B1 The nature and variety of living organisms

The characteristics of a plant

- Multicellular
-Contain chloroplasts for photosynthesis
-Cells have cell walls- made of cellulose
-Store carbohydrates as sucrose or starch

Flowering plants like:
-Cereals (e.g. maize)
-herbaceous legumes (e.g. peas and beans)

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The characteristics of an animal

-Multicellular
-No chloroplasts so no photosynthesis
-No cell walls on cells
-Most have some kind of nervous coordination, so they can respond rapidly to changes in the environment.
-Can usually move from one place to another
- Carbohydrates are stored as glycogen

- mammals (e.g. humans)
- insects (e.g. houseflies and mosquitoes)

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The characteristics of fungi

- Some are single celled
- Others have a body called a mycelium, which is made up of hyphae (thread-like structures) The hyphae contain lots of nuclei.
- Can't photosynthesise
- Their cells have cell walls made of chitin

- Most feed by saprotrophic nutrition- they secrete extracellular enzymes into the area outside their body to dissolve their food, so they can then absorb the nutrients

-They can store carbohydrates as glycogen

Examples:

- yeast - single celled fungus

- mucor - this is multi-cellular and has mycelium and hyphae

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The characteristics of a protoctists

- single celled and microscopic

- Some have chloroplasts and are similar to plant cells

- others are more liked animal cells

Examples:

- chlorella (plant cell like)

- amoeba (animal cell like) lives in pond water

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The characteristics of bacteria

- single celled and microscopic

- don't have a nucleus

- circular chromosome of DNA

- some can photosynthesise

- most bacteria feed off other organisms- both living and dead

Examples:

- Lactobacillius and bulgarious- can be used to make milk go sour and turn into yogurt- it's rod shaped.

- Pneumococcus- spherical (round) in shape

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The characteristics of viruses

- These are particles, rather than cells, and are smaller than bacteria

- They can only reproduce inside living cells. A virus is an example of a parasite- it depends on another organism to grow and reproduce

- They infect all types of living organisms

- They come in loads of different shapes and sizes

-They don't have a cellular structure- they have a protein coat around some genetic material (either DNA or RNA)

Examples:

- influenza virus

-Tobacco mosaic virus- this makes the leaves of tobacco plants discoloured by stopping them from producing chloroplasts

-HIV

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