International Baccalaureate Diploma (IB) Group 4: Sciences (Biology) Syllabus

Group 4: Sciences (Biology) syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Group 4: Sciences (Biology) in International Baccalaureate Diploma (IB), not a summary of it.

1. 1

   Unity and Diversity

   3 topics

   • Molecules of Life
     • Water and its properties
     • Carbohydrates, lipids, and proteins
     • Nucleic acids and DNA structure
   • Cells
     • Cell structure and the cell theory
     • Prokaryotic and eukaryotic cells
   • Origins and Classification
     • Origin of cells and viruses
     • Classification and cladistics
2. 2

   Form and Function

   3 topics

   • Membranes and Transport
     • Membrane structure and fluidity
     • Passive and active transport
   • Organisms and Gas Exchange
     • Respiration and ventilation systems
     • Transport systems in plants and animals
   • Adaptation to Environment
3. 3

   Interaction and Interdependence

   3 topics

   • Cell Signalling and Homeostasis
     • Neural and hormonal coordination
     • Regulation of blood glucose and temperature
   • Enzymes and Metabolism
     • Enzyme action and inhibition
     • Cellular respiration and photosynthesis
   • Ecology and Ecosystems
     • Energy flow and nutrient cycling
     • Populations and carrying capacity
4. 4

   Continuity and Change

   3 topics

   • Cell Division and Reproduction
     • Mitosis and the cell cycle
     • Meiosis and sexual reproduction
   • Inheritance and Genetics
     • Mendelian genetics and pedigrees
     • Mutation and gene expression
   • Evolution and Biodiversity
     • Natural selection and speciation
     • Conservation and human impact
5. 5

   Scientific Practice and Assessment

   3 topics

   • Experimental Design and Data Analysis
     • Variables, controls, and uncertainty
     • Statistical analysis and error
   • Scientific Investigation (Internal Assessment)
   • Collaborative Sciences Project

Group 4: Sciences (Biology) flashcards for International Baccalaureate Diploma (IB)

23 of 76 cards from the Group 4: Sciences (Biology) deck — real questions with worked answers.

1. What four elements make up the vast majority of living matter, and roughly what percentage of body mass do they account for?

   Carbon, hydrogen, oxygen and nitrogen (CHON); together they make up about 96% of the mass of living organisms.

2. Why is carbon central to the molecules of life?

   Each carbon atom forms four stable covalent bonds, allowing it to build long chains, branches and rings, giving rise to the huge diversity of organic macromolecules.

3. Name the four major classes of biological macromolecules and their monomers.

   Carbohydrates (monosaccharides), proteins (amino acids), nucleic acids (nucleotides), and lipids (built from glycerol and fatty acids; lipids are not true polymers).

4. What type of reaction joins monomers into polymers, and what reaction breaks them apart?

   Condensation (removes a water molecule per bond formed) joins monomers; hydrolysis (adds a water molecule per bond broken) breaks polymers apart.

5. Describe the four levels of protein structure.

   Primary: sequence of amino acids. Secondary: alpha-helices and beta-pleated sheets from hydrogen bonding. Tertiary: overall 3D folding from R-group interactions. Quaternary: assembly of multiple polypeptide subunits.

6. Give the molecular formula of glucose and contrast its alpha and beta forms.

   C6H12O6. In alpha-glucose the hydroxyl on carbon 1 is below the ring; in beta-glucose it is above. Alpha forms starch/glycogen; beta forms cellulose.

7. What distinguishes a saturated from an unsaturated fatty acid?

   Saturated fatty acids have no carbon-carbon double bonds (single bonds only, straight chains, solid at room temperature); unsaturated ones have one or more double bonds (kinked chains, liquid/oils).

8. State the four DNA bases and their complementary base-pairing rules.

   Adenine, thymine, guanine, cytosine. Adenine pairs with thymine (2 hydrogen bonds); guanine pairs with cytosine (3 hydrogen bonds).

9. List the three differences between DNA and RNA.

   DNA is double-stranded, uses deoxyribose, and contains thymine; RNA is single-stranded, uses ribose, and contains uracil instead of thymine.

10. What are the three components of a single nucleotide?

    A pentose (5-carbon) sugar, a phosphate group, and a nitrogenous base.

11. State the three principles of cell theory.

    All living organisms are composed of cells; the cell is the smallest unit of life; all cells arise from pre-existing cells.

12. List four key differences between prokaryotic and eukaryotic cells.

    Prokaryotes lack a nucleus (DNA free in cytoplasm), have no membrane-bound organelles, have 70S ribosomes, and a single circular chromosome; eukaryotes have a true nucleus, membrane-bound organelles, 80S ribosomes, and linear chromosomes.

13. What is the function of mitochondria and why are they called the powerhouse of the cell?

    They carry out aerobic respiration, producing ATP; their folded inner membrane (cristae) increases surface area for the electron transport chain.

14. Compare the structure of plant and animal cells (three differences).

    Plant cells have a cellulose cell wall, a large permanent vacuole, and chloroplasts; animal cells lack all three but have centrioles and store glycogen rather than starch.

15. What is the function of the rough endoplasmic reticulum versus the smooth ER?

    Rough ER (studded with ribosomes) synthesises and transports proteins; smooth ER synthesises lipids and steroids and detoxifies.

16. Explain the relationship between surface area to volume ratio and cell size.

    As a cell grows, volume increases faster than surface area, so the SA:V ratio falls; this limits cell size because the membrane can no longer exchange materials fast enough for the cell's needs.

17. What is the role of the Golgi apparatus?

    It modifies, sorts, packages and secretes proteins and lipids received from the ER, often forming vesicles.

18. What are the three domains of life in the modern classification system?

    Bacteria, Archaea, and Eukarya.

19. List the taxonomic hierarchy from largest to smallest grouping.

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

20. What is the binomial naming system and how is it written?

    A two-part Latin name: the genus (capitalised) followed by the species (lowercase), both italicised or underlined, e.g. Homo sapiens.

21. Define the biological species concept.

    A species is a group of organisms that can interbreed to produce fertile, viable offspring and are reproductively isolated from other such groups.

22. What is a dichotomous key?

    An identification tool using a series of paired, contrasting statements; at each step the user chooses one option, progressively narrowing down to identify an organism.

23. Describe the fluid mosaic model of the cell membrane.

    A phospholipid bilayer (fluid) with proteins, cholesterol, glycoproteins and glycolipids embedded or attached (mosaic); components can move laterally within the bilayer.

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