Characteristics of living organisms Flashcards
What must an object do to be considered living
Movement
Respiration
Sensitivity
Control
Growth
Reproduction
Excretion
Nutrition
What is an example of a non living agent
Viruses are a good example of non-living particles/agents
What are Eukaryotic organisms
Eukaryotic organisms can be multicellular or single-celled and are made up of cells that contain a nucleus with a distinct membrane
What are the main features of animals
They are multicellular
Their cells contain a nucleus with a distinct membrane
Their cells do not have cellulose cell walls
Their cells do not contain chloroplasts (so they are unable to carry out photosynthesis)
They feed on organic substances made by other living things
They often store carbohydrates as glycogen
They usually have nervous coordination
They are able to move from place to place
What are the main features of plants
They are multicellular
Their cells contain a nucleus with a distinct membrane
Their cells have cell walls made out of cellulose
Their cells contain chloroplasts (so they can carry out photosynthesis)
They feed by photosynthesis
They store carbohydrates as starch or sucrose
They do not have nervous coordination
What are the main features of fungi
They are usually multicellular but some are single-celled (e.g. yeast)
Multicellular fungi are mainly made up of thread-like structures known as hyphae that contain many nuclei and are organised into a network known as a mycelium
Their cells contain a nucleus with a distinct membrane
Their cells have cell walls made of chitin (chitinous cell walls)
Their cells do not contain chloroplasts (so they cannot carry out photosynthesis)
They feed by secreting extracellular digestive enzymes (outside the mycelium) onto the food (usually decaying organic matter) and then absorbing the digested molecules. This method of feeding is known as saprotrophic nutrition
Some fungi are parasitic and feed on living material
Some fungi store carbohydrates as glycogen
They do not have nervous coordination
Examples of fungi include: moulds, mushrooms, yeasts
What are the main features of protoctsts
They are mainly microscopic and single-celled but some aggregate (group together) into larger forms, such as colonies or chains of cells that form filaments
Their cells contain a nucleus with a distinct membrane
Some have features, such as cell walls and chloroplasts, making them more like plant cells e.g. green algae, such as Chlorella
This means some protoctists photosynthesise and some feed on organic substances made by other living things
They do not have nervous coordination
Examples of protoctists include: amoeba, Paramecium, Plasmodium, Chlorella
What are prokaryotes
organisms are always single-celled and do not contain a nucleus
Instead, the nuclear material of prokaryotic cells is found in the cytoplasm
Bacteria are prokaryotic organisms
how do bacteria feed
Bacteria feed in different ways:
Some bacteria can carry out photosynthesis despite having no chloroplasts. This is because they still possess chlorophyl and enzymes necessary to synthesize sugars from carbon dioxide.
Most feed on other living or dead organisms (if they feed on dead organic matter then they are known as saprobionts or decomposers)
What is a pathogen
A pathogen is any microorganism that causes disease in another organism (e.g. in plants or animals)
What are examples of pathogens
Bacteria
Fungi
Protoctists
Viruses
What are pathogenic fungi
Fungal diseases are much more common in plants than animals
Cattle ringworm and athletes foot are fungal diseases that exist on the surface of the skin
Fungal diseases in plants tend to be much more serious and can threaten entire crops
Black Sigatoka is a fungal disease in bananas
It spreads through the leaves of the plant, reducing its ability to photosynthesise
The lack of photosynthesis causes parts of the leaf to die; producing black streaks
Eventually, the whole leaf dies
