Board Question Paper: July 2022 - Biology
Max. Marks: 70 | Time: 3 Hrs.
SECTION − A
Q.1. Select and write the correct answer for the following multiple choice type of questions: [10]
(i) In lac operon the structural gene z codes for _______ enzyme.
(ii) The special hygroscopic tissue found in the aerial roots of some epiphytic plants is _______.
(iii) Due to specific mating behaviour, the members of population do not mate in _______ type of isolation.
(iv) The sequence of nitrogenous bases on DNA molecule is ATCGA. Which of the following is the correct complementary sequence of nitrogenous bases on mRNA Molecule?
(v) The oral vaccine for prevention of typhoid recommended by WHO is _______.
(vi) The large holes in Swiss cheese are developed due to the production of large amounts of _______.
(vii) Miyawaki is a method of plantation adapted by the government for the project mission Harit Kranti from the country.
(viii) In ecological succession, the _______ community does not evolve further.
(ix) Which of the following sets or organisms are used as cloning organisms in plant biotechnology?
(x) Aspergillus niger is the microbial source of _______.
(Note: While A. niger is primarily the source of Citric Acid, in the context of Maharashtra Board textbook curriculum, it is associated with the production process of Vitamin C.)
HSC Biology
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Q.2. Answer the following questions: [8]
(i) Write the name of the small molecule required to initiate / start the process of synthesis of new complementary strand during replication of DNA.
Answer: RNA Primer
(ii) Name the country where industrial melanism was observed in moths due to industrialization.
Answer: Great Britain (England / UK)
(iii) Give the other name for epidermal cells in roots of plants.
Answer: Epiblema cells (or Rhizodermis)
(iv) Name the hormone used for early rooting in propagation by cutting.
Answer: Auxin (specifically Indole Butyric Acid [IBA] or Naphthalene Acetic Acid [NAA])
(v) In human pharynx, there is a set of lymphoid organs called _______.
Answer: Tonsils
(vi) State the other name for Dentist’s nerve.
Answer: Trigeminal nerve (V Cranial Nerve)
(vii) Name the type of Mycorrhiza that grows in between and within the cortical cells of root.
Answer: Endomycorrhiza (or VAM - Vesicular Arbuscular Mycorrhiza)
(viii) Identify the part labelled ‘A’ in the given diagram:
(Diagram shows a Blastocyst where A points to the outer layer of cells)
Answer: Trophoblast
SECTION − B
Attempt any EIGHT of the following questions: [16]
Q.3. Sketch and label the diagram of ovule most commonly seen in angiosperms.
The most common type is the Anatropous Ovule.
[Diagram of Anatropous Ovule]Key Labels required:
1. Funiculus
2. Hilum
3. Integuments (Outer and Inner)
4. Micropyle
5. Nucellus
6. Embryo Sac (Female Gametophyte)
7. Chalaza
Q.4. Explain “Law of dominance” with suitable example.
Law of Dominance: It states that when two homozygous individuals with one or more sets of contrasting characters are crossed, the alleles (characters) that appear in the F1 generation are called dominant and those that do not appear in F1 are called recessive.
Example: In Pea plants, when a pure tall plant (TT) is crossed with a pure dwarf plant (tt):
- Parents: Tall (TT) x Dwarf (tt)
- Gametes: (T) and (t)
- F1 Generation: Tt (All plants are Tall)
Here, the character 'Tallness' appears in the F1 generation, so it is dominant, while 'Dwarfness' is suppressed, so it is recessive.
Q.5. A woman is unable to conceive due to blockage in her upper segment of oviduct. State the infertility treatment to be given to her and describe it.
Treatment: In Vitro Fertilization (IVF) or Test Tube Baby technique.
Description:
- In this method, the ova from the wife (or donor) and sperms from the husband (or donor) are collected.
- Fertilization is induced outside the body in a laboratory culture medium (simulating body conditions).
- The zygote or early embryo (up to 8 blastomeres) is then transferred into the fallopian tube (ZIFT - Zygote Intrafallopian Transfer) or if it has more than 8 blastomeres, it is transferred into the uterus (IUT - Intra Uterine Transfer) for further development.
Q.6. Identify the types of chromosomal aberrations in the following figures A, B, C, D:
[Diagram of hromosomal aberrations]- A: Deletion (Loss of a segment of chromosome).
- B: Duplication (A segment of chromosome is repeated).
- C: Inversion (A segment of chromosome breaks and rejoins in reverse direction).
- D: Translocation (Exchange of segments between non-homologous chromosomes).
Q.7. The process of transcription takes place on a part of DNA molecule known as transcription unit. Draw a well labelled diagram of the same showing different regions of the unit.
[Diagram of Transcription Unit]Labels required:
1. Promoter (at 5' end of coding strand)
2. Structural Gene
3. Terminator (at 3' end of coding strand)
4. Template Strand (3' to 5' polarity)
5. Coding Strand (5' to 3' polarity)
Q.8. Identify labels A, B, C, D:
(Refer to Oogenesis diagram in the question paper)
- A: Primary Oocyte (2n)
- B: Secondary Oocyte (n)
- C: Ovum / Ootid (n)
- D: Second Polar Body (n)
Q.9. Match the pairs and rewrite:
| Column I | Column II |
|---|---|
| (a) Connecting link between ape and man | (4) Australopithecus |
| (b) Ape man | (1) Homo erectus |
| (c) Handy man like | (2) Homo habilis |
| (d) Advanced prehistoric man | (3) Neanderthal man |
Q.10. Define polyembryony. State its different types.
Definition: The phenomenon of development of more than one embryo inside the seed is called polyembryony.
Types:
- Simple Polyembryony: Due to fertilization of more than one egg cell.
- Cleavage Polyembryony: Due to splitting of the proembryo.
- Adventive Polyembryony: Embryos develop from diploid cells of nucellus or integuments (e.g., Citrus, Mango).
Q.11. Which are the major abiotic factors that influence habitat?
The major abiotic factors are:
- Temperature: Affects enzyme kinetics and basal metabolism.
- Water: Essential for life; affects productivity and distribution.
- Light: Required for photosynthesis and photoperiodism.
- Soil (Edaphic factors): Composition, grain size, and aggregation determine vegetation.
Q.12. Identify A and B in the given diagram and explain T wave.
- A: P-wave (represents atrial depolarization).
- B: QRS complex (represents ventricular depolarization).
Explanation of T wave: It represents ventricular repolarization. It marks the return of the ventricles from an excited to a normal state (relaxation phase). The end of the T-wave marks the end of systole.
Q.13. Water acts as a thermal buffer. Justify the statement.
Water acts as a thermal buffer because:
- It has a high specific heat capacity, meaning it can absorb or lose a large amount of heat with only a small change in its own temperature. This helps in maintaining a constant body temperature.
- It has a high heat of vaporization, allowing organisms to cool down efficiently through evaporation (sweating/transpiration) without losing excessive body fluid.
- It has high heat of fusion, preventing body fluids from freezing easily.
Q.14. The following diagram indicates which type of interaction? Write a note on the same.
Interaction Type: Mutualism (Specifically, a Lichen).
Note:
- The diagram shows an intimate association between Algae (phycobiont) and Fungi (mycobiont).
- This is an example of Mutualism where both species benefit.
- The algae prepare food through photosynthesis for the fungus.
- The fungus provides shelter and absorbs water and minerals from the soil for the algae.
SECTION − C
Attempt any EIGHT of the following questions: [24]
Q.15. Suresh is doing his studies on a plant related to absorption of water. He found different forms of water available in the soil.
(i) Name them.
(ii) Which form of water is absorbed by the plants?
(iii) Name the region in the soil from where roots absorb water.
(i) Forms of soil water: Gravitational water, Hygroscopic water, Combined water, and Capillary water.
(ii) Absorbed form: Capillary water.
(iii) Region: Rhizosphere (specifically the Zone of Absorption or Root Hair Zone).
Q.16. Name the stress hormone in plants. Describe its physiological effects.
Name: Abscisic Acid (ABA).
Physiological Effects:
- Stomatal Closure: It induces closure of stomata during water stress (drought) to reduce transpiration.
- Seed Dormancy: It induces dormancy in seeds and buds to withstand unfavorable conditions.
- Abscission: It promotes the abscission (falling) of leaves, flowers, and fruits.
- Inhibition of Growth: It generally acts as a growth inhibitor.
Q.17. (a) Sketch and label the diagram of brain to show ventricles in coronal plane.
(b) Name the cavity which is continuation of IV ventricle.
(a) Diagram:
[Sketch of Brain Ventricles]Labels: Lateral Ventricles, Third Ventricle (Diocoel), Fourth Ventricle (Metacoel), Foramen of Monro, Iter.
(b) Cavity: The central canal of the spinal cord is the continuation of the IV (fourth) ventricle.
Q.18. Complete the following chart and rewrite:
| Blood Group | Genotype | Antigen on Surface of RBC | Antibody in serum |
|---|---|---|---|
| A | \(I^A I^A\) or \(I^A I^O\) | A | Anti-B (b) |
| B | \(I^B I^B\) or \(I^B I^O\) | B | a (Anti-A) |
| AB | \(I^A I^B\) | A and B | (Nil) |
| O | \(I^O I^O\) | (Nil) | Anti-A and Anti-B (a and b) |
Q.19. Explain the various steps of biogas production.
Biogas production involves anaerobic digestion in three stages:
- Hydrolysis (Solubilization): Complex organic polymers (cellulose, proteins, fats) are broken down into simple soluble monomers by hydrolytic bacteria (e.g., Clostridium).
- Acidogenesis: The monomers are converted into simple organic acids (acetic acid, formic acid) by acidogenic bacteria.
- Methanogenesis: Methanogenic bacteria (e.g., Methanococcus, Methanobacillus) convert the organic acids into Methane (\(CH_4\)), Carbon dioxide (\(CO_2\)), and other gases.
Q.20. How ‘melt in mouth’ vaccines are administered? Mention any two benefits of the same.
Administration: 'Melt in mouth' vaccines are administered by placing them under the tongue or simply eating them (e.g., edible vaccines in transgenic plants/fruits) where they dissolve and are absorbed into the bloodstream.
Benefits:
- They eliminate the need for needles/injections, increasing patient compliance (needle-free).
- They can be stored at room temperature, reducing the cost and logistics of a cold chain (refrigeration).
Q.21. Enumerate or enlist the various levels of biodiversity. Explain any one of it.
Levels of Biodiversity:
- Genetic Diversity
- Species Diversity
- Ecological (Ecosystem) Diversity
Explanation (Genetic Diversity):
It refers to the variation in genes within a particular species. It allows a population to adapt to changing environments. For example, there are thousands of varieties of rice or mangoes in India, which differ in their genetic makeup.
Q.22. Write down various sequential stages of hydrarch succession in plants after phytoplankton stage.
The sequential stages after the Phytoplankton stage are:
- Submerged Plant Stage: (e.g., Hydrilla, Vallisneria)
- Submerged Free-Floating Plant Stage: (e.g., Pistia, Eichhornia)
- Reed-Swamp Stage (Amphibious stage): (e.g., Typha, Sagittaria)
- Marsh-Meadow Stage: (e.g., Cyperus, Grasses)
- Scrub Stage: (Shrubs like Salix)
- Climax Forest: (Trees / Mesophytic vegetation)
Q.23. With the help of a suitable example, write the mechanism of hormone action through membrane receptors.
This mechanism is for peptide/protein hormones (e.g., FSH, Insulin) which cannot cross the cell membrane.
Mechanism:
- Binding: The hormone (First Messenger) binds to a specific receptor on the cell membrane to form a Hormone-Receptor Complex.
- Activation: This complex triggers the release of an enzyme (like Adenylate cyclase).
- Second Messenger: The enzyme converts ATP into cyclic AMP (cAMP) or releases \(Ca^{++}\). cAMP acts as the Second Messenger.
- Biochemical Response: The second messenger activates intracellular enzyme systems that regulate cellular metabolism, leading to the specific physiological response.
Example: FSH binds to ovarian cell membrane receptors -> generates cAMP -> promotes ovarian follicle growth.
Q.24. Classify the given proteins produced by rDNA technology to treat various diseases in human and rewrite as shown in the table:
| Disorders / Diseases / Health Conditions | Recombinant Protein (s) |
|---|---|
| Atherosclerosis | Platelet derived growth factor |
| Anaemia | Erythropoietin |
| Parturition | Relaxin |
| Blood clots | Tissue plasminogen activator |
| Diabetes | Insulin |
| Haemophilia A | Factor VIII |
| Haemophilia B | Factor IX |
Q.25. Write a note on transport of carbon dioxide by bicarbonate ions at tissue level.
About 70% of \(CO_2\) is transported in this form.
- In RBCs, \(CO_2\) reacts with water in the presence of the enzyme Carbonic Anhydrase to form Carbonic acid (\(H_2CO_3\)).
- \(H_2CO_3\) is unstable and dissociates into Bicarbonate ions (\(HCO_3^-\)) and Hydrogen ions (\(H^+\)).
- The \(HCO_3^-\) ions diffuse out of the RBCs into the plasma.
- To maintain ionic balance, Chloride ions (\(Cl^-\)) move from plasma into the RBCs. This is called the Chloride Shift or Hamburger Phenomenon.
- This process allows blood to carry \(CO_2\) efficiently to the lungs.
Q.26. Anita observed apical dominance in her plant. Name and describe the plant hormone that will reverse the effect.
Name: Cytokinin.
Description:
- Cytokinins promote cell division (cytokinesis).
- They counteract apical dominance induced by Auxins.
- By applying Cytokinins, the growth of lateral buds is stimulated even in the presence of the apical bud, making the plant bushy.
SECTION − D
Attempt any THREE of the following questions: [12]
Q.27. (a) Kabban Park in Bengaluru is having dull flowers with strong fragrance, abundant nectar and edible pollen grains. Identify the type of pollination, the flowers are adapted for.
(b) The process of fruit formation without fertilization is termed as _______.
(c) Differentiate between albuminous and exalbuminous seeds.
(a) Type of Pollination: Chiropterophily (Pollination by Bats). The characteristics (dull color, strong fragrance, abundant nectar) are adaptations for nocturnal pollinators like bats.
(b) Parthenocarpy.
(c) Difference:
| Albuminous (Endospermic) Seeds | Exalbuminous (Non-endospermic) Seeds |
|---|---|
| Endosperm persists in the mature seed. | Endosperm is completely consumed during embryo development. |
| Food is stored in the endosperm. | Food is stored in the cotyledons. |
| Example: Maize, Castor, Wheat. | Example: Pea, Bean, Gram. |
Q.28. Give reasons :
(a) Though fertilization takes place in the ampulla of fallopian tube, implantation of embryo takes place after reaching the uterus only.
(b) Corpus luteum persists in the ovary after fertilization.
(c) Explain the role of oxytocin hormone and describe the dilation stage of parturition.
(a) Reason: The fertilized egg (zygote) undergoes cleavage as it moves towards the uterus. It takes about 4-7 days to form a blastocyst. Implantation requires the blastocyst stage and a prepared uterine endometrium, which prevents ectopic pregnancy and ensures proper nourishment.
(b) Reason: After fertilization, the trophoblast cells of the embryo secrete hCG (Human Chorionic Gonadotropin). This hormone signals the Corpus Luteum to persist and continue secreting Progesterone, which is essential to maintain the endometrium and the pregnancy until the placenta takes over.
(c) Oxytocin and Dilation Stage:
- Role of Oxytocin: It acts on the uterine muscles and causes stronger uterine contractions (Labor pains). This creates a positive feedback loop leading to expulsion of the baby.
- Dilation Stage: This is the first stage of parturition. Uterine contractions begin from the top. The cervix dilates (opens) fully (up to 10cm). The amniotic sac ruptures, releasing amniotic fluid. This stage lasts for about 12 hours.
Q.29. Give the graphic representation of back cross and test cross. Differentiate between them.
Graphic Representation:
Let T = Tall (Dominant), t = Dwarf (Recessive). F1 Hybrid = Tt.
- Back Cross: F1 Hybrid (Tt) x Any Parent (TT or tt).
- Test Cross: F1 Hybrid (Tt) x Recessive Parent (tt).
Differentiation:
| Back Cross | Test Cross |
|---|---|
| Cross between F1 hybrid and any one of the parents (Dominant or Recessive). | Cross between F1 hybrid and the homozygous recessive parent only. |
| Used to improve breeds or traits. | Used to determine the unknown genotype of the F1 hybrid. |
| All test crosses are back crosses. | All back crosses are not test crosses. |
Q.30. (a) Name the nerve fibres internally connecting the cerebral hemispheres.
(b) Name the sulci which divide each cerebral hemisphere into 4 lobes.
(c) Describe the various functional areas found in the different lobes of cerebral hemispheres.
(a) Connection: Corpus callosum.
(b) Sulci:
- Central Sulcus (divides Frontal and Parietal).
- Lateral Sulcus (divides Frontal/Parietal and Temporal).
- Parieto-occipital Sulcus (divides Parietal and Occipital).
(c) Functional Areas:
- Frontal Lobe: Motor area (voluntary movements), Broca’s area (speech production), Association area (intellect, memory).
- Parietal Lobe: Somatosensory area (sensation of pain, touch, temperature, pressure).
- Temporal Lobe: Auditory area (hearing), Wernicke’s area (understanding speech/language), Olfactory area (smell).
- Occipital Lobe: Visual area (vision and visual interpretation).
Q.31. (a) Describe the structure of lymphocytes and mention its types.
(b) Name the disorder caused due to abnormal and uncontrolled increase in number of WBCs.
(c) State the functions of neutrophils.
(a) Structure & Types of Lymphocytes:
- Structure: They are agranulocytes with a large, spherical nucleus and very little peripheral cytoplasm. They constitute 25-30% of WBCs.
- Types:
- B-Lymphocytes: Mature in bone marrow; produce antibodies (humoral immunity).
- T-Lymphocytes: Mature in thymus; responsible for cell-mediated immunity (Helper T, Cytotoxic T, Suppressor T, Memory T cells).
(b) Disorder: Leukemia (Blood Cancer).
(c) Functions of Neutrophils:
- They are the first line of defense against pathogens.
- They perform phagocytosis (engulfing and destroying bacteria/pathogens).
- They release pus after dying at the site of infection.