CBSE Sample Papers for Class 12 Biology Paper 6 are part of CBSE Sample Papers for Class 12 Biology. Here we have given CBSE Sample Papers for Class 12 Biology Paper 6.
CBSE Sample Papers for Class 12 Biology Paper 6
| Board | CBSE |
| Class | XII |
| Subject | Biology |
| Sample Paper Set | Paper 6 |
| Category | CBSE Sample Papers |
Students who are going to appear for CBSE Class 12 Examinations are advised to practice the CBSE sample papers given here which is designed as per the latest Syllabus and marking scheme as prescribed by the CBSE is given here. Paper 6 of Solved CBSE Sample Paper for Class 12 Biology is given below with free PDF download solutions.
Time: 3 Hours
Maximum Marks: 100
General Instructions:
- There are total 26 questions and five sections in the question paper. All questions are compulsory.
- Section A contains question number 1 to 5, Very Short Answer Type Questions of one mark each.
- Section B contains question number 6 to 10, Short Answer Type Questions of two marks each.
- Section C contains question number 11 to 22, Short Answer Type Questions of three marks each.
- Section D contains question number 23, Value Based Question of four mark.
- Section E contains question number 24 to 26, Long Answer Type Questions of five marks each.
- There is no overall choice in the question paper, however, an internal choice is provided in one question of two marks, one question of three marks and all three questions of five marks. An examiner is to attempt any one of the question out of the two given in the question paper with the same question number.
- No. of printed pages are three.
SECTION-A
Question 1.
Opuntia is often termed as Xerophytic plants. Comment.
Question 2.
Name the two components of an ecosystem with examples.
Question 3.
Zygote begin to divide only after the division of primary endosperm cell (PEC). Justify.
Question 4.
Why do bottled fruit juices appear clearer?
Question 5.
Which is the most commonly used as a medium/matrix in gel electrophoresis?
SECTION-B
Question 6.
In what way you can determine the age of any rock? Discuss.
Question 7.
Why emasculation is not required in unisexual flowers?
Question 8.
Rachit suggested his friend’s father that the chemicals that they use for agriculture often harm our environment. In such way they can use microbes in place of them. Discuss the role of microbes in reducing environmental degradation.
Question 9.
Draw a diagrammatic sketch of a biogas plant labelling its various components such as sludge chamber, digester, gas holder, dung water chamber.
Question 10.
Fertilisation does not act as a compulsory event in all plants for the fruit production. Comment.
SECTION-C
Question 11.
Given below are the events that are observed in an artificial hybridization programme. Arrange them in the correct sequential order in which they are followed in the hybridization programme.
Question 12.
Rebagging, bagging selection of parents, dusting the pollen on stigma, emasculation, collection of pollen from male parent.
Question 13.
Reproductive DNA vaccine has been confirmed as an important tool for the research and in the treatment of many diseases. Justify its role, method of production, utility. Also give two common examples.
Question 14.
Reproductive and child health care programme is under action. It holds a seminar in your locality for creating awareness. Explain the roles played by the following in controlling reproduction and its related issues.
- Role of government and NGOs.
- Role of local people.
Question 15.
(1) Identify the type of RNA out of three having the shape of the clover leaf in two dimensional structure.
(2) Draw the diagram of the process of transcription in eukaryotes.
Question 16.
What are introns and exons? What process removes the unwanted RNA region and joins those that code for amino acids?
OR
What are the functions of
(1) methylated guanosine cap; and
(2) poly-A tail in a mature mRNA? QI6. Discuss the latest methods of detection of cancer.
Question 17.
Give three differences between plasmid DNA and chromosomal DNA.
Question 18.
Bacterium Thermus aquaticus has been employed in recombinant DNA technology and has lead to many benefits. How can you prove this statement?
Question 19.
In what way co-extinction acts as one of the cause of biodiversity loss? Explain giving one example. List the other three causes also.
Question 20.
Within what age group sexually transmitted diseases (STDs) are reported to be very high? Mention three practices to avoid them.
Question 21.
The traits are known to get inherited through generations. This fact was proved by principles of law of inheritance proposed by Gregor Mendel in 1865. However, Mendel did not discover these principles of inheritance by studying human beings, then how his principles are applied in case of humans?
Question 22.
(1) How does analogous organs support the theory of organic evolution? Explain.
(2) Elucidate the phenomenon of homologous organs with one example of an organ homologous to the hand of man.
SECTION-D
Question 23.
While explaining the global warming, teacher makes a remark that “It is the most serious threat .to civilization now”. Kalpana gets curious about the various aspects of global warming and asks some questions to her teacher.
- What is global warming?
- What are various cause of global warming?
- What values are shown by Kaplana as environmentalist?
SECTION-E
Question 24.
Illustrated below is a DNA segment which constitutes a gene.
- Will the whole gene be transcribed in RNA primarily?
- Name the shaded & unshaded part of the gene.
- Explain how is gene expressed.
- How is this gene different from prokaryotic gene in its expression?
OR
There is only one possible sequence of amino acids when deduced from a given nucleotide. But multiple nucleotide sequences can be deduced from a single amino acid sequence. Explain this phenomena.
Question 25.
(1) How does a chromosomal disorder differ from a Mendelian disorder?
(2) Name two chromosomal aberrations-associated disorders.
(3) List the characteristics of the disorders mentioned above that help in their diagnosis.
OR
Explain the causes, inheritance pattern, symptoms of two Mendelian genetic disorders.
Question 26.
What measures as an individual would you take to reduce environmental pollution?
OR
(1) What do you understand by the terms slash and bum cultivation?
(2) What was Montreal Protocol?
Answers
SECTION-A
Answer 1.
Opuntia is termed as xerophytic plant because its roots grows very deep to explore any possibility of available underground water. It has no leaves and often reduced to spines. The process of photosynthesis takes place in flattened stems.
Answer 2.
Two components of ecosystems are biotic components (flora and fauna) and abiotic components (light, wind, water, temperature and soil).
Answer 3.
Zygote often needs a nourishment during its development. The mature cell fertilized embryo sac offers little nourishment to the zygote. So, the primary endosperm cell divides and generates the endosperm tissue to provide nourishment to the zygote.
Answer 4.
Due to the action of pectinase and protease enzymes, the bottled fruit juices appear clearer.
Answer 5.
Agarose is the most commonly used matrix. It is a natural linear polymer of D-galactosc and 3,6- anhydro L-galactose which is extracted from sea weeds.
SECTION-B
Answer 6.
Age of rocks and fossils can be easily determined by radiometric age dating technique. It is based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products.
Answer 7.
The female flowers are bagged before the flowers open. When the stigma becomes receptive, pollination is carried out using the desired pollen and the flowers are rebagged. Therefore, emasculation is not needed in unisexual flowers.
Answer 8.
Microbes transform the complex organic substances into relatively simpler, non-toxic substances by the process of bioremediation the microbes the environmental pollutants found in water, soil and air.
Answer 9.
Answer 10.
Though most of the fruit develop by the process of fertilisation but there are certain species which does not require such process. These form fruits without fertilisation and are called parthenocarpic fruits. These do not have seeds, e.g. banana.
SECTION-C
Answer 11.
The correct sequential order of the events shown in artificial hybridization are
Selection of parent → Emasculation (i.e. removal of anthers from the flower bud before anther dehisces) → Bagging (i.e. process of covering the emasculated flower with a bag made up of butter paper → Collection of pollen from the male parent → Dusting of pollen on stigma → Rebagging.
Answer 12.
Recombinant DNA vaccine is produced by using genetically engineered plasmids. They have gene inserts for the surface proteins of a pathogen that elicit immunity but do not result in f infection. These plasmids are inserted in bacteria or yeast cells that express the viral proteinswhich are then injected into the human host as vaccine. There they are recognized as foreign and an immune response is elicited. Recombinant DNA vaccine is used for treating diseases such as vaccinia virus, hepatitis B, polio etc. Example: Recombinant hepatitis-B vaccine and polio vaccine are the examples of recombinant DNA vaccine.
Answer 13.
(1) Role of Government and NGOs
(a) Effective implementation of different programmes.
(b) Population controlling measures to be implemented effectively.
(c) With the help of audio visual and the print media, government and non-governmental agencies can take various steps to create awareness.
(2) Role of Local People
(a) Parents, teachers and friends play a very important role in the dissemination of information about reproduction related information.
(b) Introduction of sex education in schools in the adolescent age group should be encouraged.
(c) Educating people, especially fertile couples those in marriageable age group about
available birth control options, care of pregnant mothers, post-natal care of the mother and child.
Answer 14.
(1) mRNA has the shape of clover leaf.
(2) Process of transcription in eukaryotes is as follows:
Answer 15.
The non-coding region of DNA or gene are called introns and coding region of DNA or gene which translate polypeptide are called exons.
RNA splicing is the process that removes the unwanted RNA region and joins those that code for amino acids.
OR
(1) Methylated guanosine cap helps in binding of mRNA to smaller ribosomal sub-unit during initiation of translation.
(2) Poly-A tail provides longevity to mRNA’s life. Tail length and longevity of mRNA are positively correlated.
Answer 16.
Latest method for cancer detection are:
(1) Biopsy A piece of suspected tissue cut into thin sections is stained and examined under microscope (histopathological studies) by a pathologist.
(2) Computed Tomography Uses X-rays to generate a 3-dimensional image inside the tissue
(3) Monoclonal antibodies against cancer-specific antigens are also used for cancer detection.
Answer 17.
| Plasmid DNA | Chromosomol DNA |
| (1) This is present in prokaryotic cells (bacteria) | This is present in both prokaryotic and eukaryotic cells |
| (2) This is the circular extra-chromosomal DNA which is not associated with histone proteins. | It is linear and associated with histones proteins in eukaryotes but is double stranded and circular in prokaryotes. |
| (3) It gives the cell extra characters like antibiotic resistance. | It contains genes for characters essential for life of organsism. |
Answer 18.
Thermus aquaticus, a bacterium yields that DNA polymerase as employed in recombinant DNA technology in the following ways:
- This enzyme remains active during the high temperature applied during denaturation of double-stranded DNA.
- It extends the primers using the nucleotides provided in the reaction and genomic DNA as template.
- Repeated amplification is achieved by this enzyme. The fragments thus amplified, if desired, can be used to ligate with a vector for further cloning.
Answer 19.
Co-extinction refers to the indirect extinction of a species as a result of the extinction of another species on which the first one was dependent. Co-extinctions occur due to inter-connectedness of organisms.
For example, extinction of a type of Hibiscus due to extinction of its pollinator species, like honey creeper bird. Other causes of biodiversity loss are over exploitation, alien species invasion, loss and fragmentation of habitat etc.
Answer 20.
In the age group of 15-24 years, STDs are reported to be very high. Following are the three practices to avoid them:
(1) Avoid sex with unknown partners or multiple partners.
(2) Always use condoms during coitus.
(3) In case of any doubt, medical help should be taken for early detection.
Answer 21.
Mendel performed his experiments on pea plant, i.e. Pisum sativum. After eight years of tedious experiments with pea plants, he proposed three fundamental principles of inheritance. These principles eventually assisted clinicians in human disease research. For example, after a few years of the discovery of Mendel’s work, Archibald Garrod applied Mendel’s principles to his study of alkeptonuria. Today, whether we talk about pea plants or humans, genetic traits that follow, the rules of inheritance that Mendel proposed are called Mendelian principles.
Answer 22.
(1) Analogous organs have different developmental origin and structural design but perform similar function. For example, the wings of birds and insects are analogous organs indicating that they have different ancestors but have a convergent evolution.
(2) Homologous organs are similar with structural designs and developmental origin but differ in their functions. Forelimb of human being is homologous to the forelimbs of whales and bats.
SECTION-D
Answer 23.
(1) The gradual continuous increase in average temperature of surface of the earth, is called global warming.
(2) Various causes of global warming are:
(a) High level of green house gases in the atmosphere.
(b) Rise in atmospheric temperature
(3) Kalpana was curious to know about her nature. She also wants to spread awareness among the people.
SECTION-E
Answer 24.
(1) The entire gene will not be transcribed primarily.
(2) The shaded parts are introns and unshaded parts are exons.
(3) The primary RNA script undergoes splicing, in this process, the interons are removed exons are joined together to form mRNA.
(4) In prokaryotes, the information is continuous and there is no need for splicing, the entire DNA is transcribed into RNA.
OR
Some amino acids are coded by more than one codon (known as degeneracy of codon), hence on deducing a nucleotide sequence from an amino acid sequence, multiple nucleotide sequences will be obtained.
For example, isoleucine has three codons AUU, AUC and AUA. Hence, a dipeptide Met-Ile can have any of the following nucleotide sequences:
(1) AUG-AUU
(2) AUG-AUC
(3) AUG-AUA
If we deduce amino acid sequences of the above nucleotide sequences, all the three will code for Met-Ile.
Answer 25.
(1) Mendelian disorders are caused by alteration or mutation in a single gene. These arc transmitted to the offspring from the parents and can be traced by the pedigree analysis whereas chromosomal disorders are caused due to the absence or excess of abnormal arrangement of one or more chromosomes.
(2) The chromosomal aberrations associated disorders are: Down’s Syndrome, Klinefelter’s Syndrome.
(3)
(a) Down’s Syndrome: It is caused due to the presence of an additional copy of chromosome number 21. The affected individual is short-statured with small round head, furrowed tongue and partially open mouth.
(b) Klinefelter’s Syndrome: It is caused due to the presence of an additional copy of X-Chromosome resulting into Karyotype of 47, XXY. The affected individual has masculine development. Gnaecomastia is also expressed and such individuals are sterile.
OR
Mendelian genetic disorders are determined by alteration or mutation in the single gene. These are transmitted into next generation according to the principle of inheritance and can be studied by pedigree analysis.
Causes, inheritance pattern and symptoms of two Mendelian disorders are given below
(1) Haemophillia: It is a sex-linked recessive disease, which transmits from an unaffected Carrier female to some of the male offspring. It is caused by the defect in one of the gene (located on X-chromosome) that determine how the body makes blood clotting factor VIII or IX.
Inheritance Pattern
Symptoms: Prolonged bleeding after even a minor cut are the major diagnostic symptoms of haemophillia due to which person may die of blood loss.
(2) Sickle–cell anaemia: It is an autosomal linked recessive trait that can transmitted when both parents are carriers of the gene. It is caused by the substitution of amino acid glutamic acid by valine at the sixth positions of the beta globin chain of the haemoglobin molecule.
Symptoms: Most common symptoms is fatigue (feeling of tiredness and weakness). Other symptoms include shortness of breath, headache, coldness in hands and feet, jaundice, paler than normal skin or mucous membrane. It is to be noted that the signs of symptoms of sickle anaemia may vary form mild to severe ones.
Answer 26.
To reduce environmental pollution, I will change my habits and lifestyle so as to reduce the use of disposable materials. I will also use preferably those items, which can easily be recycled and also will minimize the use of fossil fuels.
Following steps may be taken to reduce pollution
- Prevention of noise pollution by using fire crackers/TV/loudspeakers at permissible limits.
- Reduction in air pollution from automobile exhaust by using proper speed and regular servicing and using catalyst converters in vehicles.
- No use of polythene bags.
- Tree plantation around my residential area.
- Minimum use of fossil fuels.
OR
(1) Slash and bum is also called as Jhum cultivation. It is practiced in the North-Eastern states of India. In this method, the farmers cut down the trees of the forest and bum the plant remains. The ash is used as a fertilizer and the land is then used for farming or cattle grazing. After cultivation, the area is left for several years so as to allow its recovery. This same process is repeated at some other area.
(2) Montreal Protocol is an international treaty signed in 1987 to control the emission of chlorine emitting substances. According to this protocol, emission of CFCs (chlorofluorocarbons) and other chlorine containing compounds were to be reduced or prevented by the countries.
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