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A-LEVEL BIOLOGY – COMPREHENSIVE Q&A NOTES

Based on the Cameroon GCE A-Level Syllabus

1. CELL STRUCTURE & FUNCTION

Q1. What is a cell?

A cell is the basic structural, functional, and genetic unit of all living organisms. It is the smallest unit capable of independent life.

Q2. Distinguish between prokaryotic and eukaryotic cells.

Q3. What are the functions of major cell organelles?

• Nucleus: Stores genetic information, controls cell activities.

• Mitochondria: Site of aerobic respiration and ATP production.

• Ribosomes: Protein synthesis.

• Golgi body: Packaging and secretion of proteins.

• Endoplasmic reticulum:
  • Rough ER – protein transport.

  • Smooth ER – lipid synthesis.

• Chloroplast: Photosynthesis in plants.

• Lysosomes: Intracellular digestion.

Q4. What is the fluid mosaic model?

It describes the structure of the cell membrane as a phospholipid bilayer with proteins embedded and moving freely, resembling a “mosaic.”
It explains membrane properties like:

• Selective permeability

• Flexibility

• Transport mechanisms

2. BIOLOGICAL MOLECULES

Q1. What are the major biological molecules?

• Carbohydrates

• Proteins

• Lipids

• Nucleic acids

Q2. Distinguish between monosaccharides, disaccharides, and polysaccharides.

• Monosaccharides: Simple sugars (glucose).

• Disaccharides: Two monosaccharides (sucrose, lactose).

• Polysaccharides: Many units (starch, cellulose, glycogen).

Q3. What are enzymes?

Biological catalysts made of proteins that speed up reactions without being used up.

Q4. How do enzymes work?

They lower activation energy through:

• Lock-and-key mechanism

• Induced fit model

Q5. What factors affect enzyme activity?

• Temperature

• pH

• Substrate concentration

• Enzyme concentration

• Inhibitors (competitive & non-competitive)

3. GENETICS AND MOLECULAR BIOLOGY

Q1. What is DNA?

DNA (deoxyribonucleic acid) is the hereditary material made of nucleotides arranged in a double helix.

Q2. Describe DNA replication.

• Semi-conservative

• DNA helicase unzips strands

• DNA polymerase adds complementary bases

• Two identical DNA strands form

Q3. What is a gene?

A sequence of DNA coding for a polypeptide or RNA molecule.

Q4. Explain transcription and translation.

• Transcription: DNA → mRNA (in nucleus)

• Translation: mRNA → protein (on ribosomes)

Q5. What is Mendel’s first law?

Law of segregation: allele pairs separate during gamete formation.

Q6. What is a test cross?

Crossing an organism showing a dominant trait with a homozygous recessive to determine its genotype.

4. EVOLUTION

Q1. Define evolution.

The gradual change in populations over generations due to genetic variation and natural selection.

Q2. What is natural selection?

The process by which individuals with favorable traits survive and reproduce, passing traits to offspring.

Q3. Give evidence for evolution.

• Fossil record

• Comparative anatomy

• Molecular biology

• Embryology

• Biogeography

5. ECOLOGY

Q1. What is an ecosystem?

A community of organisms interacting with each other and their physical environment.

Q2. Define the following terms:

• Habitat: Where an organism lives.

• Niche: Role an organism plays in its environment.

• Population: Members of the same species living in an area.

• Community: All species living together.

Q3. Distinguish between food chains and food webs.

• Food chain: Single pathway of energy flow.

• Food web: Interconnecting food chains.

Q4. What causes ecological succession?

• Disturbances (fire, floods, farming)

• New substrates (volcanic rock)

6. HUMAN PHYSIOLOGY

A. Transport System

Q1. What is the function of blood?

• Transport of gases

• Transport of nutrients

• Protection (white blood cells)

• Temperature regulation

Q2. Distinguish between arteries, veins, and capillaries.

Q3. What is the cardiac cycle?

Sequence of events in one heartbeat:

• Atrial systole

• Ventricular systole

• Diastole

B. Respiration

Q1. What is respiration?

The release of energy from food substances.

Q2. Distinguish between aerobic and anaerobic respiration.

• Aerobic: Uses oxygen, releases more energy.

• Anaerobic: No oxygen, produces lactic acid or ethanol.

C. Reproduction

Q1. What is fertilization?

Fusion of male and female gametes to form a zygote.

Q2. What are the main parts of the male reproductive system?

• Testes

• Epididymis

• Vas deferens

• Prostate gland

• Penis

Q3. What are the stages of the menstrual cycle?

• Menstruation

• Follicular phase

• Ovulation

• Luteal phase

7. PLANT PHYSIOLOGY

Q1. What is photosynthesis?

The process by which green plants convert light energy into chemical energy using CO₂ and water.

Q2. What factors affect photosynthesis?

• Light intensity

• CO₂ concentration

• Temperature

• Chlorophyll amount

Q3. What is transpiration?

Loss of water vapour from plant leaves through stomata.

Q4. What factors affect transpiration?

• Humidity

• Wind

• Temperature

• Light

8. MICROBIOLOGY & BIOTECHNOLOGY

Q1. What are microorganisms?

Microscopic organisms such as bacteria, fungi, protozoa, and viruses.

Q2. What is genetic engineering?

Manipulation of DNA to produce desired traits (e.g., insulin production).

Q3. What is fermentation?

Anaerobic breakdown of sugars by microorganisms (e.g., yeast).

9. PRACTICAL SKILLS (PAPER 3)

Q1. How do you calculate magnification of a microscope image?

Magnification = Image size / Actual size

Q2. What precautions ensure accurate experiments?

• Use of control

• Replicates

• Proper calibration

• Avoiding parallax errors

Q3. What is a hypothesis?

A testable statement predicting the relationship between variables.

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4 months ago

CAMEROON GCE ADVANCED LEVEL CHEMISTRY – Q&A NOTES (COMPREHENSIVE)

For: ClickUP Learning Platform
Format: Q&A for each syllabus topic
Level: Advanced Level (Sciences)

1. ATOMIC STRUCTURE & PERIODICITY

Q1: What is meant by the term “atomic orbital”?

An atomic orbital is a region around the nucleus where there is a high probability of finding an electron. Each orbital has a specific shape and orientation (s, p, d, f).

Q2: State the three quantum numbers and what each represents.

• n (principal quantum number): Energy level and size of orbital

• l (azimuthal quantum number): Shape of orbital

• mₗ (magnetic quantum number): Orientation of orbital

Q3: Why do elements in the same group have similar chemical properties?

They have the same number of valence electrons, resulting in similar bonding behaviour.

Q4: Explain why ionization energy increases across a period.

Nuclear charge increases while shielding remains relatively constant; electrons are held more tightly, requiring more energy to remove.

Q5: Why does atomic radius increase down a group?

Additional energy levels are added, increasing the size of the atom despite increasing nuclear charge.

2. CHEMICAL BONDING

Q1: What is a covalent bond?

A covalent bond is formed when two atoms share one or more pairs of electrons.

Q2: Why are ionic compounds usually soluble in water?

Water molecules are polar and can stabilize ions by hydration, breaking the ionic lattice.

Q3: What is hydrogen bonding? Give examples.

A strong dipole-dipole attraction between H and highly electronegative atoms (N, O, F)
Examples: Water, HF, ammonia.

Q4: Why does diamond have a high melting point?

It has a giant covalent structure where each carbon is covalently bonded to four others, making the structure extremely strong.

Q5: Explain metallic bonding.

Positively charged metal ions are surrounded by a sea of delocalized electrons, giving metals conductivity and malleability.

3. STOICHIOMETRY & CALCULATIONS

Q1: What is the mole?

The amount of substance containing 6.02 × 10²³ particles (Avogadro’s number).

Q2: How do you calculate empirical formula?

Convert masses to moles → divide by smallest mole value → multiply to whole numbers.

Q3: Define percentage purity.

Percentage purity = (mass of pure substance ÷ total mass of impure sample) × 100.

Q4: What is molar volume at RTP?

At room temperature and pressure, 1 mole = 24 dm³ of gas.

4. STATES OF MATTER & KINETIC THEORY

Q1: What is Boyle’s Law?

For a fixed mass of gas at constant temperature:
P ∝ 1/V or PV = constant

Q2: Why do real gases deviate from ideal behaviour?

Because real molecules have intermolecular forces and non-zero volumes.

Q3: What happens at the boiling point on the energy level?

Energy is used to break intermolecular forces, not increase temperature.

5. THERMODYNAMICS

Q1: Define enthalpy change of formation.

Heat change when 1 mole of a compound is formed from its elements in their standard states.

Q2: What is Hess’s Law?

The total enthalpy change of a reaction is the same regardless of the route taken.

Q3: Why are bond-breaking processes endothermic?

Energy is required to overcome attraction between particles.

6. CHEMICAL KINETICS

Q1: What is activation energy?

Minimum energy needed for reacting molecules to form products.

Q2: How does temperature affect reaction rate?

Increases frequency and energy of collisions → more particles exceed activation energy.

Q3: Why do catalysts increase reaction rate?

They provide an alternative pathway with lower activation energy.

7. CHEMICAL EQUILIBRIUM

Q1: State Le Chatelier’s Principle.

A system at equilibrium adjusts to oppose any applied change.

Q2: What happens to equilibrium when pressure is increased?

It shifts towards the side with fewer moles of gas.

Q3: What is the equilibrium constant Kc?

Kc = (product concentrations) / (reactant concentrations), each raised to stoichiometric powers.

8. ACIDS, BASES & SALTS

Q1: What is a Bronsted-Lowry acid?

A proton donor.

Q2: Why is water amphoteric?

It can act as both a proton donor and acceptor.

Q3: What is a buffer solution?

A solution that resists changes in pH when small amounts of acid or base are added.

Q4: What is hydrolysis of salts?

Reaction of salt ions with water to form acidic or basic solutions.

9. REDOX REACTIONS & ELECTROCHEMISTRY

Q1: Define oxidation in terms of electrons.

Loss of electrons.

Q2: What is a standard electrode potential?

Voltage developed when a metal is in contact with 1M of its ions under standard conditions.

Q3: Why do reactive metals have highly negative electrode potentials?

They easily lose electrons to form positive ions.

Q4: What is electrolysis?

Decomposition of an electrolyte using electric current.

10. ORGANIC CHEMISTRY

Q1: What is a homologous series?

A family of organic compounds with similar chemical properties and the same functional group.

**Q2: State the general formula of:

• Alkanes • Alkenes • Alkynes**

• Alkanes: CₙH₂ₙ₊₂

• Alkenes: CₙH₂ₙ

• Alkynes: CₙH₂ₙ₋₂

Q3: What is isomerism?

Compounds with the same molecular formula but different structural arrangements.

Q4: Why do alcohols have higher boiling points than alkanes?

Presence of hydrogen bonding.

Q5: What are nucleophiles and electrophiles?

• Nucleophiles: Electron-pair donors

• Electrophiles: Electron-pair acceptors

11. ANALYTICAL CHEMISTRY

Q1: What is chromatography?

A separation technique based on different rates of movement through a medium.

Q2: What is the Rf value?

Distance travelled by substance ÷ distance travelled by solvent.

Q3: Why is titration used?

For accurate determination of unknown concentrations.

Q4: How does a calorimeter work?

It measures heat changes during chemical reactions.

12. TRANSITION METALS

Q1: Why do transition metals form coloured ions?

Due to d–d electron transitions when light is absorbed.

Q2: Why do transition metals act as catalysts?

They can change oxidation states and provide alternative reaction pathways.

Q3: What is a complex ion?

A central metal ion surrounded by ligands bonded through coordinate bonds.

13. NUCLEAR CHEMISTRY

Q1: What is radioactive decay?

Spontaneous emission of radiation from unstable nuclei.

Q2: State the three types of radiation.

Alpha, Beta, Gamma.

Q3: What is half-life?

Time taken for half of the radioactive nuclei to decay.