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Worksheet 1

Characteristics and classification of life

IB MYP Biology · Cells and organisms · 30 marks · about 35 minutes

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NameClassDate
Answer in the spaces provided. Marks are shown in brackets; the parts follow the four MYP Sciences criteria. Use the mark scheme only after you have tried every question.

APart A — Knowing and understanding

Criterion A · 14 marks

1
State three characteristics of living organisms and define each one.[3 marks]
2
Explain why most biologists do not consider viruses to be living.[2 marks]
3
Put these groups in order from largest to smallest: genus, class, kingdom, species, family.[2 marks]
4
The Sumatran tiger is Panthera tigris sumatrae and the lion is Panthera leo. (i) Name the genus they share. (ii) Explain what the names tell you about their relationship. (iii) State one rule for writing scientific names.[3 marks]
5
Give two features that distinguish mammals from reptiles.[2 marks]
6
Explain how comparing DNA can show how closely related two species are.[2 marks]

BPart B — Inquiring and designing

Criterion B · 5 marks

Students collect six different leaves from the school garden and want to make a dichotomous key so that younger students can identify them.

7
Describe how the students should choose the questions for their key, and why.[3 marks]
8
Suggest how the students could test whether their key works.[2 marks]

CPart C — Processing and evaluating

Criterion C · 7 marks

A survey counted the number of species in each vertebrate class found in a national park.

Classfishamphibiansreptilesbirdsmammals
Number of species48213611243
9
Draw a bar chart of the data.[3 marks]
10
Calculate the percentage of the total vertebrate species that are birds.[2 marks]
11
Suggest one reason why the survey may have under-counted the number of amphibian species.[2 marks]

DPart D — Reflecting on the impacts of science

Criterion D · 4 marks

12
New species are still being discovered in Indonesia, often in forests threatened by logging or mining. Discuss why describing and naming new species is important for conservation, and whether scientists should delay publishing the location of rare species.[4 marks]
Mark scheme — 30 marks

1 [3]

  • Any three from MRS GREN, each with a correct definition, e.g. respiration: chemical reactions in cells that release energy from nutrients [3].

2 [2]

  • They are not made of cells / do not respire, feed or grow [1].
  • They can only reproduce inside a host cell [1].

3 [2]

kingdom, class, family, genus, species (2 marks; 1 mark for one error).

4 [3]

  • (i) Panthera [1]
  • (ii) Same genus, so closely related / recent common ancestor; different species [1].
  • (iii) Genus with capital letter, species lower case, in italics/underlined [1].

5 [2]

  • Mammals have hair/fur (reptiles have dry scales) [1].
  • Mammals feed young on milk / most give birth to live young (reptiles lay leathery eggs) [1].

6 [2]

  • The more similar the DNA base sequences [1]
  • the more recently they shared a common ancestor / the more closely related [1].

7 [3]

  • Use features that are clearly visible and do not vary much, e.g. leaf shape, simple or compound, edge smooth or toothed, vein pattern [1].
  • Each question must have only two answers (yes/no) [1].
  • Avoid size and colour, which change with age/season, so the key works for any leaf of that species [1].

8 [2]

  • Give the key and the leaves to other students who did not make it [1].
  • Check whether they identify every leaf correctly; revise unclear questions [1].

9 [3]

  • Classes on x-axis, number of species on y-axis with label [1].
  • Suitable scale [1].
  • Bars accurate, equal width, not touching (categorical data) [1].

10 [2]

  • Total = 260 [1].
  • 112 ÷ 260 × 100 = 43% [1].

11 [2]

  • Amphibians are small, hidden, often nocturnal or seasonal [1].
  • So surveys in the day or dry season may miss them; use night surveys/more sampling [1].

12 [4]

  • Species must be formally described/named before they can be legally protected or assessed as endangered [1].
  • Naming raises awareness and funding; helps understand biodiversity [1].
  • Publishing location may attract collectors/poachers (e.g. rare reptiles, orchids) [1].
  • Balanced judgement, e.g. share with authorities but delay/withhold precise public location [1].

For Parts B–D, credit any scientifically valid answer that meets the same point; the answers given are models, not the only acceptable wording.