What Is Biology & Characteristics of Life

Question 1 (10 marks)

(a) Award 1 mark per characteristic correctly discussed (max 6 = up to 4 characteristics with evidence + reasoning). Expected:

• Growth — diameter 4→6 cm: supports living (increase in size). (1)
• Nutrition/Metabolism — absorbs liquid, releases gas suggests chemical reactions/gas exchange: supports living. (1)
• Homeostasis — internal temp tracks external, does NOT stabilise: argues against living (no self-regulation). (1)
• Reproduction — splitting produces growing copies resembles asexual reproduction: supports living. (1)
• Responsiveness/irritability — no response to poke/shake/light: argues against living. (1)
• (Movement/excretion may be mentioned — gas release = excretion, supports.) (1)

(b) Verdict: Undetermined / most likely non-living (2). Justify: it shows some criteria (growth, apparent reproduction) but crucially FAILS homeostasis and responsiveness — a genuine living thing should display all seven; growth + splitting can occur in non-living crystals/chemical systems. (Full marks for consistent verdict backed by the missing criteria.)

(c) 1 mark for valid test + 1 for expected "living" result. E.g. test for response to a stimulus over time / offer a nutrient and check for controlled uptake and metabolic waste / check for cells under a microscope. Living result = shows response OR contains cells as basic unit of life.

Question 2 (10 marks)

(a) Yes, functioning (1). Glucose rose to 8.5 at +30 (2) then returned to baseline 5.0 by +120 min — the return to the original set-point demonstrates regulation (1).

(b) Anabolic (1). Glycogen is a larger molecule built from smaller glucose units (1); anabolism = building complex molecules from simpler ones, requiring/storing energy (1).

(c) Catabolic (1). Catabolism breaks larger molecules into smaller ones and releases energy, whereas the anabolic reaction in (b) consumes/stores energy (1).

(d) Metabolism is simply the sum of chemical reactions; homeostasis is the maintenance of a stable internal set-point (1) — here glucose is actively returned toward ~5.0 mmol/L despite the disturbance from the meal, showing regulation, not just reaction (1).

Question 3 (10 marks)

(a) Smallest → largest (award 4 for fully correct; –1 per misplaced): oxygen atom → nerve cell → muscle tissue → heart (organ) → single frog (organism) → all frogs in pond (population) → whole pond community. (4)

(b) Emergent property = a new characteristic that appears at a higher level of organisation that is not present in the individual parts alone (2). Two valid examples (1 each), e.g.:

• Cells → tissue: coordinated contraction (muscle tissue contracts, a lone property vs single cell).
• Organs → organism: the whole frog can move, feed and reproduce — properties no single organ has.

(c) Demonstrates emergent properties / that the whole is more than the sum of parts (1): pumping arises from the organised arrangement of many cells into an organ, not from any single cell (1).

Question 4 (12 marks)

(a) E.g. "Seedlings watered with sugar-water will grow taller than seedlings watered with plain water." Must be testable & predictive. (2)

(b) Independent variable = type of water (sugar vs plain) (1); Dependent variable = plant height/growth (1); Controlled variables (2, any two): light, temperature, volume of water, soil type, seedling species/initial size. (2)

(c) The plain-water group is the control (1): it provides a baseline/comparison so any difference in growth can be attributed to the sugar rather than to watering itself (1).

(d) With n=1, results may be due to individual variation/chance, not the treatment (1); no repetition means no reliability and no way to spot anomalous results (1).

(e) A theory (1): a well-supported explanation backed by repeated evidence — it is not a mathematical law, and it is more than a single untested hypothesis (1). (Accept reasoned discussion that a claim/prediction alone is a hypothesis.)

Question 5 (8 marks)

(a) Population doubles each hour → exponential/geometric growth (1); a line graph would show an upward-curving (J-shaped) exponential curve, getting steeper over time (1).

(b) Total increase = 3200 − 200 = 3000 cells (2).

(c) $0.000002\text{ m} = 2\times10^{-6}\text{ m} = \mathbf{2\ \mu m}$ (since $1\ \mu m = 10^{-6}$ m). (2)

(d) 30 minutes = 30 × 60 = 1800 s; SI unit = second (s) (2).

[
  {"claim": "Total cell increase hour0 to hour4 is 3000", "code": "result = (3200 - 200 == 3000)"},
  {"claim": "0.000002 m equals 2 micrometres", "code": "result = (0.000002 / 1e-6 == 2)"},
  {"claim": "30 minutes equals 1800 seconds", "code": "result = (30 * 60 == 1800)"},
  {"claim": "Bacterial population doubles each hour (200,400,800,1600,3200)", "code": "vals=[200,400,800,1600,3200]; result = all(vals[i+1]==2*vals[i] for i in range(len(vals)-1))"}
]