1b: Variety of living organisms Flashcards
Describe the common features of plants and describe examples and their features
Multicellular organisms; their cells contain chloroplasts and are able to carry out photosynthesis; their cells have cellulose cell walls; they store carbohydrates as starch or sucrose.
Examples: flowering plants such as a cereal (example maize), and a herbaceous legume (peas or beans)
Describe the common features of animals and describe examples and their features
Multicellular organisms;their cells do not contain chloroplasts and are not able to carry out photosynthesis; they have no cell walls; they usually have nervous coordination and are able to move from one place to another; they often store carbohydrates as glycogen.
Examples include mammals (humans) and insects (housefly and mosquito)
Describe the common features of fungi and describe examples and their features
Organisms that are not able to carry out photosynthesis; their body is usually organised into a mycelium made from thread-like structures called hyphae, which contain many nuclei; some examples are single-celled; their cells have cell walls made of chitin; they feed by extracellular secretion of digestive enzymes onto food material and absorption of the organic products; this is known as saprotrophic nutrition; they may store carbohydrates as glycogen.
Examples include Mucor, which has a typical fungal hyphal structure, and yeast , which is single-celled.
Describe the common features of bacteria and describe examples and their features
Microscopic single-celled organisms; they have a cell wall, cell membrane, cytoplasm and plasmids; they lack a nucleus but contain a circular chromosome of DNA; some bacteria can carry out photosynthesis but most feed off other living things or dead organisms.
Examples include Lactobacillus bulgaricus, a rod-shaped bacterium used in the production of yoghurt from milk, and Pneumococcus, a spherical bacterium that acts as the pathogen causing pneumonia.
Describe the common features of protoctists and describe examples and their features.
Mostly microscopic single-celled organisms, although some, such as the seaweeds are large and multicellular. Some, like Amoeba, that live in pond water, have features like an animal cell, while others, like Chlorella, have chloroplasts and are more like plants. A pathogenic example is Plasmodium, responsible for causing malaria.
Describe the common features of viruses and describe examples and their features
Small particles, smaller than bacteria; they are parasitic and can reproduce only inside living cells; they infect every type of living organism. They have a wide variety of shapes and sizes; they have no cellular structure but have a protein coat and contain one type of nucleic acid, either DNA or RNA.
Examples include the tobacco mosaic virus that causes discolouring of the leaves of tobacco plants by preventing the formation of chloroplasts, the influenza virus that causes ‘flu’ and the HIV virus that causes AIDS.
What is a pathogen?
An organism or virus which causes a disease in another organism. Some fungi, protoctist, bacteria and all viruses are pathogens.
