12th Biology Question Paper 2022 Maharashtra Board Pdf

Maharashtra State Board Class 12th Biology Question Paper 2022 with Solutions Answers Pdf Download.

Class 12 Biology Question Paper 2022 Maharashtra State Board with Solutions

Time : 3 Hrs.
Total Marks : 70

Section – A

Question 1.
Select and write the correct answer for the following multiple choice type of questions: (10)

(i) How many meiotic and mitotic divisions occur during the development of male gametophyte from the mother cell?
(a) One meiotic and two mitotic
(b) Two meiotic only
(c) Two mitotic only
(d) One mitotic and one meiotic
Answer:
(a) One melotic and two mitotic

(ii) During replication of DNA, the separated strands are prevented from recoiling by using ……….
(a) single strand binding protein
(b) reverse transcriptase
(c) endonuclease
(d) potymerase
Answer:
(a) single strand binding proteins

(iii)

Which event is represented by the above diagram, related to chromosomal aberrations?
(a) Deletion
(b) Duplication
(c) Inversion
(d) Translation
Answer:
(c) Inversion

(iv) …….. hormone responsible for efflux of K⁺ ions from guard cells and act as antitranspirant.
(a) Gibberellins
(b) Cytokinin
(c) Ethylene
(d) Abscisicacid
Answer:
(d) Abscisic acid

(v) …….. Test tube baby technique is called
(a) In-vitro fertilization
(b) In-situ fertilization
(c) In-vivo fertilization
(d) Artificial insemination
Answer:
(a) in-vitro fertilization

(vi) While playing cricket Raju faces problem of severe pain and heaviness in the-chest. Pain spreads from neck, lower jaw, left arm and to left shoulder. From above symptoms identify disease:
(a) Malaria
(b) Angina pectoris
(c) Kidney failure
(d) Typhoid
Answer:
(b) Angina pectoris

(vii) …….. Layer is in close contact of CNS in human being.
(a) Cranium
(b) Dura matter
(c) Arachnoid matter
(d) Pia matter
Answer:
(d) Pia mater

(viii) Cellular factors in innate immunity is provided by ………
(a) phagocytes
(b) antibody
(c) T-lymphocyte
(d) B-lymphocyte
Answer:
(a) phagocytes

(ix) Pick out the appropriate association representing brood parasitism.
(a) Hermit crab and sea anemone
(b) Asian koeland common Indian crow
(c) Algae and fungi
(d) Buffalo and cattle egret
Answer:
(b) Asian koel and common Indian crow

(x) Annealing step of PCR, operates at ………°C.
(a) 90-98
(b) 40-60
(c) 70-75
(d) 100-120
Answer:
(b) 40-60

Question 2.
Answer the following questions: (8)

(i) Name the part of gynoecium that determines the compatibility of pollen grains.
Answer:
Stigma of the Pistil is the part of gynoecium that determines the compatibility of pollen grains.

(ii) Which is the primary precursor of IAA in plants?
Answer:
Tryptophan is the primary precursor of IAA in plants.

(iii) Name the cell which is responsible for nitrogen fixation in cyanobacteria.
Answer:
Heterocyst is responsible for nitrogen fixation in cyanobacteria. They have the ability to differentiate specialized nitrogen – Fixing cells.

(iv) How many Biodiversity hotspots have been identified around the world?
Answer:
Biodiversity hot spots.

(v) Name the plant disease caused by Agrobacterium tumefaciens.
Answer:
Crown gall disease.

(vi) Identify the trophobLast cells which are in contact with embryonal knob during blastulation.
Answer:
Cells of Rauber.

(vii) From the given diagram, identify the type of population growth curve:

Answer:
Exponetial or Geometric growth curve.

(viii) What do you mean by Pioneer species?
Answer:
The first species that develop a bare area (in ecological succession), are called pioneer species.

Section – B

Attempt any EIGHT of the following questions: (16)

Question 3.
Identify A, B, C, D, in the given diagram of human reproductive system:

Answer:
A. Testis
B. Vas deferens
C. Seminal Vesicle
D. Prostate gland

Question 4.
Identify chromosomal disorder caused due to non-disjunction of 21 number of chromosome and enlist its symptoms.
Answer:
Down syndrome is usually caused by an error in cell division called non-disjunction. Non-disjunction results in an embryo with three copies of chromosome 21 instead of usual two.
Common Symptoms of Down syndrome are:

1. Patients have mild or moderate mental retardation and skeletal development is poor.

2. Distinct facial features like small head, ears and mouth, face is typically flat and rounded with flat nose, open mouth and protruding tongue, eyes slant up and out with internal epicanthal folds, flat rands, stubby fingers and palm is broad with single palmer creases.
[Any 3 symptoms 1/2 Mark each]

Question 5.
Write the aims of human genome project.
Answer:
Aims of Human Genome Project are

1. Mapping the entire human genome at the level of Nucleotide sequences.
2. To store the information collected from the project in databases.
3. To develop tools and techniques for analysis of the data.
4. Transfer of the related technologies to the private sectors, such as industries.
5. Taking care of the legal, ethical and social issues which may arise from project.
   [Any Four Correct Aims-2M]

Question 6.
Match the parts of ovule given in column I with parts of seed given in column II:

column I	column II
(a) egg	(1) testa
(b) nucellus	(2) tegmen
(c) outer integument	(3) perisperm
(d) inner integument	(4) embryo

Answer:

Column I	Column ll
(a) Egg	(4) Embryo
(b) Nucellus	(3) Perisperm
(c) Outer integument	(1) Testa
(d) Inner integument	(2) Tegmen

Question 7.
Enlist the characteristics of Neanderthal Man.
Answer:
Characteristics of the Neanderthal Man are:

1. Neanderthals had strong, muscular bodies, and wide hips and shoulders.
2. Adults grew to about 1.50-1.75m tall and weighed about 64-82kg.
3. Early Neanderthals were taller on average than later Neanderthals, but their weight was about the same.
4. Model of a Homo neanderthalensis skeleton from the front and back views.

Question 8.
Define the following:
(a) Gravitational water
(b) Hygroscopic water
(c) Combined water
(d) Capillary water
Answer:
(a) The water which percolates deep in the soil, due to gravity is called gravitational water. This water is not usually available for the plants.

(b) Hygroscopic water is the water which is absorbed by the particles of dry soil from the atmosphere and is held as a very thin film on the surface of the soil due to adhesion or attraction between the surface of particle and water molecules.

(c) A small portion of soil water which is chemically bound with soil materials is called combined water. It is present in the form of hydrated oxides of Si, aluminium etc. This water is not usually available for the plants.

The water that remains in the soil after gravitational water is drained out, that is subject to the laws of capillary movement, and is in the form of a film around the soil grains is called capillary water.

Question 9.
Give different properties of water.
Answer:
Properties of water are:

1. It is in the liquid form at room temperature.
2. It is the best solvent for most of the solutes.
3. It is inert inorganic compound with neutral pH when in pure form.
4. It is best aqueous medium for all biochemical reactions occurring in the cells.
5. It is an essential raw material for photosynthesis.
6. Water has high specific heat, high heat of vapourisation and high heat of fusion. Due to this it acts as thermal buffer.

[Any Four Properties- 1/2 mark each]

Question 10.
A person met with a small accident and bleeds, but very soon stops bleeding. Explain the physiological process responsible for this.
Answer:

Question 11.
Match the antibiotics in column I with their microbial sources in column II:

Column I	Column II
(a) Chloromycetin	(1) Streptomyces griseus
(b) Erythromycin	(2) Streptomyces aurifaciens
(c) Streptomycin	(3) Streptomyces venezuelae
(d) Terramycin	(4) Streptomyces erythreus

Answer:

Column-I	Column-II
(a) Chloromcetin	3. Streptomyces venezuelae
(b) Erythromycin	4. Streptomyces erythreus
(c) Streptomycin	1. Streptomyces griseus
(d) Terramycin	2. Streptomyces aurifaciens

Question 12.
Abscisic acid is the common name given to two identical substances isolated separately. Name them. Give the chemical features of abscisic acid.
Answer:
The two chemical substances are Abscissin and Dormin and their chemical formula is C₁₅H₂OO₄.
The chemical features of Abscisic acid are:

1. 1. It promotes abscission of leaves and induces dormancy in many plants.
   2. It controls the dormancy in buds and seeds by inhibiting growth processes.
   3. It accelerates the senescence of leaves, flowers and fruits.
   4. It inhibits and delays cell division and cell elongation and suppresses cambium activity by inhibiting mitosis in vascular cambium.
   5. ABA could cause efflux of K⁺ ions from the guard cells and result in closure of stomata. So, it is known as an anti-transpirant.
   6. It acts as a stress hormone by inducing the plant to bear the adverse environmental conditions.
   7. It inhibits flowering in long day plants but stimulates flowering in short day plants.

Question 13.
What are the effects of biotechnology with relation to human health?
Answer:
Effects of Biotechnology on Human Health are:

1. Allergies: GMO crops could potentially have negative effects on human health as well. Consumers have developed unexpected allergic reactions. E.g. Researchers used a gene from the Brazil nut to increase the production of Methionine in soya beans. The insertion of this gene inadvertently caused allergic reactions to the soya bean in those with known nut allergies (“Biotech Soybeans”).

2. Long-Term Effects: This is because GMO technology has been available for such a short amount of time, there is relatively little research which has been conducted on the long-term effects on health which we cannot anticipate at this point.

3. New Proteins: Proteins that have never been ingested before by humans are now part of the foods that people consume every day. Their potential effects on the human body are as of yet unknown.

4. Food Additives: GMOs also present us with possibilities of introducing additional nutrients into foods, as well as antibiotics and vaccines.

This availability of technology can provide nutrition and disease resistance to those countries that do not have the means to provide these, otherwise. However, there is possibility of the creation of antibiotic and vaccine-resistant strains of diseases.

Question 14.
Give the adaptations shown by desert animals.
Answer:
Adaptations Shown by Desert animals are:

1. Desert lizards manage to keep their body temperature fairly constant by adaptations.
2. They bask in sun and absorb heat when their body temperature drops below the comfort zone, but move into shade where ambient temperature starts increasing.
3. Some species burrow into sand to hide and escape from heat, e.g.:, Camel, Kangaroo, rat,
   [Any 2 Desert Adaptations -1 Mark each]

Section – C

Attempt any EIGHT of the following questions: (24)

Question 15.
Explain natural selection with example of industrial melanism.
Answer:
Industrial melanism is one of the best examples for Natural selection.
In Great Britain, before industrialisation (1845), grey white winged moths (Biston betuiaria) were more in number than black-winged moth (Biston carbonaria).

These moths are nocturnaL and during day time they rest on tree trunk. White winged moth can camouflaged well with lichen covered trees that helped them to escape from predator.

On other hand, black winged moth resting on lichen covered tree trunks were easy victims for the predatory birds and their number was reduced. During industrial revolution, large number, of industries came up in Great Britain. The industries released black sooty smoke that covered and killed the lichens growing on tree and turned the tree black due to pollution.

This change became an advantage to the black winged moth that camouflaged well with the black tree trunks and their number increased while the white-winged moth become victims to predatory birds, due to which their number reduced. Thus natural selections has resulted in the establishment of a phenotypic traits in changing the environment conditions.

Question 16.
Describe physiological effect and applications of gaseous hormone in plants.
Answer:
Ethylene is the gaseous hormone. Its applications and physiological effects are as follows:

1. It promotes ripening of fruits like bananas, apples and mangoes.
2. It stimulates initiations of lateral roots in pLants and breaks the dormancy of bud and seed.
3. It accelerates abscission activity in leaves, flowers and fruits by forming the abscission layer.
4. Ethylene inhibits the growth of lateral buds and causes apical dominance and retards flowering.
5. Promotes Senescence.
6. Inhibits flowering (Except in pineapple).
7. It causes epinasty.
8. It increases activity of chlorophyllase enzyme causing degreening effect in banana and citrus fruits.

Question 17.
What is ecological succession?
Name various seral stages from pioneer species to climax community with suitable example in hydrarch succession.
Answer:
Ecological Succession: The gradual and predictable change in the species composition of a given area is called ecological succession.

Various serai stages from pioneer species to climax community are:

1. Phytoplankton stage
2. Root submerged stage
3. Rooted floating stage
4. Reed-swamp stage
5. Marsh meadow stage.
6. Scrub stage
7. Climax forest

Question 18.
With the help of a neat, labelled diagram describe the structure of root hair.
Answer:

1. Root hair is cytoplasmic extension (prolongation) of epiblemma cells.
2. Each root hair is approx. 1-10 mm long and tube-like structure.
3. It is colourless unbranched, short lived (ephermal) and very delicate.
4. It has a large central vacuole surrounded by thin film of cytoplasm, plasma membrane and thin cell-wall. Outer layer of cell-well is pectin and inner layer is cellulose.
5. Cell wall is freely permeable but plasma membrane is selectively permeable.

Question 19.
Complete the following flow diagram of double circulation:

Answer:
Double Circulation

Question 20.
Distinguish between hyperthyroidism and hypothyroidism.
Answer:
Difference between hyperthyroid and hypo-thyroidism are:

Hyperthyroidism	Hypothyroidism
Increase in level of thyroid hormone.	Decrease in level of thyroid hormone.
Increase in BMR,	Decrease in BMR.
Weight loss.	Weight gain.
Increase in heart rate and blood pressure.	Decrease in heart rate and blood pressure.
Higher body temperature.	Lowers body temperature.
It causes exophthalmic goitre.	It causes simple goitre.
Shows high irritability and nervousness.	Lacks alertness and intelligence.

Question 21.
Give the applications of DNA fingerprinting.
Answer:
Applications of DNA fingerprinting are:

1. In forensic science, DNA fingerprinting is used to solve problems of rape and some complicated murder cases.
2. DNA fingerprinting is used to find out the biological father or mother or both, of child in case of disputed parentage.
3. It is used in pedigree analysis of cats, dogs, horses and humans.

Question 22.
Write a note on In-situ and Ex-situ conservation.
Answer:
In-situ Conservation:

1. Protection of an organism will automatically take place, if its natural habitat is protected, eg. Kanha National Park as tiger reserve.
2. There are 36 biodiversity hotspots.
3. It involves introduction of varieties of traditionally used organisms into farming and horticulture.
   Eg., In Maharashtra, Pawra tribals in Satpuda have protected varieties of corn with different coloured kernels.

Ex-situ Conservation.

1. Sometimes when a species is critically endangered special measures have to be undertaken to protect it.
2. It might be protected as captivity e.g:.. Wild Life safari parks, Zoological parks, Botanical gardens.
3. Seed banks are established to conserve varieties of food grains and vegetables.

Question 23.
Explain the properties of nerve fibres.
Answer:
Properties of nerve fibre

1. Excitability or Irritability: Nerve fibres have polarized membrane, thus they have the ability to perceive stimulus and enter into a state of activity.
2. Conductivity: Ability of the nerve to transmit impulses along the whole length of the axon.
3. Synaptic Fatigue: The transmission of nerve impulses across the synapse stops temporarily 26, due to the depletion of the neurotransmitter.
4. All of none law: The nerve will either conduct the impulse along its entire length or will not conduct the impulse at all. This occurs in the case of a subliminal or weak stimulus.

Question 24.
Give the causative agent, mode of transmission and symptoms of typhoid.
Answer:
Causative agent of Typhoid is: Salmonella typhi
Mode of Transmission of typhoid are:

1. It is a food and water borne disease.
2. Insects like housefly and cockroaches feeding an fecal matter, may transfer the bacteria to food material.
3. Poor hygiene habits and poor sanitation conditions are responsible for spread of typhoid.
4. Droplet spread or by using shared clothes and utensils of infected persons.

Signs and Symptoms of Typhoid are:

1. Prolonged fever as high as 104°F.
2. General nausea, fatigue, headache.
3. Abdominal pain, constipation or diarrhoea.
4. Rose coloured rashes on skin.
5. While coat on tongue, cough.
6. Anorexia (loss of appetite).
7. Breathlessness, Irregular heart beats and haemorrhage.

Question 25.
Match the following products with their microbial sources:
Products

Products	Microbial Sources
(a) Vitamin B2	(1) Rhizopus arrhizus
(b) Fuma nc acid	(2) Candida lipolytica
(c) Vitamin B12	(3) Trichoderma Konigii
(d) Lipase	(4) Neurospora gossypii
(e) Celtulase	(5) Psuedomonas denitrificans
(f) Citric Acid	(6) Aspergillus niger

Answer:

Products	Microbial Source
(a) Vit-B2	(4) Neurospora gossypii
(b) Fumaric acid	(1) Rhizopus arrhizus
(c)Vit-B12	(5) Psuedomonas denitrificans
(d) Lipase	(2) Candida lipolytica
(e) Cellulose	(3) Trichoderma konigii
(f) Citric-Acid	(6) Aspergillus niger

Question 26.
Explain any three examples of biopiracy.
Answer:
1. Patenting of Neam- Azadirachta indica: The people of India in a variety of ways have used neem, since time immemorial.

Indians have shared the knowledge of properties of neem with the entire world.
Pirating this knowledge, the USDA and an American MNC W.R. Grace in the early 90s sought a patent from EPO as the method of controlling on plants by the aid of hydrophobic extracted neem oil.
The patenting of the fungicidal properties of Neem is an example of biopiracy.

2. Patenting of Basmati: It is a long-grained aromatic variety of rice indigeneous to the Indian sub-continent.
In 1997 the US Patent and Trademark Office (USPTO) granted a patient to a Texas based American Company Ricetec Inic. for “Basmati rice lines and grains”, having trade named Texamati.

3. Haldi (Turmeric) Biopiracy: Two American researchers of Indian origin of the University of Mississippi Medical Centre put a claim to the US Patent and Trademark Office, maintaining that they had discovered haldi’s healing properties.

Section – D

Attempt any THREE of the following questions: (12)

Question 27.
With the help of neat and labelled diagrams, distinguish between artery and vein.
Answer:

The difference between the arteries and veins are:

Arteries	Veins
1. These blood vessels carry blood from heart to various parts or organs of the body. There they branch into arterioles and further into fine capillaries.	Veins are thin walled, mostly superficial vessels which carry blood from the organs towards the heart.
2. They carry oxygenated blood to all parts of the body (except pulmonary artery).	They carry deoxygenated blood from all parts of the body to the heart.
3. They are situated deep in the body.	They are situated superficially.
4. Blood flows under high pressure.	They have valves.
5. They do not have valves.	Blood does not flow under pressure.

Question 28.
State the names of hormone and glands secreting them:
(a) Growth of thyroid gland.
(b) Controls tubular absorption of water in kidney.
(c) Stimulates liver and muscles for glycogenesis.
(d) Development of immune system and maturation of T-lymphocyte.
Answer:

Hormone	Glands
(a) TSH-Thyroid Stimulating Hormone	Pituitary Gland
(b) ADH-Antidiuretic hormone	Hypothalamus
(c) Insulin	Pancreas/lslets of Langerhans
(d) Thymosin	Thymus Gland

Question 29.
Describe outbreeding devices which encourage cross pollination.
Answer:
Outbreeding Devices to Encourage Cross Pollination

1. Unisexuality: In this case, plant bears either male or female flowers. It is also called as dioecism. Self pollination is not possible, plants may be monoecuious eg. maize or dioecious eg. mulberry, papaya.

2. Dichogamy: Anthers and stigmas mature at different times in a bisexual flower so as to prevent self-pollination.

(a) Protandry: Androecium matures before gynoecium, e.g., disc florets of sunflowers.
(b) Protogyny: Gynoecium matures before androecium, e.g., Salvia.
(c) Prepotency: Pollen grains of other flowers germinate rapidly over the stigma than the pollen grains from same flower e.g., Apple.

3. Heterostyly (Heteromorphy): Style are of different length i.e., short, medium, tall. This prevents the pollens from reaching the stigma and pollinating it. In Reteromorphic flowers, pollen grains produced from anther pollinate stigmas produced at the same level, eg. Primrose.

4. Herkogamy: It is a mechanical device to prevent self-pollination in a bisexual flower. In plants, Natural physical barrier is present between two sex-organs and avoid contact of pollen with stigma of same flower, eg. calotropis.

5. Self-Incompatibility (Self-Sterility): This is genetic mechanism due to which the germination of pollen or stigma of the same flower is inhibited eg. Tobacco, Tea.

Question 30.
Explain the law of dominance and compare how it differs from incomplete dominance and co-dominance.
Answer:
Law of Dominance: When two homozygous individuals with one or more sets of contrasting characters are crossed the alleles (characters) that appear in F₁ are dominant and those which do not appear in F₁ are recessive.

1. Incomplete Dominance: Both the alleles (genes) of an allelomorphic pair express themselves partially, e.g.: Flower colour of Mirabitesjalapa.
2. Co-dominance: Both the alleles (genes) of an allelomorphic pair express themselves equally in F₁ hybrids. Such alleles which are able to express themselves equally and independently in a hybrid.
   e.g:, Coat color in cattle.

Chart of Dominance.

Question 31.
Describe hormonal control in various phases of menstrual cycle.
Answer:
Hormonal control in various phares of menstrual cycle:

1. Menstrual Phase: Day 1^st—5^th day. Endometrium of uterus breaks down under effect of prostaglandins released due to decreased levels of progesteron and estrogen.

2. Proliferative Phase/Follicular Phase or Post Menstrual Phase: Day 6^th—13^th day.
A few secondary follicles proceed to develop but usually one of them develops into graafian follicle. The other secondary follicles degenerate. This process of degeneration is called atresia. Developing secondary follicles secrete the hormone estrogen. The stimulation for proliferation of now follicles is influenced by GnRH which stimulates release of FSH.

3. Ovulatory Phase: It is the shortest phase of menstrual cycle. It involves rupturing of the mature graafian follicle and release of ovum (secondary-oocyte) into pelvic cavity usually on 14^th day of cycle. Secretion of LH by positive feedback mechanism causes mature follicle to rupture.

4. Secretory phase or Luteal Phase: Day 15^th to 28^th day.
After release of secondary oocyte, remaining tissues of graafian follicle transform into corpus luteum under the effect of LH.

Corpus luteum begins to secrete progesterone and estrogens. The ovulated egg may get fertilised within 24 hrs.

If egg not fertilised corpus luteum gets converted into corpus albicans.

The corpus luteum releases progesterone, small amount of estrogens and inhibin under the influence of these hormones, the endometrial gland grow, become coiled and start uterine secretions. Endometrium becomes more vascularised and thickens upto 8-10 mm. Inhibin stops secretion of FSH.

Maharashtra Board Class 12 Biology Previous Year Question Papers