AIIMS Nursing (BSc) Entrance Biology - Zoology Syllabus

What is tidal volume and its approximate value in a healthy human?

Tidal volume is the volume of air inspired or expired during normal breathing, approximately 500 mL.

How is most carbon dioxide transported in the blood?

About 70% as bicarbonate ions (HCO3-), ~20-25% bound to haemoglobin as carbamino-haemoglobin, and ~7% dissolved in plasma.

What is the role of carbonic anhydrase in respiration?

It catalyses the reversible conversion of CO2 and water to carbonic acid (and bicarbonate), facilitating CO2 transport in red blood cells.

Name the formed elements of human blood.

Erythrocytes (RBCs), leucocytes (WBCs), and thrombocytes (platelets).

What are the two main categories of leucocytes and examples of each?

Granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes).

What is the universal donor and universal recipient blood group?

O negative is the universal donor; AB positive is the universal recipient.

Describe the path of blood through the four chambers of the human heart.

Deoxygenated blood enters the right atrium, passes to the right ventricle, goes to the lungs; oxygenated blood returns to the left atrium, passes to the left ventricle, and is pumped to the body.

What does a 'double circulation' mean in mammals?

Blood passes through the heart twice per complete circuit: pulmonary circulation (heart-lungs-heart) and systemic circulation (heart-body-heart).

What initiates the heartbeat and why is the heart called myogenic?

The sino-atrial node (SA node) initiates the heartbeat; the heart is myogenic because the impulse originates from the heart muscle itself, not from nerves.

What are the main nitrogenous excretory products and the animals associated with each?

Ammonia (ammonotelic, e.g., many fishes), urea (ureotelic, e.g., mammals), and uric acid (uricotelic, e.g., birds, reptiles, insects).

Name the functional unit of the kidney and its two main components.

The nephron; it consists of the Malpighian body (glomerulus + Bowman's capsule) and the renal tubule.

What are the three main processes of urine formation?

Glomerular filtration, tubular reabsorption, and tubular secretion.

Which hormone regulates water reabsorption in the kidney and from where is it released?

Antidiuretic hormone (ADH/vasopressin), released from the posterior pituitary.

What are the three types of muscle fibre arrangement that enable movement, and what protein pair drives contraction?

Movement is driven by the contractile proteins actin (thin filament) and myosin (thick filament).

State the sliding filament theory of muscle contraction.

Muscle contraction occurs when actin (thin) filaments slide over myosin (thick) filaments, shortening the sarcomere; the filaments themselves do not shorten.

How many bones are in the adult human skeleton and what are its two divisions?

206 bones, divided into the axial skeleton (80 bones: skull, vertebral column, rib cage) and the appendicular skeleton (126 bones: limbs and girdles).

Name the parts of a neuron and the direction of impulse flow.

Dendrites receive impulses, the cell body (cyton) processes them, and the axon transmits the impulse away toward the synapse.

What is a synapse and how is an impulse transmitted across a chemical synapse?

A synapse is the junction between two neurons; the impulse is transmitted by release of neurotransmitters (e.g., acetylcholine) across the synaptic cleft.

Distinguish the roles of the sympathetic and parasympathetic nervous systems.

Sympathetic prepares the body for 'fight or flight' (e.g., increases heart rate); parasympathetic conserves energy and promotes 'rest and digest' (e.g., slows heart rate).

Match these endocrine glands to a key hormone: thyroid, pancreas (islets), adrenal medulla.

Thyroid - thyroxine; pancreas (islets of Langerhans) - insulin/glucagon; adrenal medulla - adrenaline (epinephrine).

Which hormone lowers blood glucose and which raises it?

Insulin lowers blood glucose; glucagon (and adrenaline) raises it.

Name the male and female primary reproductive organs (gonads) and the gametes they produce.

Testes produce sperm in males; ovaries produce ova (eggs) in females.

What is the function of the seminiferous tubules and the Leydig (interstitial) cells?

Seminiferous tubules are the site of sperm production (spermatogenesis); Leydig cells secrete testosterone.

List the four phases of the human menstrual cycle in order.

Menstrual phase, follicular (proliferative) phase, ovulatory phase, and luteal (secretory) phase.

Which hormone surge triggers ovulation and around which day of a 28-day cycle does ovulation occur?

A surge of luteinising hormone (LH) triggers ovulation, which occurs around day 14.

What is the role of the corpus luteum and the hormone it secretes?

The corpus luteum secretes progesterone, which maintains the uterine lining (endometrium) to support a possible pregnancy.

Where does fertilisation normally occur and what is the resulting structure that implants in the uterus?

Fertilisation occurs in the ampulla of the fallopian tube; the resulting blastocyst implants in the uterine wall.

What is the normal human gestation period and the function of the placenta?

About 9 months (approximately 280 days); the placenta supplies the foetus with oxygen and nutrients and removes wastes, also acting as an endocrine organ.

Differentiate STDs from contraceptive methods, giving one example of each category of contraceptive.

STDs are infections transmitted sexually (e.g., gonorrhoea, syphilis, HIV/AIDS); contraceptives prevent pregnancy and include barrier methods (condoms), hormonal (pills), IUDs (Copper-T), and surgical (vasectomy/tubectomy).

Classify these diseases by pathogen: Malaria, Typhoid, Common cold, Ringworm.

Malaria - protozoan (Plasmodium); Typhoid - bacterium (Salmonella typhi); Common cold - virus (rhinovirus); Ringworm - fungus.

Differentiate innate (non-specific) and acquired (specific) immunity.

Innate immunity is present from birth and provides non-specific defence (skin, phagocytes); acquired immunity develops after exposure to a pathogen and is specific, involving antibodies and memory cells.

Distinguish active immunity from passive immunity.

Active immunity: the body produces its own antibodies after exposure/vaccination (long-lasting); passive immunity: ready-made antibodies are given from outside (e.g., mother's milk, antiserum), giving immediate but short-lived protection.

What is Darwin's theory of natural selection in one sentence?

Individuals with favourable heritable variations are better suited to their environment, survive, and reproduce more, so those traits become more common over generations ('survival of the fittest').

What are homologous and analogous organs, with an example of each?

Homologous organs have the same basic structure but different functions (e.g., forelimbs of human, whale, bat - divergent evolution); analogous organs have different structure but similar function (e.g., wings of insect and bird - convergent evolution).

What is the significance of microbes Rhizobium and Lactobacillus in human welfare?

Rhizobium fixes atmospheric nitrogen in legume root nodules (biofertiliser); Lactobacillus converts milk to curd by producing lactic acid.

Which microbes are used in producing antibiotics like penicillin and in making bread/alcohol?

Penicillin is produced by the fungus Penicillium notatum; bread and alcoholic fermentation use yeast (Saccharomyces cerevisiae).

What role do methanogens play in biogas (gobar gas) production?

Methanogenic bacteria (e.g., Methanobacterium) act on cellulosic waste/dung anaerobically to produce biogas, which is mainly methane.