Class 11 Question Paper 2024 Biology (with Answers)

ANNUAL EXAMINATION

Question Paper
2024

NCERT BASED SYLLABUS
FOR CBSE AND STATE BOARD
FOLLOWING NCERT

Annual Exam Question Paper 2024

SESSION ENDING EXAM (2023-24)
BIOLOGY (044)
CLASS- XI
TIME ALLOWED: 3 HRS MAX. MARKS: 70
GENERAL INSTRUCTIONS:
● All questions are compulsory.
● The question paper has five sections and 33 questions. All questions are compulsory.
● 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.
● 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.
● Wherever necessary, neat and properly labelled diagrams should be drawn.

Section- A
Q1 Respiratory process is regulated by certain specialized centers in the brain. One 1
of the following centres can reduce the inspiratory duration upon stimulation:
a-Medullary inspiratory centre b-Pneumotaxic centre
c-Apneustic centre d-Chemosensitive centre
Q2 Which of the following suffixes used for units of classification in plants 1
indicates a taxonomic category of family?
a-Ales b-Onae
c-Aceae d-Ae
Q3 Identify the different types of placentations shown in figure and select the 1
correct option:

A. B. C. D E
a- Axile. Marginal. Free Parietal. Basal
central.
b- Marginal Basal. Axile. Free Parietal
central
c- Marginal Axile Parietal Free Basal
Central
d-Marginal Parietal Axile Basal Free -central

Q4 Arrangement of microtubule in a flagellum and a centriole is respectively 1
a- 9+2 and 9+1 b- 9+0 and 9+2
c- 9+1 and 9+0 d- 9+2 and 9+0
Q5 Zygotene of prophase-I is characterized by: 1
a- Chromosomes b-Synaptonemal complex

b- Crossing over d-Terminalization of chiasmata
Q6 Enzyme catalyze the biochemical reactions by……………the activation energy: 1
a- Lowering b-Increasing c-Unaltering d-Either a or b

1

Q7 Adenosine, guanosine, thymidine, uridine, cytidine, are all ………………. but 1
adenylic acid, uridylic acid, Cytidylic acid are………………….
a- Nucleotides, nucleosides b-Nucleosides, nucleotides
c-Nucleotides, nucleic acids d-Nucleosides, nucleic acids
Q8 The phase in which active synthesis of DNA takes place, is 1
(a) G0 phase (b) G1 phase
(c) G2 phase (d) S-phase
Q9 Alternate name of Kreb’s cycle is: 1
a- TCA cycle b-Citric acid cycle
b- Both a and b d-None of these
Q 10 Which of the following structure is found in diencephalon? 1
a- Pons b-Basal ganglia
c- Corpora quadrigemina d-Hypothalamus
Q 11 Select the mismatched pair: 1
a- Insulin- gluconeogenesis
b- Glucagon- glycogenolysis
c- Oxytocin- contraction of uterine muscles
d- Prolactin- milk production in mammary glands
Q 12 Basic functional unit of human kidney is: 1
a- Nephridia b-Henle’s loop
d- Nephron d-Pyramid
Question no. 13 to 16 consist of two statements – Assertion(A) and Reason (R) .
Answer these questions by selecting the appropriate option given below:
(A)• Both A and B are true, and R is the correct explanation of A
(B)• Both A and R are true, and R is not the correct explanation of A
(C)• A is true but R is false
(D)• A is false but R is true
Q 13 Assertion: Cell wall of chrysophytes are indestructible. 1
Reason : Cell wall of chrysophytes have layer of magnesium pectate embedded
in it.
Q 14 Assertion: Small disc shaped structures at the surface of the centromeres are 1
called kinetochores.
Reason: Kinetochores serve as the sites of attachment of spindle fibers to the
centromere.
Q 15 Assertion: Decapitation is widely used in tea plantation and hedge making. 1
Reason: Removal of shoot tips usually results in the growth of lateral buds.
Q 16 Assertion: Sino- atrial node (SAN) is called the pacemaker. 1
Reason: SAN generates the maximum number of action potentials and is
responsible for initiating and maintaining the rhythmic contractions of the heart.

Section-B
Q 17 In classification of animals cats and dogs are kept in separate families. Name 2
family and genus of following animals:
a- Cats b-Dogs
Q 18 Differentiate between dicot stem and monocot stem. 2
OR

What is mesosome in a prokaryotic cell? Mention the functions that it performs.
Q 19 Mention two function of centrioles. 2
Q 20 Differentiate between cyclic and non-cyclic photophosphorylation. 2
Q 21 Explain the standard ECG. 2

2

Section-C
Q 22 Name the phylum having largest number of animals. Name the major category 3
of animals it has. Write any two special morphological features of this phylum.
Q 23 Write the name of plant growth regulator for the following: 3
a- Bolt a rosette plant
b- Quickly ripen a fruit
c- Induce rooting in a twig
Q 24 Write the name of family with the help of following floral formula: 3
Write any two-characteristic feature of this family.

Q 25 Write any three economic importance of algae. 3
OR
What is heterospory? Briefly comment on its significance. Give two examples.
Q 26 Draw the structure of amino acid: 3
Alanine, glycine, serine
Q 27 Explain oxygen dissociation curve. Write any reason for its sigmoidal pattern. 3
Q 28 Give a brief account of the counter current mechanism in nephron. 3

Section-D
Q 29 Case study-based question: 1 Study the equation given below and answer the 4
following questions:
Pyruvic acid+CoA+NAD+ Mg2+ AcetylCoA+CO2+NADH+H+
(A)

A- Name the type of reaction and where does it take place?
B- Why this process does not take place in the cytoplasm of eukaryotes?
C- Name the enzyme (A) involved in the reaction.
D- What is the fate of AcetylCoA formed?
OR
Total gain of ATP molecules in aerobic respiration is:-
Q 30 Case study-based question: 2 4
Frogs can live both on land and in freshwater and belong to class Amphibia of
phylum Chordata. The most common species of frog found in India is Rana
tigrina. Frogs do not have constant body temperature as their body temperature
varies with the temperature of the environment. Such animals are called cold
blooded or poikilotherms. Frogs have the ability to change the color to hide
them from their enemies (camouflage). This protective coloration is called
mimicry. Frogs are not seen during peak summer and winter. During this period,
they take shelter in deep burrows to protect them from extreme heat and cold.
This is known as summer sleep (aestivation) and winter sleep (hibernation)
respectively.
The skin of frog is smooth and slippery due to the presence of mucus. The skin
is always maintained in a moist condition. The color of dorsal side of body is

generally olive green with dark irregular spots. On the ventral side the skin is
uniformly pale yellow. The frog never drinks water but absorb it through the
skin. Body of a frog is divisible into head and trunk. A neck and tail are absent.
Above the mouth, a pair of nostrils is present. Eyes are bulged and covered by a

3

nictitating membrane that protects them while in water. On either side of eyes, a
membranous tympanum (ear) receives sound signals. The forelimbs and hind
limbs help in swimming, walking, leaping and burrowing. The hind limbs end in
five digits and they are larger and muscular than fore limbs that end in four
digits. Feet have webbed digits that help in swimming. Frogs exhibit sexual
dimorphism. Male frogs can be distinguished by the presence of sound
producing vocal sacs and also a copulatory pad on the first digit of the fore
limbs which are absent in female frogs.
Answer any four of the following questions:-
1.) Frogs’ eyes are generally covered by _____ which is protective in function.
a) Camouflage membrane b) Copulatory membrane
c) Nictitating membrane d) Tympanum membrane
2.) _______ is the unique and distinguishing as well as sexual character of male
frog.
a) Presence of webbed digits b) Presence of copulatory pad
c) Presence of Nictitating membrane
d) Presence of membranous tympanum
3.) What is mean by poikilotherms?
4.) Why Frogs are not seen during peak summer and winter?
5.) What is mean by camouflage ?

Section-E
Q 31 a) Write any two differences between phycomycetes and Ascomycetes. 5
b) What do the terms phycobiont and mycobiont signify?
c) What is the nature of cell wall in diatoms.
Or
a) Give a comparative account of the nature of cell wall and the
characteristic of flagella among three classes of algae.
b) Differentiate between thallophytes and bryophytes.
Q 32 Explain various stages of Meiosis-I with the help of well labelled diagram. 5
Or
A) Both lysosomes and vacuoles are membraneous structures, yet they
differ in terms of their functions.
B) Draw the diagram of cilia and flagella.
C) Who discovered ribosome and give its function.
Q 33 a) In old age people suffer from stiffness and inflammation in joints. What 5
is this condition called? What is the cause of osteoporosis?
b) Explain the sliding theory of the mechanism of muscle contraction.
Or
Differentiate between:
a) Myelinated and non-mylinated neuron
b) Dendrites and axon
c) Rods and cones
d) Thalamus and hypothalamus
e) Cerebrum and cerebellum

*******************************************************************

4

SESSION ENDING EXAM
CLASS XI
BIOLOGY
MARKING SCHEME

Max marks- 70
Q.No Expected answer Marks
1 A 1
2 C 1
3 B 1
4 D 1
5 B 1
6 A 1
7 B 1
8 D 1
9 C 1
10 D 1
11 A 1
12 C 1
13 A 1
14 B 1
15 A 1
16 A 1
17 a) cat – felidae, felis 1+1
b) dog- canidae, canis

18 Any two difference 2
19 Any two function 1+1
20 Any two difference 2
21 It is graphical representation of the electrical activity of the heart during a 2
single cardiac cycle. The electro cardiogram is obtained by a machine known
as electrocardiograph.
22 Arthropoda, ½+½ +2
Insecta.
They have an open circulatory system with dorsal heart and arteries.They
have compound eyes and mosaic vision

23 a. Bolt a rossette plant- gibberellins 1+1+1
b. Quickly ripen a fruit – ethylene
c. Induce rooting in a twig- auxins

24 Solanaceae 1+2
Features- Alternate, simple, rarely pinnately compound
By carpellary, syncarpous
25 Any three importance 1+1+1
OR
Correct Explanation
26 1+1+1

27 The relationship between the partial pressure of oxygen (pO2) and percentage 1+2
saturation of the haemoglobin with oxygen (O2)is graphically illustrated by a
curve called oxygen haemoglobin dissociation curve (also called oxygen
dissociation curve).
The sigmoidal pattern of oxygen haemoglobin dissociation curve is the result
of two properties which play significant role in the transport of oxygen. These
two properties are:
(i) Minimal loss of oxygen from haemoglobin occurs above p02 of 70-80 mm
Hg despite significant changes in tension of oxygen beyond this. This is
depicted by relatively flat portion of the curve.
(ii)Any further decline in p02 from 40 mm Hg causes a disproportionately
greater release of oxygen from the haemoglobin. It results in the steeper
portion of the curve and causes the curve .to be sigmoid.
28 Correct explanation 3
29 A) During aerobic respiration the final product of glycolysis i.e pyruvic acid 1+1+1+1
is transported from the cytoplasm into mitochondria and undergoes oxidative
decarboxylation reaction to form acetyl CoA, mitochondrial matrix.

B) electron transport chain proteins and the ATP synthase are located in inner
mitochondrial membrane. They are not present in cytoplasm of eukaryotes.

C) Pyruvate dehydrogenase

D) oxydative decarboxylation
OR
36 ATP
30 1) c) nictitating membrane 1+1+1+1

2) b) Presence of copulatory pad

3) An animal that regulates its internal body temperature throughout a wide
range of temperatures, frequently in response to changes in the ambient
temperature is known as poikilotherms.

4)The frogs are not seen during peak summer and winter because during this
period they take shelter in deep burrows to protect them from extreme heat
and cold. This is called as summer sleep (Aestivation) and winter sleep
(Hibernation) respectively.

OR

5) Camouflage is a natural phenomenon used by plants and animals to blend
into their environment. Predators and prey alike use camouflage to avoid
detection
(Any four to be attempted)
31 a) Correct any two differences 2+2+1
b) Correct explanation
c) Correct explanation Or

Or

a) Cell Wall Nature of Flagella

ChlorophyceaeCellulose 2-8 equal. Apical 3+2

PhaeophyceaeCellulose and algin 2 unequal , lateral

Rhodophyceae. Cellulose, pectin and poly sulphate estersAbsent

b) ThallophytesBryophytes

1. Aquatic, freshwater or marine

1. Land plants , living in damp and shady places

2. Sex organs are unicellular and do not have a protective covering.
2. Sex organs are multicellular and have a protective covering.

3. Sporophyte is absent and zygote is the only diploid phase

3. Zygote develops into an embryo and then into a diploid sporophyte.

4. Have a thalloid body.

4. Root like , stem like parts present.

32 Correct explanation with suitable diagrams 5
Or
Or

A)Lysosomes are membrane-bound vesicular structures holding a variety of 2+2+1
enzymes such as lipases, proteases, and carbohydrases. The purpose of
lysosomes is to digest worn out cells. They are involved in the intracellular
digestion of foreign food particles and microbes. Sometimes, they also act as
suicidal bags. They are involved in the self-digestion of cells. They are a kind
of waste disposal systems of a cell. On the other hand, vacuoles are storage
sacs found in cells. They might store the waste products of cells. In unicellular
organisms, the food vacuole contains the consumed food particles. It also
plays a role in expelling excess water and some wastes from the cell.

B) Correct diagram.

C ) George palade 1953 it help in proteinsynthesis.

33 a ) arthritis, Decreased level of oestrogen causes osteoporosis.(Proper 2+3
Explanation)

(b)The sliding filament theory explains the process of muscle contraction Or
during Which the thin filaments slide over the thick filaments, which shortens
the Myofibril. Each muscle fibre has an alternate light and dark band, which 1+1+1+1+1
contains a Special contractile protein, called actin and myosin respectively.
Actin is a Thin contractile protein present in the light band and is known as
the I-band, Whereas myosin is a thick contractile protein present in the dark
band and is Known as the A-band. There is an elastic fibre called z line that
bisects each I-band. The thin filament is firmly anchored to the z line. The
central part of The thick filament that is not overlapped by the thin filament is
known as the H-zone. During muscle contraction, the myosin heads or cross
bridges come in close Contact with the thin filaments. As a result, the thin
filaments are pulled Towards the middle of the sarcomere. The Z line attached
to the actinFilaments is also pulled leading to the shortening of the sarcomere.
Hence, the length of the band remains constant as its original length and the I-
band shortens and the H-zone disappears.

Or

Correct difference (any two) in each case

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