Edexcel International GCSE Biology Section 1: The Nature and Variety of Living Organisms Exam Questions

About Edexcel International GCSE Biology Section 1: The Nature and Variety of Living Organisms

Section 1 opens Edexcel International GCSE Biology and is examined across Paper 1 and Paper 2. It sets out the characteristics shared by all living organisms and the features of the main groups: plants, animals, fungi, bacteria, protoctists and viruses, using named examples from the specification. It is short but underpins the whole course, especially cell structure in Section 2 and the use of microorganisms in Section 5. Examiners often ask you to identify a group from a description, compare structures such as hyphae and plasmids, and explain why viruses are not considered living cells.

What you need to know

• Characteristics of living organisms All living organisms require nutrition, respire, excrete waste, respond to their surroundings, move, control their internal conditions, reproduce and grow and develop.
• Plants Multicellular organisms with chloroplasts that photosynthesise. Cells have cellulose cell walls and store carbohydrates as starch or sucrose. Examples: flowering plants such as a cereal (maize) and a herbaceous legume (peas or beans).
• Animals Multicellular organisms without chloroplasts that cannot photosynthesise. Cells have no cell walls, they usually have nervous coordination, can move from place to place and often store carbohydrate as glycogen. Examples: mammals (humans) and insects (housefly and mosquito).
• Fungi Cannot photosynthesise; the body is usually a mycelium of thread-like hyphae containing many nuclei. Cell walls are made of chitin. They feed by saprotrophic nutrition, secreting extracellular enzymes and absorbing the products, and may store glycogen. Examples: Mucor and yeast (single-celled).
• Bacteria Microscopic single-celled organisms with a cell wall, cell membrane, cytoplasm and plasmids, and no nucleus but a circular chromosome of DNA. Some photosynthesise but most feed off other organisms. Examples: Lactobacillus bulgaricus (makes yoghurt) and Pneumococcus (causes pneumonia).
• Protoctists Microscopic single-celled organisms; some, like Amoeba, have features like animal cells, while others, like Chlorella, have chloroplasts and are more like plants. Plasmodium is a pathogenic protoctist that causes malaria.
• Viruses and pathogens Viruses are small particles, smaller than bacteria, that are parasitic and can only reproduce inside living cells. They have a protein coat around DNA or RNA. Examples: tobacco mosaic virus, influenza virus and HIV. Pathogens can be fungi, bacteria, protoctists or viruses.

Common mistakes in Section 1: The Nature and Variety of Living Organisms

• Saying fungi photosynthesise or are plants. Fungi cannot photosynthesise and feed by saprotrophic nutrition.
• Saying fungal cell walls are made of cellulose. Fungal cell walls are made of chitin.
• Saying bacteria have a nucleus. Bacteria have a circular chromosome free in the cytoplasm, plus plasmids.
• Saying viruses are cells or that they reproduce by dividing. Viruses are particles that can only reproduce inside host cells.
• Mixing up the storage carbohydrates. Plants store starch or sucrose; animals and fungi store glycogen.

Try three Section 1: The Nature and Variety of Living Organisms exam-style questions