NEB Grade 12 Biology Model Question Paper

PART: I [BOTANY]

Group A (5 x 1 = 5)

Circle the correct answer from the given alternatives.

1.       There are many types of chromosomal disorders in organisms, among them euploidy is very common in the population. Which one of the following conditions is true for euploidy?
a. Addition or deletion of one or more chromosome in diploid chromosome
b. Addition of one or more chromosome in diploid chromosome
c. Deletion of one or more chromosome in diploid chromosome
d. Addition or deletion of one set or more than one set of chromosomes in diploid chromosome.

2.       The formation of two male gametes is a peculiar feature in angiosperm. If the first male gamete is fused to oosphere, in which part does the second male gamete fuse?
a. Synergids
b. Egg cell
c. Polar nuclei
d. Antipodal cell

3.       The given vascular bundle is highly specialised by centripetal protoxylem. What is it called?
a. Exarch
b. Endarch
c. Mesarch
d. Centrach

4.       Which of the following plants is used as bio fertilizer?
a. Ko/vox
b. Funaria
c. Azolla
d. Rhizopus

5.       When a plant cell is placed in hypertonic solution, it gets plasmolysed as shown in the diagram. Which of the following occupies the space between the cell wall and the shrunken protoplast in such plasmolysed cell?
a. Water
b. Hypertonic solution
c. Isotonic solution
d. Hypotonic solution

 

Group B (4 x 4 = 16)

Give short answers to the following questions.

1.       The anatomical structure of vascular plant is given. Study the given diagram and answer the following questions. (1+3=4)
(a) Write the main characteristics of the given layer Y.
(b) Draw the given diagram and label the tissues which is responsible for secondary growth. Elaborate the activities of this tissue up to the formation of cambial ring.

2.       Write the salient features of a monocot embryo in reference to its development pattern with diagrams. (3+1=4)

3.       “Micropropagation is an analytical and conventional bulk breeding technique for rapid cloning of desirable stock”. Justify the statement by describing it briefly with the various stages of micropropagation technique in plants. (4)

4.       What is genetic material? Describe the structure and functions of RNA. (1+2+1=4)

OR

What are plant growth hormones? Write the physiological functions of auxin. Mention its shortcoming of hyper use in crops.

GROUP ‘C’ (2 x 8 = 16)

Give long answers to the following questions.

5.       One of the Mendelian inheritances states that ’The alleles of different traits can be segregated during gametogenesis and passed independently’. State and explain the essential pattern of inheritance verifying the statement with examples showing cross up to second filial generation with chart and ratio. (1+ 3+2+2= 8)

OR

In Drosophila, an eye colour is X-linked. Explain. If white eye female Drosophila is crossed to red-eye male Drosophila, what result do you expect? Analyse briefly with the help of crosses.

6.       How are the Glycolysis and Krebs (TCA) cycle linked? Draw a detailed flow chart of the Krebs cycle? (4+ 4= 8)

PART: II [Zoology]

Group ‘A’ (6 x 1 = 6)

Circle the correct answer from the given alternatives.

1.       The parasympathetic nervous system releases a hormone acetylcholine. Which one of the following is activated by this hormone?
a. Regulate the involuntary response
b. Decrease the rate of heart beat
c. Increase blood pressure
d. Increase myocardial contractility.

2.       After the release of mature ovum from the ovary, the Graffian follicle changes into corpus luteum which is the source of female sex hormones. In the woman, what would be the condition of corpus luteum in absence of pregnancy?
a. Secretes FSH and LH continuously
b. Secretes oxytocin and relaxin
c. Automatically degenerates after sometime
d. Remains intact and active.

3.       Which of the following statement is more appropriate for early an amniocentesis test?
a. It takes place between 15 and 20 weeks of pregnancy
b. It may cause fetal injury and lethality
c. It helps to detect fetal complications
d. It may cause infertility.

4.       What are the main processes involved in gastrulation of a frog?
a. Epiboly, involution, cleavage
b. Epiboly, invagination, Involution
c. Involution, epiboly, invagination
d. Involution, invagination, cleavage.

5.       Blood cells are formed in the bone marrow. What is the process of formation of blood called?
a. Haemopoiesis
b. Haemolysis
c. Lymphopoiesis
d. Erythroblastosis.

6.       A person suddenly falls down and becomes unconscious. A doctor checked and said that it is due to inadequate blood supply to the brain. What would be the type of disorder?
a. Asthma
b. Syncope
c. Heart attack
d. Oedema.


Group ‘B’ (4 x 4 = 16)

Give short answers to the following questions.

1.       Compare and contrast areolar tissue and adipose tissue. 2+2=4

2.       Describe the process of fertilization of an egg with reference a frog. 4
OR
Describe the various steps applied in poultry farming. 4

3.       Study the given diagram and answer the following questions. 1+3=4
(a) Label A and B.
(b) Write any three differences between A and B.


4.       Overpopulation is a major issue in the development of the nation. Highlight the socio-economic problems caused by overpopulation and mention how to solve such problems. 2+2=4


Group ‘C’ (2 x 8 = 16)

5.       Mention the causative agent, mode of transmission, symptoms and control measures of tuberculosis in the community. (1+2+3+ 2 =8)

6.       Draw a labelled diagram of the alimentary canal of a human being. Explain the mechanism of the digestion of foods that a person under takes. What would happen in digestion when the pancreas is removed? (3+4+1)
OR
Draw a labelled drawing of respiratory system of a human being. Why and how oxygen and carbon dioxide are exchanged rapidly in the lungs? What would happen if a person moves to high altitude? Write your views on how to solve it. (2 +4+ 1+1 =8)

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