Which of the following best describes what makes something 'alive'?

Living things carry out organized processes including metabolism, growth, response to stimuli, reproduction, and maintaining internal balance (homeostasis) Anything that moves and consumes energy is alive Living things must be able to think and communicate Anything made of carbon atoms is considered alive

What does cell theory state?

All living things are made of one or more cells, the cell is the basic unit of life, and all cells come from pre-existing cells Cells are only found in animals and plants, not in bacteria or fungi All cells are identical and perform the same functions Cells can appear spontaneously in nutrient-rich environments

What is the key difference between prokaryotic and eukaryotic cells?

Eukaryotic cells have a membrane-bound nucleus and complex organelles; prokaryotic cells have no nucleus — their DNA floats freely in the cytoplasm Prokaryotic cells are larger and more complex than eukaryotic cells Prokaryotic cells have a nucleus but no mitochondria Eukaryotic cells are only found in animals; plants have prokaryotic cells

What is metabolism?

All the chemical reactions taking place in a living cell or organism to sustain life — including breaking down food for energy and building new molecules The speed at which an organism moves or responds to its environment The process by which plants convert sunlight into food The way organisms exchange gases with their environment

What is homeostasis?

The ability of a living organism to maintain a stable internal environment despite changes in external conditions — for example, keeping body temperature at 37°C The process of organisms living in the same habitat without competing When all the cells in an organism divide at the same time The balance between producers and consumers in an ecosystem

Which types of organisms are made of only a single cell?

Bacteria, archaea, and many protists (like amoeba and paramecium) — they carry out all life functions within that one cell Only bacteria are single-celled; all other organisms have multiple cells Single-celled organisms do not have DNA since they are too simple Fungi are always single-celled; plants are always multicellular

What does it mean for an organism to 'respond to stimuli'?

Detecting a change in the environment (the stimulus) and reacting to it in a way that helps the organism survive — like a plant growing toward light or a person pulling their hand from a hot surface Only organisms with brains can respond to stimuli Responding to stimuli means moving from one place to another Stimuli only come from other living organisms, not from the physical environment

What is the difference between a plant cell and an animal cell?

Plant cells have a cell wall, chloroplasts, and a large central vacuole; animal cells have none of these, but animal cells do have centrioles that plant cells lack Animal cells are always larger than plant cells Plant cells have no nucleus because their chloroplasts do the same job Animal cells have a cell wall made of chitin instead of cellulose

What is a bacterial cell's structure like compared to a human cell?

A bacterial cell is much smaller, has no membrane-bound nucleus or complex organelles, and its single circular DNA chromosome floats in the cytoplasm Bacterial cells are larger than human cells because they need to contain everything in one cell Bacteria have the same organelles as human cells but arranged differently Bacteria have no DNA — they reproduce using RNA only

Why is the cell considered the 'basic unit of life'?

A cell is the smallest structure that can carry out all the processes required for life — metabolism, growth, response, and reproduction — below the cell level, these processes break down The cell is called the basic unit of life because all cells are identical Cells are basic because they are simpler than the molecules inside them The atom is the basic unit of life — cells are made of atoms