Unit 1 Topic 2 Biology 2025

Amylase

Enzyme that breaks down starch (a carbohydrate) into simple sugars.

Protease

Enzyme that breaks down proteins into amino acids.

Lipase

Enzyme that breaks down lipids (fats) into fatty acids and glycerol.

Chemical digestion

The breakdown of complex food molecules into simpler molecules using enzymes.

Villi

Finger-like projections in the small intestine that increase surface area for nutrient absorption.

Capillary

A small blood vessel where exchange of nutrients, gases, and wastes occurs between blood and tissues.

Surface area

A larger surface area increases the rate of absorption and exchange.

Thin membrane

A thin barrier reduces diffusion distance and speeds up exchange.

Rich blood supply

Maintains concentration gradients for efficient diffusion of substances.

Closed circulatory system

A system where blood is enclosed in vessels, allowing faster and more efficient transport.

Nutrient exchange

Movement of nutrients from the digestive system into the bloodstream and then into cells.

Transport system

The network (e.g., blood vessels) that moves materials to and from cells.

Plasma

The liquid part of blood that carries dissolved nutrients, hormones, and wastes.

Enzyme

A biological catalyst that speeds up chemical reactions without being used up.

Substrate

The molecule an enzyme acts upon.

Active site

The specific region of an enzyme where the substrate binds and the reaction occurs.

Enzyme-substrate complex

Temporary binding between enzyme and substrate during a reaction.

Catalyst

A substance that speeds up a chemical reaction.

Regulation

Control of enzyme activity to ensure reactions occur at the right time and rate.

Lock-and-key model

Enzyme fits exactly with its substrate, like a key in a lock.

Induced-fit model

Enzyme changes shape slightly to better fit the substrate.

Temperature

Affects the speed of enzyme activity; too high can denature enzymes.

pH

Each enzyme works best at a specific pH; extreme pH can denature the enzyme.

Inhibitor

A molecule that reduces or blocks enzyme activity.

Substrate concentration

Increasing this generally increases enzyme activity, up to a point.

Denaturation

Loss of enzyme shape (especially active site), making it non-functional.

Control variable

A factor kept constant during an experiment.

Independent variable

The factor changed to test its effect on enzyme activity.

Dependent variable

The factor measured (e.g. rate of reaction).

Rate of reaction

Speed at which substrates are converted to products by enzymes.