cbse.nic.in : Class XII Biology Question Paper Sample Central Board Of Secondary Education
Board : Central Board Of Secondary Education
Exam : Class XII
Subject : Biology
Document Type : Sample Paper
Website : cbse.nic.in
Download Model/Sample Question Paper : https://www.pdfquestion.in/uploads/cbse.nic.in/7038-bio2.pdf
Biology Sample Question Paper II :
XII- Std:
Time : 3 Hours
Max. Marks : 70
Related : Central Board Of Secondary Education Class XII Chemistry Paper Sample : www.pdfquestion.in/7037.html
GENERAL INSTRUCTIONS :
1. All questions are compulsory.
2. The question paper consists of four sections A, B, C and D. Section-A contains 8 questions of 1 mark each, Section B is of 10 questions of 2 marks each, Section C has 9 questions of 3 marks each whereas Section D is of 3 questions of 5 marks each.
3. There is no overall choice. However, an internal choice has been provided in one question of 2 marks, one question of 3 marks and all the three questions of 5 marks weightage. A student has to attempt only one of the alternatives in such questions.
4. Wherever necessary, the diagrams drawn should be neat and properly labelled.
SECTION – A :
(1) In the whiptail lizards only females are born generation after generation. There are no males How is this possible? 1
(2) In the following figure of a fruit, label the part which is protective in function and that which is responsible for producing new plants. 1
(3) Which Mendel’s law of inheritance is universally acceptable and without any exception? State the law. 1
(4) In the following pedigree chart, state if the trait is autosomal dominant, autosomal recessive or sex linked. Give a reason for your answer. 1
(5) Given below are pairs of disease and causative organism. Which out of these is not a matching pair and why? 2
Filariasis : Wuchereria
Ringworm : Ascaris
AIDS : Human immuno virus
Malaria : Plasmodium
(6) In the picture provided, what is the relationship between (1) and (2) with respect to population interaction and between (3) and (4) with respect to trophic levels.
(7) Provide one word or one sentence information about ‘plasmid’ with respect to its (i) chemical nature and (ii) its duplication.
(8) Expand the following
(i) PCR
(ii) Bt
SECTION -B :
(9) In the adjacent population growth curve,
(i) What is the status of food and space in the curves (a) and (b)?
(ii) In the absence of the predators, which curve (a) or (b) would appropriately depict the prey population?
(10) Given below is a sequence of steps of transcription in a eukaryotic cell.
Fill up the blanks (1, 2, 3, 4) left in the sequence.
OR
(10) Name the type of inheritance in which the genotypic ratio is the same as the phenotypic ratio. Also give the ratio. 2
(11) In the following table the ecological units are mentioned in the first column vertically and their attributes are mentioned horizontally. Match the ecological units and its attribute and put a tick in the blanks within the table: 2
(12) Certain molecular processes are given in column (A). Provide the terms given to these processes in column (B), after selecting them from the terms: Recombination, gene regulation, prokaryotic, transcription, eukaryotic transcription, translation, replication, gene transfer, DNA fingerprinting
Column A | Column B :
(i) DNA DNA
(ii) DNA hnRNA
(iii) mRNA Protein
(iv) Repressor Protein
(14) If the chromosome number of a plant species is 16, what would be the chromosome number and the ploidy level of the (i) microspore mother cell and (ii) the endosperm cells? 2
(15) In the pie charts (A) and (B) drawn below to show the global animal diversity, which groups of animals would you name and write on the areas shaded black in (A) and (B). In which kind of habitat would you find these groups of animals? 2
(16) In the pyramid of biomass drawn below, name the two crops : (i) one which is supported and (ii) the one which supports. In which ecosystem is such a pyramid found? (½ + ½ + 1) =2
(17) The steps in a programme are: 2
– Collection of germplasm
– Crossbreeding the selected parents
– Selecting superior recombinant progeny
– Testing, releasing and marketing new cultivars.
(I) What is this programmme related to?
(ii) Name two special qualities as basis of selection of the progeny.
(iii) What was the outcome of the programme?
(iv) What is the popular term given to this outcome? Also name the Indian scientist who is credited with chalking out of this programme.
(18) A multinational company (XYZ) marked a medicine extracted from medicinal herbs grown in the sprawling fields in a foreign country. This herb is found only in our country and no compensation was paid or permission taken from relevant authority. 2
(i) What is the term used to refer to such an act committed by the multinational company?
(ii) Justify the meanig of the term.
(iii) What has our government done to prevent such deeds?
SECTION – C :
(19) How are biofertilisers different from fertilisers such as NPK that we buy in the market? Justify the role of Rhizobium as a biofertiliser. 3
(20) In the adjacent figure of a typical dicot embryo, label the parts (1), (2) and (3). State the function of each of the labelled part. 3
(21) The events of the menstrual eycle are represented below. Answer the questions following the diagram.
(i) State the levels of FSH, LH and Progesterone simply by mentioning high or low, around 13th and 14th day and 21st to 23 rd day
(ii) In which of the above mentioned phases does the egg travel to the fallopian tube?
(iii) Why is there no menstruation upon fertilisation? 3
(22) Few gaps have been left in the following table showing certain terms and their meanings. Fill up the gaps. 3
Terms Meanings :
(i) – Non coding sequence in eukaryotic DNA
(ii) – Technique used in solving paternity disputes
(iii) Restriction endonuclease ______________________
(iv) Plasmid _______________________
(v) Transgenics _________________________
(vi) – Nucleotide sequences with single base differences
(24) “A population has been exhibithing genetic equilibrium”. 3
Answer the following with regard to the above statement.
(i) Explain the above statement.
(ii) Name the underlying principle.
(iii) List any two factors which would upset the genetic equilibruim of the populationn.
(iv) Take up any one such factor and explain how the gene pool will change due to that factor
OR
In the 1950s, there were hardly any mosquitoes in Delhi. The use of the pesticide DDT on standing water killed their larve. It is believed that now there are mosquitoes because they evolved DDT resistance through the interaction of mutation and Natural Selection. Pointwise, state in a sequence how that could have happened. 3
(25) A thallasemic child needed repeated blood transfusions got infected by HIV. 3
(i) Use a rough diagrammatic sketch and arrows to show how the virus increased in number.
(ii) Why did the increased number of the HIV virus deteriorate the child’s immunity?
(iii) Which diagnostic test showed that the infective virus was HIV?