SRMJEEE Biology (Zoology) Syllabus

Which class of vertebrates first showed amniotic eggs, and what defines class Reptilia?

Reptilia first showed amniotic (shelled) eggs; characterised by dry, scaly skin, creeping/crawling, three-chambered heart (four in crocodiles), and being poikilothermic. Example: Naja, Chelone.

What are the defining features of class Aves?

Warm-blooded (homeothermic); body covered with feathers; forelimbs modified into wings; presence of a beak without teeth; pneumatic bones; four-chambered heart. Example: Corvus, Columba.

List the key characteristics of class Mammalia.

Presence of mammary glands, hair on skin, external ears (pinnae), a muscular diaphragm, four-chambered heart, warm-blooded, and (mostly) viviparous with internal fertilisation. Example: Homo sapiens.

Define a tissue and name the four types of animal tissues.

A tissue is a group of similar cells with a common origin performing a specific function. Four types: epithelial, connective, muscular, and nervous tissue.

What are the main functions and a key feature of epithelial tissue?

It covers surfaces, lines cavities, and forms glands; functions in protection, secretion, and absorption. It rests on a basement membrane and has cells packed tightly with little intercellular material.

Differentiate simple from compound epithelium.

Simple epithelium is a single layer of cells for absorption, secretion, and diffusion; compound epithelium has multiple cell layers providing protection (e.g. skin epidermis).

Name the types of cell junctions and their roles in epithelia.

Tight junctions (prevent leakage of substances), adhering junctions (cement neighbouring cells together), and gap junctions (allow cytoplasmic communication between cells).

What are the main types of connective tissue?

Loose connective tissue (areolar, adipose), dense connective tissue (tendons, ligaments), and specialised connective tissue (cartilage, bone, blood).

Name the three types of muscle tissue and one distinguishing feature of each.

Skeletal (striated, voluntary, multinucleate), smooth/visceral (non-striated, involuntary, spindle-shaped), and cardiac (striated, involuntary, branched with intercalated discs).

What is a neuron and what are its functional regions?

A neuron is the structural and functional unit of nervous tissue; it consists of a cell body (cyton), dendrites that receive impulses, and an axon that conducts impulses away.

Define an organ and an organ system.

An organ is a structure made of two or more tissue types performing a specific function; an organ system is a group of organs working together to carry out a major body function (e.g. digestive system).

What are biomolecules and into which two broad categories are they grouped by size?

Biomolecules are organic compounds present in living tissues. They are grouped as micromolecules (small, MW < 1000 Da, e.g. amino acids, sugars) and macromolecules (large, e.g. proteins, polysaccharides, nucleic acids).

Give the general empirical formula of carbohydrates and name their three classes by complexity.

General formula $(\ce{CH2O})_n$. Classes: monosaccharides, oligosaccharides (e.g. disaccharides), and polysaccharides.

Match the disaccharides to their monosaccharide units: sucrose, maltose, lactose.

Sucrose = glucose + fructose; Maltose = glucose + glucose; Lactose = glucose + galactose.

Name three important storage/structural polysaccharides and their roles.

Starch (plant energy storage), glycogen (animal energy storage in liver/muscle), and cellulose (structural component of plant cell walls).

What is the basic structural unit of proteins and the bond linking them?

Amino acids are the building blocks; they are joined by peptide bonds ($\ce{-CO-NH-}$) formed by dehydration (condensation).

Describe the four levels of protein structure.

Primary (linear amino-acid sequence), secondary (local folding into $\alpha$-helix or $\beta$-pleated sheet), tertiary (overall 3D folding), and quaternary (arrangement of multiple polypeptide subunits).

What are the building blocks of lipids and name the two main classes of fatty acids?

Lipids are made of glycerol and fatty acids. Fatty acids are saturated (no C=C double bonds) or unsaturated (one or more C=C double bonds).

What are enzymes and of what chemical nature are most of them?

Enzymes are biological catalysts that speed up biochemical reactions without being consumed; most are proteins (some are RNA, called ribozymes).

How do enzymes accelerate reactions in terms of activation energy?

Enzymes lower the activation energy ($E_a$) required for the reaction to proceed, increasing the rate without altering the equilibrium.

Explain the effect of temperature and pH on enzyme activity.

Each enzyme has an optimum temperature and optimum pH at which activity is maximal; beyond these, activity declines and the enzyme may denature (lose its 3D shape and function).

Differentiate competitive and non-competitive enzyme inhibition.

Competitive inhibitors resemble the substrate and bind the active site (overcome by raising substrate concentration); non-competitive inhibitors bind elsewhere (allosteric site), altering the active site regardless of substrate concentration.

What is the lock-and-key (and induced-fit) model of enzyme action?

The substrate fits the enzyme's active site like a key in a lock (lock-and-key); in the induced-fit model the active site changes shape slightly to fit the substrate snugly upon binding.

List the regions of the human alimentary canal in order from mouth to anus.

Mouth (buccal cavity) → pharynx → oesophagus → stomach → small intestine (duodenum, jejunum, ileum) → large intestine (caecum, colon, rectum) → anus.

What is the dental formula of an adult human?

$\frac{2123}{2123}$ for one half of each jaw, representing 2 incisors, 1 canine, 2 premolars, and 3 molars; total 32 teeth.

Name the three major digestive glands and their secretions.

Salivary glands (saliva with salivary amylase), liver (bile), and pancreas (pancreatic juice with trypsin, amylase, lipase).

What enzyme is in saliva and what does it digest?

Salivary amylase (ptyalin), which hydrolyses starch into maltose; it acts at a slightly alkaline-to-neutral pH in the mouth.

Name the gastric enzymes/secretions and their functions.

Pepsin (secreted as pepsinogen) digests proteins into peptides; HCl provides acidic pH and activates pepsinogen; mucus protects the stomach lining; rennin (in infants) curdles milk.

What is the role of bile in digestion, and does it contain enzymes?

Bile contains no digestive enzymes; bile salts emulsify fats into small droplets (increasing surface area for lipase) and help activate lipases; it also makes the medium alkaline.

What are the main functional units of fat, protein, and carbohydrate absorption sites in the small intestine?

Villi and microvilli of the small intestine greatly increase surface area; carbohydrates and proteins are absorbed into blood capillaries, while fats (as chylomicrons) enter the lacteals (lymph).

Name two disorders of the digestive system and their causes.

Jaundice (yellowing of skin/eyes due to bile pigment deposition from liver dysfunction) and PEM disorders—Kwashiorkor (protein deficiency) and Marasmus (protein and calorie deficiency).

Differentiate breathing from cellular respiration.

Breathing (external respiration) is the physical exchange of $\ce{O2}$ and $\ce{CO2}$ between the body and environment; cellular respiration is the intracellular oxidation of food to release energy as ATP.

List the parts of the human respiratory system in order of air flow.

External nostrils → nasal cavity → pharynx → larynx → trachea → primary bronchi → bronchioles → alveoli.

Where does gas exchange occur and why are alveoli suited for it?

Gas exchange occurs in the alveoli; they have thin walls, a large surface area, and a rich capillary network allowing efficient diffusion of $\ce{O2}$ and $\ce{CO2}$.

How is oxygen mainly transported in the blood?

About 97% of $\ce{O2}$ is transported bound to haemoglobin as oxyhaemoglobin ($\ce{Hb + O2 -> HbO2}$); about 3% is dissolved in plasma.

How is carbon dioxide transported in the blood?

About 70% as bicarbonate ions ($\ce{HCO3^-}$), about 20–25% bound to haemoglobin as carbamino-haemoglobin, and about 7% dissolved in plasma.

What is the role of the diaphragm and intercostal muscles in inspiration?

During inspiration the diaphragm contracts and flattens, and external intercostals contract to raise the ribs, increasing thoracic volume and decreasing pressure so air rushes in.

Name the four chambers of the human heart and what each receives or pumps.

Right atrium (receives deoxygenated blood from body), right ventricle (pumps it to lungs), left atrium (receives oxygenated blood from lungs), left ventricle (pumps it to the body).

Name the heart valves and their locations.

Tricuspid valve (between right atrium and right ventricle), bicuspid/mitral valve (between left atrium and left ventricle), and the semilunar valves at the openings of the pulmonary artery and aorta.

Distinguish pulmonary from systemic circulation.

Pulmonary circulation carries blood between the heart and lungs (right ventricle → lungs → left atrium); systemic circulation carries blood between the heart and the rest of the body (left ventricle → body → right atrium).

What is the pacemaker of the heart and where is it located?

The sino-atrial node (SA node), located in the wall of the right atrium; it initiates and sets the rhythm of the heartbeat.

Name the formed elements of blood and their primary functions.

Erythrocytes (RBCs) transport gases via haemoglobin; leucocytes (WBCs) provide immunity/defence; thrombocytes (platelets) help in blood clotting.

What are the excretory products and modes of excretion that define ammonotelic, ureotelic, and uricotelic animals?

Ammonotelic excrete ammonia (aquatic animals, e.g. bony fishes); ureotelic excrete urea (mammals, amphibians); uricotelic excrete uric acid (birds, reptiles, insects).

Name the parts of the human urinary system.

A pair of kidneys, a pair of ureters, a urinary bladder, and a urethra.

What is the nephron and its two main structural parts?

The nephron is the structural and functional unit of the kidney; it consists of the Malpighian body (glomerulus + Bowman's capsule) and the renal tubule (PCT, loop of Henle, DCT).

List the three main steps of urine formation.

Glomerular filtration (in the Bowman's capsule), tubular reabsorption (of useful substances like glucose, ions, water), and tubular secretion (of $\ce{H+}$, $\ce{K+}$, $\ce{NH3}$).

Which hormone controls water reabsorption in the kidney and how?

ADH (antidiuretic hormone/vasopressin) increases water reabsorption from the DCT and collecting duct, producing concentrated urine and conserving body water.

Name the three types of muscles based on location and control.

Skeletal (striated, voluntary, attached to bones), smooth/visceral (non-striated, involuntary, in internal organs), and cardiac (striated, involuntary, in the heart).

What are the contractile proteins of muscle and the basic contractile unit?

Actin (thin filament) and myosin (thick filament) are the contractile proteins; the sarcomere is the basic functional contractile unit of a myofibril.

State the sliding filament theory of muscle contraction in brief.

Muscle contraction occurs when actin (thin) filaments slide over myosin (thick) filaments, shortening the sarcomere; this requires $\ce{Ca^2+}$ and ATP.

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

The adult human skeleton has 206 bones, divided into the axial skeleton (80 bones: skull, vertebral column, ribs, sternum) and the appendicular skeleton (126 bones: limbs and girdles).

Define a joint and name the three structural types.

A joint is the point of contact between bones (or bone and cartilage). Types: fibrous (immovable, e.g. skull sutures), cartilaginous (slightly movable, e.g. between vertebrae), and synovial (freely movable, e.g. knee).

Give examples of synovial joints by type of movement.

Ball-and-socket joint (shoulder, hip), hinge joint (knee, elbow), pivot joint (between atlas and axis), gliding joint (between carpals), and saddle joint (thumb).

Differentiate tendons and ligaments.

Tendons are dense connective tissue connecting muscle to bone; ligaments are dense connective tissue connecting bone to bone at joints.