PAPER – II
(English Version)
Time: 3 hours
Max. Marks: 60
Note:
Read the following instructions carefully.
- Answer all the questions of Section ‘A’. Answer any six questions in Section ‘B’ and answer any two questions in Section ‘C’.
- In Section ‘A’, questions from Sr. Nos. 1 to 10 are of Very Short Answer Type. Each question carries two marks. Every answer may be limited to 5 lines. Answer all these questions at one place in the same order.
- In Section ‘B’, questions from Sr. Nos. 11 to 18 are of Short Answer Type. Each question carries four marks. Every answer may be limited to 20 lines.
- In Section ‘C’, questions from Sr. Nos. 19 to 21 are of Long Answer Type. Each question carries 8 marks. Every answer may be limited to 60 lines.
- Draw labelled diagrams wherever necessary in Sections ‘B’ and ‘C’.
SECTION – A
10 × 2 = 20
Answer all questions in 5 lines each.
1. Draw a diagram of the oxyhaemoglobin dissociation curve.
Answer:
The oxyhaemoglobin dissociation curve is typically a sigmoid curve. The curve represents the relationship between the partial pressure of oxygen (pO2) and the percentage of hemoglobin saturated with oxygen. As the pO2 increases, more oxygen binds to hemoglobin, and at higher oxygen levels, the binding rate slows.
(Diagram of a sigmoid curve showing pO2 on the x-axis and % saturation of hemoglobin on the y-axis)
2. Name the structural and functional units of the kidney. What are the two main types of structural units in it?
Answer:
The structural and functional unit of the kidney is the nephron. The two main types of structural units are:
- Cortical nephrons: Located in the cortex of the kidney.
- Juxtamedullary nephrons: Located at the junction of the cortex and medulla.
3. What is a ‘motor unit’ with reference to muscle and nerve?
Answer:
A motor unit consists of a single motor neuron and all the muscle fibers it innervates. When the motor neuron sends a signal, all the muscle fibers in that unit contract together.
4. Name the type of joint between (a) atlas and axis (b) carpal and metacarpal of the human thumb.
Answer:
(a) The joint between the atlas and axis is a pivot joint.
(b) The joint between the carpal and metacarpal of the human thumb is a saddle joint.
5. What are androgens? Which cells secrete them?
Answer:
Androgens are male sex hormones, the primary one being testosterone. They are primarily secreted by the Leydig cells in the testes.
6. What is erythropoietin? What is its function?
Answer:
Erythropoietin is a hormone produced by the kidneys. It stimulates the production of red blood cells (erythropoiesis) in the bone marrow in response to low oxygen levels in the blood.
7. What is amniocentesis? Name any two disorders that can be detected by amniocentesis.
Answer:
Amniocentesis is a medical procedure where a small amount of amniotic fluid is withdrawn from the sac surrounding a fetus to diagnose genetic disorders. Two disorders that can be detected by amniocentesis are Down syndrome and Cystic fibrosis.
8. Mention the advantages of the “Lactational Amenorrhea Method”.
Answer:
The Lactational Amenorrhea Method (LAM) is a natural form of contraception based on breastfeeding. Advantages include:
- No cost or medical intervention.
- It delays ovulation and menstruation.
- Provides natural bonding and nourishment for the baby.
9. Mention any four fish by-products.
Answer:
Four fish by-products include:
- Fish oil
- Fish meal
- Fish fertilizer
- Fish glue
10. What does ADA stand for? Deficiency of ADA causes which disease?
Answer:
ADA stands for Adenosine Deaminase. A deficiency of ADA causes Severe Combined Immunodeficiency (SCID), a genetic disorder that results in a severely weakened immune system.
SECTION – B
6 × 4 = 24
Answer any six questions in 20 lines each.
11. Draw a neat labelled diagram of the L.S. of a tooth.
Answer:
The diagram of the longitudinal section (L.S.) of a tooth typically includes the following parts:
- Crown: The visible part of the tooth.
- Enamel: The outer hard layer of the crown.
- Dentin: The layer beneath the enamel, providing strength.
- Pulp: The soft tissue inside the tooth, containing nerves and blood vessels.
- Root: The part embedded in the jawbone.
- Cementum: A layer covering the root.
- Periodontal Ligament: Tissue that attaches the tooth to the bone.
(Diagram of a tooth showing all parts above)
12. What are the major transport mechanisms for CO2? Explain.
Answer:
CO2 is transported in the blood by three major mechanisms:
- Dissolution in plasma: A small amount of CO2 dissolves directly in plasma.
- Carbaminohemoglobin: CO2 binds with hemoglobin to form carbaminohemoglobin.
- Bicarbonate ion (HCO3-) formation: CO2 reacts with water in the red blood cells to form carbonic acid, which dissociates into bicarbonate ions (HCO3-) and hydrogen ions (H+). Most CO2 is transported as bicarbonate.
13. Give an account of synaptic transmission.
Answer:
Synaptic transmission is the process by which nerve impulses are transmitted from one neuron to another across a synapse. The steps are:
- An action potential arrives at the axon terminal of the presynaptic neuron.
- This triggers the release of neurotransmitters from vesicles into the synaptic cleft.
- Neurotransmitters bind to receptors on the postsynaptic neuron.
- This binding causes an electrical change in the postsynaptic neuron, either initiating or inhibiting an action potential.
- Neurotransmitters are then removed from the synapse by enzymes or reuptake into the presynaptic neuron.
14. Explain the mechanism by which HIV multiplies and leads to AIDS.
Answer:
HIV (Human Immunodeficiency Virus) targets CD4+ T cells, which are crucial for the immune response. The mechanism is:
- HIV binds to the CD4 receptor and enters the host cell.
- The viral RNA is reverse transcribed into DNA, which integrates into the host’s genome.
- The host cell then replicates the virus, producing new viral particles.
- Over time, HIV reduces the number of CD4+ T cells, impairing the immune system.
- This leads to AIDS (Acquired Immunodeficiency Syndrome), where the body becomes vulnerable to opportunistic infections.
15. Describe erythroblastosis foetalis.
Answer:
Erythroblastosis fetalis is a condition in which the mother’s immune system attacks the red blood cells of her fetus. This happens when the mother is Rh-negative and the fetus is Rh-positive. The mother’s immune system produces antibodies against Rh-positive blood cells, leading to hemolysis (destruction) of fetal red blood cells, which can cause anemia, jaundice, and even death in severe cases.
16. Distinguish between homologous and analogous organs.
Answer:
- Homologous organs: These organs have a similar structure and origin but may serve different functions. They are evidence of common ancestry (e.g., human arm and bat wing).
- Analogous organs: These organs have a similar function but different structures and origins. They arise due to convergent evolution (e.g., wings of birds and insects).
17. Explain Darwin’s Theory of Natural Selection with industrial melanism as an experimental proof.
Answer:
Darwin’s theory of natural selection suggests that organisms with advantageous traits are more likely to survive and reproduce, passing on their traits to offspring. Industrial melanism is an example where, during the Industrial Revolution, the frequency of dark-colored moths increased in polluted areas due to better camouflage against soot-covered trees, while light-colored moths were more easily preyed upon. This is a case of natural selection in action.
18. Write about the procedure involved in MRI.
Answer:
Magnetic Resonance Imaging (MRI) is a non-invasive imaging technique that uses powerful magnetic fields and radio waves to create detailed images of internal body structures. The procedure includes:
- The patient is placed inside a strong magnetic field.
- Radiofrequency pulses are directed at the body, causing hydrogen atoms to emit signals.
- These signals are captured and analyzed to generate cross-sectional images of tissues, which are displayed on a computer screen.
SECTION – C
2 × 8 = 16
Answer any two questions in 60 lines each.
19. Describe the structure of the heart of a man. Draw a neat labelled diagram of it.
Answer:
The human heart is a muscular organ divided into four chambers:
- Right atrium: Receives deoxygenated blood from the body through the superior and inferior vena cava.
- Right ventricle: Pumps deoxygenated blood to the lungs via the pulmonary artery.
- Left atrium: Receives oxygenated blood from the lungs via the pulmonary veins.
- Left ventricle: Pumps oxygenated blood to the body through the aorta.
The heart also contains valves:
- Tricuspid valve (between right atrium and ventricle).
- Bicuspid valve (between left atrium and ventricle).
- Pulmonary valve (between right ventricle and pulmonary artery).
- Aortic valve (between left ventricle and aorta).
The heart’s structure is designed for efficient circulation of blood, ensuring oxygenated blood reaches the body and deoxygenated blood is sent to the lungs.
(Diagram of the human heart with labeled chambers and valves)
20. Describe the male reproductive system of a man with the help of a labelled diagram.
Answer:
The male reproductive system includes:
- Testes: The organs where sperm and testosterone are produced.
- Epididymis: The structure where sperm mature and are stored.
- Vas deferens: Tubes that carry sperm from the epididymis to the urethra.
- Seminal vesicles: Glands that produce a fluid that nourishes sperm.
- Prostate gland: Produces a fluid that protects and enhances sperm motility.
- Penis: The organ used for sexual intercourse and excretion of urine.
The system is responsible for producing and delivering sperm during reproduction.
(Diagram of the male reproductive system with all labeled parts)
21. What is crisscross inheritance? Explain the inheritance of one sex-linked recessive character in humans.
Answer:
Crisscross inheritance refers to the inheritance pattern where a gene is passed from a father to a daughter and then to her son. This often occurs with X-linked traits, where the father passes the gene to his daughter (who carries it on the X chromosome), and the daughter passes it to her son.
An example of a sex-linked recessive character is color blindness:
- Father: A color-blind male has the genotype XcY (where Xc represents the color blindness allele).
- Mother: A normal female has the genotype XX.
- Daughter: The daughter receives the X chromosome from the father (Xc) and the normal X chromosome from the mother, so she becomes a carrier (XcX).
- Son: The son receives the Y chromosome from the father and the X chromosome from the mother, and thus he will have normal vision if the mother does not carry the gene.
The inheritance of such traits follows the pattern of X-linked recessive inheritance.