Life Science 2024 Madhyamik (W.B)

2024

Life Science

Time – 3 Hours 15 Minutes

(First 15 minutes for reading the question paper)

Full\ Marks =\begin{cases} \ \ 90\ - For\ Regular\ Candidates\\ 100\ - For\ External\ Candidates\end{cases}

Special credit will be given for answers which are brief and to the point.

Marks will be deducted for spelling mistakes, untidiness and bad handwriting.

Regular Candidates will answer questions from Groups A, B, C and D.

External Candidates will answer questions from Group E in addition to Groups A, B, C and D.

(Special Instruction for Visually Handicapped Candidates)

Answer Question No. 4.1 (A) instead of Question No. 4.1 in Group D.

Instruction on how many questions from a group must be attempted is provided

in the beginning of each group.

GROUP—A

(All Questions are Compulsory)

1. Choose the correct answer for each question and write it with its respective serial

number:— 1×15=15

1.1 Select the correct pair from the following:

(a) Lens – Accomplishes accommodation by changing the curvature of its plane

(b) Retina – Holds the lens with the help of the suspensory ligament

(c) Cornea – Secretes aqueous humor

(d) Choroid – Helps to maintain the shape of the eyeball

Solution

1.2 Consider the differences between hormone and nervous system mentioned below and choose which ones are correct:

	Hormone	Nervous System
I	Hormone is physical coordinator	Nervous system is chemical coordinator
II	The function of hormone occurs at a slow pace	The function of nervous system is quick and instant
III	The effect of hormone is long lasting	The effect of nervous system is short lasting
IV	Hormone remains unchanged after itsfunction is over	Nervous system gets destroyed after itsfunction is over

(a) I, IV

(b) I, III

(c) II, III

(d) II, IV

Solution

1.3 The natures of Biceps, Pyriformis and Latissimus dorsi muscles respectively are:

(a) Adductor, Extensor, Abductor

(b) Extensor, Flexor, Rotator

(C) Flexor, Rotator, Adductor

(d) Rotator, Abductor, Adductor

Solution

1.4 In a certain phase of mitosis nuclear reticulum is reconstructed, nuclear membrane reappears, regeneration of nucleolus takes place and Spindle fibre disappears.

What is the phase ?

(a) Prophase

(b) Telophase

(c) Metaphase

(d) Anaphase

Solution

1.5 Which of the following events occurs during sexual reproduction of flowering plants ?

(a) Zygote is converted into fruit

(b) Zygote is converted into seed

(c) Unicellular zygote is converted into multicellular embryo

(d) Ovary is converted into embryo

Solution

1.6 Which structural part of a chromosome may occur either in the middle or at any one end of the Chromosome ?

(a) Telomere

(b) Nucleolar Organizer

(c) Satellite

(d) Centromere

Solution

1.7 What are the dominant and recessive traits regarding the character related to the colour of flower of Pea plant ?

(a) Purple and Green

(b) Purple and White

(c) White and Purple

(d) Purple and Yellow

Solution

1.8 What is the numerical ratio of the four genotypes BBRR, BBrr, bbRR and bbrr produced in the F2-generation resulting from dihybrid cross in Guinea pig ?

(a) 1 : 1 : 1 : 1

(b) 2 : 4 : 2 : 4

(c) 4 : 2 : 2 : 1

(d) 2 : 4 : 1 : 2

Solution

1.9 If a female, looking apparently normal but being carrier of haemophilia, marries a normal male and if two sons and two daughters are born to them, then what would be the probability of manifestation of haemophilia among the children ?

(a) 100% haemophilic son and 0% haemophilic daughter

(b) 50% haemophilic son and 50% haemophilic daughter

(c) 0% haemophilic son and 50% haemophilic daughter

(d) 50% haemophilic son, and 50% apparently normal but carrier daughter

Solution

1.10 Which of the following is a feature of Equus ?

(a) Three digits with hoof on each forelimb and hindlimb

(b) Four digits with hoof on each forelimb and two digits with hoof on each hindlimb

(c) Two digits with hoof on each forelimb and hindlimb

(d) One digit with hoof on each forelimb and hindlimb

Solution

1.11 Which of the following is an inference of Darwin’s theory of evolution ?

(a) Natural Selection

(b) Variation

(c) Prodigality of reproduction

(d) Food and Space is constant

Solution

1.12 What is the adaptive feature of Camel related to its ability to withstand extreme water loss ?

(a) Cylindrical Red Blood Corpuscle

(b) Circular Red Blood Corpuscle

(c) Oval Red Blood Corpuscle

(d) Cuboidal Red Blood Corpuscle

Solution

1.13 With which step of Nitrogen Cycle microbes like Nitrosomonas and Nitrobacter are associated ?

(a) Nitrification

(b) Denitrification

(c) Nitrogen fixation

(d) Ammonification

Solution

1.14 Which biological hotspots include Mizoram and Nicobar Islands respectively ?

(a) Eastern Himalayas, Western Ghats and Sri Lanka

(b) Sundaland, Indo-Burma

(c) Indo-Burma, Sundaland

(d) Sundaland, Eastern Himalayas

Solution

1.15 Which types of in-situ conservation are Gorumara, Nilgiri and Kulik respectively?

(a) National Park, Biosphere Reserve, Sanctuary

(b) Biosphere Reserve, Sanctuary, National Park

(c) Sanctuary, National Park, Biosphere Reserve

(d) Biosphere Reserve, National Park, National Park

Solution

GROUP—B

2.  Answer 21 questions out of the 26 questions given below, as instructed. 1×21=21

Fill in the blanks with proper words in the following sentences (any five): 1×5=5

2.1 The nucleated oval___________  cells occur between Medullary Sheath and Neurilemma of the axon of a neurone.

2.2 Spindle fibres and chromosomes are not formed in the __________  cell division.

2.3 Genetic Counselling helps to ascertain the presence of ___________  gene of Thalassaemia disease.

2.4 The cause of biodiversity on earth is _________ .

2.5 Excessive amount of _________  is secreted from the walls of bronchi and bronchioles of trachea during Asthma.

2.6 If the detergent rich in _________ used for washing human clothes gets mixed in a pool, it results in eutrophication.

Decide whether the following statements are True or False (any five): 1×5=5

2.7 Accommodation is the ability of the retina of the eye to adjust the focal length as needed.

2.8 Mitotic cell division occurs while producing haploid spores.

2.9 The Guinea pig having the genotype BbRr is heterozygous for both the loci.

2.10 Vegetative organs indicate convergent evolution.

2.11 Liquid Nitrogen and-196℃ temperature are used in Cryopreservation.

2.12 Blind spot is the part of the eye devoid of light sensitive cells formed at the junction of optic nerve and retina.

Solution

Match the words in Column A with the most appropriate words in Column B and rewrite the correct pair mentioning the serial no. of both columns (any five): 1×5=5

	Column A	Column B
2.13	Adrenaline	(a) Air Pollutant
2.14	Self pollination	(b)According to Haldane the hot marine water containing different organic compounds
2.15	The position of flower is axial	(c)The adoloscent phase of human development
2.16	Hot Dilute Soup	(d)No need of agent
2.17	SPM	(e)The senescence phase of human development.
2.18	Britleness of bone and pain at bone joints	(f) Increases heart beat, cardiac output and blood pressure.
		(g) Dominant trait

Solution

Answer in a single word or in a single sentence (any six): 1×6=6

2.19 Choose the odd word and write it:

ADH, FSH, LH, TSH

Solution

2.20 What is the name of the plant hormone breaking the dormancy of bud and seed ?

Solution

2.21 On the basis of the relationship in the first related pair of words, write a suitable word in the gap of the second pair.

Purine : Adenine :: Pyrimidine : ____________  .

Solution

2.22 What is the similarity between the two genes responsible for colour blindness and haemophilia ?

Solution

2.23 What is the difference between the two genes responsible for the expression of attached ear lobes and roller tongue ?

Solution

2.24 What is the role of salt gland present on the surface of the leaves of Sundari ?

Solution

2.25 Among the following four terms, one includes the other three. Find it out and write it:

Coughing up thick phlegm, Bronchitis, Higher probability of smokers being affected, inflammation of the bronchi of Respiratory System of Man.

Solution

2.26 Which aspect is the most emphasized in Project Crocodile’ launched for crocodile conservation ?

Solution

GROUP—C

3. Answer any 12 questions each in 2-3 sentences out of the 17 questions given below:— 2×12=24

3.1 What are the roles of Insulin hormone regarding the following two aspects related with metabolism of carbohydrates ?

• Breakdown of glucose
• Transformation of glucose

Solution

3.2 Compare between Myopia and Hyperopia on the following two features:

• Cause
• Symptom

Solution

3.3 One of the driving forces of locomotion is “Aggregation for the purpose of reproductive activities”—Establish the validity of the statement with the help of two marine animals.

Solution

3.4 Which reflex actions does a spectator execute while watching a high voltage game on television ?

Solution

3.5 Prepare a list of sites of occurrence of meiotic cell division in plants as well as in animals.

Solution

3.6 Explain the alternation of generation in Fern with the help of a word diagram.

Solution

3.7 How does the Cytokinesis of plant cell happen ?

Solution

3.8 Explain the following two terms related with heredity —

• Allele
• Locus

Solution

3.9 With the help of an example explain how the phenotypic and genotypic ratios found inF2 generation of certain hybrid crosses indicate exception to Mendel’s first law of heredity.

Solution

3.10 What advantages did Mendel enjoy owing to pea-flowers being bisexual and self pollinating?

Solution

3.11 What types of struggle for existence can be found among the animals of a forest over eating meat of a freshly killed prey ?

Solution

3.12 How does a Rohu fish float and sink in water ?

Solution

3.13 Prepare a list of reactants used and products in the experiment of Miller and Urey regarding biochemical origin of life.

Solution

3.14 What environmental problems can originate if the concentration of different greenhouse gases polluting air increases in a steady manner ?

Solution

3.15 Explain the causes of endangeredness of Polar Bear and Gangetic Dolphin.

Solution

3.16 What might be the environmental causes behind asthma ?

Solution

3.17 ‘Scarcity of food and poaching are two main reasons behind the endangeredness of a mammal found in Eastern Himalayas biodiversity hotspot’ – Justify the validity of the statement.

Solution

GROUP—D

4. Write all the 6 questions or their alternatives given below. Visually handicapped candidates have to answer Question No. 4. 1 (A) instead of Question No. 4. 1. The marks allotted for each question are 5 (the division of marks is cither 3+2, 2+3 or 5). (5 x 6 = 30)

4.1 Draw a scientific diagram of neuron and label the following parts: 3+2=5

(a) Dendron

(b) Myelin Sheath

(c) Schwann Cell

(d) Node of Ranvier

Solution

OR

Draw a scientific diagram of eukaryotic chromosome and label the following parts: 3+2=5

(a) Centromere

(b) Satellite

(c) Nucleolar Organizer

(d) Telomere

Solution

(For Visually Handicapped Candidates Only)

4.1 (A) Write one function each of the following five parts of a neuron: 1×5=5

(a) Dendron

(b) Axon

(c) Myelin Sheath

(d) Schwann Cell

(e) Node of Ranvier

Solution

OR

Write one function each of the following five parts of an eukaryotic chromosome: 1×5=5

(a) Chromatid

(b) Centromere

(c) Nucleolar Organizer

(d) Satellite

(e) Telomere

Solution

4.2 Write the name of the chemical constituents of eukaryotic chromosome with the help of a table. What happens to a cell when the cell loses control at different points in cell cycle on division ? 3+2=5

Solution

OR

What events occur during Anaphase stage of mitotic cell division ?Show the steps of sexual reproduction of flowering plants with the help of word diagram. 3+2=5

Solution

4.3 With the help of a checkerboard show the phenotypic ratio of offsprings produced inF2 generation as a result of a cross between a pea plant having pure round yellow coloured seed and another pea plant having wrinkled green coloured seed. Write Mendel’s law of heredity derived from this experiment. 3+2=5

Solution

OR

Demonstrate a cross for eradication of misconceptions prevailing among human society regarding the process of determination of sex among children. What are the symptoms of thalassaemia? 3+2=5

Solution

4.4 What information related to evolution can be obtained from the discussion on comparative structure of hearts of different vertebrate groups ?Explain the following two terms in the light of Darwinism – 3+2=5

• Survival of the fittest
• Natural selection

Solution

OR

Explain the evolutionary significance of homologous and analogous organs with the help of example. What are the adaptive significances of air sacs of Pigeon ? 3+2=5

Solution

4.5 Explain the following three problems related to ever-increasing human population-

• Over-exploitation and depletion of natural resourcese
• Changes in atmospheric condition and global warming
• Deforestation and loss of ecosystems

Two major causes behind the loss of biodiversity are over-exploitation and destruction of habitat due to change in land use pattern – establish the validity of the statement with proper example. 3+2=5

Solution

OR

What might be the reasons behind the disturbances in Nitrogen Cycle ?It is very much essential to publish a PBR document for each village of India — which information can be gathered from a PBR regarding biodiversity ? 3+2=5

Solution

4.6 One of the environmental problems of Sunderbans is imbalance in prey – predator number — Justify the validity of the statement with three examples. What are the roles of biosphere reserve and sanctuary in the conservation of biodiversity ? 3+2=5

Solution

OR

What are the causes for the endangeredness of the following wild animals ? 3+2=5

• Royal Bengal Tiger
• One-horned Rhinoceros
• Lion

What are the two effects of air pollution on human health ?

Solution

(For External Candidates Only)

GROUP—E

5. Answer any four questions: 1×4=4

5.1 Write one feature of connective tissue.

Solution

5.2 What is the function of lysosome ?

Solution

5.3 Write one function of collenchyma tissue.

Solution

5.4 Write one disadvantage of cross pollination.

Solution

5.5 Give one example of lipolytic enzyme.

Solution

6. Answer any three questions: 2×3=6

6.1 Write the names of the two structural parts of axon.

Solution

6.2 Write the names of two non-nitrogenous excretory products of plants.

Solution

6.3 Write one function each of cell wall and cell membrane.

Solution

6.4 Write the names of two National Parks of West Bengal.

Solution