Yr 9 Science Exam Revision

What are the three subatomic particles of an atom, and what are their charges?

Protons (+), Neutrons (0), and Electrons (–).

How do you determine the number of protons, electrons, and neutrons in an atom using the periodic table?

Protons = atomic number; Electrons = protons (in neutral atom); Neutrons = mass number – atomic number.

How is the Periodic Table of Elements used to predict properties of elements?

Elements in the same group have similar valence electrons and chemical properties.

What is the electronic configuration of sodium (Na)?

2,8,1

Draw the electron shell diagram for oxygen (O).

2 electrons in the first shell, 6 in the second shell.

Balance the following equation: H₂ + O₂ → H₂O.

2H₂ + O₂ → 2H₂O

What is the difference between cations and anions? Give examples.

Cations are positively charged (Na⁺), anions are negatively charged (Cl⁻).

Write the formula for aluminum sulfate and name the ions involved.

Al₂(SO₄)₃; Ions: Al³⁺ and SO₄²⁻.

Write the worded equation and symbol equation for the reaction of magnesium with hydrochloric acid.

Magnesium + hydrochloric acid → magnesium chloride + hydrogen; Mg + 2HCl → MgCl₂ + H₂.

What is the general reaction between an acid and a base?

They react to form salt and water (neutralisation).

Write the general formula for a neutralisation reaction.

Acid + Base → Salt + Water.

Define: ecology, ecosystem, habitat, niche, biotic factor, abiotic factor, biosphere.

Ecology: study of interactions; Ecosystem: community + environment; Habitat: where an organism lives; Niche: organism’s role; Biotic: living factors; Abiotic: nonliving factors; Biosphere: all ecosystems on Earth.

Identify the biotic and abiotic factors in a desert ecosystem.

Biotic: cactus, lizard, snake; Abiotic: sand, temperature, sunlight, water.

How do biotic and abiotic factors influence each other in an ecosystem?

Abiotic factors affect survival (e.g., temperature); biotic factors can modify abiotic ones (e.g., plants add oxygen).

Explain the role of producers, consumers, and decomposers in an ecosystem.

Producers make food (photosynthesis); consumers eat others; decomposers break down waste and dead matter.

Draw and explain a simple food chain and a food web.

Example: Grass → Grasshopper → Frog → Snake → Hawk; interconnected chains form a web.

What is meant by energy flow and trophic levels in an ecosystem?

Energy moves from producers to consumers through trophic levels; energy decreases at each level.

Write the worded equation for photosynthesis and for cellular respiration.

Photosynthesis: carbon dioxide + water → glucose + oxygen; Respiration: glucose + oxygen → carbon dioxide + water + energy.

Compare photosynthesis and respiration in terms of energy transfer.

Photosynthesis stores energy in glucose; respiration releases it.

Describe the stages of the water cycle.

Evaporation → Condensation → Precipitation → Collection.

What is the difference between infectious and non-infectious diseases? Give examples.

Infectious: caused by pathogens, spread between organisms (e.g., flu); Non-infectious: not spread (e.g., diabetes).

Name the main types of pathogens and explain how they spread (including vectors).

Bacteria, viruses, fungi, protozoa; spread via air, water, food, contact, or vectors.

How can the spread of disease be minimised?

Hygiene, vaccination, isolation, sanitation, vector control.

Identify and distinguish between bacteria, viruses, fungi, and protozoa.

Bacteria: single-celled; Viruses: need host; Fungi: spores; Protozoa: microscopic animals.

What are the three levels of the body’s defence mechanisms against disease?

1. Physical barriers (skin), 2. Non-specific defences (inflammation), 3. Specific defences (immune response).

How does the inflammatory response work as a non-specific defence?

Injury triggers histamine release → blood flow increases → white blood cells fight infection.

How does immunisation protect against infectious disease?

Introduces weakened pathogen → body makes antibodies → immunity develops.

What is herd immunity, and why is it important?

When most are immune, disease spread is reduced → protects unvaccinated people.

Draw and label the symbols for circuit components (cell, battery, switch, resistor, lamp, etc.).

Symbols: cell, battery, switch, resistor, lamp, etc.

Label the components in a given circuit diagram.

Identify cell, wires, resistors, switches, lamps, meters.

What is the difference between a series circuit and a parallel circuit?

Series: one path for current; Parallel: multiple paths.

What are the advantages and disadvantages of series circuits compared to parallel circuits?

Series: simple, but if one fails all fail; Parallel: devices work independently, but more complex.

In a series circuit, how is voltage and current distributed?

Current is same; voltage divides across components.

In a parallel circuit, how is voltage and current distributed?

Voltage is same; current splits between branches.

What is the correct way to connect an ammeter and a voltmeter in a circuit?

Ammeter in series, voltmeter in parallel.

Predict the ammeter and voltmeter readings in a simple series and parallel circuit.

Series: same current everywhere; Parallel: voltage same across each branch.

Define: voltage, current, cell, battery, wire, switch, load, terminal, resistor.

Voltage: potential difference; Current: flow of charge; Cell: energy source; Battery: multiple cells; etc.

What are conductors and insulators? Give examples.

Conductors allow current (e.g., copper); Insulators resist (e.g., plastic).

State Ohm’s Law and solve for resistance if V = 12 V and I = 3 A.

R = V/I = 12/3 = 4 Ω.

What are the three types of heat transfer? Give examples of each.

Conduction, convection, radiation.

What are the two main types of waves? Give examples and draw a diagram showing wave parts.

Transverse (light) and longitudinal (sound).

Explain how heat transfers from one place to another, with examples.

Conduction: solids; Convection: fluids; Radiation: electromagnetic waves.