]
(b) What is artificial insemination? Mention two ways in which it is useful in breeding of dairy animals. [3]
(c) What is single cell protein? Give its source and significance. [3]
Answer:
(a) The bacterium Diplococcus pneumoniae causes pneumonia in humans. Frederick Griffith observed two strains of this bacteria. One strain has polysaccharide forming a large capsule around the cell called the smooth types (S). The colony of such cells has a smooth appearance. The other strain bacterial cells do not have the polysaccharide capsule and the colony formed by these cells has an irregular appearance and is called the rough type (R). The S-strain is virulent while the R-strain is non-virulent.

In his experiments, Griffith injected mice with live R-type of bacteria. They did not develop the disease. When he injected ‘S’-type of bacteria, the mice developed the disease and died. However, when heat killed S-type of bacteria were injected into the mice, they did not develop ‘ pneumonia. However, when he injected the mice with a mixture of living R-type (non-virulent)
However, when he injected the mice with a mixture of living R-type (non-virulent)
with heat-killed S-type (virulent) bacteria, the mice developed the disease and died. Griffith observed that in the blood of dead mice, both R and S type of bacteria were present. He thus concluded that heat killed smooth type bacteria caused a transformation of the living rough type into live S-type bacteria. Later experiments by other scientists suggested that DNA and not proteins is the genetic material.

(b) Artificial insemination is performed to get improved and better variety of animals. In this method, semen from the desired type of animal (e.g., bull) is collected and preserved by chemical methods or freezing. This preserved semen is then injected into the genital tract of the chosen cow during its maximum fertility period. Normal reproductive process then occurs and the progeny thus obtained is a hybrid of desired characters.

Artificial insemination is useful in breeding animals because :

  1. It is economical as semen from a desired animal e.g., bull can be transported to far away places while transporting the animal is not easy.
  2. High quality semen is available all the time but a high-quality bull may not be available all the time and at all places.

(c) Single cell protein (SCP) refers to dried microbial cells or total protein extracted from pure microbial cell culture. SCP is not pure protein. It refers to the whole cells of bacteria, yeast, filamentous fungi or algae. It also contains carbohydrates, lipids, nucleic acids, mineral salts and vitamins. The composition depends upon the organism and the substrate on which it grows, sources – Chlorella (algae), Rhodopseudomonas capsulate (bacteria), Trichoroderma (fungi). Significance SCP can be used as food supplement to humans food or animals as feed. It has application in animal nutrition as fattening calves, poultry and fish breeding. In food, it is used as aroma carriers, vitamin carriers, emulsifying aids and to improve nutrition value of baked products, soups, in ready to serve meals and in the technical field in paper processing, leather processing and as foam stabilisers.

Question 9.    (ISC Biology 2014 Class-12 Solved Previous Year Question )
(a) How did Hershey and Chase prove that DNA is the genetic material? [4]
(b) Give one main application of each of the following : [3]
(i) MRI
(ii) Ultrasound
(iii) ECG
(c) Explain the role of stem cells in medical treatment. [3]
Answer:
(a) Alfred Hershey and Martha Chase conducted experiments on virus T2 bacteriophage that attacks the common bacterium Escherichia coli. The bacteriophage has two chemical components i.e., protein and DNA. Protein forms the external structures like head, sheath and tail fibres and a DNA molecule is in the head. The phage attacks E. coli by attaching with its tail fibres to the bacterial wall and injecting its genetic material into the bacterial cell to produce new phages.

Hershey and Chase labelled the DNA and protein components of the phage separately with specific radioactive tracers and then followed these components through the life cycle of the phage. They developed two strains of the virus, one with labelled protein and other with labelled DNA. Almost all proteins contain sulphur which is not found in DNA while all DNA molecules contain phosphorus which is not found in proteins. The T2 phages grown in the presence of radioactive sulphur (35S) has labelled proteins and T2 phages grown in presence of radioactive phosphorus (32P) had labelled DNA.

After developing these strains, Hershey and Chase allowed each strain to infect the bacteria. Soon after infection, the bacterial cells were gently agitated in a blender to separate the adhering phage particles. It was observed that only radioactive 32P was found in the bacterial cells and 32S was present only in viral coats in the surrounding medium and not inside the bacterial cells. When they studied the viral progeny for radioactivity, it was found that it had only 32P and no 35S .

The results clearly show that only DNA is the genetic material and not protein coat.

(b)

(i) MRI-Mapping of brain tissues and study tissue metabolism.
(ii) Ultrasound – Used in diagnosis of various diseases of the heart, gall bladder, liver, pancreas, uterus and ovary.
(iii) ECG – Diagnosis of various heart diseases like coronary thrombosis, myocardial ischaemia, etc.

(c) Stem cells are found in all multicellular organisms and are capable of dividing to form new cells which can the differentiated into various types of specialized cells.

Role of Stem cells in Medical treatment:

  1. The stem cells have been used for treatment of various cancers like leukemia and lymphoma.
  2. It may also be used for treatment of severe autoimmune diseases like multiple sclerosis.
  3. Study of human embryonic stem cells will yield information about the complex events that occur during human development.
  4. Embryonic stem cells may be directed to differentiate into specific cell types, offer the possibility of renewable source of replacement cells and tissues to treat diseases like Alzheimer’s disease, spinal cord injury, stroke, bums, diabetes, arthritis and heart diseases.

Question 10.   (ISC Biology 2014 Class-12 Solved Previous Year Question )
(a) Write short notes on : [4]
(i) Multiple Alleles
(ii) Artificial measures to control population.
(b) What complications will arise if the blood of an Rh positive person is transfused to an Rh negative person and vice versa? [3]
(c) State any three goals of the human genome project. [3]
Answer:
(a) (i) Multiple Alleles : Most genes occur in two alternative forms, both controlling the same character and occupy the same locus in homologous chromosomes. These different form of the same gene are called alleles. However, some genes may occur in more than two allelic forms and they are called multiple alleles. A set of such multiple alleles may contain 3 to 20 or even more members which occupy the same locus in homologous chromosomes. In such a set of multiple alleles one member is always dominant and one recessive to all others. An individual carry only two such alleles e.g., ABO blood groups.

(ii) Artificial method to control population : The unreliable the natural methods of con-traception and are replaced by artificial methods :

(a) Contraceptive pills : Birth control pills which contain hormones, prevent a woman from getting pregnant if used regularly. Contraceptive pills also help women to have regular menstrual cycles and reduce the chances of anemia.

(b) Barrier contraception : Most popular barriers are the condom and the diaphragm that keep the sperm coming in contact with eggs in female reproductive system.

(c) Intra uterine device (IUD) : It is small device placed in the uterus to prevent pregnancy. Once the medicated IUD is in place, it can provide birth control for 5 to 10 years.

(d) Injection for birth control: Vaccination is another method of birth control. This vaccine is effective for three months and has to be applied four times a year.

(b) The Rh-factor or Rh-antigen was first reported in Rhesus monkeys RBCs by Landsteiner. Later it was found in most of human population. 85-99% of population, depending upon the race, have the Rh-factor, hence are Rh + ve. There is no antibody against Rh-antigen in human body. The Rh-antigen is produced due to a dominant gene, hence Rh + ve individuals are presented as RR or Rr with Rh-ve as rr.

Rh-ve blood can be given safely to a Rh + ve individual. But when Rh + ve blood is transfused into Rh -ve person, then during first transfusion, there is no complexity arising because of absence of Rh-antibody in the recipients blood; but this transfusion induces the synthesis of antibodies in recipients blood. In case of second transfusion of Rh (+ ve) blood to Rh (- ve) person, the RBCs of donors blood starts clumping due to presence of previously formed antibodies in recipients blood, thus causing death of the recipient. Hence Rh-factor should be determined before any blood transfusion.

(c) Human Genome Project (HGP) is an international research program to analyse the complete genetic material of human being and also selected experimental animals. HGP’s goal is to decode the complete DNA material or genome of human beings by 2003 and make them accessible for further biological study.

Objectives of Human Genome Project (HGP) are :

  • To improve forensic science.
  • The diagnosis of diseases is accurate.
  • To develop new and improved medicines.
  • To predict and prevent diseases.

-: End of ISC Biology 2014 Class-12 Solved Previous Year Question Paper :-


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