CHANDA

South End Model School

Half Yearly Examination (2025-26)
Subject: Biology (044)
Full marks:70 Class: XI Duration: 3 Hours

General Instructions:
1.All questions are compulsory.
2.The question paper has five sections and 33 questions. All questions are compulsory.
3.Section – A has 16 questions of 1 mark each; Section – B has 5 questions of 2 marks each; Section – C has 7 questions
of 3 marks each; Section- D has 2 case – based questions of 4 marks each; and Section – E has 3 questions of 5 marks
each.
4.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.
5.Wherever necessary, neat and properly labeled diagrams should be drawn.
Section A
1. The total number of microtubules present in a cilium/flagellum is
(a) two. (b) nine. (c) eighteen. (d) twenty
2. In the mitochondria, the electron transport system is located in the
(a) intermembrane space. (b) outer membrane. (c) inner membrane. (d) matrix
3. Morels and truffles are the edible fungi belonging to the class
(a) Phycomycetes (b) Ascomycetes. (c) Basidiomycetes. (d) Deuteromycetes
4. Coelom is a cavity between the body wall and Aalimentary canal and is lined by
(a) ectoderm and endoderm (b) ectoderm and mesoderm.
(c) endoderm on both sides. (d) mesoderm on both sides.
5. Reptiles differ from amphibians in
(a) dry and cornified skin (b) internal fertilisation (c) the presence of neck (a) All of these

6. A flower is zygomorphic, when

(a) it can be cut into two equal halves along only one vertical plane that passes through the centre.
(b) it can be cut into two equal halves along any radial plane that passes through the centre.
(c) it can not be cut into two equal halves along any vertical plane that passes through its centre.
(d) it can be cut into two equal halves along any vertical plane that passes through its centre.

7. Match the symbols used in a floral formula in Column I with what they represent, in Column II and select
the correct option

(a) A-1,B-4,C-3,D-2. (b) A-3,B-4,C-2,D-1 (c) A-4,B-3, C-2,D-1. (d) A-1,B-4,C-2,D-3

8. Cytoskeleton in a cell is involved in
(a) mechanical support to the cell (b) motility of the cell (c) maintaining the cell shape (d) all of these
9. Microtubules are the components of
(a) cilia, flagella, centrioles and spindle fibres (b) centrosome, spindle fibres and cilia
(c) spindle fibres, centrioles and peroxisomes (d) centrosome, centrioles and nucleosome
10. Decarboxylation is involved
(a) alcohol fermentation (b) Kreb's cycle (c) lactic acid fermentation (d) both (a) and (b)
11. In glycolysis, during oxidation, electrons are removed/ accepted by
(a) NAD+ (b) molecular oxygen (c) ATP (d) glyceraldehyde 3-phosphate
12. Electron Transport System (ETS) is located in mitochondrial
(a) Outer membrane (b) Inter membrane space (c) Inner membrane. (d)Matrix
Directions: In the following questions, the Assertions (A) and Reason(s) (R) have been put
forward. Read both the statements carefully and choose the correct alternative from the
following.
Assertion: A lunar eclipse can occur only on the night of a full moon.
Reason: lunar eclipse is considered inauspicious.
1. Both the Assertion and the Reason are correct and the Reason is the correct explanation of the
Assertion.
2. The Assertion and the Reason are correct but the Reason is not the correct explanation of the
Assertion.
3. Assertion is true but the Reason is false.
4. Assertion is false but the Reason is true

13. Assertion: Glycolysis occurs in the cytoplasm and it is common for both aerobic and anaerobic respiration.
Reason: The enzymes necessary for glycolysis are found in the cytoplasm.
14. Assertion: In acrocentric chromosomes, one of the arms is very short and the other is very long. Reason:
The centromere is situated closer to one end of the chromosome.
15. Assertion: m. jasmine, the inflorescence is cymose. Reason: In jasmine, the main axis ends in a flower and
the buds below continue to grow.
16. Assertion: Most of the mammals are viviparous. Reason: Mammals feed their young ones with the milk
secreted by the mammary glands.

Section B
17. Name the two types of inflorescence and differentiate between them.
18. (a) What are prions?
(b) Name the disease it causes in: (i) cattles and (ii) humans.
Or
Write any four characteristic features of viruses.
19. What is diatomaceous earth? Mention any two economic uses of it.
20. Differentiate between integral and peripheral proteins of plasma membrane.
Or
Give reasons for the following:
(a) Mitochondria are called 'semiautonomous organelles'?
(b) Mitochondria/chloroplasts are not considered with the endomembrane system?

21. Mention the two steps in glycolysis, where ATP is consumed.

Section C
22. Represent schematically the pathway of fermentation of lactic acid.
23. What are the two crucial or key events in aerobic respiration? Where does each of them occur in the
mitochondria?
24. Draw a labelled diagram of 'fluid mosaic model' of plasma membrane.
25. Two types of compound leaves are shown below.

(a) Identify the types of compound leaves, A and B.

(b) Give an example of each.
(c) How do they differ from each other?

26. Describe the three common steps in the sexual reproduction of fungi.
27. Explain the structure of TMV
28. Justify the statement “Mammals are the most successful and dominant animals today”.
 Section D

29. Read the following passage and answer the questions that follow:
The flower is the reproductive structure of an angiosperm, meant for sexual reproduction. A
typical/complete flower has four different whorls arranged successively on the swollen end of the flower
stalk, called pedicel.
(a) What name is given to the swollen end of the pedicel where the different floral whorls are
arranged?
(b) Name the accessory whorls of a complete flower. Mention their function.
Or
(b) What is perianth? Give an example.
(c) Give one example each of:
(i) an asymmetrical flower
(ii) a zygomorphic flower

30. Study the equation given below and answer the questions that follow:

(a) Name the type of reaction, the pyruvic acid undergoes.

(b) Where does this process take place?
(c)(i) Name the enzyme A involved in the reaction.
(ii) How many molecules of ATP can be formed from the metabolism of one molecule of glucose in this
reaction?
Or
(c)(i) What is the fate of acetyl CoA formed?
(ii) How many carbon atoms does a molecule of acetyl CoA have?

Section E
31. Why is Kreb's cycle also called citric acid cycle? Explain the major steps of the cycle.(Draw the cycle also)
Or
In glycolysis, a chain of ten reactions, under the control of different enzymes, takes place. Give a
schematic representation of the process showing the formation of ATP, consumption of ATP and reduction
of NAD+.

32. What is aestivation? Describe its various types found in petals.

Or
Describe the arrangement of floral members in relation to their insertion on thalamus.

33. What is the relationship between germinal layers and the formation of body cavity in case of coelomates,
acoelomates and pseudocoelomates?
Or
Comment upon the habitats and external features of animals belong to class Amphibia and Reptilia.

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