Bio yr 9

Flashcards for Edexcel Biology GCSE Topic 1, focusing on key vocabulary and concepts from the lecture notes. The flashcards cover cell biology, microscopy, enzymes, and transport mechanisms.

Eukaryotic Cell

A type of cell that has a nucleus containing DNA, such as animal and plant cells.

Prokaryotic Cell

A smaller type of cell that does not have a nucleus, such as bacterial cells; contains a single circular strand of DNA and plasmids.

Organelle

A structure within a cell that has a specific function (e.g., cell membrane, nucleus).

Nucleus

Organelle in eukaryotic cells that contains DNA coding for a particular protein; enclosed in a nuclear membrane.

Cytoplasm

Liquid substance within a cell where chemical reactions occur and which contains enzymes and organelles.

Cell Membrane

The structure that controls what enters and leaves the cell.

Mitochondria

Organelles where aerobic respiration reactions occur, providing energy for the cell.

Ribosomes

Sites of protein synthesis; found on the rough endoplasmic reticulum.

Chloroplasts

Organelles in plant cells where photosynthesis takes place; contain chlorophyll pigment to harvest light.

Permanent Vacuole

An organelle in plant cells containing cell sap; functions to improve cell rigidity.

Cell Wall (Plant Cells)

The outer layer of plant cells made from cellulose which provides strength to the cell.

Cell Wall (Bacterial Cells)

The outer layer of bacterial cells made of a different compound, peptidoglycan.

Chromosomal DNA (circular)

Circular DNA found floating in the cytoplasm of bacterial cells.

Plasmids

Small rings of DNA found in bacterial cells that code for extra genes.

Flagella

Long, thin ‘whip-like’ tails attached to bacteria that allow them to move.

Differentiation

Process by which cells become specialized by gaining new sub-cellular structures to suit their role.

Sperm Cell

Specialized animal cell to carry the male’s DNA to the egg cell for successful reproduction (streamlined head, long tail, many mitochondria, acrosome with digestive enzymes, haploid nucleus).

Egg Cell

Specialized animal cell to accept a single sperm cell and develop into an embryo (special cell membrane, lots of mitochondria, large size and cytoplasm).

Ciliated Epithelial Cell

Specialized animal cell to waft bacteria (trapped by mucus) to the stomach (long, hair-like processes called cilia).

Root Hair Cell

Specialized plant cell to take up water by osmosis and mineral ions by active transport from the soil (large surface area due to root hairs, large permanent vacuole, many mitochondria).

Xylem Cell

Specialized plant cell to transport water and mineral ions up the plant from the roots to the shoots (hollow and joined end-to-end, lignin deposited in spirals).

Phloem Cell

Specialized plant cell to carry the products of photosynthesis (food) to all parts of the plant (sieve plates, energy supplied by companion cells).

Magnification

Enlargement of an image using a microscope.

Resolving Power

The ability to distinguish between two points; affects resolution (lower RP = more detail).

Light Microscope

Microscope that typically has a maximum magnification of 2000x and a resolving power of 200nm; used to view tissues, cells, and large sub-cellular structures.

Electron Microscope

Microscope that uses electrons to form an image; two types: scanning (3D images) and transmission (2D images, detailing organelles); magnification up to 2,000,000x and resolving power of 10nm (SEM) and 0.2nm (TEM).

Standard Form

A way of writing very large or small numbers using powers of 10.

Enzyme

A biological catalyst that increases the rate of reaction without being used up; protein molecule with a uniquely shaped active site where the substrate binds.

Active Site

The specific region of an enzyme where the substrate binds.

Substrate

The molecule that an enzyme acts upon.

Lock and Key Hypothesis

Simplified explanation of how enzymes work: the substrate's shape is complementary to the active site, forming an enzyme-substrate complex.

Enzyme Specificity

Enzymes can only catalyse reactions when they bind to a substrate that has a complementary shape.

Optimum pH

The pH at which an enzyme is most active (typically around 7, but can vary).

Optimum Temperature

The temperature at which an enzyme is most active (around 37 degrees Celsius in humans).

Denatured

When an enzyme's active site is changed due to high heat or non-optimal pH; the enzyme can no longer work.

Amylase

An enzyme that breaks down carbohydrates such as starch into simple sugars such as maltose. Can be tested for using iodine which will turn will turn blue-black if there starch is present.

Rate of Reaction

The speed at which an enzyme is working; calculated as change / time.

Carbohydrase

Enzymes that convert carbohydrates into simple sugars (e.g., amylase).

Protease

Enzymes that convert proteins into amino acids (e.g., pepsin).

Lipase

Enzymes that convert lipids (fats) into fatty acids and glycerol.

Macronutrients

Essential nutrients needed in large quantities: starch, reducing sugars, protein, and lipids (fats and oils).

Calorimetry

A way to measure the amount of ‘energy’ (calories) in food.

Diffusion

A form of passive transport where molecules move from an area of high concentration to one of low concentration.

Osmosis

The passive transport of water from a dilute solution to a more concentrated solution across a selectively permeable membrane.

Active Transport

A form of transport that requires energy (ATP) to move molecules against a concentration gradient.