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Flashcards · 4BI1 · Topic 1
The nature and variety of living organisms flashcards
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Topic 1: The nature and variety of living organisms
- The eight characteristics of living organisms
- Nutrition, respiration, excretion, growth, movement, sensitivity, reproduction, and control of internal conditions (homeostasis).
- Excretion (and how it differs from egestion)
- Excretion is the removal of the waste products of metabolism, substances the body itself produced. Egestion is undigested food leaving the gut; it was never absorbed, so it is not excretion.
- Growth
- A permanent increase in size and dry mass. Taking up water increases mass without being growth.
- Plant kingdom: key features and examples
- Multicellular, with chloroplasts and a cellulose cell wall; store starch and sucrose. Examples: flowering plants, ferns.
- Animal kingdom: key features and examples
- Multicellular, no cell wall, no chloroplasts; store glycogen; usually have nervous co-ordination. Examples: mammals, insects.
- Fungi: key features and examples
- Body of thread-like hyphae forming a mycelium; cell wall made of chitin; saprotrophic nutrition; store glycogen; no chloroplasts. Examples: Mucor, and yeast (single-celled).
- Describe saprotrophic nutrition, in the right order
- Enzymes are secreted onto the food, digestion happens outside the organism, then the soluble products are absorbed. Digestion first, absorption second.
- Protoctists: key features and examples
- Microscopic and single-celled, with a nucleus; some are plant-like (with chloroplasts) and some animal-like. Examples: Amoeba, Chlorella, Plasmodium.
- Prokaryotes (bacteria): key features and examples
- Single-celled, no nucleus; circular DNA and plasmids. Examples: Lactobacillus, Pneumococcus.
- Why are viruses not classed as living organisms?
- They have no cellular structure (no cytoplasm or organelles), only genetic material (DNA or RNA) inside a protein coat, and they can only reproduce inside a living host cell. Examples: influenza virus, HIV, tobacco mosaic virus.
- Pathogen vs vector, using malaria as the example
- The pathogen is the organism that causes the disease: Plasmodium, a protoctist. The vector carries and transmits it: the mosquito.
- Which kingdoms store starch, and which store glycogen?
- Plants store starch (and sucrose). Animals and fungi store glycogen.