characteristics of living organisms
1) Understand how living organisms share the following characteristics: nutrition, respire, excrete their waste, respond to their surroundings, move, control their internal conditions, reproduce, grow and develop
- Movement: can change position
- Reproduction: can produce offspring
- Sensitivity: can detect stimuli and respond to them
- Growth: can increase in mass
- Respiration: can produce energy aerobically or anaerobically
- Excretion: can remove toxic or waste from the body
- Nutrition: can absorb nutrients in order to use for growth and repair
variety of living organisms
2) Describe the common features shown by eukaryotic organisms: plants, animals, fungi and protoctists
- Eukaryotes: organisms that have a nucleus and organelles found within a membrane that performs specific roles.
- multicellular organisms;
- cells contain chloroplasts and able to carry out photosynthesis;
- cells have cellulose cell walls;
- they store carbohydrates as starch or sucrose.
- Examples include flowering plants, such as a cereal (for example, maize), and a herbaceous legume (for example, peas or beans).
- multicellular organisms;
- cells do not contain chloroplasts and not able to carry out photosynthesis;
- no cell walls;
- usually have nervous co-ordination and are able to move from one place to another;
- often store carbohydrate as glycogen.
- Examples include mammals (for example, humans) and insects (for example, housefly and mosquito).
- not able to carry out photosynthesis;
- body is usually organised into a mycelium made from thread-like structures called hyphae, which contain many nuclei;
- some are single-celled;
- cells have walls made of chitin;
- feed by extracellular secretion of digestive enzymes onto food material and absorption of the organic products; this is known as saprotrophic nutrition;
- may store carbohydrate as glycogen.
- Examples include Mucor, which has the typical fungal hyphal structure, and yeast, which is single-celled.
- microscopic single-celled organisms.
- some, like Amoeba, that live in pond water, have features like an animal cell;
- others, like Chlorella, have chloroplasts and are more like plants.
- A pathogenic example is Plasmodium, responsible for causing malaria.
3) Describe the common features shown by prokaryotic organisms such as bacteria
- Prokaryotes: organisms that lack a nucleus.
- are microscopic single-celled organisms
- have a cell wall, cell membrane, cytoplasm and plasmids
- lack a nucleus but contain a circular chromosome of DNA
- some bacteria can carry out photosynthesis but most feed off other living 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.
4) Understand the term pathogen and know that pathogens may include fungi, bacteria, protoctists or viruses
- Pathogens: disease-carrying organisms and can be fungi, bacteria or viruses.
- unicellular organisms or multicellular without specialised tissues.
- example amoeba, euglena
- are not living organisms.
- are small particles, smaller than bacteria;
- are parasitic and can reproduce only inside living cells;
- they infect every type of living organism
- have a wide variety of shapes and sizes;
- 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.