AQA Biology: Digestion, Enzymes and Health

Comprehensive vocabulary flashcards covering the digestive system organs, enzymes, factors affecting enzyme activity, adaptations of the small intestine, and foundational health concepts.

Digestion

The breakdown of large, insoluble food molecules into small, soluble molecules that can be absorbed.

Absorption

The movement of digested nutrients, such as glucose and amino acids, through the small intestine wall into the blood.

Cell

The basic building block of a living organism.

Tissue

A group of cells with a similar structure and function.

Organ

Different tissues working together to perform a particular function.

Organ system

Organs working together to perform a specific function, such as the digestive system digesting and absorbing food.

Organism

The whole living thing, made up of its cooperating organ systems.

Oesophagus

A muscular tube that carries food from the mouth to the stomach.

Stomach

An organ that churns food and produces protease and hydrochloric acid, which kills bacteria and provides acidic conditions for stomach protease.

Liver

An organ that produces bile.

Gall bladder

An organ that stores bile before its release into the small intestine.

Pancreas

An organ that produces amylase, protease, and lipase, releasing them into the small intestine.

Small intestine

An organ that completes digestion and absorbs digested nutrients into the blood.

Large intestine

An organ that absorbs water from the remaining gut contents.

Rectum

The section of the digestive tract that stores faeces before excretion.

Anus

The opening through which faeces leave the body.

Bile

An alkaline substance made in the liver and stored in the gall bladder that neutralises stomach acid and emulsifies fats.

Emulsification

The process by which bile splits large fat droplets into smaller droplets, increasing the surface area for lipase and speeding up fat digestion.

Enzyme

A protein that acts as a biological catalyst to speed up a chemical reaction without being used up.

Substrate

The specific substance that an enzyme acts on.

Active site

The specific region of an enzyme that has a shape complementary to its substrate, allowing the substrate to fit and bind.

Amylase

A carbohydrase enzyme made in the salivary glands, pancreas, and small intestine that breaks down starch into sugars.

Protease

An enzyme made in the stomach, pancreas, and small intestine that breaks down proteins into amino acids.

Lipase

An enzyme made in the pancreas and small intestine that breaks down lipids (fats and oils) into fatty acids and glycerol.

Optimum temperature

The temperature at which an enzyme works fastest, which is around $37\,^\circ\text{C}$ for many human enzymes.

Denaturation

A process where high temperatures or extreme pH alter the shape of an enzyme's active site so the substrate is no longer complementary and cannot bind.

Optimum pH

The pH level at which an enzyme works fastest.

Villi

Tiny finger-like projections on the inner lining of the small intestine that provide a large surface area for rapid absorption of nutrients.

Health

A state of physical and mental well-being, not simply the absence of disease.

Communicable disease

An infectious disease caused by a pathogen that can spread between organisms.

Pathogen

A microorganism that causes infectious disease, classified in GCSE biology as bacteria, viruses, fungi, or protists.

Non-communicable disease

A disease that cannot be passed from one person to another, such as coronary heart disease or cancer.

Risk factor

A factor that increases the likelihood of developing a disease but does not guarantee it.