CLASS XII

BIOLOGY (044)

SAMPLE PAPER-02

 

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: 

Justify the statement, “Offspring produced by sexual form of reproduction have better chances of survival.”

Question 2:  

In this angiospermic plant, if the diploid number of chromosome is 16. How many chromosomes would you expect to find in the nucleus of the endosperm, formed after fertilisation?

Question 3:

Classify the following as nitrogenous bases, nucleosides and nucleotides.

Adenosine, Guanosine monophosphate, Thymidine, Cytidine, Uracil

Question 4:

A plasmid without a selectable marker is chosen as a vector for cloning a gene. How would this affect the experiment?

Question 5:

In ecological context, why are herbivores considered equivalent to the predators?

SECTION B

Question 6:  

Name the microorganism responsible for maturation of Swiss cheese. Why do Swiss cheese have large holes in them?

Question 7:

Give the functions of the following:
(i) Leydig cells
(ii) Sertoli cells

Question 8:

Under which two conditions, the independent assortment of genes result into 50% recombination.

OR

During translation, three codons on mRNA are not recognized by the tRNA. What are these three codons? What is the general term used for them?

Question 9:

Into which category of morphological evidence (homologous or analogous organs) would you classify the wings of a butterfly and the wings of a bat. Give an example of one such organ from the plant kingdom.

Question 10:

Describe and name the type of interaction between an orchid plant and a tree, where the orchid maintains its erectness making the use of the tree just for support.

SECTION - C

Question 11:

Draw a neat labeled diagram of the longitudinal section through an anatropous ovule.

Question 12:

With the help of a test cross, explain how one can predict whether the genotype of an individual bearing the dominant trait, is homozygous or heterozygous.

Question 13:

Explain Co-dominance taking the inheritance of blood groups as an example.

Question 14:

Briefly explain the role of following enzymes involved in the process of DNA replication:

(i) Helicase
(ii) DNA polymerase
(iii) Ligase

Question 15:

Who established the technique of DNA Fingerprinting? List down the steps involved in this technique.

Question 16:

Describe Industrial melanism as an example of Natural selection.

Question 17:

What is meant by biodiversity? Describe the various levels of biodiversity?

OR

What is biofortification? Name any two crops that have been produced by biofortification.

Question 18:

What is artificial hybridization? Briefly describe the steps involved in artificial hybridization?

Question 19:

After a survey of an area inhabited by human population, it was found that the age pyramid of the population was ‘bell-shaped’.

(i) What information does this pyramid of age conveys to you about the
      population of that area?

(ii) How many types of pyramids of age can be seen?

(iii) What is the significance of studying the age distribution on a population.

Question 20:

What is a biosphere reserve? Briefly describe its various zones.

Question 21:

Name the organism which is considered as a missing link between reptiles and birds. Justify your answer giving two characters of each?

Question 22:

Why do the sons of a haemophilic mother and a normal father suffer from haemophilia whereas the son of a haemophilic father and a normal mother would not?

SECTION – D

Question 23:

Your school premises has been infested with mosquitoes. One of the students’ parents were seriously concerned about it and reported it to the school administration. The school management took an immediate action to eradicate the mosquitoes by calling a team of officials from the municipal corporation.
(a) Which are the places that the officials should look for as the breeding ground for the mosquitoes and laying their eggs?
(b) Name any two diseases which could be spread through the mosquitoes along with their causative pathogens and two symptoms of each.

SECTION – E

Question 24:

Given below is figure representing the transverse section through a mammalian testis. Study the figure carefully and answer the questions that follow:

(i) Label parts A, B, C and D

(ii) What are the roles associated with the parts labeled B and C?

(iii) What is meant by the terms ‘spermiation’ and ‘spermiogenesis’.

OR

What are STDs? Describe any four STDs along with their causative agents and two symptoms of each.

Question 25:

  P   3’                                                 5’  Q

  R   5’                                                 3’  S

PQ and RS represent two strands of a DNA molecule. It undergoes the process of replication forming a replication fork between P and R.

(i) Using which strand as the template will there be continuous synthesis of a complementary DNA strand?

(ii) Complementary to which strand will Okazaki fragments get synthesized and discontinuous synthesis will occur?

(iii) What is meant by template strand and Okazaki fragments?

(iv) In which direction (3’      5’ or 5’       3’) does a new strand gets synthesized?  

(v) Name the enzyme primarily responsible for the synthesis of new complementary strand during the replication process?

OR

(i) In Antirrhinum majus, RR is phenotypically red, rr is white and Rr is pink. Work out a cross, and mention the phenotype and their ratio in F1 generation in each of the following cases:

(a) RR x Rr        (b) rr x RR        (c) Rr x Rr      (d) rr x Rr

(ii) Give the scientific name of another plant that exhibits similar type of inheritance.

Question 26:

(i) Identify the system of gene regulation in prokaryotes depicted in the figure given above.

(ii) What are the functions of the genes designated as z, y and a? What are these genes collectively called?

(iii) What is the significance promoter region (marked as ‘p’) in the figure given above?
(iv) What would happen if lactose is added to the medium in which E. coli were growing?

OR

What is a retrovirus? Give an example. Draw a well labeled diagram of its life cycle. Name any one disease caused by a retrovirus.

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