John Monash Science School Flashcards

What is osmosis?

The movement of water molecules from a high water concentration (dilute solution) to a low water concentration (concentrated solution) through a semi-permeable membrane.

What happens to a cell placed in a hypotonic (dilute) solution?

Water moves INTO the cell by osmosis — the cell swells and may burst (lysis).

What happens to a cell placed in a hypertonic (concentrated) solution?

Water moves OUT of the cell by osmosis — the cell shrinks (crenation in animal cells, plasmolysis in plant cells).

What is diffusion?

The movement of particles from an area of high concentration to low concentration (down a concentration gradient).

What factors increase the rate of diffusion?

Higher temperature, steeper concentration gradient, smaller particle size, larger surface area.

What is the pH scale?

A scale from 0-14 measuring acidity/alkalinity. pH 0-6 = acidic, pH 7 = neutral, pH 8-14 = alkaline/basic.

What is an acid?

A substance that releases hydrogen ions (H+) in solution. pH below 7.

What is a base/alkali?

A substance that releases hydroxide ions (OH-) in solution. pH above 7.

What is a neutralisation reaction?

Acid + Base = Salt + Water. The pH moves toward 7.

What is an atom made of?

A nucleus containing protons (+) and neutrons (no charge), surrounded by electrons (-) in shells/orbitals.

What is atomic number?

The number of protons in the nucleus of an atom. It identifies the element.

What is ionic bonding?

The transfer of electrons from a metal to a non-metal, forming oppositely charged ions that attract each other.

What is covalent bonding?

The sharing of electrons between two non-metal atoms.

What is the difference between an element and a compound?

An element contains only one type of atom. A compound contains two or more different elements chemically bonded.

What is photosynthesis?

Plants use sunlight, water, and CO2 to produce glucose and oxygen. 6CO2 + 6H2O = C6H12O6 + 6O2

What is cellular respiration?

Breaking down glucose to release energy. C6H12O6 + 6O2 = 6CO2 + 6H2O + energy (ATP)

Aerobic vs anaerobic respiration?

Aerobic uses oxygen, produces CO2 + water + lots of ATP. Anaerobic has no oxygen, produces lactic acid (animals) or ethanol + CO2 (yeast), less ATP.

What is a food chain?

Energy flow: Producer > Primary consumer > Secondary consumer > Tertiary consumer.

What is a producer in an ecosystem?

An organism (usually a plant) that makes its own food via photosynthesis. Base of every food chain.

What is a predator-prey relationship?

Predators rise = prey falls. Prey falls = predators fall. Predators fall = prey recovers. A repeating cycle.

What is the role of decomposers?

They break down dead organic matter, recycling nutrients back into the soil for plants to use.

Habitat vs niche?

Habitat = where an organism lives. Niche = its role in the ecosystem (what it eats, what eats it, how it behaves).

Order of planets from the Sun?

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. (My Very Educated Mother Just Served Us Nachos)

What keeps planets in orbit?

Gravity from the Sun keeps planets in orbit. The planet's velocity balances the gravitational pull.

What is a light-year?

The distance light travels in one year — about 9.46 x 10^12 km. Used to measure distances between stars.

Star vs planet?

A star produces its own light via nuclear fusion. A planet orbits a star and reflects light — it does not produce its own.

How do you read a graph trend?

Identify axes and units. Describe direction (increasing/decreasing/constant), rate of change, anomalies, and quote specific values.

What is a control variable?

A variable kept constant so only the independent variable affects the results.

What is the independent variable?

The variable deliberately changed by the experimenter.

What is the dependent variable?

The variable measured in response to the independent variable.

How do you find a percentage of a number?

Multiply by the decimal. E.g. 35% of 80 = 0.35 x 80 = 28.

How do you calculate percentage change?

(New - Old) / Old x 100. Positive = increase, negative = decrease.

How do you find the original value from a percentage?

Divide by the decimal. E.g. 120 is 150% of X, so X = 120 / 1.5 = 80.

What is BODMAS?

Brackets, Orders (powers/roots), Division, Multiplication, Addition, Subtraction.

How do you solve 3x + 5 = 20?

Subtract 5: 3x = 15. Divide by 3: x = 5.

What is the speed formula?

Speed = Distance / Time. D = S x T. T = D / S.

Area of a triangle?

Area = 0.5 x base x height.

Area and circumference of a circle?

Area = pi x r squared. Circumference = 2 x pi x r.

How do you find the mean?

Add all values, divide by the count.

Mean vs median vs mode?

Mean = sum/count. Median = middle value when ordered. Mode = most frequent value.

How do you simplify a ratio?

Divide both parts by their HCF. E.g. 12:8 = 3:2.

How do you divide a quantity in a ratio?

Add ratio parts, divide total by that sum to get one part, then multiply. E.g. 50 in 2:3 = one part is 10, answer is 20 and 30.

Fraction to decimal?

Divide numerator by denominator. E.g. 3/4 = 0.75.

What is a prime number?

A number greater than 1 with only two factors: 1 and itself. E.g. 2, 3, 5, 7, 11, 13.

What is the LCM?

Lowest Common Multiple — the smallest number that is a multiple of two or more numbers. E.g. LCM of 4 and 6 = 12.

What is the HCF?

Highest Common Factor — the largest number that divides exactly into two or more numbers. E.g. HCF of 12 and 18 = 6.

Simple interest formula?

Interest = Principal x Rate x Time. E.g. 500 at 4% for 3 years = 500 x 0.04 x 3 = 60.

Multiplying indices with the same base?

Add the exponents. E.g. x^3 x x^4 = x^7.

How do you expand 3(x + 4)?

Multiply each term inside by the outside term. 3(x + 4) = 3x + 12.

What is the 3-read rule for word problems?

1) Read for big picture. 2) Underline key numbers and conditions. 3) Read the question last to confirm what is being asked.

Snail in a well — what is the trick?

On the final day the snail reaches the top before slipping back. Check the last day separately and do not subtract the nightly slip.

Broken clock/watch — how to solve?

Calculate how many minutes per hour the clock gains or loses. Multiply by elapsed time for total drift. Add or subtract from the shown time.

How to approach a multi-step logic puzzle?

Write every step out explicitly. Use a table or list. Never track it all in your head.

How do you identify a number pattern rule?

Find differences between terms. Constant = arithmetic. Differences of differences constant = quadratic. Each term multiplied = geometric.

What is an arithmetic sequence?

Same amount added or subtracted each time. E.g. 3, 7, 11, 15 (add 4). nth term = a + (n-1)d.

What is a geometric sequence?

Each term multiplied by the same ratio. E.g. 2, 6, 18, 54 (multiply by 3).

What is the Fibonacci sequence?

1, 1, 2, 3, 5, 8, 13, 21… Each term = sum of the two before it.

How to solve a logic grid puzzle?

Eliminate impossible options first. Work from the most specific clues. Update the grid after every deduction.

Speed-distance-time common trap?

Units must match. If speed is km/h, time must be in hours. Divide minutes by 60 to convert.

Ladder/staircase problem approach?

Write out every step. Check if the final step is full or partial — that is usually the trick.

Inclusive vs exclusive counting?

Inclusive = count both endpoints (1 to 5 = 5 numbers). Exclusive = exclude endpoints (1 to 5 = 3 numbers: 2, 3, 4).

How to avoid detail errors in multi-step problems?

Label each result after every step. Re-read the question at the end to confirm you answered what was asked.

Aim format?

To investigate the effect of [independent variable] on [dependent variable].

Hypothesis format?

It is predicted that [result] because [scientific reason]. Always include a reason.

What tense is the Method written in?

Past tense. E.g. The student ran for 5 minutes — not Run for 5 minutes.

What must Results always include?

Specific numbers from the data, the trend (increasing/decreasing/constant), and any anomalies.

Discussion formula?

Observation + Reason + Link. What happened, WHY it happened (science), link back to the hypothesis.

What goes in the Conclusion?

Restate the finding, state whether it supports the hypothesis, suggest one improvement.

Scientific power words to use?

increased/decreased, demonstrated/indicated, due to/as a result of, significant, gradually, the data suggests.

What to avoid in a science report?

Avoid: I think, I did, it went up/down. Use: the data suggests, the student, increased/decreased.

How to use data in Discussion?

Quote specific values with units. E.g. Heart rate increased from 72 bpm to 140 bpm, an increase of 68 bpm.

Time allocation for 25-min report?

Aim 1 min, Hypothesis 2, Materials 2, Method 3, Results 3, Discussion 8, Conclusion 2, Planning 4.

Results vs Discussion — difference?

Results = what happened (describe the data). Discussion = why it happened (scientific explanation).

What makes a Discussion sentence high quality?

Observation with numbers + scientific reason (mechanism) + link to the hypothesis. All three parts needed.