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Grade 9 · Science · curriculum collection

Grade 9 Science, NGSS domains

8 units for Grade 9 science, organised by NGSS disciplinary core idea domain: Physical Sciences, Life Sciences, Earth and Space Sciences. Each unit has a short lesson, a practice worksheet and a review worksheet, both with answer keys.

8 units16 worksheets192 questions with answers
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Answer-checked and approved on 29 October 2026

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Aligned by StudyBrix at domain level. Not an official publication of, or endorsed by, the standards' authors. Framework: Next Generation Science Standards.

Units in teaching order

01

PS Physical Sciences

Motion and energy

Calculations with velocity, acceleration, force, work, energy and power.

Short lesson: Energy efficiency

Study guide for Grades 7 to 11: 2 worked examples and 2 practice questions. Useful output cannot exceed total input in this simple energy accounting model.

efficiency % = useful output / input × 100

Useful output cannot exceed total input in this simple energy accounting model.

Worked example

A device receives 4100 J and delivers 615 J of useful energy. Find its efficiency as a percentage.

615/4100 × 100 = 15%

Answer: 15 %

Read the full study guide

Worksheets

A practice worksheet and a review worksheet, 12 and 12 questions.

Worksheets (PDF)Answer keys (PDF)
Practice worksheet: 12 questions

  1. A device transfers 174 J in 2 s. Find average power in W.

  2. A constant 56 N force acts in the same direction as a 26 m displacement. Find work in J.

  3. A 44 kg object has speed 13 m/s. Find its classical kinetic energy in J.

  4. An object moves at constant velocity 4 m/s for 28 s. Find displacement in m.

  5. Velocity changes from 15 m/s to 27 m/s in 3 s. Find average acceleration in m/s².

  6. A spring has constant 110 N/m and extension 18 cm within its linear range. Find the restoring-force magnitude in N.

  7. An object of mass 37 kg accelerates at 13 m/s². Find the net force in N.

  8. A perpendicular force of 648 N acts over 18 m². Find the pressure in Pa.

  9. Lift a 28 kg mass vertically by 23 m. Using g = 10 m/s², find the increase in gravitational potential energy in J.

  10. A mass of 2 kg has velocity -27 m/s. Find its signed momentum in kg·m/s.

  11. A 10 kg sample has specific heat 500 J/(kg·°C). Its temperature rises 4°C with no phase change. Find the energy gained in J.

  12. A device receives 6600 J and delivers 660 J of useful energy. Find its efficiency as a percentage.

Answer key
  1. 87 W 174 ÷ 2 = 87
  2. 1456 J 56 × 26 = 1456
  3. 3718 J ½ × 44 × 13² = 3718
  4. 112 m 4 × 28 = 112
  5. 4 m/s² (27 − 15)/3 = 4
  6. 19.8 N 110 × 0.18 = 19.8
  7. 481 N 37 × 13 = 481 N
  8. 36 Pa 648 ÷ 18 = 36
  9. 6440 J 28 × 10 × 23 = 6440
  10. -54 kg·m/s 2 × -27 = -54
  11. 20000 J 10 × 500 × 4 = 20000
  12. 10 % 660/6600 × 100 = 10%
Review worksheet: 12 questions

  1. An object moves at constant velocity -5 m/s for 2 s. Find displacement in m.

  2. A constant 35 N force acts in the same direction as a 37 m displacement. Find work in J.

  3. A spring has constant 200 N/m and extension 7 cm within its linear range. Find the restoring-force magnitude in N.

  4. A 8 kg object has speed 12 m/s. Find its classical kinetic energy in J.

  5. An object of mass 13 kg accelerates at 9 m/s². Find the net force in N.

  6. A perpendicular force of 1320 N acts over 15 m². Find the pressure in Pa.

  7. Velocity changes from 16 m/s to 25 m/s in 9 s. Find average acceleration in m/s².

  8. A 9 kg sample has specific heat 200 J/(kg·°C). Its temperature rises 8°C with no phase change. Find the energy gained in J.

  9. A mass of 5 kg has velocity -14 m/s. Find its signed momentum in kg·m/s.

  10. A device transfers 828 J in 18 s. Find average power in W.

  11. A device receives 7500 J and delivers 6750 J of useful energy. Find its efficiency as a percentage.

  12. Motion, forces and energy: which term fits this description? The rate at which distance is travelled.

    1. Impulse
    2. Weight
    3. Speed
    4. Elastic collision
Answer key
  1. -10 m -5 × 2 = -10
  2. 1295 J 35 × 37 = 1295
  3. 14 N 200 × 0.07 = 14
  4. 576 J ½ × 8 × 12² = 576
  5. 117 N 13 × 9 = 117 N
  6. 88 Pa 1320 ÷ 15 = 88
  7. 1 m/s² (25 − 16)/9 = 1
  8. 14400 J 9 × 200 × 8 = 14400
  9. -70 kg·m/s 5 × -14 = -70
  10. 46 W 828 ÷ 18 = 46
  11. 90 % 6750/7500 × 100 = 90%
  12. Speed Speed: The rate at which distance is travelled.

Related ready-made worksheets: Grade 9 Motion & energy worksheet

02

PS Physical Sciences

Motion & graphs

Distance, displacement, speed, velocity and acceleration.

Short lesson: Distance is not displacement

Study guide for Grades 6 to 9: 4 key ideas, including path length, change in position and round trips; 2 worked examples and 3 practice questions. Use paths and signed positions to explain round trips.

  • Path length. Distance is the total length travelled and is non-negative.
  • Change in position. Displacement is final position minus initial position and includes a direction or sign.
  • Round trips. Returning to the start makes displacement zero, but travelled distance need not be zero.
  • State the reference. Define your origin and positive direction before calculating signed displacement.

Worked example

A learner walks 9 m east, then 4 m west on one line. Find total distance.

Distance adds both path lengths: 9 + 4 = 13 m.

Answer: 13 m

Read the full study guide

Worksheets

A practice worksheet and a review worksheet, 12 and 12 questions.

Worksheets (PDF)Answer keys (PDF)
Practice worksheet: 12 questions

  1. A rover travels 224 m in 61 s, then 35 m in 31 s. Find its average speed for both stages. Round to 3 decimal places if needed. Answer in m/s.

  2. Use one signed axis. Initial velocity is 5 m/s and constant acceleration is 2 m/s² for 12 s. Find the displacement. Round to 3 decimal places if needed. Answer in m.

  3. In one dimension, u = -11 m/s and constant a = -5 m/s². Find the signed velocity after 12 s. Round to 3 decimal places if needed. Answer in m/s.

  4. Two carts approach each other on a straight track at 28 m/s and 4 m/s. How fast is their separation decreasing? Round to 3 decimal places if needed. Answer in m/s.

  5. A robot moves 41 m east and then 25 m west along a straight line. Find the total distance travelled. Round to 3 decimal places if needed. Answer in m.

  6. A cart moves along a straight track. Its position is recorded every second: t = 0 s: 9 m; t = 1 s: 10 m; t = 2 s: 11 m; t = 3 s: 12 m; t = 4 s: 13 m. What is its average speed over the 4 seconds?

  7. On an east-positive axis, position changes from -12 m to 41 m in 11 s. Find the signed average velocity. Round to 3 decimal places if needed. Answer in m/s.

  8. Signed velocity changes from 29 m/s to 27 m/s in 15 s. Find the average acceleration. Round to 3 decimal places if needed. Answer in m/s².

  9. A model cart starts at 23 m/s and slows uniformly at 3 m/s² until rest. Ignore reaction time. Find the stopping time. Round to 3 decimal places if needed. Answer in s.

  10. An object falls from rest for 7 s in an ideal model with no air resistance, on a model planet where g = 5 m/s². Find the downward distance. Round to 3 decimal places if needed. Answer in m.

  11. Which quantity needs a direction or sign in one dimension?

    1. Elapsed time
    2. Displacement
    3. Distance

  12. What does the area under a velocity-time graph represent?

    1. acceleration
    2. mass
    3. displacement
Answer key
  1. 2.815 m/s v̄ = (d₁ + d₂)/(t₁ + t₂) (224 + 35) / (61 + 31) = 2.815
  2. 204 m s = ut + ½at² 5 × 12 + 0.5 × (2) × 12² = 204
  3. -71 m/s v = u + at -11 + (-5) × 12 = -71
  4. 32 m/s closing speed = v₁ + v₂ 28 + 4 = 32
  5. 66 m distance = forward path + return path 41 + 25 = 66
  6. 1 m/s (13 − 9) ÷ 4 = 1
  7. 4.818 m/s v̄ = (x₂ − x₁)/Δt (41 − (-12)) / 11 = 4.818
  8. -0.133 m/s² a = (v₂ − v₁)/Δt (27 − 29) / 15 = -0.133
  9. 7.667 s t = u/b 23 / 3 = 7.667
  10. 122.5 m d = ½gt² 0.5 × 5 × 7² = 122.5
  11. Displacement Displacement is a vector quantity, represented by a sign on a one-dimensional axis.
  12. displacement Velocity × time = displacement, so the area gives displacement.
Review worksheet: 12 questions

  1. Use one signed axis. Initial velocity is 20 m/s and constant acceleration is 5 m/s² for 3 s. Find the displacement. Round to 3 decimal places if needed. Answer in m.

  2. A robot moves 114 m east and then 38 m west along a straight line. Find the total distance travelled. Round to 3 decimal places if needed. Answer in m.

  3. A rover travels 30 m in 39 s, then 296 m in 61 s. Find its average speed for both stages. Round to 3 decimal places if needed. Answer in m/s.

  4. Two carts approach each other on a straight track at 14 m/s and 26 m/s. How fast is their separation decreasing? Round to 3 decimal places if needed. Answer in m/s.

  5. In one dimension, u = 3 m/s and constant a = -2 m/s². Find the signed velocity after 9 s. Round to 3 decimal places if needed. Answer in m/s.

  6. Signed velocity changes from 4 m/s to 31 m/s in 9 s. Find the average acceleration. Round to 3 decimal places if needed. Answer in m/s².

  7. On an east-positive axis, position changes from 13 m to -3 m in 19 s. Find the signed average velocity. Round to 3 decimal places if needed. Answer in m/s.

  8. A cart moves along a straight track. Its position is recorded every second: t = 0 s: 6 m; t = 1 s: 8 m; t = 2 s: 12 m; t = 3 s: 18 m; t = 4 s: 26 m. How is the cart moving?

    1. It moves at a constant speed.
    2. It is slowing down.
    3. It is not moving.
    4. It is speeding up.

  9. A model cart starts at 6 m/s and slows uniformly at 10 m/s² until rest. Ignore reaction time. Find the stopping time. Round to 3 decimal places if needed. Answer in s.

  10. An object falls from rest for 1 s in an ideal model with no air resistance, on a model planet where g = 2 m/s². Find the downward distance. Round to 3 decimal places if needed. Answer in m.

  11. A runner returns to the start after one complete lap. Which is zero?

    1. Elapsed time necessarily
    2. Displacement
    3. Distance travelled

  12. What does the slope of a velocity-time graph represent?

    1. position
    2. acceleration
    3. displacement
Answer key
  1. 82.5 m s = ut + ½at² 20 × 3 + 0.5 × (5) × 3² = 82.5
  2. 152 m distance = forward path + return path 114 + 38 = 152
  3. 3.26 m/s v̄ = (d₁ + d₂)/(t₁ + t₂) (30 + 296) / (39 + 61) = 3.26
  4. 40 m/s closing speed = v₁ + v₂ 14 + 26 = 40
  5. -15 m/s v = u + at 3 + (-2) × 9 = -15
  6. 3 m/s² a = (v₂ − v₁)/Δt (31 − 4) / 9 = 3
  7. -0.842 m/s v̄ = (x₂ − x₁)/Δt (-3 − (13)) / 19 = -0.842
  8. It is speeding up. Distance in each second: 2, 4, 6, 8 m.
  9. 0.6 s t = u/b 6 / 10 = 0.6
  10. 1 m d = ½gt² 0.5 × 2 × 1² = 1
  11. Displacement Final and initial positions coincide, so displacement is zero.
  12. acceleration Slope = change in velocity ÷ time = acceleration.

Related ready-made worksheets: Grade 9 Motion & graphs worksheet

03

PS Physical Sciences

Electricity & circuits

Charge, current, voltage, resistance and electrical power.

Short lesson: Waves and electric circuits

Study guide for Grades 7 to 12: 20 key ideas, including electric current, potential difference and resistance; 3 practice questions.

Voltage is measured across a component; current is measured through a path. Never practise these concepts on household mains wiring.

  • Electric current. The rate at which electric charge passes a point.
  • Potential difference. Energy transferred per unit charge between two points.
  • Resistance. The ratio of potential difference to current for the stated operating conditions.
  • Series circuit. A circuit arrangement with components connected along one current path.

Read the full study guide

Worksheets

A practice worksheet and a review worksheet, 12 and 12 questions.

Worksheets (PDF)Answer keys (PDF)
Practice worksheet: 12 questions

  1. A model device uses constant power 125 W for 6 h. Find the energy in kilowatt-hours. Round to 3 decimal places if needed. Answer in kWh.

  2. Why is a circuit diagram more reliable than saying two resistors are next to each other?

  3. A steady DC device operates at 35 V and 9 A. Find power in W.

  4. Three ideal resistors of 60 Ω, 50 Ω and 45 Ω are in series. Find total resistance in Ω.

  5. An ohmic resistor of 9 Ω has potential difference 37 V. Find current. This is a paper calculation, not a construction instruction. Round to 3 decimal places if needed. Answer in A.

  6. A constant current of 6 A flows for 108 s. How much charge passes in C?

  7. A constant current of 3.4 A flows for 69 s. Find transferred charge. Round to 3 decimal places if needed. Answer in C.

  8. An ideal ohmic resistor of 19 Ω carries 7 A. Find the voltage across it in V.

  9. A 24 V battery is connected to two resistors in series. The voltage across the first resistor is 19.5 V. What is the voltage across the second resistor? (Assume ideal wires and an ideal battery.)

  10. Parallel branch currents are 0.4 A and 0.7 A. Find total source current.

  11. A component has 6 V across it and current 2 A. Find electrical power.

  12. Waves and electric circuits: which term fits this description? A strong response when a system is driven near one of its natural frequencies.

    1. Insulator
    2. Period
    3. Resonance
    4. Parallel circuit
Answer key
  1. 0.75 kWh E(kWh) = P(W) × t(h)/1000 125 × 6 / 1000 = 0.75
  2. Electrical connection depends on shared nodes and paths, not merely physical closeness.
  3. 315 W 35 × 9 = 315
  4. 155 Ω 60 + 50 + 45 = 155
  5. 4.111 A I = V/R 37 / 9 = 4.111
  6. 648 C 6 × 108 = 648
  7. 234.6 C Q = It 3.4 × 69 = 234.6
  8. 133 V 7 × 19 = 133
  9. 4.5 V 24 − 19.5 = 4.5
  10. 1.1 A Currents add at the junction: 0.4 + 0.7 = 1.1 A.
  11. 12 W P = VI = 6 × 2 = 12 W.
  12. Resonance Resonance: A strong response when a system is driven near one of its natural frequencies.
Review worksheet: 12 questions

  1. A model device uses constant power 75 W for 6 h. Find the energy in kilowatt-hours. Round to 3 decimal places if needed. Answer in kWh.

  2. Why must the ideal-circuit assumptions be stated?

  3. A steady DC device operates at 49 V and 2 A. Find power in W.

  4. An ohmic resistor of 56 Ω has potential difference 14 V. Find current. This is a paper calculation, not a construction instruction. Round to 3 decimal places if needed. Answer in A.

  5. Three ideal resistors of 73 Ω, 55 Ω and 68 Ω are in series. Find total resistance in Ω.

  6. A constant current of 7 A flows for 43 s. How much charge passes in C?

  7. A constant current of 0.3 A flows for 75 s. Find transferred charge. Round to 3 decimal places if needed. Answer in C.

  8. An ideal ohmic resistor of 28 Ω carries 6 A. Find the voltage across it in V.

  9. A battery supplies 5.5 A to two parallel branches. One branch carries 5.4 A. What current flows in the other branch? (Assume ideal wires and an ideal battery.)

  10. Resistors 4 Ω and 6 Ω are in series. Find equivalent resistance.

  11. A 4 Ω resistor carries 3 A. Find its power.

  12. Waves and electric circuits: which term fits this description? The distance between successive points in the same phase on a wave.

    1. Transverse wave
    2. Wavelength
    3. Resistance
    4. Refraction
Answer key
  1. 0.45 kWh E(kWh) = P(W) × t(h)/1000 75 × 6 / 1000 = 0.45
  2. Real sources, wires and components may have additional resistance or non-ideal behaviour that changes results.
  3. 98 W 49 × 2 = 98
  4. 0.25 A I = V/R 14 / 56 = 0.25
  5. 196 Ω 73 + 55 + 68 = 196
  6. 301 C 7 × 43 = 301
  7. 22.5 C Q = It 0.3 × 75 = 22.5
  8. 168 V 6 × 28 = 168
  9. 0.1 A 5.5 − 5.4 = 0.1
  10. 10 Ω Series resistances add: 4 + 6 = 10 Ω.
  11. 36 W I²R = 3² × 4 = 36 W.
  12. Wavelength Wavelength: The distance between successive points in the same phase on a wave.

Related ready-made worksheets: Grade 9 Electricity & circuits worksheet

04

PS Physical Sciences

Analytical chemistry

Concentration, titration, chromatography and yield.

Short lesson: Chromatography Rf

Study guide for Grades 9 to 12: 2 worked examples and 2 practice questions. Measure both distances from the same origin. Rf is dimensionless and depends on the chromatographic conditions.

Rf = spot distance / solvent-front distance

Measure both distances from the same origin. Rf is dimensionless and depends on the chromatographic conditions.

Worked example

Measured from the same origin, a spot travels 95 mm and the solvent front 112 mm. Find Rf. Round to 3 decimal places if needed.

Rf = spot distance / solvent-front distance 95/112 = 0.848

Answer: 0.848

Read the full study guide

Worksheets

A practice worksheet and a review worksheet, 12 and 12 questions.

Worksheets (PDF)Answer keys (PDF)
Practice worksheet: 12 questions

  1. A model solution contains 2.5 mol in a final volume of 1.99 L. Find its molar concentration. Round to 3 decimal places if needed. Answer in mol/L.

  2. An aqueous solution has concentration 0.5 mol/L. A model aliquot has volume 419 mL. Find the solute amount. Round to 3 decimal places if needed. Answer in mol.

  3. Measured from the same origin, a spot travels 25 mm and the solvent front 56 mm. Find Rf. Round to 3 decimal places if needed.

  4. The theoretical dry pure product mass is 89 g; the actual dry pure product mass is 42 g. Find percentage yield. Round to 3 decimal places if needed. Answer in %.

  5. Five repeated measurements of the mass of the same sample (g) are: Trial 1 = 12.14; Trial 2 = 12.09; Trial 3 = 12.08; Trial 4 = 11.17; Trial 5 = 12.13. Leave out the outlier (trial 4) and find the mean of the other four. Round to 2 decimal places.

  6. A 214 g sample is 37% desired substance by mass. Find the desired substance mass. Round to 3 decimal places if needed. Answer in g.

  7. A 35 mL aliquot at 1.5 mol/L is diluted to 70 mL total without reaction or loss. Find the final concentration. Round to 3 decimal places if needed. Answer in mol/L.

  8. A model solution contains 13 g solute and 404 g solvent. Find the solute mass percentage. Round to 3 decimal places if needed. Answer in %.

  9. Why can c₁V₁ = c₂V₂ fail if the solute reacts during mixing?

  10. A spot has Rf = 0.25 and the solvent front traveled 8 cm. How far did the spot travel?

  11. A model solution contains 2.3 mol in a final volume of 1.8 L. Find its molar concentration. Round to 3 decimal places if needed. Answer in mol/L.

  12. An aqueous solution has concentration 0.4 mol/L. A model aliquot has volume 25 mL. Find the solute amount. Round to 3 decimal places if needed. Answer in mol.

Answer key
  1. 1.256 mol/L c = n/V 2.5/1.99 = 1.256
  2. 0.21 mol n = cV; V(L) = V(mL)/1000 0.5 × (419/1000) = 0.21
  3. 0.446 Rf = spot distance / solvent-front distance 25/56 = 0.446
  4. 47.191 % yield % = actual/theoretical × 100 42/89 × 100 = 47.191
  5. 12.11 g (12.14 + 12.09 + 12.08 + 12.13) ÷ 4 ≈ 12.11
  6. 79.18 g component mass = sample mass × purity/100 214 × 37/100 = 79.18
  7. 0.75 mol/L c₂ = c₁V₁/V₂ 1.5 × 35/70 = 0.75
  8. 3.118 % mass % = solute mass / solution mass × 100 13/(13 + 404) × 100 = 3.118
  9. The amount of that solute is no longer conserved in the simple dilution sense. Reaction stoichiometry must be included.
  10. 2 cm Distance = 0.25 × 8 = 2 cm.
  11. 1.278 mol/L c = n/V 2.3/1.8 = 1.278
  12. 0.01 mol n = cV; V(L) = V(mL)/1000 0.4 × (25/1000) = 0.01
Review worksheet: 12 questions

  1. Measured from the same origin, a spot travels 36 mm and the solvent front 106 mm. Find Rf. Round to 3 decimal places if needed.

  2. The theoretical dry pure product mass is 119 g; the actual dry pure product mass is 71 g. Find percentage yield. Round to 3 decimal places if needed. Answer in %.

  3. A model solution contains 0.3 mol in a final volume of 0.25 L. Find its molar concentration. Round to 3 decimal places if needed. Answer in mol/L.

  4. An aqueous solution has concentration 1.1 mol/L. A model aliquot has volume 30 mL. Find the solute amount. Round to 3 decimal places if needed. Answer in mol.

  5. Five repeated measurements of the mass of the same sample (g) are: Trial 1 = 22.86; Trial 2 = 22.26; Trial 3 = 22.94; Trial 4 = 22.92; Trial 5 = 22.92. Which trial is most likely an outlier?

    1. Trial 4
    2. Trial 3
    3. Trial 5
    4. Trial 1
    5. Trial 2

  6. A 26 mL aliquot at 1.5 mol/L is diluted to 234 mL total without reaction or loss. Find the final concentration. Round to 3 decimal places if needed. Answer in mol/L.

  7. A 170 g sample is 55% desired substance by mass. Find the desired substance mass. Round to 3 decimal places if needed. Answer in g.

  8. A model solution contains 31 g solute and 284 g solvent. Find the solute mass percentage. Round to 3 decimal places if needed. Answer in %.

  9. During dilution with no loss or reaction, what stays unchanged?

    1. The solution volume.
    2. The concentration.
    3. The amount of solute.

  10. Why should solvent and stationary phase be controlled when comparing Rf values?

  11. Measured from the same origin, a spot travels 111 mm and the solvent front 120 mm. Find Rf. Round to 3 decimal places if needed.

  12. The theoretical dry pure product mass is 90 g; the actual dry pure product mass is 66 g. Find percentage yield. Round to 3 decimal places if needed. Answer in %.

Answer key
  1. 0.34 Rf = spot distance / solvent-front distance 36/106 = 0.34
  2. 59.664 % yield % = actual/theoretical × 100 71/119 × 100 = 59.664
  3. 1.2 mol/L c = n/V 0.3/0.25 = 1.2
  4. 0.033 mol n = cV; V(L) = V(mL)/1000 1.1 × (30/1000) = 0.033
  5. Trial 2 Trial 2 (22.26 g) is far from the other four values.
  6. 0.167 mol/L c₂ = c₁V₁/V₂ 1.5 × 26/234 = 0.167
  7. 93.5 g component mass = sample mass × purity/100 170 × 55/100 = 93.5
  8. 9.841 % mass % = solute mass / solution mass × 100 31/(31 + 284) × 100 = 9.841
  9. The amount of solute. Adding solvent lowers concentration but preserves solute amount.
  10. Changing conditions changes the distribution and movement of components. Rf is condition-dependent.
  11. 0.925 Rf = spot distance / solvent-front distance 111/120 = 0.925
  12. 73.333 % yield % = actual/theoretical × 100 66/90 × 100 = 73.333

Related ready-made worksheets: Grade 9 Analytical chemistry worksheet

05

LS Life Sciences

Cells & microscopy

Cells, organelles, microscopes and cell division.

Short lesson: Cell structures and their jobs

Study guide for Grades 9 to 12: 2 worked examples and 2 practice questions. Link each structure to its job.

structure ↔ function · plant cells add wall, chloroplasts, large vacuole · bacteria lack a nucleus

Link each structure to its job. Plant and animal cells share most organelles; prokaryotes such as bacteria have ribosomes and a membrane but no nucleus or membrane-bound organelles.

Worked example

Which structure is found in plant cells but not in animal cells: the cell wall or the cell membrane?

Cell walls, chloroplasts and a large central vacuole are typical of plant cells; both plant and animal cells have a nucleus, mitochondria, ribosomes and a cell membrane.

Answer: the cell wall

Read the full study guide

Worksheets

A practice worksheet and a review worksheet, 12 and 12 questions.

Worksheets (PDF)Answer keys (PDF)
Practice worksheet: 12 questions

  1. A printed image is 19 mm long at 40× magnification. Find the actual length in micrometers. Round to 3 decimal places if needed. Answer in µm.

  2. Supplied plant-tissue data show initial mass 4 g and final mass 3.5 g. Find signed percentage mass change. No experiment is required. Round to 3 decimal places if needed. Answer in %.

  3. When is DNA copied for a typical mitotic division?

    1. Before mitosis, during S phase.
    2. Never.
    3. Only after all daughter nuclei have separated.

  4. Which cell structure gives a plant cell a rigid outer layer for support?

    1. the mitochondrion
    2. the chloroplast
    3. the cell wall
    4. the cell membrane

  5. A cell is modeled as a cube of side 9 µm. Find surface area divided by volume. This geometry is a simplified model. Round to 3 decimal places if needed. Answer in µm⁻¹.

  6. What is a selectively permeable membrane?

    1. A barrier that always blocks everything.
    2. A wall that ignores molecule properties.
    3. A barrier that permits some substances more readily than others.

  7. Why can digitally enlarging an image fail to show new cellular detail?

  8. A printed image is 71 mm long at 50× magnification. Find the actual length in micrometers. Round to 3 decimal places if needed. Answer in µm.

  9. Supplied plant-tissue data show initial mass 14.4 g and final mass 15 g. Find signed percentage mass change. No experiment is required. Round to 3 decimal places if needed. Answer in %.

  10. Which outcome fits the standard role of mitosis in growth and repair?

    1. Creating four gametes in all cases.
    2. Halving chromosome number for every daughter cell.
    3. Producing genetically similar daughter nuclei, apart from mutations.

  11. Which structure is found in plant cells but not in animal cells: the cell wall or the cell membrane?

    1. the cell wall
    2. the cell membrane

  12. A cell is modeled as a cube of side 8 µm. Find surface area divided by volume. This geometry is a simplified model. Round to 3 decimal places if needed. Answer in µm⁻¹.

Answer key
  1. 475 µm actual size (µm) = image size (mm) × 1000 / magnification 19 × 1000/40 = 475
  2. -12.5 % (final − initial)/initial × 100 (3.5 − 4)/4 × 100 = -12.5
  3. Before mitosis, during S phase. Replication precedes mitotic chromosome separation.
  4. the cell wall The cell wall gives a plant cell a rigid outer layer for support.
  5. 0.667 µm⁻¹ SA/V = 6s²/s³ = 6/s for a cube 6/9 = 0.667
  6. A barrier that permits some substances more readily than others. Permeability differs by substance and transport mechanism.
  7. It may enlarge existing pixels without improving the captured resolution. Bigger does not necessarily mean more information.
  8. 1420 µm actual size (µm) = image size (mm) × 1000 / magnification 71 × 1000/50 = 1420
  9. 4.167 % (final − initial)/initial × 100 (15 − 14.4)/14.4 × 100 = 4.167
  10. Producing genetically similar daughter nuclei, apart from mutations. Mitosis differs from the chromosome-reduction process of meiosis.
  11. the cell wall Cell walls, chloroplasts and a large central vacuole are typical of plant cells; both plant and animal cells have a nucleus, mitochondria, ribosomes and a cell membrane.
  12. 0.75 µm⁻¹ SA/V = 6s²/s³ = 6/s for a cube 6/8 = 0.75
Review worksheet: 12 questions

  1. Supplied plant-tissue data show initial mass 6.4 g and final mass 8.7 g. Find signed percentage mass change. No experiment is required. Round to 3 decimal places if needed. Answer in %.

  2. A printed image is 18 mm long at 500× magnification. Find the actual length in micrometers. Round to 3 decimal places if needed. Answer in µm.

  3. Which structure is found in plant cells but not in animal cells: the ribosome or the large central vacuole?

    1. the ribosome
    2. the large central vacuole

  4. One side of a simplified model has 30 solute units in 10 volume units. Find its concentration.

  5. A cell is modeled as a cube of side 12 µm. Find surface area divided by volume. This geometry is a simplified model. Round to 3 decimal places if needed. Answer in µm⁻¹.

  6. Does every mature cell divide at the same rate?

    1. Only if cells are the same color.
    2. Yes, all once per hour.
    3. No.

  7. Convert 0.4 mm to micrometers.

  8. Supplied plant-tissue data show initial mass 5.6 g and final mass 7.5 g. Find signed percentage mass change. No experiment is required. Round to 3 decimal places if needed. Answer in %.

  9. A printed image is 44 mm long at 50× magnification. Find the actual length in micrometers. Round to 3 decimal places if needed. Answer in µm.

  10. Which structure is found in plant cells but not in animal cells: the large central vacuole or the ribosome?

    1. the large central vacuole
    2. the ribosome

  11. Why cannot active transport be identified from movement direction alone without knowing the relevant gradient?

  12. A cell is modeled as a cube of side 18 µm. Find surface area divided by volume. This geometry is a simplified model. Round to 3 decimal places if needed. Answer in µm⁻¹.

Answer key
  1. 35.937 % (final − initial)/initial × 100 (8.7 − 6.4)/6.4 × 100 = 35.937
  2. 36 µm actual size (µm) = image size (mm) × 1000 / magnification 18 × 1000/500 = 36
  3. the large central vacuole Cell walls, chloroplasts and a large central vacuole are typical of plant cells; both plant and animal cells have a nucleus, mitochondria, ribosomes and a cell membrane.
  4. 3 30/10 = 3 solute units per volume unit.
  5. 0.5 µm⁻¹ SA/V = 6s²/s³ = 6/s for a cube 6/12 = 0.5
  6. No. Division rates differ by cell type and conditions.
  7. 400 µm 0.4 × 1000 = 400 µm.
  8. 33.929 % (final − initial)/initial × 100 (7.5 − 5.6)/5.6 × 100 = 33.929
  9. 880 µm actual size (µm) = image size (mm) × 1000 / magnification 44 × 1000/50 = 880
  10. the large central vacuole Cell walls, chloroplasts and a large central vacuole are typical of plant cells; both plant and animal cells have a nucleus, mitochondria, ribosomes and a cell membrane.
  11. The concentrations, charges and membrane conditions determine whether movement is uphill. For ions, the electrical contribution may matter as well.
  12. 0.333 µm⁻¹ SA/V = 6s²/s³ = 6/s for a cube 6/18 = 0.333

Related ready-made worksheets: Grade 9 Cells & microscopy worksheet

06

LS Life Sciences

Genetics & inheritance

DNA, inheritance, genotypes and variation.

Short lesson: DNA base pairing and transcription

Study guide for Grades 9 to 12: 2 worked examples and 2 practice questions. Bases pair by shape and hydrogen bonding: adenine with thymine (uracil in RNA) and cytosine with guanine. Work one base at a time.

DNA: A-T, C-G · RNA: A-U, C-G

Bases pair by shape and hydrogen bonding: adenine with thymine (uracil in RNA) and cytosine with guanine. Work one base at a time.

Worked example

A DNA template strand reads AAGCCT. Which mRNA sequence is transcribed from it, read base by base in the same order?

AAGCCT → UUCGGA (A-U, T-A, C-G, G-C)

Answer: UUCGGA

Read the full study guide

Worksheets

A practice worksheet and a review worksheet, 12 and 12 questions.

Worksheets (PDF)Answer keys (PDF)
Practice worksheet: 12 questions

  1. In a canonical double-stranded DNA sample, adenine is 25% of all bases. Find the guanine percentage, assuming A = T and C = G. Round to 3 decimal places if needed. Answer in %.

  2. In the simple Aa × Aa inheritance model with independent outcomes, the probability of aa is 1/4. Among 280 offspring, find the expected aa count, not a guaranteed outcome. Round to 3 decimal places if needed.

  3. In pea plants, the allele for yellow seeds (Y) is dominant over the allele for green seeds (y). Two plants, yy × yy, are crossed. What percentage of the offspring are expected to show green seeds?

  4. A DNA template strand reads GATAGATA. Which mRNA sequence is transcribed from it, read base by base in the same order?

    1. CUAUCUAA
    2. GATAGATA
    3. CUAUCUAU
    4. CTATCTAT

  5. A fictional diploid organism has 38 chromosomes in a normal somatic nucleus. In the standard meiosis model, how many chromosomes are in a haploid gamete? Round to 3 decimal places if needed.

  6. Why need four offspring not include exactly one aa in an Aa × Aa cross?

  7. How many DNA replications precede the two meiotic divisions in the usual model?

    1. None.
    2. One.
    3. Two separate replications, one before each division.

  8. A double-stranded DNA sample has 20% adenine in the ideal model. What percentage is thymine?

  9. In a canonical double-stranded DNA sample, adenine is 21% of all bases. Find the guanine percentage, assuming A = T and C = G. Round to 3 decimal places if needed. Answer in %.

  10. In the simple Aa × Aa inheritance model with independent outcomes, the probability of aa is 1/4. Among 320 offspring, find the expected aa count, not a guaranteed outcome. Round to 3 decimal places if needed.

  11. In pea plants, the allele for round seeds (R) is dominant over the allele for wrinkled seeds (r). Two plants, RR × Rr, are crossed. What percentage of the offspring are expected to have the genotype Rr?

  12. Using base-pairing rules, which sequence pairs with the DNA strand TGAATGT, read base by base in the same order?

    1. ACTTACA
    2. ACTTGCA
    3. ACUUACA
    4. TGAATGT
Answer key
  1. 25 % G% = (100 − 2A%)/2 (100 − 2 × 25)/2 = 25
  2. 70 expected aa count = offspring count × 1/4 280 × 1/4 = 70
  3. 100 % yy × yy → yy, yy, yy, yy → 4/4 = 100%
  4. CUAUCUAU GATAGATA → CUAUCUAU (A-U, T-A, C-G, G-C)
  5. 19 haploid chromosome count = diploid count/2 38/2 = 19
  6. The one-quarter value is a probability, not a fixed small-sample outcome. Independent random events can vary around the expected proportion.
  7. One. DNA replication occurs once before meiosis I.
  8. 20 % A and T occur in matching counts across the double-stranded sample.
  9. 29 % G% = (100 − 2A%)/2 (100 − 2 × 21)/2 = 29
  10. 80 expected aa count = offspring count × 1/4 320 × 1/4 = 80
  11. 50 % RR × Rr → RR, Rr, RR, Rr → 2/4 = 50%
  12. ACTTACA TGAATGT → ACTTACA (A-T, C-G)
Review worksheet: 12 questions

  1. In the simple Aa × Aa inheritance model with independent outcomes, the probability of aa is 1/4. Among 644 offspring, find the expected aa count, not a guaranteed outcome. Round to 3 decimal places if needed.

  2. In pea plants, the allele for round seeds (R) is dominant over the allele for wrinkled seeds (r). Two plants, RR × Rr, are crossed. What percentage of the offspring are expected to have the genotype RR?

  3. Using base-pairing rules, which sequence pairs with the DNA strand CAAGTTTCA, read base by base in the same order?

    1. GTTCAAAGG
    2. CAAGTTTCA
    3. GTTCAAAGT
    4. GUUCAAAGU

  4. A fictional diploid organism has 88 chromosomes in a normal somatic nucleus. In the standard meiosis model, how many chromosomes are in a haploid gamete? Round to 3 decimal places if needed.

  5. In a canonical double-stranded DNA sample, adenine is 5% of all bases. Find the guanine percentage, assuming A = T and C = G. Round to 3 decimal places if needed. Answer in %.

  6. Does dominant mean more common or biologically better?

    1. Only for every human trait.
    2. Yes, always both.
    3. No.

  7. Two gametes each have 5 chromosomes. What chromosome number follows their fusion in the model?

  8. A nucleotide contains which three types of components?

    1. Sugar, phosphate and base.
    2. Only protein, lipid and oxygen.
    3. Only three amino acids.

  9. In the simple Aa × Aa inheritance model with independent outcomes, the probability of aa is 1/4. Among 248 offspring, find the expected aa count, not a guaranteed outcome. Round to 3 decimal places if needed.

  10. In pea plants, the allele for yellow seeds (Y) is dominant over the allele for green seeds (y). Two plants, Yy × Yy, are crossed. What percentage of the offspring are expected to have the genotype YY?

  11. Using base-pairing rules, which sequence pairs with the DNA strand TATTGCTA, read base by base in the same order?

    1. ATAACGAT
    2. TATTGCTA
    3. AUAACGAU
    4. ATAACGAA

  12. A fictional diploid organism has 14 chromosomes in a normal somatic nucleus. In the standard meiosis model, how many chromosomes are in a haploid gamete? Round to 3 decimal places if needed.

Answer key
  1. 161 expected aa count = offspring count × 1/4 644 × 1/4 = 161
  2. 50 % RR × Rr → RR, Rr, RR, Rr → 2/4 = 50%
  3. GTTCAAAGT CAAGTTTCA → GTTCAAAGT (A-T, C-G)
  4. 44 haploid chromosome count = diploid count/2 88/2 = 44
  5. 45 % G% = (100 − 2A%)/2 (100 − 2 × 5)/2 = 45
  6. No. Dominance describes expression in the specified heterozygote model.
  7. 10 5 + 5 = 10.
  8. Sugar, phosphate and base. These are the basic nucleotide components.
  9. 62 expected aa count = offspring count × 1/4 248 × 1/4 = 62
  10. 25 % Yy × Yy → YY, Yy, Yy, yy → 1/4 = 25%
  11. ATAACGAT TATTGCTA → ATAACGAT (A-T, C-G)
  12. 7 haploid chromosome count = diploid count/2 14/2 = 7

Related ready-made worksheets: Grade 9 Genetics & inheritance worksheet

07

LS Life Sciences

Ecology & populations

Ecosystems, food webs, populations and biodiversity.

Short lesson: Ecological sampling and population estimates

Study guide for Grades 8 to 11: 4 key ideas, including sampling, placement and estimate; 2 worked examples and 3 practice questions. Make estimates with assumptions and report their limits.

  • Sampling. A sample is used to infer properties of a larger population or area.
  • Placement. Random or systematic designs can reduce some selection biases when applied appropriately.
  • Estimate. For a simple quadrat model, mean count per area can be scaled to a stated comparable area.
  • Uncertainty. Distribution, detectability, season and sample size affect confidence in an estimate.

Worked example

Four equal 1 m² quadrats contain 2, 4, 6 and 8 plants. Find the mean per m².

The total 20 divided by four is 5 plants/m².

Answer: 5

Read the full study guide

Worksheets

A practice worksheet and a review worksheet, 12 and 12 questions.

Worksheets (PDF)Answer keys (PDF)
Practice worksheet: 12 questions

  1. A supplied food-web model transfers 8% of 1064 kJ to the next level. Find transferred energy. The stated efficiency is not a universal ecological constant. Round to 3 decimal places if needed. Answer in kJ.

  2. A fictional population starts at 258. During one interval: 63 births, 11 arrivals, 48 deaths and 3 departures. Find the final count. Round to 3 decimal places if needed.

  3. A supplied survey counts 124 plants in 9 non-overlapping quadrats, each 1 m². Find the mean density in the sampled area. Round to 3 decimal places if needed. Answer in plants/m².

  4. In this simplified food chain: willow shrubs → moose → wolf. At which trophic level is “willow shrubs”? (Producers are level 1.)

  5. A population changes from 80 to 100. Find its percentage increase.

  6. Why should season be recorded in a field survey?

  7. A supplied food-web model transfers 14% of 1173 kJ to the next level. Find transferred energy. The stated efficiency is not a universal ecological constant. Round to 3 decimal places if needed. Answer in kJ.

  8. A fictional population starts at 791. During one interval: 10 births, 26 arrivals, 6 deaths and 17 departures. Find the final count. Round to 3 decimal places if needed.

  9. A supplied survey counts 81 plants in 10 non-overlapping quadrats, each 2 m². Find the mean density in the sampled area. Round to 3 decimal places if needed. Answer in plants/m².

  10. In this simplified food chain: grass → grasshopper → frog → snake → hawk. If the population of “grasshopper” suddenly drops, what is the most likely short-term effect on the population of “frog”?

    1. It will most likely decrease.
    2. It will not be affected at all.
    3. It will most likely increase.

  11. Which term adds individuals to an area without births there?

    1. Immigration.
    2. Mortality.
    3. Emigration.

  12. Does a sample estimate equal a complete census?

    1. Only if rounded.
    2. Yes, always.
    3. No.
Answer key
  1. 85.12 kJ transferred energy = available energy × stated efficiency/100 1064 × 8/100 = 85.12
  2. 281 N₂ = N₁ + births + immigration − deaths − emigration 258 + 63 + 11 − 48 − 3 = 281
  3. 13.778 plants/m² density = total count / total sampled area 124/(9 × 1) = 13.778
  4. 1 Count from the producer: willow shrubs → moose → wolf.
  5. 25 % (100 − 80)/80 × 100 = 25%.
  6. Presence, activity and abundance can change with season. A time-specific survey may not represent all periods.
  7. 164.22 kJ transferred energy = available energy × stated efficiency/100 1173 × 14/100 = 164.22
  8. 804 N₂ = N₁ + births + immigration − deaths − emigration 791 + 10 + 26 − 6 − 17 = 804
  9. 4.05 plants/m² density = total count / total sampled area 81/(10 × 2) = 4.05
  10. It will most likely decrease. With less food available, the predator population is likely to decrease.
  11. Immigration. Immigration is inward movement.
  12. No. An estimate infers unobserved parts of the population.
Review worksheet: 12 questions

  1. A supplied food-web model transfers 23% of 289 kJ to the next level. Find transferred energy. The stated efficiency is not a universal ecological constant. Round to 3 decimal places if needed. Answer in kJ.

  2. A fictional population starts at 531. During one interval: 45 births, 12 arrivals, 60 deaths and 9 departures. Find the final count. Round to 3 decimal places if needed.

  3. A supplied survey counts 20 plants in 10 non-overlapping quadrats, each 1 m². Find the mean density in the sampled area. Round to 3 decimal places if needed. Answer in plants/m².

  4. In this simplified food chain: algae → zooplankton → herring → seal. If the population of “zooplankton” suddenly drops, what is the most likely short-term effect on the population of “herring”?

    1. It will not be affected at all.
    2. It will most likely decrease.
    3. It will most likely increase.

  5. Births plus immigration total 30 and deaths plus emigration total 45. What is net change?

  6. Four equal 1 m² quadrats contain 2, 4, 6 and 8 plants. Find the mean per m².

  7. A supplied food-web model transfers 8% of 1397 kJ to the next level. Find transferred energy. The stated efficiency is not a universal ecological constant. Round to 3 decimal places if needed. Answer in kJ.

  8. A fictional population starts at 781. During one interval: 76 births, 14 arrivals, 7 deaths and 29 departures. Find the final count. Round to 3 decimal places if needed.

  9. A supplied survey counts 18 plants in 9 non-overlapping quadrats, each 1 m². Find the mean density in the sampled area. Round to 3 decimal places if needed. Answer in plants/m².

  10. In this simplified food chain: grass → grasshopper → frog → snake → hawk. What is the role of “grasshopper” in this chain?

    1. secondary consumer
    2. tertiary consumer
    3. primary consumer
    4. quaternary consumer

  11. A model starts with 100 organisms, has 20 births, 5 immigrants, 10 deaths and 3 emigrants. Find the final population.

  12. Which report is more informative?

    1. Only one large total with no method.
    2. Method, sample counts, area and uncertainty.
    3. Only the expected answer.
Answer key
  1. 66.47 kJ transferred energy = available energy × stated efficiency/100 289 × 23/100 = 66.47
  2. 519 N₂ = N₁ + births + immigration − deaths − emigration 531 + 45 + 12 − 60 − 9 = 519
  3. 2 plants/m² density = total count / total sampled area 20/(10 × 1) = 2
  4. It will most likely decrease. With less food available, the predator population is likely to decrease.
  5. -15 30 − 45 = −15 individuals.
  6. 5 The total 20 divided by four is 5 plants/m².
  7. 111.76 kJ transferred energy = available energy × stated efficiency/100 1397 × 8/100 = 111.76
  8. 835 N₂ = N₁ + births + immigration − deaths − emigration 781 + 76 + 14 − 7 − 29 = 835
  9. 2 plants/m² density = total count / total sampled area 18/(9 × 1) = 2
  10. primary consumer Level 2 in this chain: primary consumer.
  11. 112 100 + 20 + 5 − 10 − 3 = 112.
  12. Method, sample counts, area and uncertainty. Readers need the sampling basis to evaluate an estimate.

Related ready-made worksheets: Grade 9 Ecology & populations worksheet

08

ESS Earth and Space Sciences

Earth & space

The Sun, Moon and planets, day and night, the water cycle and Earth's layers.

Short lesson: Earth systems

Study guide for Grades 4 to 9: 20 key ideas, including crust, mantle and outer core; 3 practice questions.

Weathering breaks material down; erosion transports it. These processes can happen together, but they are not the same.

  • Crust. Earth's thin outermost solid rocky layer.
  • Mantle. The thick rocky region between Earth's crust and core.
  • Outer core. The mostly liquid metallic layer surrounding Earth's inner core.
  • Inner core. Earth's solid central metallic region.

Read the full study guide

Worksheets

A practice worksheet and a review worksheet, 12 and 12 questions.

Worksheets (PDF)Answer keys (PDF)
Practice worksheet: 12 questions

  1. Must every rock pass through the same cycle steps in the same order?

    1. Yes, exactly once each.
    2. Only if it contains quartz.
    3. No.

  2. Earth systems: which term fits this description? The thick rocky region between Earth's crust and core.

    1. Weather
    2. Climate
    3. Mantle
    4. Igneous rock

  3. Should a model use a light beam as a safe instruction to look directly at the Sun?

    1. Only at midday.
    2. Yes, for better detail.
    3. No.

  4. What process forms an igneous rock in the basic model?

    1. Cooling and solidification of molten material.
    2. Every type of evaporation.
    3. Only compacting plastic litter.

  5. Earth systems: which term fits this description? Molten rock that has reached Earth's surface.

    1. Weathering
    2. Lava
    3. Weather
    4. Climate

  6. Why should a solar-angle diagram state the location and time of year?

  7. What can transform existing rock without fully melting it?

    1. Removing every atom.
    2. Heat and pressure during metamorphism.
    3. Only writing a new label.

  8. Earth systems: which term fits this description? Earth's solid central metallic region.

    1. Inner core
    2. Transpiration
    3. Water cycle
    4. Precipitation

  9. What primarily explains the opposite seasons of the two hemispheres?

    1. Every location being closer to the Sun in its summer.
    2. Axial tilt relative to the orbital plane.
    3. The Moon blocking all winter light.

  10. Why should a field observation be recorded before choosing a rock name?

  11. Earth systems: which term fits this description? Loss of water vapour from a plant, mainly through its leaves.

    1. Transpiration
    2. Erosion
    3. Climate
    4. Precipitation

  12. What does one orbital revolution correspond to in the basic Earth model?

    1. One year.
    2. One ordinary hour.
    3. One lunar crater.
Answer key
  1. No. The cycle shows alternative pathways.
  2. Mantle Mantle: The thick rocky region between Earth's crust and core.
  3. No. Never look directly at the Sun for this activity; use diagrams or safe supplied data.
  4. Cooling and solidification of molten material. Igneous rock forms from magma or lava cooling.
  5. Lava Lava: Molten rock that has reached Earth's surface.
  6. The geometry depends on latitude and orbital position. A single drawing does not describe every location simultaneously.
  7. Heat and pressure during metamorphism. Metamorphic change occurs under changed conditions without complete melting in the basic distinction.
  8. Inner core Inner core: Earth's solid central metallic region.
  9. Axial tilt relative to the orbital plane. Tilt changes sunlight angle and day length differently in the hemispheres.
  10. Texture, composition and context provide evidence for classification. Use evidence rather than guessing from one color.
  11. Transpiration Transpiration: Loss of water vapour from a plant, mainly through its leaves.
  12. One year. Earth's orbital period defines the year-scale cycle.
Review worksheet: 12 questions

  1. Earth systems: which term fits this description? Water falling from clouds as rain, snow or other forms.

    1. Igneous rock
    2. Precipitation
    3. Inner core
    4. Sedimentary rock

  2. A fictional sediment layer is 2 cm thicker each year for 5 years under a stated model. What added thickness is predicted?

  3. Does winter in one hemisphere necessarily mean winter in the other?

    1. Yes, always.
    2. No.
    3. Only if both have oceans.

  4. Earth systems: which term fits this description? Rock changed by heat, pressure or fluids without fully melting.

    1. Crust
    2. Metamorphic rock
    3. Magma
    4. Weather

  5. Why can a rock contain several different minerals?

  6. A fictional daylight record rises from 10 to 13 hours. What is the increase?

  7. Earth systems: which term fits this description? Rock formed as magma or lava cools and solidifies.

    1. Transpiration
    2. Plate tectonics
    3. Igneous rock
    4. Runoff

  8. What is weathering?

    1. All melting deep in Earth.
    2. Breakdown or alteration of material at or near the surface.
    3. Only transport by a river.

  9. Earth systems: which term fits this description? The ongoing movement of water among Earth's reservoirs.

    1. Mantle
    2. Inner core
    3. Water cycle
    4. Plate tectonics

  10. Why should a simple layer-rate calculation not be treated as a universal geological clock?

  11. Earth systems: which term fits this description? The settling or accumulation of transported sediment.

    1. Runoff
    2. Outer core
    3. Deposition of sediment
    4. Plate tectonics

  12. Earth systems: which term fits this description? The breakdown of rock in place at or near Earth's surface.

    1. Transpiration
    2. Weathering
    3. Water cycle
    4. Outer core
Answer key
  1. Precipitation Precipitation: Water falling from clouds as rain, snow or other forms.
  2. 10 cm 2 × 5 = 10 cm; real deposition need not be constant.
  3. No. Seasonal patterns are broadly opposite.
  4. Metamorphic rock Metamorphic rock: Rock changed by heat, pressure or fluids without fully melting.
  5. Rocks can be aggregates of multiple mineral components. Rock and mineral are not interchangeable terms.
  6. 3 hours 13 − 10 = 3 hours.
  7. Igneous rock Igneous rock: Rock formed as magma or lava cools and solidifies.
  8. Breakdown or alteration of material at or near the surface. Weathering differs from the transport commonly called erosion.
  9. Water cycle Water cycle: The ongoing movement of water among Earth's reservoirs.
  10. Deposition, erosion and compaction can vary over time. The rate assumption is limited.
  11. Deposition of sediment Deposition of sediment: The settling or accumulation of transported sediment.
  12. Weathering Weathering: The breakdown of rock in place at or near Earth's surface.