3.1 Living organisms and cells

PLANTS

• multi-cellular organisms
• cells contain chloroplasts so that they are able to carry out photosynthesis
• have cell walls made of cellulose
• store carbohydrates as starch or sucrose
• e.g. elodea

ANIMALS

• are multi-cellular organisms
• cells do not contain chloroplasts, so they do no photosynthesize
• no cell walls
• normally have nervous co-ordination and are able to move from one place to another
• store carbohydrates as glycogen
• e.g. lions, grasshopper

FUNGI

• unable to photosynthesize
• bodies are normally organised into mycelium - mycelium are made of thread-like structures called hyphae, which have many nuclei
• cell walls are made of chitin
• they feed by extra-cellular secretion of digestive enzymes into their surroundings, and absorb the organic products - this is known as saprotrophic nutrition
• store carbohydrate as glycogen
• some are single-celled e.g. yeast
• some are multi-cellular e.g. mucor

PROTOCTISTS

• microscopic single-celled organisms
• e.g. amoeba - have features of an animal cell, and live in pond water
• e.g. chlorella - have chloroplasts and are more like plants
• pathogenic e.g. plasmodium, which causes malaria