AQA Biology GCSE Topic 2: Organisation Flashcards

Vocabulary flashcards covering AQA Biology GCSE Topic 2: Organisation, including human digestive and circulatory systems, enzymes, health issues, and plant transport systems.

Tissue

A group of specialised cells with a similar structure and function, which can be made of more than one type of cell.

Organ

Formed from a number of different tissues working together to produce a specific function.

Organ system

A group of organs which work together to perform a certain function.

Digestive system

An organ system that breaks down large, insoluble food molecules into a form that can be absorbed by cells.

Glands

Organs like the salivary glands and the pancreas that produce digestive juices containing enzymes.

Enzymes

Biological catalysts; protein molecules that increase the rate of reaction without being used up.

Active site

A uniquely shaped area of an enzyme where the substrate binds.

Lock and Key Hypothesis

A simplified explanation of how enzymes work, where the substrate shape is complementary to the enzyme's active site.

Denatured

The state of an enzyme when its active site changes shape due to extreme pH or high temperature, preventing the substrate from fitting.

Optimum temperature for human enzymes

A range around $37\,^{\circ}\text{C}$ (body temperature).

Carbohydrases

Enzymes that convert carbohydrates into simple sugars.

Amylase

An enzyme produced in the salivary glands, pancreas, and small intestine that breaks down starch into maltose.

Proteases

Enzymes that convert proteins into amino acids, such as pepsin in the stomach.

Lipases

Enzymes produced in the pancreas and small intestine that convert lipids into fatty acids and glycerol.

Benedict’s test

A chemical test for sugars that turns brick red if they are present.

Iodine test

A chemical test for starch that turns blue-black if starch is present.

Biuret test

A chemical test for protein that turns purple.

Sudan III test

A test for lipids where a red layer forms on top of the solution.

Bile

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

Double circulatory system

A system where blood passes through the heart twice for every complete circuit: once to the lungs and once to the rest of the body.

Pacemaker

A group of cells in the right atrium that control the natural resting heart rate (around $70$ beats per minute).

Arteries

Blood vessels with strong muscular walls and elastic fibres that carry blood AWAY from the heart.

Veins

Blood vessels with wide lumens and valves that carry blood TOWARDS the heart at low pressure.

Capillaries

Vessels with walls that are one cell thick to enable substances to move between cells and the blood.

Alveoli

Air sacs in the lungs where gaseous exchange occurs, adapted with thin walls and a large surface area.

Plasma

The liquid component of blood that carries red blood cells, white blood cells, platelets, glucose, and waste products like urea.

Haemoglobin

A red pigment in red blood cells that binds to oxygen to form oxyhaemoglobin.

Platelets

Small fragments of cells without a nucleus that help blood clot at the site of a wound.

Coronary heart disease

A non-communicable disease where coronary arteries become blocked by fatty material, reducing oxygen supply to the heart.

Stents

Metal mesh tubes inserted into arteries to keep them open.

Statins

Drugs that decrease levels of LDL (bad) cholesterol to reduce the risk of heart attacks.

Communicable diseases

Infectious diseases caused by pathogens (bacteria, viruses, fungi) that are passed between people.

Causal mechanism

An explanation of how one factor influences another to prove causation rather than just correlation.

Benign tumour

Growths of cells contained within a membrane in one place that are not cancerous.

Malignant tumour

A cancerous growth that spreads to other tissues and can form secondary tumours via the bloodstream.

Xylem

Plant tissue made of dead cells and lignin that transports water and mineral ions from the roots to the leaves.

Phloem

Plant tissue with sieve plates that transports food substances in both directions via translocation.

Translocation

The movement of food substances made in the leaves up or down the phloem for use or storage.

Transpiration

The loss of water vapour from the leaves and stems of a plant due to evaporation at the stomata.

Guard cells

Kidney-shaped cells with thin outer and thick inner walls that control the opening and closing of stomata.