QCAA Year 11 Biology Units 1 & 2 Master Revision Flashcards

Comprehensive vocabulary flashcards for QCAA Year 11 Biology Units 1 and 2, covering cell theory, biochemistry, physiology, homeostasis, and infectious disease.

Stem cell

An unspecialized cell capable of self-renewal and differentiating into one or more specialized cell types.

Totipotent

A stem cell potency level where the cell can form every cell type, including extra-embryonic tissues and a complete organism.

Fluid Mosaic Model

Represented as a phospholipid bilayer with various embedded proteins, where 'fluid' refers to the lateral movement of components.

SA:V Ratio

The relationship between surface area and volume, which limits cell size as volume increases faster than surface area, reducing exchange efficiency.

Amylase

A digestive enzyme that facilitates the breakdown of starch into smaller sugar molecules.

Nephron

The functional unit of the kidney responsible for filtration, reabsorption, and secretion.

Glomerulus

A capillary knot within the nephron where high hydrostatic pressure drives the filtration of blood.

Metabolism

The total sum of all chemical reactions occurring within an organism.

Activation energy

The minimum amount of energy required to initiate a chemical reaction, which enzymes function to lower.

Catabolism

Metabolic pathways that break down complex molecules into simpler ones, usually releasing energy.

Anabolism

Metabolic pathways that construct complex molecules from simpler ones, requiring an input of energy.

Aerobic Respiration

The process of breaking down glucose in the presence of oxygen to produce energy, summarized as $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$.

Glycolysis

The first stage of respiration occurring in the cytosol, splitting glucose into two pyruvate molecules with a net yield of $2\,\text{ATP}$.

Light-dependent reactions

The phase of photosynthesis occurring in the thylakoids where light is absorbed, water is split, and $O_2$, $ATP$, and $NADPH$ are produced.

Xylem

Plant tissue made of lignified, mostly dead cells that transports water and minerals upward from the roots.

Phloem

Living plant tissue consisting of sieve tubes and companion cells that translocates organic solutes from sources to sinks.

Homeostasis

The process of maintaining a relatively stable internal environment within set limits despite changes in the external surroundings.

Negative feedback

A homeostatic mechanism where the response results in the reduction or reversal of the original stimulus.

Resting potential

The negative membrane potential of a non-conducting neuron, typically measured at approximately $-70\,mV$.

Sodium-potassium pump

A membrane protein that uses $ATP$ to move $3\,Na^+$ out of the cell and $2\,K^+$ into the cell to maintain ion gradients.

Action potential

An all-or-none electrical impulse that travels along an axon when a stimulus depolarizes the membrane to a certain threshold.

Synapse

The junction where chemical neurotransmitters are released from a presynaptic terminal to bind receptors on a postsynaptic cell.

ADH (Antidiuretic Hormone)

A hormone released by the posterior pituitary that increases water reabsorption in the kidney collecting ducts by inserting aquaporins.

Prion

An infectious pathogen consisting of misfolded proteins that lacks a DNA or RNA genome.

Antigen

A molecule or structure recognized by immune receptors that can trigger an adaptive immune response.

MHC (Major Histocompatibility Complex) proteins

Surface molecules on body cells used by the immune system to distinguish self from non-self.

Inflammation

An innate immune response characterized by redness, heat, swelling, and pain, involveing the release of histamine and prostaglandins.

B lymphocytes

White blood cells of the adaptive immune system that produce specific antibodies during the humoral response.

Cytotoxic T cells

Adaptive immune cells that recognize and induce death in infected or abnormal cells displaying foreign antigens.

Active immunity

Long-term immunity acquired when the body's own immune system produces a response and memory cells following exposure to an antigen.

Passive immunity

Immediate but temporary protection gained from receiving pre-made antibodies, which does not result in the formation of memory cells.

Herd immunity

Indirect protection of a population that occurs when a high proportion of individuals are immune, making disease transmission difficult.

Quarantine

A disease control measure that restricts the movement of individuals who may have been exposed to a pathogen during the incubation period.