Biology Revision: Cells, Transport, and Microscopy

Vocabulary flashcards covering cell biology, membrane transport mechanisms, specialised cells, surface area to volume ratio, and microscopy principles.

Diffusion

The movement of particles from an area of high concentration to an area of low concentration requiring no energy, such as oxygen moving into cells.

Osmosis

The movement of water through a partially permeable membrane from a dilute solution to a more concentrated solution without requiring energy, such as water entering root hair cells.

Active transport

The process by which particles move from a low concentration to a high concentration against the concentration gradient, which requires energy from respiration.

Hypotonic solution

A solution that is more dilute outside compared with the inside of a cell, causing water to enter the cell.

Isotonic solution

A solution that has the same concentration as the inside of a cell, resulting in no net movement of water.

Hypertonic solution

A solution that is more concentrated outside compared with the inside of a cell, causing water to leave the cell.

Turgid

The firm, normal condition of a plant cell when water enters it in a hypotonic solution.

Plasmolysed

The condition of a plant cell when water leaves it in a hypertonic solution, causing the cell membrane to pull away from the cell wall.

Flaccid

The state of a plant cell when placed in an isotonic solution where there is no net movement of water.

Nucleus

A cell organelle that contains DNA and controls cell activities.

Cytoplasm

The gel-like substance in a cell where many chemical reactions take place.

Cell membrane

The barrier surrounding a cell that controls which substances enter and leave.

Mitochondria

Cell organelles that act as the site of aerobic respiration to supply energy.

Ribosomes

Small cellular structures that serve as the site of protein synthesis.

Cell wall

A rigid outer layer made of cellulose that supports and strengthens plant cells and helps prevent them from bursting when taking in water.

Chloroplasts

Plant organelles that contain chlorophyll and carry out photosynthesis to produce food for the plant.

Permanent vacuole

A plant cell organelle that contains cell sap and helps maintain cell turgor.

Prokaryotic cell

A smaller, simpler cell type found in bacteria that lacks a nucleus and has DNA free in the cytoplasm in a nucleoid region.

Eukaryotic cell

A larger, more complex cell type found in animals, plants, and fungi that possesses a nucleus enclosing its DNA.

Red blood cell

A specialised animal cell that carries oxygen using haemoglobin; it has a biconcave shape to provide a large surface area and contains no nucleus when mature.

Nerve cell

A specialised cell with a long axon designed to carry electrical impulses over long distances.

Sperm cell

A specialised reproductive cell featuring a tail for swimming, many mitochondria for energy, and an acrosome containing enzymes.

Palisade cell

A specialised plant cell packed with many chloroplasts to absorb light efficiently for photosynthesis.

Root hair cell

A specialised plant root cell with a long projection that increases surface area for absorbing water and mineral ions.

Xylem vessel

A plant transport tissue made of hollow, dead cells with lignified walls that transports water and mineral ions upwards.

Phloem

A plant transport tissue that transports dissolved sugars and other substances around the plant.

Muscle cell

A specialised animal cell that contracts to create movement and contains many mitochondria to supply energy.

Surface area to volume ratio (SA:V)

A measure given by $\text{SA:V ratio} = \frac{\text{surface area}}{\text{volume}}$; as a cell increases in size, its SA:V ratio decreases.

Transmission electron microscope (TEM)

An electron microscope where electrons pass through a thin specimen to reveal 2D internal detail inside the specimen.

Scanning electron microscope (SEM)

An electron microscope where an electron beam scans the surface of a specimen to provide 3D-like surface detail.

Magnification

A measure of how many times bigger an image is compared to the real object, calculated as $\text{Magnification} = \frac{\text{image size}}{\text{actual size}}$.

Resolution

The ability of a microscope to distinguish two close points as separate structures.