Madhyamik 2025 Life Science Question Paper | Madhyamik 2025 Life Science Question Paper

Section — ‘A’
(All questions must be answered)

1. Complete the sentence by choosing the correct answer to each question and writing its serial number: 1 x 15 = 15

1.1 Select which of the following statements regarding tropic movement is correct:

(a) It is controlled by the intensity of the stimulus
(b) The overall position of the plant or plant organ changes
(c) This movement is seen in the moss Volvox
(d) It is a cyclic movement controlled by the direction of the stimulus

1.2 Read the sentences below and mark the one that is incorrect—

(a) TSH,
(b) ADH
(c) Estrogen
(d) ACTH

1.3 Which of the following is the correct reflex pathway –

(a) Receptor → Agent → Efferent nerve → Nerve center → Afferent nerve
(b) Nerve center → Receptor → Afferent nerve → Agent → Efferent nerve
(c) Efferent nerve → Receptor → Afferent nerve → Nerve center → Agent
(d) Receptor → Afferent nerve → Nerve center → Afferent nerve → Agent

1.4 In which stage of mitosis cell division is the nuclear membrane and nucleolus seen to disappear?

(a) Anaphase
(b) Prophase
(c) Metaphase
(d) Telophase

1.5 Which of the following is not a structural component of DNA –

(a) Deoxyribose sugar
(b) Uracil base
(c) Thymine base
(d) Phosphoric acid

1.6 Which of the following statements regarding sexual reproduction is correct –

(a) The production of haploid gametes is essential in sexual reproduction
(b) Sexual reproduction depends only on mitosis
(c) In sexual reproduction, only one reproductive organism can produce offspring
(d) The offspring produced as a result of sexual reproduction are genetically identical to the parent organism

1.7 Which of the following is the genotype ratio of the F2 offspring of Mendel’s monohybrid breeding experiment?

(a) 1 : 2 : 1
(b) 3 : 1
(c) 9 : 3 : 3 : 1
(d) 2 ; 1 ; 3

1.8 Which of the following is not controlled by genes located on human autosomes –

(a) Roller tongue
(b) Hemophilia
(c) Thalassemia
(d) Ear lobe

1.9 In case of incomplete dominance, what would be the phenotype ratio in F2 generation in a hybridization experiment?

(a) 3 : 1
(b) 2 : 1 : 1
(c) 9 : 3 : 3 : 1
(d) 1 : 2 : 1

1.10 Which of the following is an interspecific struggle for the same food?

(a) The struggle between a vulture and a hyena
(b) The struggle between an eagle and a hawk
(c) The struggle between the fish in a pond
(d) The struggle between a buck and a fishmonger

1.11 Which of the following changes did not occur in the evolution of horses?

(a) Increase in the length of the foot
(b) Increase in the length and width of all the toes
(c) Increase in the length and width of only the third toe
(d) Increase in the size of the entire body

1.12 According to scientists, the environment before the creation of life on Earth was like this:

(a) Hot thin soup in sea water
(b) Cold thick soup in sea water
(c) Cold thick soup in river water
(d) Hot thick soup in groundwater

1.13 Which of the following bacteria participates in nitrification?

(a) Nitrosomonas
(b) Azotobacter
(c) Pseudomonas
(d) Thiobacillus

1.14 An example of ex-situ conservation is:

(a) Sundarbans Tiger Conservation Project
(b) Corbett National Park
(c) Nilgiri Biosphere Reserve
(d) Cryopreservation

1.15 Which of the following occurs as a result of water pollution –

(a) Global warming
(b) Eutrophication
(c) Deafness
(d) Bronchitis

Category – B

2. Write the answer to any 21 of the 26 questions below as per the instructions: 1 x 21 = 21

Fill in the blanks in the following sentences with the appropriate words: (Any five): 1 x 5 = 5

2.1 Iodine deficiency disrupts the synthesis of ______ hormones. 2.2 During the development and growth of the embryo of vertebrates, ______ cell division occurs.

2.3 Different ______ of pea plants can show the same phenotype.

2.4 ______ evolution results in the emergence of homologous organs.

2.5 The name of an exotic species that damages local biodiversity is ______.

2.6 Fine particles of smoke, ash, dust, pollen, etc. floating in the air are collectively called ______, which cause various diseases in the lungs.

Determine whether the following sentences are true or false (any five) 1 x 5 = 5

2.7 The hypothalamus helps maintain balance in the human body.

2.8 In DNA, adenine is linked to guanine through hydrogen bonds.

2.9 In Mendel’s experiment on monohybrid breeding of pea plants, he obtained 75% pure tall pea plants in the first offspring.

2.10 According to Lamarck, an organism can acquire certain hereditary physical characteristics according to its needs.

2.11 Acid rain is caused by SO2 and NO2 gases caused by air pollution.

2.12 Auxin helps seeds break dormancy and germinate.

Match the word given in column A with the most appropriate word given in column B and rewrite the correct pair by mentioning the serial number of both the columns (any five) 1 x 5 = 5

Pillar A Pillar B

2.13 CSF (a) Large colloid coordination
2.14 Crossing-over (b) Active participation of local residents in forest restoration
2.15 Hemophilia (c) Meiosis
2.16 Quasacrate (d) Polar migration of daughter chromosomes
2.17 JFM (e) X-linked recessive genetic diseases in humans
2.18 Grafting (f) Provides nutrients to brain cells (g) Stock and scion

Answer in one word or one sentence (any six) 1 x 6 = 6

2.19 Choose the most similar one: dwarfism, goiter, thalassemia, diabetes.

2.20 Mention one function of the lens in the human eyeball.

2.21 A related pair of words is given below. Understand the relationship of the first pair and fill in the blanks of the second pair with the appropriate word: Mitosis: Embryo :: ____________: Nucleus Matricellular.

2.22 In guinea pigs, are the phenotypes of the bbRR and bbRr genotypes the same?

2.23 Write the phenotypic ratio obtained in the F2 generation in Mendel’s two-hybrid experiment.

2.24 Mention one adaptation of Sundari tree for salt tolerance.

2.25 Three of the four topics below belong to one topic. Find out and write about that topic: All knowledge about local biological resources, PBR, Traditional beliefs about local biological resources, Sustainable use of local biological resources

2.26 Write the name of an endangered animal protected in Singalila National Park.

Section – C

3. Write the answer to any 12 of the 17 questions below in two or three sentences: 2 x 12 = 24

3.1 When the following events occur, reflex actions occur in human daily life. Write the importance of these two reflex actions.

(a) When food particles enter the airway
(b) When a foreign object enters the nose

3.2 For which visual defects of the eyes are glasses with concave lenses used?

3.3 List the names of hormones associated with the following functions: (a) Control of blood sugar levels (b) Stimulate the secretion of hormones by the thyroid gland (c) Stimulate the growth of the corpus luteum in the female body and stimulate the secretion of progesterone hormone (d) Increase in blood pressure due to anxiety

3.4 An animal at rest starts to move. Mention four possible reasons for this.

3.5 Write the difference between human autosomes and sex chromosomes based on the following characteristics: (a) Nature (b) Number

3.6 By what methods is asexual reproduction carried out in Spirogyra and Planaria?

3.7 Mention two changes related to vision and bone in the final stages of human development or old age.

3.8 In humans, show with the help of a cross how the sex of a child is determined.

3.9 One day the students read an article about Thalassemia in the newspaper and were scared to know the fate of a person suffering from Thalassemia. Write what initiatives they can take to eliminate this disease from the population.

3.10 What are all the possible gametes that can be produced from the hybrid plant YyRr produced in the F2 generation in a dihybrid breeding experiment?

3.11 What are two adaptive significances of the air sacs of pigeons?

3.12 Write the name of one inactive organ each located in the spine and esophagus of the human body.

3.13 List the names of the four main fossil ancestors in the evolutionary history of horses in chronological order.

3.14 “The nitrogen cycle is being disrupted due to human activities” — Prove the correctness of this statement by mentioning two facts.

3.15 What are the possible environmental consequences of continued wetland destruction and reduction in agricultural land?

3.16 What harmful effects can noise pollution have on the human body, including the ears and heart?

3.17 Mention the role of biodiversity in the development of human civilization in the following two areas: (a) Food production (b) Preparation of medicines

Category – 1

(Long answer based question)

4. Answer the following 6 questions or their alternative questions. 5×6 = 30

4.1 Draw a reflex arc diagram and identify the following parts: 3 + 2

(a) Receptor
(b) Sensory nerve
(c) Nerve center
(d) Afferent nerve

Or,

Draw a diagram of the morphology of a eukaryotic chromosome and identify the following parts: 3 + 2

(a) Chromatid
(b) Centromere
(c) Nucleolar organizer
(d) Telomere

4.2 What types of chemicals are synthesized at different stages of interphase in a cell cycle? What can happen if normal control is disrupted at different points in a cell cycle? 3 + 2

Or,

Show the genetic sequence of a fern through a phase diagram. “Opposite changes occur in prophase and telophase” — Write two such opposite changes. 3 + 2

4.3 Mendel conducted a cross-breeding experiment on the color and size of pea seeds. Write the genotypes of the pea plants with yellow and round seeds produced in the F2 generation of this experiment. State Mendel’s law of independent assortment. 2+3

Or,

Mendel mentioned the contrasting characteristics of each of the pea flower characters he experimented with. Mendel’s pea experiments were groundbreaking in developing the scientific concept of heredity. Mention three reasons for his success in these experiments. 2 + 3

4.4 How is the special character of camels’ red blood cells (RBCs) related to their ability to tolerate excessive water loss? Give an example of how chimpanzees solve problems intelligently in food gathering and disease prevention. 2+3

Or,

Explain the method of natural selection proposed by Darwin with the help of a suitable example. What is the role of the gills in the aquatic adaptation of the rui fish? 3+2

4.5 “Many uncontrolled human activities pollute the environment” – support the statement with three examples. Give examples of a national park and a biosphere reserve located in West Bengal. 3+2

Or,

Show the steps of the nitrogen cycle with the help of a periodic table. 5

4.6 What environmental factors can cause cancer in humans? What problems could arise for the people and biodiversity of the Sundarbans if sea level rises due to global warming? 3+2

Or,

Mention the in-situ measures taken in Gir National Park, India for the conservation of lions. What environmental problems can arise in a region due to increasing population? 2+3