Sample Question Paper for class 12th Biology (Annual Examination)

Sample Question Paper for class 12th 

Biology (Annual Examination)

PRE BOARD EXAMINATION 2021

Class: XII

SUBJECT- BIOLOGY

(044)

Time: 3Hours                                                                                Max. Marks: 70

 

General Instructions:

(i) All questions are compulsory.

(ii) The question paper has four sections: Section A, Section B, Section C and Section D. There are 33 questions in the question paper.

(iii) Section–A has 14 questions of 1 mark each and 02 case-based questions. Section–B has 9 questions of 2 marks each. Section–C has 5 questions of 3 marks each and Section–D has 3

Questions of 5 marks each. (iv)There is no overall choice. However, internal choices have been provided in some questions. A student has to attempt only one of the alternatives in such questions. (v) Wherever necessary, neat and properly labeled diagrams should be drawn.

SECTION A

 

1 A bilobed, dithecous anther has 50 microspore mother cells per microsporangium. How many male gametophytes can this anther produce?                                                                (1)

2 Why are pollen grains produced in enormous quantity in Maize?                                       (1)

3 After a successful in vitro fertilization, the fertilized egg begins to divide. Where is this egg transferred before it reaches the 8-celled stage and what is this technique called?           (1)

4 What are the major components of human seminal plasma?                                                (1)

5 If the sequence of the coding strand in transcription unit is written as follows:

5’-ATGC ATGC ATGC ATGC ATGC ATGC ATG-3’ Write down the sequence of mRNA.           (1)

6.  Differentiation between “ZZ” and “XY” type of sex-determination mechanisms.            (1)

7 In which direction, the new strand of DNA synthesized during DNA replication.                (1)

8 An extra chromosomal segment of circular DNA of a bacterium is used to carry gene of interest into the host cell. What is the name given to it?                                                            (1)

9 Name the species that can withstand a close range of temperature?                                   (1)

10 Mention the relationship where a species generates poisonous particles which harm other species?                                                                                                                                     (1)

11 Assertion: Trisomy is the condition in which a particular chromosome is present in three copies in a diploid cell/ nucleus.                                                                                                   (1)

Reason: Pedigree Analysis is the analysis of the distribution and movement of trait in a series of generations of a family.

a. Both assertion and reason are true, and the reason is the correct explanation of the assertion.

b. Both assertion and reason are true, but the reason is not the correct explanation of the assertion.

c. Assertion is true but reason is false.

d. Both assertion and reason are false

OR

Assertion: Genetic code is universal:

Reason: Genetic code is same for all organism:

a) If both the assertion and the reason are true and the reason is a correct explanation of the assertion

b) If both the assertion and reason are true but the reason is not a correct explanation of the assertion

c) If the assertion is true but the reason is false

d) If both the assertion and reason are false

e) If the assertion is false but reason is true

12 Assertion: “Agrobacterium–mediated genetic engineering transformation” in plants considered as natural genetic engineering                                                                                     (1)  

Reason: Agrobacterium tumefaciens is a pathogen in many dicot plants. It is able to deliver a piece of DNA (T–DNA) to transform normal plant cell into a tumor and directs these tumor cells to produce the chemicals required by pathogen

a. Both assertion and reason are true, and the reason is the correct explanation of the assertion.

b. Both assertion and reason are true, but the reason is not the correct explanation of the assertion.

c. Assertion is true but reason is false.

d. Both assertion and reason are false

13 Assertion: Calotropis produces highly poisonous cardiac glycosides therefore they are not browsed by herbivores.                                                                                                               (1)

Reason: If two species compete for the same resource, they could avoid competition by choosing for instance different times for feeding or different for aging patterns. This is known as resource partitioning.  

a. Both assertion and reason are true, and the reason is the correct explanation of the assertion.

b. Both assertion and reason are true, but the reason is not the correct explanation of the assertion.

c. Assertion is true but reason is false.

d. Both assertion and reason are false

14 Assertion: A mangrove tree growing in marshy place has pneumatophores                (1)

Reason: pneumatophores help in better anchorage in marshy soil

a. Both assertion & reason are correct and reason is the correct explanation of assertion

b. Both assertion and reason are correct and reason is not correct explanation of assertion

c. Assertion is correct but reason is incorrect

d. Both assertion and reason is incorrect

15 Read the following and answer any four questions from 15(i) to 15(v) given below:            

(4) 

What can you do to boost your immune system?

The idea of boosting your immunity is enticing, but the ability to do so has proved elusive for several reasons. The immune system is precisely that — a system, not a single entity. To function well, it requires balance and harmony. There is still much that researchers don't know about the intricacies and interconnectedness of the immune response. For now, there are no

Scientifically proven direct links between lifestyle and enhanced immune function. But that doesn't mean the effects of lifestyle on the immune system aren't intriguing and shouldn't be studied. Researchers are exploring the effects of diet, exercise, age, psychological stress, and other factors on the immune response, both in animals and in humans. In the meantime, general healthy living strategies are a good way to start giving your immune system the upper hand.

(i)  In the immune system, interferons are a part of

(a) Physiological barriers

(b) Cellular barriers

(c) Physical barriers

(d) Cytokine barriers.

(ii) Transplantation of tissues/organs to save certain patients often fails due to rejection of such tissues/organs by the patient. Which type of immune response is responsible for such rejections?

(a) auto-immune response

(b) humoral immune response

(c) Physiological immune response

(d) cell-mediated immune response4

(iii) Neutrophils, basophil, lymphocytes, eosinophil and monocytes are examples of ________.

(a) Physical barrier

(b) Cellular barriers

(c) Cytokine barriers

(d) Physiological barriers

(iv) Which of the following conveys the longest-lasting immunity to an infectious

agent?

(a) Active immunity

(b) Passive immunity

(c) Both (a) and (b)

(d) None of the above

(v) Which of the following cells is involved in humoral immunity?

(a) T-cells

(b) B-cells

(c) Mast cells

(d) Both T and B cells

16 Read the following and answer any four questions from 16(i) to 16(v) given below:     (4)

The genetic disorders caused by a single genetic locus are referred to as Mendelian disorders. It is a type of genetic disorder in humans primarily caused either due to abnormalities in the genome or changes in a single genome. The condition is found to be present since birth. These disorders may or may not be inherited 

(i) Which of the following disorder is also called the Royal disease?

(a) Colour blindness

(b) Haemophilia

(c) Sickle cell anaemia

(d) Alzheimer’s disease

(ii) Which of the following disorder is an example of point mutation?

(a) Sickle cell anaemia5

(b) Down’s syndrome

(c) Night blindness

(d) Thalassemia

(iii) Alpha 1 anti-trypsin deficiency is an autosomal recessive genetic disorder.

What are the chances that any of the offspring do not express the disease

phenotype if both parents are genotype (Aa)?

(a) 100 per cent

(b) 75 per cent

(c) 50 per cent

(d) 25 per cent

(iv) Which of the following is a type of autosomal recessive genetic disorder?

(a) Haemophilia

(b) Skeletal dysplasia

(c) Sickle cell anaemia

(d) None of the above

(v) If the father in a family has a disease while the mother is normal, the daughters only are inherited by this disease and not the sons. Name this type of disease?

(a) Autosomal recessive

(b) Autosomal dominant

(c) Sex-linked recessive

(d) Sex-linked dominant

SECTION-B

17 What are heliophytes and sciophytes plants ?                                                                (2)

18 Lactational Amenorrhea is a method of contraception Justify. What is the maximum effectiveness of this method in terms of period/duration?                                                           (2)

19 Give two reasons why both the strands of DNA are not copied during transcription.     (2)

20 Why does the toxic insecticidal protein secreted by Bacillus thuringiensis kill the insect and not the bacteria itself?

OR

How can DNA segments separated by gel electrophoresis be visualized and isolated?       (2)

21 Name two main steps which are collectively referred to as down streaming process. Why is this process significant?                                                                                                                (2)

22 What is the difference between heterochromatin and euchromatin?

OR

What are competent cells? What does the word “competent” refer to?                                (2)

23 How do mycorrhizae act as biofertilisers? Explain. Name a genus of fungi that forms a mycorrhizal association with plants.                                                                                             (2)

24 Name the various levels of biodiversity. Which one is the basis of speciation?              (2)

25 State a difference between endemic and exotic species?                                                    (2)

SECTION-C

26 Mention any three vectors-less methods that are used to introduce recombinant DNA into a competent host cell.                                                                                                          (3)

27 Give an example for:                                                                                                  (3)

(a) An endothermic animal

(b) An ectothermic animal

(c) An organism of benthic zone

OR

a. Calculate the death rate if 6 individuals in a laboratory population of 60 fruit flies died during a particular week.

b. In biological control method, one living organism is used against another to check its uncontrolled growth. Which kind of population interaction is involved in this?

c. An organism has to overcome stressful condition for a limited period of time. Which strategies can it adopt to do so?

28 Fill in the blanks spaces a, b, c, d, e, and f, given in the following table:                              (3)                     

Sr. No.	Name of Organism	Commercial Product	Application
1.	Pencilium notatum	Penicillin	(a)
2.	(b)	Lactic acid Making	Curd
3.	Streptococcus	Clot buster enzyme	(c )
4.	Trichoderma polysporum	(d)	Immuno
5.	Saccharomyces cerevisiae	Ethanol	(e)
6.	(f)	Swiss cheese	Food Product

 

29 How would you find out the genotype of a pea plant with violet flowers? Explain with the help of Punnets’ square showing crosses.                                                                           (3)

30 Continued self-pollination lead to inbreeding depression. List three devices, which flowering plant have developed to discourage self-pollination?                                                         (3)

SECTION-D

31                                                                                                                                  (5)

 (a) Read the graph given above. Correlate the ovarian events that take place in the human female according to the level of the pituitary hormone during the following day.

(i) 10th – 14th days

(ii) 14th –15th days

(iii) 16th – 23th days

(iv) 25th – 29th days (If the ovum is not fertilized)

(b) What are the uterine events that follow beyond 29th day if the ovum is not fertilized?

(c)What is meant by L.H. Surge? Write the role of L.H.

OR

1. Failure of testes to descend into scrotal sacs leads to sterility. Why?

2. Both vaccine and colostrum produce immunity. Name type of immunity produced by these.

3. How many sperms will be produced from 10 primary spermatocytes and how many eggs will be produced from 10 primary oocytes?

4. The spermatogonial cell has 46 chromosomes in human male. Give the number of chromosomes in – (a) Primary spermatocyte (b) Spermatid

5. In ovary which structure transforms as corpus luteum and name the hormone secreted by corpus luteum?  

32 What is meant by semi conservative replication? How did Meselson and Stahl prove it experimentally?                                                                                                              (5)

OR

What does the lac operon consist of? How is the operator switch turned on and off in the expression of genes in this operon? Explain.

33 The pathogen of a disease depends on RBCs of human for growth and reproduction. The person with this pathogen suffers with chill and high fever.                                                 (5)

(a) Identify the disease.

(b) Name the pathogen.

(c) What is the cause of fever?

(d) Represent the life cycle of the pathogen diagrammatically

OR

The immune system of a person is supressed. He was found positive for a pathogen in the diagnostic test ELISA.

(a) Name the disease, the patient is suffering from.

(b) Which pathogen is identified by ELISA test?

(c) Which cells of the body are attacked by the pathogen?

(d) Suggest preventive measure of the infection.