Biology CA1

What are the 8 characteristics shared by all living organisms? MRS C GREN

Movement, respiration, sensitivity (response), growth & development, reproduction, excretion, nutrition, and control of internal conditions

What are the levels of organisation in organisms?

Organelles → cells → tissues → organs → organ systems.

What are the main cell structures to know?

Nucleus, cytoplasm, cell membrane, cell wall, mitochondria, chloroplasts, ribosomes, vacuole.

What is the function of the nucleus?

Contains genetic material and controls cell activities.

Function of cytoplasm?

Site of chemical reactions.

Function of cell membrane?

Controls entry and exit of substances.

Function of cell wall?

Provides structure and support (in plants and bacteria).

Function of mitochondria?

Site of aerobic respiration

Function of chloroplasts?

Site of photosynthesis; contains chlorophyll.

Function of ribosomes?

Site of protein synthesis

Function of vacuole?

Stores cell sap; helps maintain turgor pressure in plants.

What structures are found in plant cells but NOT in animal cells?

Cell wall, chloroplasts, large permanent vacuole.

What structures are found in both plant and animal cells?

Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes.

What is a pathogen?

A microorganism that causes disease; includes fungi, bacteria, protoctists, and viruses.

Why are viruses not considered living?

They cannot reproduce independently; must reproduce inside host cells.

What are key features of viruses?

Very small; parasitic; infect all living organisms; no cellular structure; protein coat; contain DNA or RNA.

Examples of viruses?

Influenza, COVID 19, HIV

What are common features of plants?

Multicellular, contain chloroplasts, photosynthesise, cellulose cell walls, store carbohydrates as starch or sucrose.

Examples: Maize, peas, beans.

What are common features of animals?

Multicellular, no chloroplasts, no cell wall, cannot photosynthesise, nervous coordination, can move, store carbohydrates as glycogen.

Examples: Humans, housefly, mosquito.

What are common features of fungi?

Cannot photosynthesise; body is mycelium of hyphae (many nuclei); some are single-celled; chitin cell walls; saprotrophic nutrition; store carbohydrates as glycogen.

Examples: Mucor (hyphal), yeast (single-celled).

What are common features of protoctists?

Mostly microscopic single-celled organisms; some animal-like (Amoeba), some plant-like (Chlorella).

Pathogenic example: Plasmodium (causes malaria).

What are common features of bacteria?

Microscopic, single-celled; cell wall, cell membrane, cytoplasm, plasmids; no nucleus; circular DNA chromosome.