Scottish National 5 (Nat 5) Biology Syllabus

Biology syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Biology in Scottish National 5 (Nat 5), not a summary of it.

1. 1

   Cell Biology

   6 topics

   • Cell Structure
     • Animal, plant, fungal and bacterial cells
     • Functions of organelles
   • Transport Across Membranes
     • Diffusion, osmosis and active transport
   • DNA and the Production of Proteins
     • Structure of DNA and mRNA
     • Role of ribosomes in protein synthesis
   • Enzymes and Proteins
     • Specificity, optimum conditions and denaturation
   • Respiration
     • Aerobic respiration and fermentation
     • Role of ATP
   • Cell Division
     • Mitosis and the role of stem cells
2. 2

   Multicellular Organisms

   6 topics

   • Cells, Tissues and Organs
     • Levels of organisation and cell specialisation
   • Control and Communication
     • Nervous control and reflex arc
     • Hormonal control and blood glucose regulation
   • Reproduction
     • Gametes and fertilisation
   • Variation and Inheritance
     • Discrete and continuous variation
     • Monohybrid crosses and phenotype ratios
   • Transport Systems
     • Plant transport: xylem and phloem
     • Animal transport: heart, blood vessels and blood
   • Effects of Lifestyle Choices
     • Gas exchange and absorption surfaces
3. 3

   Life on Earth

   7 topics

   • Ecosystems
     • Niche, biotic and abiotic factors
     • Sampling techniques
   • Distribution of Organisms
     • Indicator species and abiotic measurement
   • Photosynthesis
     • Stages and limiting factors
   • Energy in Ecosystems
     • Food chains, pyramids and energy loss
   • Biodiversity and Distribution
     • Competition and interdependence
   • Natural Selection and Evolution
     • Mutation, variation and speciation
   • Human Impact on the Environment
     • Increasing food yields and managing land use

Biology flashcards for Scottish National 5 (Nat 5)

22 of 51 cards from the Biology deck — real questions with worked answers.

1. What is the function of the cell membrane in both plant and animal cells?

   It controls the entry and exit of substances, acting as a selectively permeable barrier between the cell and its environment.

2. List the four structures found in a plant cell but NOT in an animal cell.

   Cell wall, chloroplasts, large permanent (central) vacuole, and sap inside the vacuole. (Cytoplasm, membrane, nucleus and mitochondria are common to both.)

3. Name three structures present in a typical bacterial cell.

   Cell wall, cell membrane, cytoplasm, plasmid and a single circular chromosome (no membrane-bound nucleus or mitochondria).

4. What is the role of the chloroplast and the mitochondrion?

   Chloroplast is the site of photosynthesis (makes glucose); mitochondrion is the site of aerobic respiration (releases energy/ATP).

5. Define diffusion.

   The net movement of molecules from an area of high concentration to an area of low concentration, down a concentration gradient. It is passive (no energy required).

6. Define osmosis.

   The movement of water molecules from a region of high water concentration (dilute solution) to a region of low water concentration (concentrated solution) across a selectively permeable membrane.

7. What happens to an animal cell placed in a solution with a lower water concentration than its cytoplasm (hypertonic)?

   Water leaves the cell by osmosis, the cell shrinks and becomes shrivelled/crenated.

8. What happens to a plant cell placed in pure water (hypotonic solution)?

   Water enters by osmosis, the vacuole swells and the cell becomes turgid; the cell wall prevents it bursting.

9. What is active transport and how does it differ from diffusion?

   Active transport is the movement of molecules across a membrane against a concentration gradient (low to high). Unlike diffusion, it requires energy from respiration and membrane protein carriers.

10. What are the three bases (excluding the sugar-phosphate backbone) and the base-pairing rule in DNA?

    Bases pair complementarily: Adenine with Thymine (A-T) and Guanine with Cytosine (G-C). DNA is a double-stranded molecule shaped as a double helix.

11. What does a gene code for, and where is the genetic code carried?

    A gene is a section of DNA that codes for a specific protein; the code is carried in the sequence (order) of bases along the DNA strand.

12. Outline the steps of protein synthesis from DNA.

    DNA is transcribed into mRNA in the nucleus; mRNA carries the code to a ribosome in the cytoplasm; the ribosome translates the base sequence into a specific sequence of amino acids forming the protein.

13. State three functions of proteins in the body.

    Enzymes (catalysts), structural (e.g. collagen), hormones (e.g. insulin), antibodies, and receptors/carrier proteins in membranes.

14. What is an enzyme?

    A biological catalyst, made of protein, that speeds up the rate of a chemical reaction without being used up in the reaction.

15. Explain why enzymes are described as specific.

    Each enzyme has an active site with a particular shape that is complementary to only one substrate, so it catalyses only one reaction (the 'lock and key' model).

16. Describe the effect of high temperature on enzyme activity.

    As temperature rises activity increases up to an optimum; above the optimum the enzyme's active site changes shape (denatures) and it can no longer bind the substrate, so activity falls sharply.

17. What is the optimum pH and temperature for most human enzymes, and what does 'denatured' mean?

    Optimum is around pH 7 and about $37^{\circ}\text{C}$. Denatured means the enzyme's active site has permanently changed shape so it no longer works.

18. Write the word equation for aerobic respiration.

    $$\text{glucose} + \text{oxygen} \rightarrow \text{carbon dioxide} + \text{water} \; (+ \text{energy})$$

19. Write the balanced chemical equation for aerobic respiration.

    $$\ce{C6H12O6 + 6O2 -> 6CO2 + 6H2O}$$ (releasing energy/ATP)

20. What are the products of fermentation (anaerobic respiration) in animal muscle cells and in yeast?

    In animal muscle cells: lactic acid (+ small amount of energy). In yeast/plant cells: ethanol (alcohol) and carbon dioxide (+ small amount of energy).

21. What is ATP and why is it important in respiration?

    ATP (adenosine triphosphate) is the energy-carrying molecule produced by respiration. It stores chemical energy that cells use for processes such as muscle contraction, cell division and protein synthesis.

22. Name the stages of mitosis in order and state its purpose.

    The chromosomes are copied, then separated equally into two identical nuclei. Mitosis produces two genetically identical diploid daughter cells, maintaining the diploid chromosome number for growth and repair.

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