Variety of Living Organisms

IGCSE Edexcel Biology
1.2 Eukaryotic Organisms
1.3 Prokaryotic Organisms
1.4 Pathogens and Viruses
Key Concepts: Eukaryotes include plants, animals, fungi, and protoctists. Prokaryotes are bacteria. Pathogens are organisms (or viruses) that cause disease.

Section A: Eukaryotic Organisms

1. Complete the table of features for eukaryotic groups. [8]
Group Key Features (write two) Example
Plants
Animals
Fungi
Protoctists
2. Classify each organism into its group (plant, animal, fungus, protoctist). [4]

a) Chlorella

b) Mucor

c) Human

d) Maize

Section B: Prokaryotic Organisms (Bacteria)

3. State four features of bacteria (prokaryotes). [4]
4. Explain two differences between bacteria and plants or animals. [4]

Section C: Pathogens and Viruses

5. Define the term pathogen and give two examples. [3]
6. State four features of viruses. [4]
7. Describe two differences between viruses and bacteria. [4]
Total marks: 31

Mark Scheme

1. Plants: multicellular, chloroplasts/photosynthesis, cellulose cell wall, starch/sucrose storage; Animals: multicellular, no chloroplasts, no cell wall, nervous coordination, glycogen; Fungi: mycelium of hyphae, chitin cell walls, saprotrophic, no photosynthesis, glycogen; Protoctists: single-celled, some animal-like (Amoeba), some plant-like (Chlorella) [8]
2. a) Protoctist b) Fungus c) Animal d) Plant [4]
3. Microscopic single-celled; cell wall, cell membrane, cytoplasm, plasmids; no nucleus; circular DNA; some photosynthetic/most heterotrophic; examples like Lactobacillus or Pneumococcus (any four) [4]
4. Any two: bacteria lack nucleus; smaller; have circular DNA and plasmids; not multicellular; different cell wall composition; plants/animals have membrane-bound organelles [4]
5. Pathogen: organism that causes disease [1]; examples: bacteria, fungi, protoctists, viruses (or named examples like Plasmodium, influenza, HIV) [2]
6. Not living; smaller than bacteria; protein coat; contain DNA or RNA; reproduce only inside living cells; parasitic (any four) [4]
7. Any two differences: viruses are not cells and lack cytoplasm/organelles; viruses only reproduce in host cells; bacteria are living cells with cell wall/membrane/cytoplasm; bacteria larger; bacteria have circular DNA and plasmids [4]