CLASS XII

BIOLOGY (044)

SAMPLE PAPER-01

 

Max. Marks 70                                                                                                                                                              Time allowed: 3 hours

General Instructions:

1) There are a total of 26 questions and five sections in the question paper. All the questions are compulsory.

2) Section A contains question number 1 to 5, Very Short Answer type questions of one mark each.

3) Section B contains question number 6 to 10, Short Answer type I questions of two marks each.

4) Section C contains question number 11 to 22, Short Answer type II questions of three marks each.

5) Section D contains question number 23, Value Based question of four marks each.

6) Section E contains question number 24 to 26, Long Answer type questions of five marks each.

7) There is no overall choice, however, internal choices have been provided in one question of two marks, one question of three marks and all three questions of five marks. An examinee has to attempt any one of the questions out of the two given in the question paper with the same question number.

 

SECTION - A

Question 1:  

Give the technical term for the flowers that get pollinated by wind along with two of its adaptations.

 

Question 2:  

Represent the chromosomal constitution of an individual suffering from Klinefelter’s syndrome.

 

Question 3:

Given below is the sequence of coding strand of DNA in a transcription unit.

                                        3’ – AATGCAGCTATT – 5’

 Write the sequence of its mRNA.

 

Question 4:

How the frequencies of formation of new recombinants would get affected if a pair of genes is located very close to each other?

 

Question 5:

A person is travelling in a crowded bus, along with people suffering from hypertension, ameobiasis, influenza and diabetes. Which among the aforesaid diseases is the person mostly likely to suffer from, if he gets infected during the journey and why?

 

Section - B

Question 6:  

Under what conditions could a child have blood group O if his/her parents have blood group A and B. Explain.

 

Question 7:

State and explain any two natural methods of contraception.

 

Question 8:

In the ELISA test, a patient was found to be positive to a pathogen, which has suppressed his immune system.
(a) Name the disease with which the patient is suffering from.
(b) Name the causative agent responsible for the disease.

 

Question 9:

How does Bt toxin released by bacterium Bacillus thuringiensis kills the insect that digests it, while doing no harm to the bacteria that produces it? Mention at least crops which have been developed on this application to get pest-resistant plants.

                                                       OR

How can one visualize DNA segments on an agarose gel?

 

Question 10:

Give any two examples of man-made ecosystems that contradicts David Tilman’s statement, ‘greater the diversity, greater is the primary productivity.’

 

SECTION - C

Question 11:

Mention and describe any three contrivances to prevent self-pollination in flowering plants.

 

Question 12:                                                        

Give a schematic representation of Spermatogenesis.

 

Question 13:

 (a) Explain the Law of Dominance with the help of a monohybrid cross using a pair of contrasting characters.

 (b) Find out the phenotypic and genotypic ratio in F2- generation.

 

Question 14:

PCR is a useful technique for making multiple copies of the gene of interest. Expand the term PCR and briefly describe the steps involved in it.

 

Question 15:

In an ecosystem, if 100000 Kcal of energy is available at the producer level, then find out the amount of energy available at the tertiary consumer level. Also state the underlying law associated with the calculations. Who proposed the law?

 

 Question 16:

What do you mean by “Biodiversity Hotspots”? List two criteria used for determining a hotspot? Name any two biodiversity hotspots present in India.

                                                                   OR

Give a brief account of the technique MOET.

 

Question 17:

Study the figure given below and answer the question that follows:

(i) Which among the nuclei labeled A to H will fuse with the male gamete to form the zygote?

(ii) What will be the ploidy of the structure formed as a result of fusion of the male gamete with the nuclei labeled D & E?

(iii) After fertilization into what structure will the part labeled ‘X’ develop?

 

Question 18:

(i) Restriction enzymes which are used to construct recombinant DNA are the endonucleases that cut the DNA at specific recognition sequence. What would be the disadvantage if they do not cut the DNA at specific recognition sequences?

(ii) A circular plasmid DNA and a linear DNA both having same size, have one recognition site for a restriction endonuclease. When cut and separated on agarose gel electrophoresis, the plasmid DNA shows one DNA band while linear DNA shows two fragments. Explain why. 

 

Question 19:

Name the scientists who experimentally proved the Oparin-Haldane theory. Give a diagrammatic representation of their experimental setup.

 

Question 20:

(i) During an experiment, pBR322 is used as a vector and the foreign DNA is to inserted in the amp^R region. Among the following restriction endonuclease enzymes, which one should be used and why?
                 BamHI,    EcoRI,     PvuI,      HindIII

(ii) Why can’t the other three enzymes be used?

 

Question 21:

A population is showing genetic equilibrium over a long period of time.

(i) Explain the above statement.
(ii) Name the underlying principle.
(iii) Write down any two factors that can upset the genetic equilibrium of this population.

Question 22:

Explain Darwin’s finches as an example of adaptive radiation.

 

SECTION - D

Question 23:

While returning from his school, Vipul, who is an adolescent, saw some of his friends smoking. He often sees many people in his locality smoking, which always made him curious about how it feels like to smoke. One day he asks his friend about his experience. His friend asks him to have his own share of experience by joining them while smoking. Vipul tries smoking, and felt more energetic. Also, it made him sense himself like an adult. Soon, he gets addicted to smoking. As a responsible classmate, you have to educate him:

(i) What makes him feel certain way while he smokes?

(ii) What is the effect of carbon monoxide on his body which is released during smoking ?

(iii) What other ill-effects can it bring to Vipul’s health?

 

SECTION - E

Question 24:

(i) Read the graph below and correlate the uterine events that take place according to the hormonal levels on:
(a) 6-15 days,
(b) 16-25 days, and
(c) 26-28 days (if the ovum is not fertilized).

 

(ii) Specify the sources of hormones mentioned in the graph.

(iii) What would be the effect on ovulation, if a woman starts taking estradiol and progesterone tablets (which are female hormones) immediately after the start of menstrual cycle?

OR

From the site of crime, a policeman finds a very small piece of body tissue. He wants it to be used as a tool to identify the culprit amongst the suspects by sending the tissue sample to the forensic department. The forensic department extracts the DNA from the tissue and amplifies its number of copies to ensure that the DNA sample is not lost during the investigation.

(i) By which technique will the forensic officials amplify the DNA collected from the tissue? Name the scientist who developed the technique used by them.

(ii) Mention and describe in correct sequence, the 3 steps involved in each cycle of this technique.

(iii) What is the name and the source of the thermostable DNA polymerase used in this technique? Why is it used in this technique?

 

Question 25:

Explain the process of “Protein synthesis” from a processed mRNA.

OR

Explain the technique of DNA fingerprinting.

 

Question 26:

(i) Define biodiversity.

(ii) What are the various causes which have resulted into the loss of biological diversity (any four)?

(iii) Enlist any four reasons to justify why we need to conserve the biodiversity.

OR

What do you mean by productivity of an ecosystem? Explain its types. Also mention the factors that affect the productivity of an ecosystem.

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