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Topic 1 Practice Paper: Characteristics and classification of living organisms — mark scheme

QuizQuipPractice Series
QQ/IGCSE-BIO/T1

IGCSE · Cambridge IGCSE Biology (Extended (Core + Supplement))

Mark scheme

Characteristics and classification of living organisms

Topic 1 Practice Paper · Maximum mark: 30

Notes for markers

  • Award one mark for each point marked [1], up to the marks shown for the part.
  • Accept answers worded differently that show the same understanding.
  • Units are required where the answer line shows one. ecf: allow an error carried forward.

Section A: Multiple-choice questions[10 marks]

QuestionAnswer
1BNutrition is the intake of materials that supply energy and building blocks for growth and development.1
2CCarbon dioxide is a waste product of the chemical reactions of respiration inside cells, so its removal is excretion.1
3AEach step of the key offers two contrasting statements, one of which is true for the organism being identified.1
4DDry scaly skin and land-laid leathery eggs are the defining features of reptiles.1
5BThe binomial system lists the genus first, capitalised, followed by the lower-case species name.1
6CDetecting a change in the environment (drying soil) and responding to it is sensitivity.1
7DCrustaceans, such as crabs and woodlice, have at least five pairs of legs and two pairs of antennae.1
8AA unicellular organism without a nucleus is a prokaryote; protoctists are unicellular but have nuclei.1
9BA species is a group that can reproduce to produce fertile offspring — the mule is sterile, so the parents stay separate species.1
10CSimilar base sequences mean fewer mutations have accumulated, so the species share a more recent common ancestor.1

Section B: Structured questions[20 marks]

QuestionAnswer and marking pointsMarks
11(a)

Respiration — the chemical reactions in cells that break down nutrient molecules and release energy for metabolism.

  • respiration [1]
  • chemical reactions in cells that break down nutrient molecules and release energy [1]
2
11(b)

Urine contains urea, a waste product made by the liver from the metabolism of excess amino acids, and excretion is the removal of waste products of metabolism. Faeces are undigested food that was never involved in cell metabolism, so passing them out is egestion.

  • urine contains urea, a waste product of metabolism [1]
  • excretion = removal of waste products of metabolism [1]
  • faeces are undigested food, so their removal is egestion [1]
3
11(c)

A temporary gain in water increases size and mass without growth; only a permanent increase in size and dry mass is growth.

  • water gain can increase size without any permanent growth, so dry mass shows real growth [1]
1
Total for Question 116
12(a)

P is a plant; Q is a prokaryote (bacterium); R is a protoctist; S is a fungus.

  • P plant (cellulose walls and chloroplasts) [1]
  • Q prokaryote (no nucleus, wall not cellulose) [1]
  • R protoctist (unicellular with a nucleus) [1]
  • S fungus (chitin cell wall, no chloroplasts) [1]
4
12(b)

Animals are multicellular, but R is unicellular (with a nucleus and no cell wall), so it fits the protoctists.

  • animals are multicellular [1]
  • R is unicellular, so it remains a protoctist [1]
2
12(c)

Viruses are not cells — they are only a protein coat around genetic material, so they lack the cell features used to define the kingdoms.

  • viruses are not cells / only a protein coat with genetic material [1]
1
Total for Question 127
13(a)

Each of W, Y and Z has 3 pairs of legs, and 3 pairs of legs with one pair of antennae and a 3-part body defines the insects.

  • W, Y and Z each have 3 pairs of legs [1]
  • 3 pairs of legs (+ 1 pair antennae, 3 body sections) is the insect defining feature [1]
2
13(b)

Arachnids have no antennae (and four pairs of legs); if X truly has no antennae it matches arachnid rather than insect features, so the label should be checked.

  • arachnids have no antennae [1]
  • an insect has one pair of antennae, so X does not fit the insect description [1]
2
13(c)

Example: 1 (a) antennae absent → X; (b) antennae present → go to 2. 2 (a) wings absent → W; (b) wings present → go to 3. 3 (a) wings spotted → Y; (b) wings plain → Z.

  • first step separates X with two contrasting statements [1]
  • later steps separate W, Y and Z one at a time [1]
  • every step has exactly two contrasting statements and ends at one specimen each [1]
3
Total for Question 137

— End of mark scheme —