Life Science: Biology — Sample exam worked answers
Student exam paperA rehearsal paper with separate worked solutions; use it before the final.
16 questions · 32 points · suggested 90 minutes
Student instructions
- Suggested time: 90 minutes; allow breaks or accommodations and record them.
- Work independently with a calculator, blank paper and the reference relationships printed in this paper. Grades 9, 11 and 12 may also use the course-linked NYSED reference tables. Use no lesson notes or answer key during an assessed attempt.
- Show reasoning and units for written tasks. All supplied datasets are illustrative; do not present them as measurements you collected.
- Objective items: 1 point each. Written items: 3 points each, one per criterion. A parent or teacher marks the written work; the app never grades an explanation automatically.
- Sample exam: try the whole paper before opening the worked key, then revisit the linked chapters. The sample and final are different papers; this is a course assessment, not an official Regents examination.
Reference relationships
| Relationship or tool | Conditions |
|---|---|
| Cell geometry | Cube area=6L², volume=L³, area/volume=6/L. A geometry model simplifies actual shapes. |
| Genetic probabilities | Specify genotypes and the inheritance model. Each offspring is a probability event; ratios are not guaranteed small-family counts. |
| Population accounting | New population=old+births+immigration−deaths−emigration. |
| Energy transfer | Next-level production=available production×the supplied efficiency, not a universal fixed 10%. |
| Molecular pathways | Replication copies DNA; transcription makes RNA; translation makes polypeptide. Track matter and energy separately. |
Coverage and marks
| Chapter | Questions | Points |
|---|---|---|
| Investigating the Chemistry of Life | 1, 2 | 4 |
| Cells, Membranes & Exchange | 3, 4 | 4 |
| Body Systems, Signals & Homeostasis | 5, 6 | 4 |
| Matter & Energy in Living Systems | 7, 8 | 4 |
| Cell Division, Reproduction & Development | 9, 10 | 4 |
| DNA, Inheritance & Gene Expression | 11, 12 | 4 |
| Evolution, Ancestry & Biodiversity | 13, 14 | 4 |
| Ecosystems & Conservation Decisions | 15, 16 | 4 |
Parent / teacher marking guide
- Mark objective answers after submission. Written marks remain pending until a parent or teacher applies the three-point criteria.
- Accept scientifically equivalent wording and valid alternative methods. Award stated method credit for a correct model or substitution even if later arithmetic fails.
- A raw percentage describes this paper only; it is not a validated course grade or a certification. Review chapter-level evidence and the learner’s independent explanations.
- Record support and accommodations, save corrections and reassess with different tasks. Do not count copied solutions as independent mastery.
Question 1 · 1 point
To test temperature alone, which factor should also be kept comparable?
- Enzyme amount
- The measured reaction rate
- The graph height
- The conclusion
Worked answer
Enzyme amount
Changing enzyme amount would introduce another potential cause.
1 point for the correct objective answer; no written-method marks for this item.
Question 2 · 3 points
Explain why saying ATP provides energy because its bond is broken is incomplete.
Worked answer
Energy availability comes from the whole reaction and coupling mechanism, not bond breaking by itself.
Bond breaking requires an input of energy.
The full reaction forms new interactions and products; its overall free-energy change can be favorable and coupled to work.
Marking criteria
- 1 point: identify the appropriate model or mechanism for this task.
- 1 point: show the calculation or evidence in the worked steps: Bond breaking requires an input of energy.
- 1 point: reach a scientifically supported conclusion: Energy availability comes from the whole reaction and coupling mechanism, not bond breaking by itself.
Question 3 · 1 point
A researcher wants to see individual ribosomes, which are about 20 nanometers across. Why won't the best light microscope work?
- Its resolution limit (~200 nm) is far larger than a ribosome, so it cannot separate that fine detail no matter how much it magnifies
- Light microscopes cannot magnify past 100×
- Ribosomes are too large to fit in the field of view
- Light microscopes only work on living cells
Worked answer
Its resolution limit (~200 nm) is far larger than a ribosome, so it cannot separate that fine detail no matter how much it magnifies
Magnification and resolution are different. A light microscope's resolution stalls near 200 nm, so a 20 nm ribosome stays a blur; an electron microscope is needed.
1 point for the correct objective answer; no written-method marks for this item.
Question 4 · 3 points
Compare area/volume ratios for cubes of side 1 mm and 2 mm.
Worked answer
The larger cube has half the area per unit volume.
At 1 mm, area=6 and volume=1, ratio=6 mm⁻¹.
At 2 mm, area=24 and volume=8, ratio=3 mm⁻¹.
Marking criteria
- 1 point: identify the appropriate model or mechanism for this task.
- 1 point: show the calculation or evidence in the worked steps: At 1 mm, area=6 and volume=1, ratio=6 mm⁻¹.
- 1 point: reach a scientifically supported conclusion: The larger cube has half the area per unit volume.
Question 5 · 1 point
Homeostasis is best described as
- maintaining a stable internal environment despite changes outside
- the total lack of any internal change
- the process of a cell dividing
- the buildup of waste inside a cell
Worked answer
maintaining a stable internal environment despite changes outside
Homeostasis is the active maintenance of stable internal conditions (temperature, pH, glucose, water) even as the outside world changes.
1 point for the correct objective answer; no written-method marks for this item.
Question 6 · 3 points
A bacterial population contains rare resistant variants before treatment. Explain a possible population change after treatment.
Worked answer
Selection can increase resistance frequency; the drug need not intentionally create the useful variant.
Susceptible bacteria are reduced by the treatment.
Resistant survivors can reproduce, increasing the resistant proportion.
Marking criteria
- 1 point: identify the appropriate model or mechanism for this task.
- 1 point: show the calculation or evidence in the worked steps: Susceptible bacteria are reduced by the treatment.
- 1 point: reach a scientifically supported conclusion: Selection can increase resistance frequency; the drug need not intentionally create the useful variant.
Question 7 · 1 point
What is the main difference between ATP and ADP?
- ATP contains DNA while ADP does not
- They are identical molecules with different names
- ATP has three phosphate groups and ADP has two
- ATP has two phosphate groups and ADP has three
Worked answer
ATP has three phosphate groups and ADP has two
ATP has three phosphate groups; ADP has two. Hydrolysis forms ADP and inorganic phosphate.
1 point for the correct objective answer; no written-method marks for this item.
Question 8 · 3 points
Why can a green plant consume oxygen in darkness?
Worked answer
Respiration continues even when light-dependent photosynthesis stops.
Cells still need ATP for maintenance and work.
Aerobic respiration can continue using stored organic molecules when photosynthesis is not occurring.
Marking criteria
- 1 point: identify the appropriate model or mechanism for this task.
- 1 point: show the calculation or evidence in the worked steps: Cells still need ATP for maintenance and work.
- 1 point: reach a scientifically supported conclusion: Respiration continues even when light-dependent photosynthesis stops.
Question 9 · 1 point
Which is the correct order of the phases of mitosis?
- Anaphase, Metaphase, Prophase, Telophase
- Prophase, Metaphase, Anaphase, Telophase
- Metaphase, Prophase, Anaphase, Telophase
- Telophase, Anaphase, Metaphase, Prophase
Worked answer
Prophase, Metaphase, Anaphase, Telophase
The order is Prophase, Metaphase, Anaphase, Telophase — remembered as PMAT.
1 point for the correct objective answer; no written-method marks for this item.
Question 10 · 3 points
Why does a multicellular embryo need cell signaling as well as cell division?
Worked answer
Signaling organizes specialized tissues rather than only a larger pile of cells.
Division increases cell number.
Signals help coordinate which cells differentiate, move or grow in particular locations.
Marking criteria
- 1 point: identify the appropriate model or mechanism for this task.
- 1 point: show the calculation or evidence in the worked steps: Division increases cell number.
- 1 point: reach a scientifically supported conclusion: Signaling organizes specialized tissues rather than only a larger pile of cells.
Question 11 · 1 point
Which best describes the overall shape of a DNA molecule?
- A double helix — a twisted ladder
- A single straight line
- A flat triangle
- A solid sphere
Worked answer
A double helix — a twisted ladder
Two strands wind around each other to form the double-helix, or twisted-ladder, shape.
1 point for the correct objective answer; no written-method marks for this item.
Question 12 · 3 points
A liver cell increases transcription after a hormone signal without changing DNA sequence. Is this a mutation?
Worked answer
No; it is regulation of expression in the supplied scenario.
The described change is in gene use.
A mutation would require a sequence change, which the prompt excludes.
Marking criteria
- 1 point: identify the appropriate model or mechanism for this task.
- 1 point: show the calculation or evidence in the worked steps: The described change is in gene use.
- 1 point: reach a scientifically supported conclusion: No; it is regulation of expression in the supplied scenario.
Question 13 · 1 point
In evolutionary biology, an individual's 'fitness' is best measured by its
- physical strength
- body size
- lifespan
- number of surviving, fertile offspring
Worked answer
number of surviving, fertile offspring
Fitness means reproductive success — how many surviving, fertile offspring an individual leaves relative to others — not strength, size, or longevity.
1 point for the correct objective answer; no written-method marks for this item.
Question 14 · 3 points
In a tree, A and B share a recent node; C joins their branch at an older node. Which pair is most closely related?
Worked answer
A and B are the closest pair in the supplied tree.
Trace the shared ancestors rather than the page spacing.
A and B share the most recent node.
Marking criteria
- 1 point: identify the appropriate model or mechanism for this task.
- 1 point: show the calculation or evidence in the worked steps: Trace the shared ancestors rather than the page spacing.
- 1 point: reach a scientifically supported conclusion: A and B are the closest pair in the supplied tree.
Question 15 · 1 point
A bacterial colony starts with 200 cells and doubles every hour. Growing exponentially, how many cells are there after 4 hours?
Worked answer
3200 cells
N = 200 × 2⁴ = 200 × 16 = 3,200 cells.
1 point for the correct objective answer; no written-method marks for this item.
Question 16 · 3 points
Site A yields 12 species in 1 h; B yields 18 in 4 h. Can you confidently rank their richness?
Worked answer
No confident ranking follows from these counts alone.
Sampling effort differs and rare species need time to detect.
Use comparable effort or a method that accounts for detection before ranking.
Marking criteria
- 1 point: identify the appropriate model or mechanism for this task.
- 1 point: show the calculation or evidence in the worked steps: Sampling effort differs and rare species need time to detect.
- 1 point: reach a scientifically supported conclusion: No confident ranking follows from these counts alone.