Study Notes
Cells are the basic building blocks of all living organisms, and they can be classified as either eukaryotic or prokaryotic. Eukaryotic cells, such as animal and plant cells, have a nucleus containing DNA, while prokaryotic cells, like bacteria, have DNA free in the cytoplasm. Eukaryotic cells — cells with a nucleus containing DNA. Example: Animal and plant cells are eukaryotic.
- Prokaryotic cells — cells without a nucleus, DNA is free in the cytoplasm. Example: Bacterial cells are prokaryotic.
- Micrometer (μm) — a unit of length equal to one millionth of a meter. Example: A micrometer is made up of 1000 nanometers (nm).
- Cell specialization — process by which cells develop different structures to perform specific functions. Example: Muscle cells are specialized for contraction.
- Diffusion — movement of molecules from a region of higher concentration to a region of lower concentration. Example: Oxygen diffuses from alveoli into blood.
- Osmosis — diffusion of water molecules through a partially permeable membrane from high to low water potential. Example: Water moves into plant cells making them turgid.
Exam Tips
Key Definitions to Remember
- Eukaryotic cells: Cells with a nucleus containing DNA.
- Prokaryotic cells: Cells without a nucleus, DNA is free in the cytoplasm.
- Diffusion: Movement of molecules from high to low concentration.
- Osmosis: Diffusion of water through a partially permeable membrane.
Common Confusions
- Confusing eukaryotic cells with prokaryotic cells.
- Misunderstanding the direction of osmosis and diffusion.
Typical Exam Questions
- What is the main difference between eukaryotic and prokaryotic cells? Eukaryotic cells have a nucleus; prokaryotic cells do not.
- How does diffusion differ from active transport? Diffusion is passive and moves particles from high to low concentration, while active transport requires energy and moves particles from low to high concentration.
- What happens to a plant cell in a hypotonic solution? The cell becomes turgid as water enters by osmosis.
What Examiners Usually Test
- Understanding of cell structures and their functions.
- Ability to explain processes like diffusion and osmosis.
- Differences between eukaryotic and prokaryotic cells.