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Grade 10 · Science · curriculum collection

Grade 10 Science, NGSS domains

8 units for Grade 10 science, organised by NGSS disciplinary core idea domain: Physical Sciences, Life 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. An object moves at constant velocity 21 m/s for 13 s. Find displacement in m.

  2. A mass of 41 kg has velocity 16 m/s. Find its signed momentum in kg·m/s.

  3. A device transfers 126 J in 18 s. Find average power in W.

  4. A 28 kg object has speed 4 m/s. Find its classical kinetic energy in J.

  5. A device receives 3000 J and delivers 2700 J of useful energy. Find its efficiency as a percentage.

  6. A perpendicular force of 98 N acts over 1 m². Find the pressure in Pa.

  7. A constant 81 N force acts in the same direction as a 13 m displacement. Find work in J.

  8. Lift a 21 kg mass vertically by 28 m. Using g = 10 m/s², find the increase in gravitational potential energy in J.

  9. A spring has constant 20 N/m and extension 1 cm within its linear range. Find the restoring-force magnitude in N.

  10. A 14 kg sample has specific heat 800 J/(kg·°C). Its temperature rises 8°C with no phase change. Find the energy gained in J.

  11. An object of mass 40 kg accelerates at 6 m/s². Find the net force in N.

  12. Velocity changes from 7 m/s to 63 m/s in 7 s. Find average acceleration in m/s².

Answer key
  1. 273 m 21 × 13 = 273
  2. 656 kg·m/s 41 × 16 = 656
  3. 7 W 126 ÷ 18 = 7
  4. 224 J ½ × 28 × 4² = 224
  5. 90 % 2700/3000 × 100 = 90%
  6. 98 Pa 98 ÷ 1 = 98
  7. 1053 J 81 × 13 = 1053
  8. 5880 J 21 × 10 × 28 = 5880
  9. 0.2 N 20 × 0.01 = 0.2
  10. 89600 J 14 × 800 × 8 = 89600
  11. 240 N 40 × 6 = 240 N
  12. 8 m/s² (63 − 7)/7 = 8
Review worksheet: 12 questions

  1. A mass of 26 kg has velocity -28 m/s. Find its signed momentum in kg·m/s.

  2. A 42 kg object has speed 20 m/s. Find its classical kinetic energy in J.

  3. A device receives 3400 J and delivers 1700 J of useful energy. Find its efficiency as a percentage.

  4. A constant 67 N force acts in the same direction as a 32 m displacement. Find work in J.

  5. A spring has constant 140 N/m and extension 15 cm within its linear range. Find the restoring-force magnitude in N.

  6. A perpendicular force of 60 N acts over 2 m². Find the pressure in Pa.

  7. Lift a 14 kg mass vertically by 10 m. Using g = 10 m/s², find the increase in gravitational potential energy in J.

  8. An object of mass 5 kg accelerates at 20 m/s². Find the net force in N.

  9. A 10 kg sample has specific heat 200 J/(kg·°C). Its temperature rises 9°C with no phase change. Find the energy gained in J.

  10. A device transfers 360 J in 18 s. Find average power in W.

  11. Velocity changes from 21 m/s to -6 m/s in 9 s. Find average acceleration in m/s².

  12. An object moves at constant velocity 12 m/s for 32 s. Find displacement in m.

Answer key
  1. -728 kg·m/s 26 × -28 = -728
  2. 8400 J ½ × 42 × 20² = 8400
  3. 50 % 1700/3400 × 100 = 50%
  4. 2144 J 67 × 32 = 2144
  5. 21 N 140 × 0.15 = 21
  6. 30 Pa 60 ÷ 2 = 30
  7. 1400 J 14 × 10 × 10 = 1400
  8. 100 N 5 × 20 = 100 N
  9. 18000 J 10 × 200 × 9 = 18000
  10. 20 W 360 ÷ 18 = 20
  11. -3 m/s² (-6 − 21)/9 = -3
  12. 384 m 12 × 32 = 384

Related ready-made worksheets: Grade 10 Motion & energy worksheet

02

PS Physical Sciences

Motion & graphs

Distance, displacement, speed, velocity and acceleration.

Short lesson: Describing motion from position data

Study guide for Grades 9 to 12: 2 worked examples and 2 practice questions. Find how far the object moves in each second. Equal steps mean constant speed; growing steps mean speeding up; shrinking steps mean slowing down.

equal distances in equal times → constant speed · average speed = total distance ÷ total time

Find how far the object moves in each second. Equal steps mean constant speed; growing steps mean speeding up; shrinking steps mean slowing down.

Worked example

A cart moves along a straight track. Its position is recorded every second: t = 0 s: 7 m; t = 1 s: 22 m; t = 2 s: 34 m; t = 3 s: 43 m; t = 4 s: 49 m. How is the cart moving?

Distance in each second: 15, 12, 9, 6 m.

Answer: It is slowing down.

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 object leaves a ledge horizontally at 17 m/s from height 80 m. Use g = 10 m/s² and no air resistance. Find its horizontal range to the ground. Round to 3 decimal places if needed. Answer in m.

  2. Use one signed axis. Initial velocity is 3 m/s and constant acceleration is 4 m/s² for 7 s. Find the displacement. Round to 3 decimal places if needed. Answer in m.

  3. A cart moves at 45 m/s, then slows at a constant 5 m/s² to rest. Find its braking distance, excluding any reaction distance. Round to 3 decimal places if needed. Answer in m.

  4. In one dimension, u = -1 m/s and constant a = 3 m/s². Find the signed velocity after 7 s. Round to 3 decimal places if needed. Answer in m/s.

  5. Signed velocity changes from 8 m/s to 12 m/s in 6 s. Find the average acceleration. Round to 3 decimal places if needed. Answer in m/s².

  6. 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.

  7. In a model without air resistance, an object is launched vertically upward at 23 m/s on Earth (use the rounded value g = 10 m/s²). Find its time to maximum height. Round to 3 decimal places if needed. Answer in s.

  8. A model cart starts at 20 m/s and slows uniformly at 2 m/s² until rest. Ignore reaction time. Find the stopping time. Round to 3 decimal places if needed. Answer in s.

  9. 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.

  10. Two carts approach each other on a straight track at 10 m/s and 23 m/s. How fast is their separation decreasing? Round to 3 decimal places if needed. Answer in m/s.

  11. On a velocity-time graph, the line is horizontal at 5 m/s. What is the object doing?

    1. It moves at a constant velocity of 5 m/s.
    2. It is accelerating at 5 m/s².
    3. It is at rest at a position of 5 m.

  12. Why can constant speed around a circle involve acceleration?

    1. Velocity direction changes.
    2. Mass must change.
    3. Elapsed time stops.
Answer key
  1. 68 m t = √(2h/g); x = vₓt √(2 × 80 / 10) = 4; 17 × 4 = 68
  2. 119 m s = ut + ½at² 3 × 7 + 0.5 × (4) × 7² = 119
  3. 202.5 m s = u²/(2b) 45² / (2 × 5) = 202.5
  4. 20 m/s v = u + at -1 + (3) × 7 = 20
  5. 0.667 m/s² a = (v₂ − v₁)/Δt (12 − 8) / 6 = 0.667
  6. 4.818 m/s v̄ = (x₂ − x₁)/Δt (41 − (-12)) / 11 = 4.818
  7. 2.3 s t = u/g 23 / 10 = 2.3
  8. 10 s t = u/b 20 / 2 = 10
  9. It is speeding up. Distance in each second: 2, 4, 6, 8 m.
  10. 33 m/s closing speed = v₁ + v₂ 10 + 23 = 33
  11. It moves at a constant velocity of 5 m/s. A horizontal velocity-time line means the velocity is not changing.
  12. Velocity direction changes. Acceleration measures vector velocity change, not only change in speed.
Review worksheet: 12 questions

  1. Use one signed axis. Initial velocity is 18 m/s and constant acceleration is -1 m/s² for 5 s. Find the displacement. Round to 3 decimal places if needed. Answer in m.

  2. Signed velocity changes from 25 m/s to 34 m/s in 12 s. Find the average acceleration. Round to 3 decimal places if needed. Answer in m/s².

  3. In one dimension, u = 0 m/s and constant a = 7 m/s². Find the signed velocity after 10 s. Round to 3 decimal places if needed. Answer in m/s.

  4. A model object leaves a ledge horizontally at 3 m/s from height 80 m. Use g = 10 m/s² and no air resistance. Find its horizontal range to the ground. Round to 3 decimal places if needed. Answer in m.

  5. A cart moves at 20 m/s, then slows at a constant 1 m/s² to rest. Find its braking distance, excluding any reaction distance. Round to 3 decimal places if needed. Answer in m.

  6. On an east-positive axis, position changes from -2 m to 34 m in 22 s. Find the signed average velocity. Round to 3 decimal places if needed. Answer in m/s.

  7. A model cart starts at 15 m/s and slows uniformly at 6 m/s² until rest. Ignore reaction time. Find the stopping time. Round to 3 decimal places if needed. Answer in s.

  8. Two carts approach each other on a straight track at 4 m/s and 10 m/s. How fast is their separation decreasing? Round to 3 decimal places if needed. Answer in m/s.

  9. In a model without air resistance, an object is launched vertically upward at 21 m/s on a model planet where g = 5 m/s². Find its time to maximum height. Round to 3 decimal places if needed. Answer in s.

  10. A cart moves along a straight track. Its position is recorded every second: t = 0 s: 6 m; t = 1 s: 15 m; t = 2 s: 23 m; t = 3 s: 30 m; t = 4 s: 36 m. What is its average speed over the 4 seconds?

  11. An object falls from rest for 3 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.

  12. Velocity rises uniformly from 2 to 10 m/s in 4 s. Find acceleration.

Answer key
  1. 77.5 m s = ut + ½at² 18 × 5 + 0.5 × (-1) × 5² = 77.5
  2. 0.75 m/s² a = (v₂ − v₁)/Δt (34 − 25) / 12 = 0.75
  3. 70 m/s v = u + at 0 + (7) × 10 = 70
  4. 12 m t = √(2h/g); x = vₓt √(2 × 80 / 10) = 4; 3 × 4 = 12
  5. 200 m s = u²/(2b) 20² / (2 × 1) = 200
  6. 1.636 m/s v̄ = (x₂ − x₁)/Δt (34 − (-2)) / 22 = 1.636
  7. 2.5 s t = u/b 15 / 6 = 2.5
  8. 14 m/s closing speed = v₁ + v₂ 4 + 10 = 14
  9. 4.2 s t = u/g 21 / 5 = 4.2
  10. 7.5 m/s (36 − 6) ÷ 4 = 7.5
  11. 22.5 m d = ½gt² 0.5 × 5 × 3² = 22.5
  12. 2 m/s² Slope is (10 − 2)/4 = 2 m/s².

Related ready-made worksheets: Grade 10 Motion & graphs worksheet

03

PS Physical Sciences

Electricity & circuits

Charge, current, voltage, resistance and electrical power.

Short lesson: Charge transferred

Study guide for Grades 8 to 12: 2 worked examples and 2 practice questions. This relation uses constant current in amperes and time in seconds.

Q = It

This relation uses constant current in amperes and time in seconds.

Worked example

A constant current of 6 A flows for 88 s. How much charge passes in C?

6 × 88 = 528

Answer: 528 C

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. An ammeter reads the current at three points in a simple series circuit. How do the three readings compare?

    1. They are all the same.
    2. They get larger after each bulb.
    3. They get smaller after each bulb.

  2. A theoretical 35 V ideal source supplies parallel ohmic resistors 36 Ω and 21 Ω. Find total source current. Round to 3 decimal places if needed. Answer in A.

  3. Three ideal resistors of 67 Ω, 33 Ω and 8 Ω are in series. Find total resistance in Ω.

  4. A constant current of 1.4 A flows for 72 s. Find transferred charge. Round to 3 decimal places if needed. Answer in C.

  5. Resistors of 47 Ω and 35 Ω are connected in parallel. Find the equivalent resistance in Ω as an exact fraction or integer.

  6. An ideal ohmic resistor of 67 Ω carries 11 A. Find the voltage across it in V.

  7. An ohmic resistor of 12 Ω has potential difference 38 V. Find current. This is a paper calculation, not a construction instruction. Round to 3 decimal places if needed. Answer in A.

  8. In a theoretical circuit, 32 Ω and 18 Ω are in series across an ideal 46 V source. Find their total electrical power. Round to 3 decimal places if needed. Answer in W.

  9. A model device uses constant power 2000 W for 3 h. Find the energy in kilowatt-hours. Round to 3 decimal places if needed. Answer in kWh.

  10. A constant current of 12 A flows for 93 s. How much charge passes in C?

  11. A steady DC device operates at 41 V and 12 A. Find power in W.

  12. What is the unit of charge?

    1. Watt
    2. Coulomb
    3. Ampere
Answer key
  1. They are all the same. Charge is not used up: the same current flows everywhere in a series loop.
  2. 2.639 A I = V/R₁ + V/R₂ 35/36 + 35/21 = 2.639
  3. 108 Ω 67 + 33 + 8 = 108
  4. 100.8 C Q = It 1.4 × 72 = 100.8
  5. 1645/82 Ω 47 × 35 / (47 + 35) = 1645/82
  6. 737 V 11 × 67 = 737
  7. 3.167 A I = V/R 38 / 12 = 3.167
  8. 42.32 W P = V²/(R₁ + R₂) 46² / (32 + 18) = 42.32
  9. 6 kWh E(kWh) = P(W) × t(h)/1000 2000 × 3 / 1000 = 6
  10. 1116 C 12 × 93 = 1116
  11. 492 W 41 × 12 = 492
  12. Coulomb An ampere is coulombs per second, not charge itself.
Review worksheet: 12 questions

  1. A battery supplies 1.1 A to two parallel branches. One branch carries 1 A. What current flows in the other branch? (Assume ideal wires and an ideal battery.)

  2. Three ideal resistors of 36 Ω, 6 Ω and 63 Ω are in series. Find total resistance in Ω.

  3. Resistors of 17 Ω and 30 Ω are connected in parallel. Find the equivalent resistance in Ω as an exact fraction or integer.

  4. A constant current of 0.3 A flows for 58 s. Find transferred charge. Round to 3 decimal places if needed. Answer in C.

  5. An ideal ohmic resistor of 51 Ω carries 4 A. Find the voltage across it in V.

  6. An ohmic resistor of 15 Ω has potential difference 59 V. Find current. This is a paper calculation, not a construction instruction. Round to 3 decimal places if needed. Answer in A.

  7. In a theoretical circuit, 29 Ω and 6 Ω are in series across an ideal 34 V source. Find their total electrical power. Round to 3 decimal places if needed. Answer in W.

  8. A theoretical 11 V ideal source supplies parallel ohmic resistors 13 Ω and 7 Ω. Find total source current. Round to 3 decimal places if needed. Answer in A.

  9. A steady DC device operates at 37 V and 9 A. Find power in W.

  10. A constant current of 15 A flows for 55 s. How much charge passes in C?

  11. 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.

  12. A 12 V ideal source is across a 3 Ω resistor. Find current in that branch.

Answer key
  1. 0.1 A 1.1 − 1 = 0.1
  2. 105 Ω 36 + 6 + 63 = 105
  3. 510/47 Ω 17 × 30 / (17 + 30) = 510/47
  4. 17.4 C Q = It 0.3 × 58 = 17.4
  5. 204 V 4 × 51 = 204
  6. 3.933 A I = V/R 59 / 15 = 3.933
  7. 33.029 W P = V²/(R₁ + R₂) 34² / (29 + 6) = 33.029
  8. 2.418 A I = V/R₁ + V/R₂ 11/13 + 11/7 = 2.418
  9. 333 W 37 × 9 = 333
  10. 825 C 15 × 55 = 825
  11. 0.45 kWh E(kWh) = P(W) × t(h)/1000 75 × 6 / 1000 = 0.45
  12. 4 A I = V/R = 12/3 = 4 A.

Related ready-made worksheets: Grade 10 Electricity & circuits worksheet

04

PS Physical Sciences

Analytical chemistry

Concentration, titration, chromatography and yield.

Short lesson: Yield, purity and limiting amounts

Study guide for Grades 10 to 12: 4 key ideas, including yield, limiting and purity; 2 worked examples and 3 practice questions. Do not confuse an impure recovered mass with a chemical yield.

  • Yield. Percent yield = actual amount / theoretical amount × 100 for the same product quantity.
  • Limiting. The limiting reactant is exhausted first under the stated stoichiometric model.
  • Purity. Mass purity is the mass of desired substance divided by sample mass.
  • Caution. A reported yield over 100% can indicate impurities, solvent or measurement/model errors.

Worked example

Theoretical product mass is 20 g and actual dry pure mass is 15 g. Find percent yield.

15/20 × 100 = 75%.

Answer: 75 %

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 valid-range calibration is S = 2c + 0.1. The signal is 8.3. Find c in the calibration's arbitrary concentration units. Round to 3 decimal places if needed.

  2. A model solution contains 26 g solute and 91 g solvent. Find the solute mass percentage. Round to 3 decimal places if needed. Answer in %.

  3. A 111 g sample is 32% desired substance by mass. Find the desired substance mass. Round to 3 decimal places if needed. Answer in g.

  4. A model solution contains 0.8 mol in a final volume of 0.18 L. Find its molar concentration. Round to 3 decimal places if needed. Answer in mol/L.

  5. An aqueous solution has concentration 0.1 mol/L. A model aliquot has volume 441 mL. Find the solute amount. Round to 3 decimal places if needed. Answer in mol.

  6. The theoretical dry pure product mass is 21 g; the actual dry pure product mass is 8 g. Find percentage yield. Round to 3 decimal places if needed. Answer in %.

  7. Measured from the same origin, a spot travels 29 mm and the solvent front 40 mm. Find Rf. Round to 3 decimal places if needed.

  8. A 78 mL aliquot at 0.1 mol/L is diluted to 312 mL total without reaction or loss. Find the final concentration. Round to 3 decimal places if needed. Answer in mol/L.

  9. Does one visible spot prove a sample is pure?

    1. Only if the spot is round.
    2. Not necessarily; components can co-migrate or be undetected.
    3. Yes, always.

  10. Five repeated measurements of the mass of the same sample (g) are: Trial 1 = 27.67; Trial 2 = 27.7; Trial 3 = 26.19; Trial 4 = 27.66; Trial 5 = 27.69. Which trial is most likely an outlier?

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

  11. In the supplied complete neutralization equation H₂A + 2OH⁻ → A²⁻ + 2H₂O, how much OH⁻ reacts with 0.29 mol H₂A? Round to 3 decimal places if needed. Answer in mol.

  12. A sample is 80% desired substance by mass and has mass 25 g. Find the desired substance mass.

Answer key
  1. 4.1 c = (S − b)/m for S = mc + b (8.3 − 0.1)/2 = 4.1
  2. 22.222 % mass % = solute mass / solution mass × 100 26/(26 + 91) × 100 = 22.222
  3. 35.52 g component mass = sample mass × purity/100 111 × 32/100 = 35.52
  4. 4.444 mol/L c = n/V 0.8/0.18 = 4.444
  5. 0.044 mol n = cV; V(L) = V(mL)/1000 0.1 × (441/1000) = 0.044
  6. 38.095 % yield % = actual/theoretical × 100 8/21 × 100 = 38.095
  7. 0.725 Rf = spot distance / solvent-front distance 29/40 = 0.725
  8. 0.025 mol/L c₂ = c₁V₁/V₂ 0.1 × 78/312 = 0.025
  9. Not necessarily; components can co-migrate or be undetected. Method resolution and detection impose limits.
  10. Trial 3 Trial 3 (26.19 g) is far from the other four values.
  11. 0.58 mol H₂A + 2OH⁻ → A²⁻ + 2H₂O; n(OH⁻) = 2n(H₂A) 2 × 0.29 = 0.58
  12. 20 g 0.80 × 25 = 20 g.
Review worksheet: 12 questions

  1. A model solution contains 11 g solute and 181 g solvent. Find the solute mass percentage. Round to 3 decimal places if needed. Answer in %.

  2. A model solution contains 0.1 mol in a final volume of 1.67 L. Find its molar concentration. Round to 3 decimal places if needed. Answer in mol/L.

  3. An aqueous solution has concentration 1.5 mol/L. A model aliquot has volume 395 mL. Find the solute amount. Round to 3 decimal places if needed. Answer in mol.

  4. The theoretical dry pure product mass is 48 g; the actual dry pure product mass is 26 g. Find percentage yield. Round to 3 decimal places if needed. Answer in %.

  5. Measured from the same origin, a spot travels 30 mm and the solvent front 66 mm. Find Rf. Round to 3 decimal places if needed.

  6. A supplied valid-range calibration is S = 9c + 0.3. The signal is 6.9. Find c in the calibration's arbitrary concentration units. Round to 3 decimal places if needed.

  7. A 10 g sample is 42% desired substance by mass. Find the desired substance mass. Round to 3 decimal places if needed. Answer in g.

  8. A 87 mL aliquot at 0.6 mol/L is diluted to 696 mL total without reaction or loss. Find the final concentration. Round to 3 decimal places if needed. Answer in mol/L.

  9. In the supplied complete neutralization equation H₂A + 2OH⁻ → A²⁻ + 2H₂O, how much OH⁻ reacts with 0.36 mol H₂A? Round to 3 decimal places if needed. Answer in mol.

  10. Five repeated measurements of the mass of the same sample (g) are: Trial 1 = 27.77; Trial 2 = 27.72; Trial 3 = 27.72; Trial 4 = 27.71; Trial 5 = 28.21. Which trial is most likely an outlier?

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

  11. Theoretical product mass is 20 g and actual dry pure mass is 15 g. Find percent yield.

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

Answer key
  1. 5.729 % mass % = solute mass / solution mass × 100 11/(11 + 181) × 100 = 5.729
  2. 0.06 mol/L c = n/V 0.1/1.67 = 0.06
  3. 0.593 mol n = cV; V(L) = V(mL)/1000 1.5 × (395/1000) = 0.593
  4. 54.167 % yield % = actual/theoretical × 100 26/48 × 100 = 54.167
  5. 0.455 Rf = spot distance / solvent-front distance 30/66 = 0.455
  6. 0.733 c = (S − b)/m for S = mc + b (6.9 − 0.3)/9 = 0.733
  7. 4.2 g component mass = sample mass × purity/100 10 × 42/100 = 4.2
  8. 0.075 mol/L c₂ = c₁V₁/V₂ 0.6 × 87/696 = 0.075
  9. 0.72 mol H₂A + 2OH⁻ → A²⁻ + 2H₂O; n(OH⁻) = 2n(H₂A) 2 × 0.36 = 0.72
  10. Trial 5 Trial 5 (28.21 g) is far from the other four values.
  11. 75 % 15/20 × 100 = 75%.
  12. The amount of that solute is no longer conserved in the simple dilution sense. Reaction stoichiometry must be included.

Related ready-made worksheets: Grade 10 Analytical chemistry worksheet

05

LS Life Sciences

Cells & microscopy

Cells, organelles, microscopes and cell division.

Short lesson: Cell cycle and mitosis

Study guide for Grades 9 to 12: 4 key ideas, including cycle, replication and mitosis; 2 worked examples and 3 practice questions. Separate DNA replication from chromosome separation.

  • Cycle. The cell cycle includes growth, DNA replication and division-related stages.
  • Replication. DNA is copied before mitosis; mitosis itself organizes and separates the copied chromosomes.
  • Mitosis. In a typical stable diploid model, mitosis preserves chromosome number in daughter nuclei.
  • Control. Division is regulated; an unregulated increase in cells is not the normal purpose of every cell type.

Worked example

When is DNA copied for a typical mitotic division?

Replication precedes mitotic chromosome separation.

Answer: Before mitosis, during S phase.

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 4 mm long at 400× 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 7 g and final mass 6.8 g. Find signed percentage mass change. No experiment is required. Round to 3 decimal places if needed. Answer in %.

  3. A cell is modeled as a cube of side 17 µm. Find surface area divided by volume. This geometry is a simplified model. Round to 3 decimal places if needed. Answer in µm⁻¹.

  4. Why does a scale bar often remain reliable when an image is resized proportionally?

  5. 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.

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

  7. Which structure does a typical bacterial cell have: the nucleus or the ribosome?

    1. the nucleus
    2. the ribosome

  8. A printed image is 27 mm long at 400× 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 5.6 g and final mass 6.3 g. Find signed percentage mass change. No experiment is required. Round to 3 decimal places if needed. Answer in %.

  10. A cell is modeled as a cube of side 25 µm. Find surface area divided by volume. This geometry is a simplified model. Round to 3 decimal places if needed. Answer in µm⁻¹.

  11. Which term means distinguishing two nearby points?

    1. Only magnification.
    2. Specimen color.
    3. Resolution.

  12. Starting with one cell, two complete rounds of division produce how many cells if none die?

Answer key
  1. 10 µm actual size (µm) = image size (mm) × 1000 / magnification 4 × 1000/400 = 10
  2. -2.857 % (final − initial)/initial × 100 (6.8 − 7)/7 × 100 = -2.857
  3. 0.353 µm⁻¹ SA/V = 6s²/s³ = 6/s for a cube 6/17 = 0.353
  4. The bar and specimen image enlarge or shrink by the same factor. The relative lengths are retained.
  5. Before mitosis, during S phase. Replication precedes mitotic chromosome separation.
  6. 3 30/10 = 3 solute units per volume unit.
  7. the ribosome Bacteria are prokaryotes: they have ribosomes and a cell membrane but no nucleus, mitochondria or Golgi apparatus.
  8. 67.5 µm actual size (µm) = image size (mm) × 1000 / magnification 27 × 1000/400 = 67.5
  9. 12.5 % (final − initial)/initial × 100 (6.3 − 5.6)/5.6 × 100 = 12.5
  10. 0.24 µm⁻¹ SA/V = 6s²/s³ = 6/s for a cube 6/25 = 0.24
  11. Resolution. Resolution concerns detail separation.
  12. 4 Each cell divides into two: one cell becomes two, then those two become four cells.
Review worksheet: 12 questions

  1. Supplied plant-tissue data show initial mass 11.4 g and final mass 12.1 g. Find signed percentage mass change. No experiment is required. Round to 3 decimal places if needed. Answer in %.

  2. A printed image is 70 mm long at 40× magnification. Find the actual length in micrometers. Round to 3 decimal places if needed. Answer in µm.

  3. A cell is modeled as a cube of side 24 µm. Find surface area divided by volume. This geometry is a simplified model. Round to 3 decimal places if needed. Answer in µm⁻¹.

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

    1. the cell wall
    2. the nucleus

  5. 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.

  6. At 200× magnification, an image is 10 mm long. Find the actual length in millimeters.

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

  8. Supplied plant-tissue data show initial mass 11.1 g and final mass 11.5 g. Find signed percentage mass change. No experiment is required. Round to 3 decimal places if needed. Answer in %.

  9. A printed image is 57 mm long at 500× magnification. Find the actual length in micrometers. Round to 3 decimal places if needed. Answer in µm.

  10. A cell is modeled as a cube of side 30 µm. Find surface area divided by volume. This geometry is a simplified model. Round to 3 decimal places if needed. Answer in µm⁻¹.

  11. Which structure does a typical bacterial cell have: the Golgi apparatus or the cell membrane?

    1. the cell membrane
    2. the Golgi apparatus

  12. Why must a question specify whether it counts chromosomes or chromatids after replication?

Answer key
  1. 6.14 % (final − initial)/initial × 100 (12.1 − 11.4)/11.4 × 100 = 6.14
  2. 1750 µm actual size (µm) = image size (mm) × 1000 / magnification 70 × 1000/40 = 1750
  3. 0.25 µm⁻¹ SA/V = 6s²/s³ = 6/s for a cube 6/24 = 0.25
  4. 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.
  5. No. Division rates differ by cell type and conditions.
  6. 0.05 mm 10/200 = 0.05 mm.
  7. The concentrations, charges and membrane conditions determine whether movement is uphill. For ions, the electrical contribution may matter as well.
  8. 3.604 % (final − initial)/initial × 100 (11.5 − 11.1)/11.1 × 100 = 3.604
  9. 114 µm actual size (µm) = image size (mm) × 1000 / magnification 57 × 1000/500 = 114
  10. 0.2 µm⁻¹ SA/V = 6s²/s³ = 6/s for a cube 6/30 = 0.2
  11. the cell membrane Bacteria are prokaryotes: they have ribosomes and a cell membrane but no nucleus, mitochondria or Golgi apparatus.
  12. A replicated chromosome consists of sister chromatids, so the counts differ by the convention used. The counting unit and stage must be clear.

Related ready-made worksheets: Grade 10 Cells & microscopy worksheet

06

LS Life Sciences

Human biology & physiology

Body systems: breathing, circulation, digestion and control.

Short lesson: Flow from supplied model values

Study guide for Grades 9 to 12: 2 worked examples and 2 practice questions. Multiply beats per minute by volume per beat. These fictional values are for arithmetic, not diagnosis.

flow = beats per minute × volume per beat

Multiply beats per minute by volume per beat. These fictional values are for arithmetic, not diagnosis.

Worked example

A fictional circulation model has 80 beats/min and 43 mL/beat. Find its flow in mL/min. These are supplied model values, not diagnostic ranges. Round to 3 decimal places if needed. Answer in mL/min.

flow = beats per minute × volume per beat 80 × 43 = 3440

Answer: 3440 mL/min

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 fictional circulation model has 76 beats/min and 41 mL/beat. Find its flow in mL/min. These are supplied model values, not diagnostic ranges. Round to 3 decimal places if needed. Answer in mL/min.

  2. Which activity happens at the cellular scale?

    1. Only chest movement.
    2. Chemical reactions coupling fuel breakdown to ATP production.
    3. Only air entering the nose.

  3. Which would fit a simple negative-feedback response to an increase?

    1. No relation to the measured quantity.
    2. A response always doubling the increase.
    3. A response tending to decrease the regulated quantity.

  4. Why is “arteries always carry oxygenated blood” an unsafe general rule?

  5. Why do folds and villi support absorption?

  6. How do many endocrine signals travel?

    1. Through body fluids such as blood.
    2. Only through wooden tubes.
    3. Only outside the body.

  7. Why are thin exchange barriers useful?

    1. They prevent every gas from moving.
    2. They shorten diffusion distance.
    3. They make gas molecules disappear.

  8. Does immune memory mean an organism can never become ill again?

    1. Yes, without exceptions.
    2. No.
    3. Only after any one exposure.

  9. A fictional circulation model has 70 beats/min and 46 mL/beat. Find its flow in mL/min. These are supplied model values, not diagnostic ranges. Round to 3 decimal places if needed. Answer in mL/min.

  10. What does aerobic refer to in the standard respiration model?

    1. Only motion through air.
    2. No chemical reactions.
    3. Use of oxygen in the pathway.

  11. Which component detects a change in a simple feedback model?

    1. Only the worksheet title.
    2. Only the output label.
    3. Sensor.

  12. What defines a vein?

    1. It carries blood toward the heart.
    2. It always contains no oxygen.
    3. It transports only air.
Answer key
  1. 3116 mL/min flow = beats per minute × volume per beat 76 × 41 = 3116
  2. Chemical reactions coupling fuel breakdown to ATP production. Cellular respiration involves metabolic reactions.
  3. A response tending to decrease the regulated quantity. The response opposes the deviation in this simplified case.
  4. Pulmonary arteries carry blood toward the lungs with lower oxygen content than pulmonary veins. Use vessel direction as the consistent definition.
  5. They increase the available surface area. Explain the structure-function relation rather than saying more area is always better without context.
  6. Through body fluids such as blood. Hormones can circulate to distant target cells.
  7. They shorten diffusion distance. Shorter paths can increase diffusion rate.
  8. No. Protection depends on many biological factors and can be incomplete.
  9. 3220 mL/min flow = beats per minute × volume per beat 70 × 46 = 3220
  10. Use of oxygen in the pathway. Oxygen has a defined role in the electron-transfer process.
  11. Sensor. A sensor obtains information about the regulated quantity.
  12. It carries blood toward the heart. Direction distinguishes veins from arteries.
Review worksheet: 12 questions

  1. A fictional circulation model has 97 beats/min and 55 mL/beat. Find its flow in mL/min. These are supplied model values, not diagnostic ranges. Round to 3 decimal places if needed. Answer in mL/min.

  2. Which process transfers products across the intestinal surface?

    1. Only swallowing.
    2. Only chewing.
    3. Absorption.

  3. Why does a large exchange surface help gas transfer?

    1. It changes oxygen to a metal.
    2. It provides more area for diffusion.
    3. It removes all need for concentration differences.

  4. A supplied signal travels 12 distance units in 3 time units. Find its average model speed.

  5. A supplied simplified model has 60 beats/min and 70 mL/beat. Find flow in mL/min.

  6. Is breathing identical to cellular respiration?

    1. No.
    2. Yes, the words describe the same event.
    3. Only in all plants.

  7. A supplied fictional chart shows response level 3 units initially and 12 later. What is the factor increase?

  8. Why is a classroom blood-glucose example not a personal medical instruction?

  9. A fictional circulation model has 57 beats/min and 88 mL/beat. Find its flow in mL/min. These are supplied model values, not diagnostic ranges. Round to 3 decimal places if needed. Answer in mL/min.

  10. Which statement is more accurate?

    1. Different nutrients have different chemical structures and processing pathways.
    2. Only vitamins contain atoms.
    3. All nutrients are identical sugar molecules.

  11. A model surface is divided into 8 equal parts of 3 area units each. Find total area.

  12. Which is part of many chemical synapses?

    1. Only sound waves in air.
    2. A released chemical messenger interacting with receptors.
    3. A new chromosome created at every message.
Answer key
  1. 5335 mL/min flow = beats per minute × volume per beat 97 × 55 = 5335
  2. Absorption. Absorption moves substances across an exchange barrier.
  3. It provides more area for diffusion. More area supports greater transfer under comparable conditions.
  4. 4 12/3 = 4 distance units per time unit.
  5. 4200 mL/min 60 × 70 = 4200 mL/min; these are supplied model values, not medical norms.
  6. No. Breathing is air movement; respiration is a cellular chemical process.
  7. 4 12/3 = 4; these units are model data, not clinical interpretation.
  8. It cannot account for an individual's condition, medicines or clinical measurements. Keep the learning model distinct from care decisions.
  9. 5016 mL/min flow = beats per minute × volume per beat 57 × 88 = 5016
  10. Different nutrients have different chemical structures and processing pathways. Nutrient classes differ chemically.
  11. 24 8 × 3 = 24 area units.
  12. A released chemical messenger interacting with receptors. Neurotransmitters bind to appropriate receptors.
07

LS Life Sciences

Genetics & inheritance

DNA, inheritance, genotypes and variation.

Short lesson: Monohybrid crosses with Punnett squares

Study guide for Grades 9 to 12: 2 worked examples and 2 practice questions. Write each parent’s two alleles along the sides of a 2 × 2 grid.

each parent gives one allele · 4 equally likely boxes

Write each parent’s two alleles along the sides of a 2 × 2 grid. Each box is one equally likely offspring genotype. A dominant allele hides a recessive one.

Worked example

In pea plants, the allele for a tall stem (T) is dominant over the allele for a short stem (t). Two plants, TT × Tt, are crossed. What percentage of the offspring are expected to show a short stem?

TT × Tt → TT, Tt, TT, Tt → 0/4 = 0%

Answer: 0 %

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 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?

  2. In the simple Aa × Aa inheritance model with independent outcomes, the probability of aa is 1/4. Among 456 offspring, find the expected aa count, not a guaranteed outcome. Round to 3 decimal places if needed.

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

    1. CTATACAGG
    2. GATATGTCC
    3. GAUAUGUCC
    4. CAUAUGUCC

  4. Which base is commonly used in RNA instead of thymine?

    1. Calcium.
    2. Adenine.
    3. Uracil.

  5. A fictional diploid organism has 12 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. In a canonical double-stranded DNA sample, adenine is 42% of all bases. Find the guanine percentage, assuming A = T and C = G. Round to 3 decimal places if needed. Answer in %.

  7. A diploid cell has 12 chromosomes. In the standard model, how many are in a haploid gamete?

  8. Which question is scientifically stronger?

    1. Which allele is morally better?
    2. Which genotype deserves more rights?
    3. What model and evidence explain the observed variation?

  9. For Aa × Aa, what fraction of offspring are expected to be aa in the simple model?

  10. Why is a sequence-answer question ambiguous if it ignores strand direction?

  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. In the simple Aa × Aa inheritance model with independent outcomes, the probability of aa is 1/4. Among 500 offspring, find the expected aa count, not a guaranteed outcome. Round to 3 decimal places if needed.

Answer key
  1. 50 % RR × Rr → RR, Rr, RR, Rr → 2/4 = 50%
  2. 114 expected aa count = offspring count × 1/4 456 × 1/4 = 114
  3. GAUAUGUCC CTATACAGG → GAUAUGUCC (A-U, T-A, C-G, G-C)
  4. Uracil. RNA commonly uses U where DNA uses T.
  5. 6 haploid chromosome count = diploid count/2 12/2 = 6
  6. 8 % G% = (100 − 2A%)/2 (100 − 2 × 42)/2 = 8
  7. 6 Half of 12 is 6.
  8. What model and evidence explain the observed variation? Genetic descriptions do not establish moral worth.
  9. 1/4 Each parent contributes a with probability one half, giving one quarter.
  10. A complementary sequence and a reverse complement can be written in different orders. The writing convention must be stated.
  11. 25 % Rr × Rr → RR, Rr, Rr, rr → 1/4 = 25%
  12. 125 expected aa count = offspring count × 1/4 500 × 1/4 = 125
Review worksheet: 12 questions

  1. In the simple Aa × Aa inheritance model with independent outcomes, the probability of aa is 1/4. Among 432 offspring, find the expected aa count, not a guaranteed outcome. Round to 3 decimal places if needed.

  2. In pea plants, the allele for purple flowers (P) is dominant over the allele for white flowers (p). Two plants, pp × pp, are crossed. What percentage of the offspring are expected to show purple flowers?

  3. A fictional diploid organism has 76 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.

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

    1. UGGCUUCC
    2. ACCGAATG
    3. UGGCUUAC
    4. TGGCTTAC

  5. In a canonical double-stranded DNA sample, adenine is 39% of all bases. Find the guanine percentage, assuming A = T and C = G. Round to 3 decimal places if needed. Answer in %.

  6. Which process produces RNA using DNA information?

    1. Translation.
    2. Transcription.
    3. Osmosis.

  7. Does dominant mean more common or biologically better?

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

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

  9. The same sample has 20% A and 20% T. What percentage is G if the remainder is equally C and G?

  10. Why does a smooth bell-shaped distribution not prove a particular number of genes?

  11. In the simple Aa × Aa inheritance model with independent outcomes, the probability of aa is 1/4. Among 620 offspring, find the expected aa count, not a guaranteed outcome. Round to 3 decimal places if needed.

  12. In pea plants, the allele for purple flowers (P) is dominant over the allele for white flowers (p). Two plants, pp × pp, are crossed. What percentage of the offspring are expected to have the genotype pp?

Answer key
  1. 108 expected aa count = offspring count × 1/4 432 × 1/4 = 108
  2. 0 % pp × pp → pp, pp, pp, pp → 0/4 = 0%
  3. 38 haploid chromosome count = diploid count/2 76/2 = 38
  4. UGGCUUAC ACCGAATG → UGGCUUAC (A-U, T-A, C-G, G-C)
  5. 11 % G% = (100 − 2A%)/2 (100 − 2 × 39)/2 = 11
  6. Transcription. Transcription copies sequence information into RNA.
  7. No. Dominance describes expression in the specified heterozygote model.
  8. 10 5 + 5 = 10.
  9. 30 % 100 − 40 = 60%, divided equally gives 30% G.
  10. Several genetic and environmental processes can produce similar distributions. Observation alone may not identify the mechanism.
  11. 155 expected aa count = offspring count × 1/4 620 × 1/4 = 155
  12. 100 % pp × pp → pp, pp, pp, pp → 4/4 = 100%

Related ready-made worksheets: Grade 10 Genetics & inheritance worksheet

08

LS Life Sciences

Ecology & populations

Ecosystems, food webs, populations and biodiversity.

Short lesson: Population estimate from supplied records

Study guide for Grades 10 to 12: 2 worked examples and 2 practice questions. Use supplied records only. Assume a closed population, equal capture probability, mixing and retained marks. The estimate has sampling uncertainty.

N ≈ MC/R

Use supplied records only. Assume a closed population, equal capture probability, mixing and retained marks. The estimate has sampling uncertainty.

Worked example

Supplied fictional records give M = 69 initially marked, C = 45 in a later sample, and R = 32 marked in that sample. Use N ≈ MC/R under the stated assumptions. No animals are to be handled. Round to 3 decimal places if needed.

N ≈ MC/R 69 × 45/32 = 97.031

Answer: 97.031

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 21% of 993 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. Supplied fictional records give M = 79 initially marked, C = 84 in a later sample, and R = 55 marked in that sample. Use N ≈ MC/R under the stated assumptions. No animals are to be handled. Round to 3 decimal places if needed.

  3. A supplied survey counts 155 plants in 12 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. Why can sampling only the greenest-looking patches bias a plant estimate?

    1. All samples are automatically random.
    2. Those patches may not represent the whole area.
    3. Plants have no spatial patterns.

  5. A fictional population starts at 864. During one interval: 19 births, 8 arrivals, 6 deaths and 27 departures. Find the final count. Round to 3 decimal places if needed.

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

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

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

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

  8. A supplied food-web model transfers 5% of 480 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.

  9. Supplied fictional records give M = 73 initially marked, C = 73 in a later sample, and R = 55 marked in that sample. Use N ≈ MC/R under the stated assumptions. No animals are to be handled. Round to 3 decimal places if needed.

  10. A supplied survey counts 194 plants in 7 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.

  11. Why should several quadrats be used rather than one?

  12. A fictional population starts at 256. During one interval: 80 births, 3 arrivals, 40 deaths and 22 departures. Find the final count. Round to 3 decimal places if needed.

Answer key
  1. 208.53 kJ transferred energy = available energy × stated efficiency/100 993 × 21/100 = 208.53
  2. 120.655 N ≈ MC/R 79 × 84/55 = 120.655
  3. 12.917 plants/m² density = total count / total sampled area 155/(12 × 1) = 12.917
  4. Those patches may not represent the whole area. Selection based on visible abundance can overestimate density.
  5. 858 N₂ = N₁ + births + immigration − deaths − emigration 864 + 19 + 8 − 6 − 27 = 858
  6. Immigration. Immigration is inward movement.
  7. It will most likely increase. With fewer predators eating it, the prey population is likely to increase at first.
  8. 24 kJ transferred energy = available energy × stated efficiency/100 480 × 5/100 = 24
  9. 96.891 N ≈ MC/R 73 × 73/55 = 96.891
  10. 13.857 plants/m² density = total count / total sampled area 194/(7 × 2) = 13.857
  11. Counts vary spatially, and repeated samples reveal variability. More samples may improve the estimate but do not fix a biased design by themselves.
  12. 277 N₂ = N₁ + births + immigration − deaths − emigration 256 + 80 + 3 − 40 − 22 = 277
Review worksheet: 12 questions

  1. A supplied survey counts 57 plants in 12 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.

  2. Supplied fictional records give M = 51 initially marked, C = 63 in a later sample, and R = 33 marked in that sample. Use N ≈ MC/R under the stated assumptions. No animals are to be handled. Round to 3 decimal places if needed.

  3. A supplied food-web model transfers 13% of 1102 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.

  4. A fictional population starts at 754. During one interval: 52 births, 16 arrivals, 12 deaths and 9 departures. Find the final count. Round to 3 decimal places if needed.

  5. In this simplified food chain: grass → mouse → snake → owl. What is the role of “snake” in this chain?

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

  6. Does a sample estimate equal a complete census?

    1. Only if rounded.
    2. Yes, always.
    3. No.

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

  8. A supplied survey counts 25 plants in 3 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.

  9. Supplied fictional records give M = 23 initially marked, C = 63 in a later sample, and R = 5 marked in that sample. Use N ≈ MC/R under the stated assumptions. No animals are to be handled. Round to 3 decimal places if needed.

  10. A supplied food-web model transfers 22% of 589 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.

  11. A fictional population starts at 855. During one interval: 74 births, 5 arrivals, 46 deaths and 13 departures. Find the final count. Round to 3 decimal places if needed.

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

    1. It will most likely increase.
    2. It will most likely decrease.
    3. It will not be affected at all.
Answer key
  1. 2.375 plants/m² density = total count / total sampled area 57/(12 × 2) = 2.375
  2. 97.364 N ≈ MC/R 51 × 63/33 = 97.364
  3. 143.26 kJ transferred energy = available energy × stated efficiency/100 1102 × 13/100 = 143.26
  4. 801 N₂ = N₁ + births + immigration − deaths − emigration 754 + 52 + 16 − 12 − 9 = 801
  5. secondary consumer Level 3 in this chain: secondary consumer.
  6. No. An estimate infers unobserved parts of the population.
  7. -15 30 − 45 = −15 individuals.
  8. 8.333 plants/m² density = total count / total sampled area 25/(3 × 1) = 8.333
  9. 289.8 N ≈ MC/R 23 × 63/5 = 289.8
  10. 129.58 kJ transferred energy = available energy × stated efficiency/100 589 × 22/100 = 129.58
  11. 875 N₂ = N₁ + births + immigration − deaths − emigration 855 + 74 + 5 − 46 − 13 = 875
  12. It will most likely increase. With fewer predators eating it, the prey population is likely to increase at first.

Related ready-made worksheets: Grade 10 Ecology & populations worksheet