Board Paper of Class 12-Science 2012 Biology Delhi(SET 1) - Solutions
(i) All questions are compulsory.
(ii) This question paper consists of four Sections A, B, C and D. Section A contains 8 questions of one mark each, Section B is of 10 questions of two marks each, Section C is of 9 questions of three marks each and Section D is of 3 questions of five marks each.
(iii) There is no overall choice. However, an internal choice has been provided in one question of 2 marks, one question of 3 marks and two questions of 5 marks weightage. A student has to attempt only one of the alternatives in such questions.
(iv) Wherever necessary, the diagrams drawn should be neat and properly labelled.
- Question 1
Mention the unique flowering phenomenon exhibited by Strobilanthus kunthiana (neelakuranaji).VIEW SOLUTION
- Question 2
How does smoking tobacco in human lead to oxygen deficiency in their body?VIEW SOLUTION
- Question 3
A garden pea plant (A) produced inflated yellow pod, and another plant (B) of the same species produced constricted green pods. Identify the dominant traits.VIEW SOLUTION
- Question 4
Why is Eichhornia crassipes nicknamed as “Terror of Bengal”? (1)VIEW SOLUTION
- Question 5
Write the location and function of the sertoli cells in humans.VIEW SOLUTION
- Question 6
Name the following:
(a) The semi-dwarf variety of wheat is high-yielding and disease-resistant.
(b) Any one inter-specific hybrid mammal.VIEW SOLUTION
- Question 7
Write the similarity between the wing of a butterfly and the wing of a bat. What do you infer from the above with reference to evolution?VIEW SOLUTION
- Question 8
Write what do phytophagous insects feed on.VIEW SOLUTION
- Question 9
(a) Highlight the role of thymus as a lymphoid organ.
(b) Name the cells that are released from the above mentioned gland. Mention how they help in immunity.VIEW SOLUTION
- Question 10
Why do clown fish and sea anemone pair up? What is this relationship called? (2)VIEW SOLUTION
- Question 11
Some organisms suspend their metabolic activities to survive in unfavourable conditions. Explain with the help of any four examples.VIEW SOLUTION
- Question 12
(a) State the role of DNA ligase in biotechnology.
(b) What happens when Meloidegyne incognitia consumes cells with RNAi gene?VIEW SOLUTION
- Question 13
Draw a schematic diagram of a part of double stranded dinucleotide DNA chain having all the four nitrogenous bases and showing the correct polarity.VIEW SOLUTION
- Question 14
Name of parasite the causes filariasis in humans. Mention its two diagnostic symptoms. How is this transmitted to others?VIEW SOLUTION
- Question 15
Name the source of streptokinase. How does this bioreactor molecule function in our body?
How do mycorrhizae act as biofertilizers? Explain. Name a genus of fungi that forms a mycorrhizal association with plants.VIEW SOLUTION
- Question 16
(a) State the difference between meiocyte and gamete with respect to chromosome number.
(b) Why is a whiptail lizard referred to as parthenogenetic?VIEW SOLUTION
- Question 17
Explain the work carried out by Cohen and Boyer that contributed immensely in biotechnology.VIEW SOLUTION
- Question 18
Where is sporopollenin present in plants? State its significance with reference to its chemical nature.VIEW SOLUTION
- Question 19
It is established that RNA is the first genetic material. Explain giving three reasons.
(a) Name the enzyme responsible for the transcription of tRNA and the amino acid the initiator tRNA gets linked with.
(b) Explain the role of initiator tRNA in initiation of protein synthesis.VIEW SOLUTION
- Question 20
State the theory of Biogenesis. How does Miller’s experiment support this theory?VIEW SOLUTION
- Question 21
Name the two different categories of microbes naturally occurring in sewage water. Explain their role in cleaning sewage water into usable water.VIEW SOLUTION
- Question 22
Write the function of each one of the following:
(a) (Oviducal) Fimbriae
(c) OxytocinVIEW SOLUTION
- Question 23
Name the genes responsible for making Bt cotton plants resistant to bollworm attack. How do such plants attain resistance against bollworm attacks? Explain. (3)VIEW SOLUTION
- Question 24
Study a part of the life cycle of malarial parasite given below. Answer the questions that follow:
(a) Mention the roles of ‘A’ in the life cycle of the malarial parasite.
(b) Name the event ‘C’ and the organ where this event occurs.
(c) Identify the organ ‘B’ and name the cells being released from it.VIEW SOLUTION
- Question 25
Given below is the representation of amino acid composition of the relevant translated portion of β-chain of haemoglobin, related to the shape of human red blood cells.
(a) Is this representation indicating a normal human or a sufferer from certain related genetic disease? Give reason in support of your answer.
(b) What difference would be noticed in the phenotype of the normal and the sufferer related to this gene?
(c) Who are likely to suffer more from the defect related to the gene represented the males, the females or both males and females equally? And why?VIEW SOLUTION
- Question 26
By the end of 2002 the public transport of Delhi switched over to a new fuel. Name the fuel. Why is this fuel considered better? Explain.VIEW SOLUTION
- Question 27
Draw a schematic sketch of pBR 322 plasmid and label the following in it:
(a) Any two restriction sites.
(b) Ori and rop genes.
(c) An antibiotic resistant gene.VIEW SOLUTION
- Question 28
Explain the carbon cycle with the help of a simplified model. (5)
Explain how does:
(a) a primary succession start on a bare rock and reach a climax community?
(b) the algal bloom eventually choke the water body in an industrial area?VIEW SOLUTION
- Question 29
The following is the illustration of the sequence of ovarian events (a − i) in a human female.
(i) Identify the figure that illustrates ovulation and mention the stage of oogenesis it represents.
(ii) Name the ovarian hormone and the pituitary hormone that have caused the above mentioned event.
(iii) Explain the changes that occur in the uterus simultaneously in anticipation.
(iv) Write the difference between ‘c’ and ‘h’.
(v) Draw a labeled sketch of the structure of a human ovum prior to fertilization.
How does the megaspore mother cell develop into 7-celled, 8 nucleate embryo sac in an angiosperm? Draw a labeled diagram of a mature embryo sac.VIEW SOLUTION
- Question 30
What is the inheritance pattern observed in the size of starch grains and seed shape of Pisum sativum? Workout the monohybrid cross showing the above traits. How does this pattern of inheritance deviate from that of Mendelian law of dominance? (5)
State the aim and describe Messelson and Stahl’s experiment.VIEW SOLUTION