NTS NAT-IM Biology Syllabus

What is an enzyme?

A biological catalyst, usually a protein, that speeds up a biochemical reaction without being consumed by lowering the activation energy.

What is the active site of an enzyme?

The specific region of an enzyme where the substrate binds and the reaction is catalyzed.

State the lock-and-key model of enzyme action.

The substrate fits precisely into the complementary active site of the enzyme like a key into a lock, forming an enzyme-substrate complex.

How do temperature and pH affect enzyme activity?

Each enzyme has an optimum temperature and pH for maximum activity; beyond these, the enzyme denatures (loses its shape) and activity decreases.

What is the difference between a competitive and a non-competitive inhibitor?

A competitive inhibitor resembles the substrate and binds the active site; a non-competitive inhibitor binds elsewhere (allosteric site), changing the enzyme's shape.

List the levels of the taxonomic hierarchy from largest to smallest.

Kingdom, Phylum, Class, Order, Family, Genus, Species.

What is binomial nomenclature, and who introduced it?

A two-name system (Genus + species) for naming organisms, introduced by Carolus Linnaeus.

Name the five kingdoms of Whittaker's classification system.

Monera, Protista, Fungi, Plantae, and Animalia.

Define biodiversity.

The variety of living organisms, including species diversity, genetic diversity, and ecosystem diversity in a given area.

What is a virus, and why is it considered on the borderline of living and non-living?

A virus is an acellular infectious particle of nucleic acid (DNA or RNA) in a protein coat (capsid); it is living inside a host (replicates) but inert (non-living) outside a host.

What is a bacteriophage?

A virus that infects and replicates within bacteria.

To which kingdom do bacteria belong, and what is their cell type?

Kingdom Monera; they are prokaryotic (no membrane-bound nucleus or organelles).

Name the three basic shapes of bacteria.

Cocci (spherical), bacilli (rod-shaped), and spirilla (spiral/helical).

What is the difference between Gram-positive and Gram-negative bacteria?

Gram-positive bacteria have a thick peptidoglycan wall and stain purple; Gram-negative bacteria have a thin peptidoglycan layer with an outer membrane and stain pink/red.

What type of organisms belong to Kingdom Protista?

Mostly unicellular eukaryotes such as protozoa, algae, and slime molds that do not fit into the other kingdoms.

What is the mode of nutrition in fungi?

Heterotrophic by absorption; they are saprotrophs (decomposers) or parasites, secreting enzymes and absorbing digested nutrients.

What is the body of a fungus called, and what are its thread-like filaments called?

The body is the mycelium; its individual filaments are called hyphae.

What is a lichen?

A symbiotic (mutualistic) association between a fungus and an alga or cyanobacterium.

What features distinguish vascular plants from non-vascular plants?

Vascular plants (e.g., ferns, gymnosperms, angiosperms) have xylem and phloem for transport; non-vascular plants (e.g., mosses) lack true vascular tissue, roots, stems, and leaves.

What is the difference between gymnosperms and angiosperms?

Gymnosperms have naked (uncovered) seeds without flowers (e.g., conifers); angiosperms are flowering plants with seeds enclosed in fruits.

What are the two main groups of angiosperms based on seed leaves?

Monocots (one cotyledon) and dicots (two cotyledons).

What is the key difference between vertebrates and invertebrates?

Vertebrates have a backbone (vertebral column); invertebrates lack a backbone.

Write the overall balanced equation for photosynthesis.

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

In which two stages does photosynthesis occur, and where does each take place in the chloroplast?

Light-dependent reactions occur in the thylakoid membranes; the light-independent reactions (Calvin cycle) occur in the stroma.

What pigment captures light energy for photosynthesis, and what gas is released?

Chlorophyll captures light energy; oxygen is released (from the splitting of water).

Write the overall equation for aerobic respiration.

C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy (ATP).

What does ATP stand for, and why is it important?

Adenosine triphosphate; it is the universal energy currency of the cell, releasing energy when its terminal phosphate bond is broken to form ADP.

What is the difference between aerobic and anaerobic respiration in terms of oxygen and ATP yield?

Aerobic respiration uses oxygen and yields ~36-38 ATP per glucose; anaerobic respiration occurs without oxygen and yields only 2 ATP (plus lactic acid or ethanol).

Through which tissues do water and food move in plants, and in which direction?

Xylem transports water and minerals upward from roots to leaves; phloem transports food (sugars) from leaves to the rest of the plant (translocation).

What is transpiration, and through which structures does it mainly occur?

Transpiration is the loss of water vapor from the aerial parts of a plant, mainly through the stomata in leaves; it creates the pull that draws water up the xylem.

What raw materials and conditions does a plant require for nutrition (photosynthesis), and what mineral element is essential for chlorophyll formation?

It requires carbon dioxide, water, light, and chlorophyll; magnesium is the essential mineral element for chlorophyll formation.