IAT Biology Syllabus

What is the difference between a macronutrient and a micronutrient in plants? Give two examples of each.

Macronutrients are needed in large amounts (>10 mmol/kg dry matter), e.g., N, P, K, Ca, Mg, S. Micronutrients are needed in trace amounts, e.g., Fe, Mn, Zn, Cu, B, Mo, Cl.

Write the overall balanced equation for photosynthesis.

6CO2 + 12H2O --(light, chlorophyll)--> C6H12O6 + 6O2 + 6H2O.

What is the difference between C3 and C4 plants regarding the first stable product and CO2-fixing enzyme?

C3 plants: first stable product is 3-carbon PGA, enzyme is RuBisCO (Calvin cycle). C4 plants: first product is 4-carbon OAA in mesophyll, enzyme is PEP carboxylase; they use Kranz anatomy and avoid photorespiration.

What is the net ATP yield from the complete aerobic respiration of one glucose molecule (eukaryotes)?

Approximately 36-38 ATP (commonly stated as 38: 8 from glycolysis [net 2 ATP + 2 NADH], plus Krebs cycle and oxidative phosphorylation).

What is the respiratory quotient (RQ), and what is its value for carbohydrates?

RQ = volume of CO2 evolved / volume of O2 consumed during respiration. For carbohydrates RQ = 1; for fats it is less than 1 (~0.7); for organic acids it is greater than 1.

Name the five major groups of plant growth regulators (phytohormones) and one function of each.

Auxins (apical dominance/cell elongation), Gibberellins (stem elongation/bolting), Cytokinins (cell division), Ethylene (fruit ripening, gaseous), and Abscisic acid (stress/dormancy, stomatal closure).

What is the role of bile in digestion, and where is it produced and stored?

Bile (produced by the liver, stored in the gall bladder) emulsifies fats into smaller droplets, increasing surface area for lipase action, and helps absorption; it contains no digestive enzymes.

What enzyme in saliva begins digestion, and which macromolecule does it act on?

Salivary amylase (ptyalin) begins the digestion of starch (carbohydrate) into maltose in the mouth.

Distinguish between inspiration and expiration in terms of diaphragm and pressure.

Inspiration: diaphragm contracts/flattens and external intercostals contract, thoracic volume increases, intrapulmonary pressure falls below atmospheric, air flows in. Expiration: diaphragm relaxes, volume decreases, pressure rises, air flows out (usually passive).

What is the role of hemoglobin in oxygen and carbon dioxide transport?

Hemoglobin carries ~97% of O2 as oxyhemoglobin in RBCs. CO2 is transported ~70% as bicarbonate, ~20-25% as carbamino-hemoglobin (bound to Hb), and ~7% dissolved in plasma.

Trace the path of blood through the human double circulation in correct sequence.

Body --> vena cava --> right atrium --> right ventricle --> pulmonary artery --> lungs --> pulmonary vein --> left atrium --> left ventricle --> aorta --> body.

What are the formed elements of blood and the main function of each?

Erythrocytes/RBCs (transport O2/CO2), Leucocytes/WBCs (immunity/defense), and Platelets/thrombocytes (blood clotting).

What are the functional units of the kidney, and what are the three main steps of urine formation?

Nephrons. Steps: glomerular filtration (ultrafiltration in Bowman's capsule), tubular reabsorption (useful substances reclaimed), and tubular secretion (wastes/ions added).

Classify animals by their main nitrogenous excretory product (ammonotelic, ureotelic, uricotelic) with an example each.

Ammonotelic: excrete ammonia (bony fish, aquatic amphibians). Ureotelic: excrete urea (mammals, adult amphibians). Uricotelic: excrete uric acid (birds, reptiles, insects).

Name the three types of muscle 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 the sliding filament theory of muscle contraction?

Muscle contraction occurs when actin (thin) filaments slide over myosin (thick) filaments, shortening the sarcomere; cross-bridges form using ATP and Ca2+, while the filaments themselves do not shorten.

Describe how a nerve impulse (action potential) is generated and propagated.

At resting potential the membrane is polarized (-70 mV). A stimulus opens Na+ channels causing depolarization; then K+ efflux causes repolarization. This wave of depolarization propagates along the axon; the Na+/K+ pump restores resting potential.

What is the difference between the sympathetic and parasympathetic nervous systems?

Sympathetic: 'fight or flight'—increases heart rate, dilates pupils, inhibits digestion. Parasympathetic: 'rest and digest'—slows heart rate, constricts pupils, stimulates digestion. They are antagonistic divisions of the autonomic nervous system.

What are hormones, and how do endocrine glands differ from exocrine glands?

Hormones are chemical messengers secreted in trace amounts that act on target cells. Endocrine glands are ductless and secrete hormones directly into blood; exocrine glands secrete products (e.g., enzymes, sweat) through ducts.

Name the hormones secreted by the pancreas (islets of Langerhans) and their roles in blood sugar.

Insulin (from beta cells) lowers blood glucose (promotes glycogenesis/uptake); Glucagon (from alpha cells) raises blood glucose (promotes glycogenolysis). Together they maintain glucose homeostasis.

What is the difference between asexual and sexual reproduction?

Asexual reproduction involves a single parent, no gamete fusion, and produces genetically identical offspring (clones). Sexual reproduction involves two parents (usually), gamete fusion (fertilization), and produces genetically variable offspring.

What is double fertilization in flowering plants?

In angiosperms, one male gamete fuses with the egg (syngamy) to form the diploid zygote, and the second male gamete fuses with the two polar nuclei (triple fusion) to form the triploid primary endosperm nucleus (PEN).

Distinguish between spermatogenesis and oogenesis in terms of number and size of gametes produced.

Spermatogenesis: one primary spermatocyte yields 4 functional, small motile sperm. Oogenesis: one primary oocyte yields 1 large functional ovum plus 2-3 polar bodies (non-functional).

What is the menstrual cycle's typical length, and what hormone surge triggers ovulation?

About 28 days. A surge in luteinizing hormone (LH), from the rising estrogen, triggers ovulation around day 14 (release of the secondary oocyte).

What does ART stand for, and give two examples of assisted reproductive technologies.

ART = Assisted Reproductive Technologies. Examples: IVF (in-vitro fertilization, 'test-tube baby'), ZIFT, GIFT, ICSI, artificial insemination (AI/IUI).

State Mendel's Law of Segregation and Law of Independent Assortment.

Law of Segregation: the two alleles of a gene separate during gamete formation, each gamete getting one allele. Law of Independent Assortment: alleles of different genes assort independently of one another during gamete formation.

What is the expected phenotypic ratio of a monohybrid and a dihybrid cross in the F2 generation?

Monohybrid: 3:1. Dihybrid: 9:3:3:1.

What are the key structural features of DNA according to the Watson-Crick double helix model?

Two antiparallel polynucleotide strands coiled into a right-handed helix; complementary base pairing (A=T with 2 H-bonds, G≡C with 3 H-bonds); ~10 base pairs per turn (pitch 3.4 nm, 0.34 nm between bases); sugar-phosphate backbone outside, bases inside.

What is the central dogma of molecular biology?

Genetic information flows from DNA --> RNA (transcription) --> Protein (translation). (Reverse transcription, RNA --> DNA, occurs in retroviruses.)

What is adaptive radiation? Give an example.

Adaptive radiation is the evolution of different species from a common ancestor in a given geographical area, each adapted to a different niche. Example: Darwin's finches of the Galapagos Islands; Australian marsupials.

State the Hardy-Weinberg principle and name factors that disturb it.

In an ideal population, allele and genotype frequencies remain constant across generations (p^2 + 2pq + q^2 = 1, with p + q = 1). It is disturbed by gene flow/migration, genetic drift, mutation, genetic recombination, and natural selection.

Differentiate between active and passive immunity.

Active immunity: the body produces its own antibodies after exposure to an antigen (infection or vaccine); slow but long-lasting. Passive immunity: ready-made antibodies are given from outside (e.g., mother's milk, antiserum); fast but short-lived.

Name the causative organisms for malaria, typhoid, and AIDS.

Malaria: Plasmodium (protozoan). Typhoid: Salmonella typhi (bacterium). AIDS: HIV (retrovirus).

What are the differences between inbreeding and outbreeding in animal husbandry?

Inbreeding: mating of closely related individuals; increases homozygosity and accumulates desirable genes but can cause inbreeding depression. Outbreeding: mating of unrelated animals; increases heterozygosity/vigour (e.g., out-crossing, cross-breeding, interspecific hybridization).

Name microbes used in producing curd, bread/alcohol, and the antibiotic penicillin.

Curd: Lactobacillus (lactic acid bacteria). Bread/alcohol: Saccharomyces cerevisiae (yeast). Penicillin: Penicillium notatum (fungus).

What are the two core techniques that form the basis of biotechnology?

Genetic engineering (recombinant DNA technology—altering the chemistry of genetic material to introduce them into host organisms) and maintenance of sterile (microbe-free) conditions for growing only the desired microbe/cell in large quantities (bioprocess/chemical engineering).

What is the role of restriction enzymes in recombinant DNA technology?

Restriction endonucleases are 'molecular scissors' that recognize specific palindromic DNA sequences and cut the DNA, often producing sticky ends that allow joining of DNA fragments from different sources by DNA ligase.

What is Bt cotton, and what makes it pest-resistant?

Bt cotton is a transgenic crop carrying cry genes from the bacterium Bacillus thuringiensis. These genes produce Bt toxin (a crystal protein) that is lethal to specific insect pests (e.g., bollworms), giving built-in pest resistance.

What is gene therapy, and name a disease it was first used to treat.

Gene therapy is the correction of a genetic defect by introducing a normal/functional gene into the patient's cells or tissues. It was first used to treat ADA (adenosine deaminase) deficiency (a form of SCID).

Define a population and name three of its key attributes studied in ecology.

A population is a group of individuals of the same species living in a defined geographical area, sharing/competing for resources and capable of interbreeding. Attributes: birth rate (natality), death rate (mortality), sex ratio, age distribution/pyramids, and population density.

What is the difference between exponential and logistic population growth?

Exponential growth (J-shaped curve) occurs with unlimited resources: dN/dt = rN. Logistic growth (S-shaped/sigmoid curve) occurs with limited resources and a carrying capacity (K): dN/dt = rN((K-N)/K).

What is an ecological pyramid, and which pyramid is always upright?

An ecological pyramid is a graphical representation of trophic levels in terms of number, biomass, or energy. The pyramid of energy is always upright (energy decreases at each successive trophic level, per the 10% law).

State the 10 percent law of energy transfer in an ecosystem.

Only about 10% of the energy at one trophic level is transferred to the next higher trophic level; the rest (~90%) is lost as heat (metabolism) and through other processes (Lindeman's 10% law).

What are the three levels of biodiversity?

Genetic diversity (variation within a species), Species diversity (variety of species in a region), and Ecological/ecosystem diversity (variety of habitats, communities, and ecological processes).

Distinguish between in-situ and ex-situ conservation with examples.

In-situ: conservation of species in their natural habitat (national parks, wildlife sanctuaries, biosphere reserves, biodiversity hotspots). Ex-situ: conservation outside natural habitats (zoos, botanical gardens, seed banks, cryopreservation).

What are the major greenhouse gases and the primary effect of their accumulation?

CO2, methane (CH4), nitrous oxide (N2O), and CFCs/water vapour. Their accumulation traps long-wave (infrared) radiation, enhancing the greenhouse effect and causing global warming.

What causes ozone layer depletion, and why is the ozone layer important?

Chlorofluorocarbons (CFCs) release chlorine atoms that catalytically destroy stratospheric ozone (the 'ozone hole'). The ozone layer is important because it absorbs harmful UV-B radiation, protecting living organisms from skin cancer, mutations, and eye damage.

What is biological magnification (biomagnification)? Give an example pollutant.

Biomagnification is the progressive increase in concentration of a non-degradable toxicant (e.g., DDT, mercury) at successive trophic levels of a food chain, because it is accumulated and not metabolized/excreted.

What are the kingdom-level features of Fungi (mode of nutrition, cell wall, reserve food)?

Fungi are heterotrophic (saprophytic/parasitic), absorptive feeders; cell wall is made of chitin; reserve food is glycogen; body is usually filamentous (hyphae forming mycelium); mostly multicellular except yeast.

What is the difference between an open and a closed circulatory system?

Open circulatory system: blood (hemolymph) flows through open spaces/sinuses bathing tissues directly (e.g., arthropods, molluscs). Closed circulatory system: blood flows within vessels at all times (e.g., annelids, vertebrates), allowing more efficient, regulated transport.