Organisation

Organ system

"Group of organs working together to perform a major function."

Tissue

"A group of similar cells working together to carry out a function."

Organ

"Structure made of tissues performing a specific function."

Organism

"A living thing made from many organ systems."

Digestive system purpose

"Break down large insoluble molecules into small soluble molecules that can be absorbed."

Mechanical digestion

"Physical breakdown of food by teeth and stomach muscles."

Chemical digestion

"Breakdown of food using enzymes."

Enzyme

"Biological catalyst that speeds up reactions without being used up."

Active site

"Region of an enzyme where the substrate binds."

Substrate

"The molecule an enzyme acts on."

Enzyme specificity

"Each enzyme fits only one substrate (lock and key)."

Optimum temperature

"Temperature where enzyme activity is fastest (usually 37°C in humans)."

Optimum pH

"pH where enzyme works best (varies: stomach = acid; small intestine = alkaline)."

Denaturation

"Change in enzyme shape so substrate no longer fits active site."

Amylase

"Breaks down starch → maltose. Produced in salivary glands

Protease

"Breaks down proteins → amino acids. Made in stomach

Lipase

"Breaks down lipids → fatty acids + glycerol. Made in pancreas and small intestine."

Bile

"Produced by liver

Emulsification

"Breaking lipids into tiny droplets to increase surface area for lipase."

Stomach

"Contains hydrochloric acid (kills pathogens) and protease for protein digestion."

Small intestine

"Absorbs nutrients; enzymes from pancreas complete digestion."

Large intestine

"Absorbs water from undigested food."

Peristalsis

"Wavelike muscular contractions that move food through the gut."

Heart

"Muscular organ that pumps blood around the body."

Double circulatory system

"Blood passes through the heart twice per circuit (lungs and body)."

Right side of heart

"Pumps deoxygenated blood to the lungs."

Left side of heart

"Pumps oxygenated blood to the body (more muscular wall)."

Vena cava

"Carries deoxygenated blood from body to heart."

Pulmonary artery

"Carries deoxygenated blood from heart to lungs."

Pulmonary vein

"Carries oxygenated blood from lungs to heart."

Aorta

"Carries oxygenated blood from heart to body."

Coronary arteries

"Supply heart muscle with oxygenated blood."

Coronary heart disease

"Coronary arteries blocked by fatty plaques reducing blood flow."

Stents

"Metal mesh tubes inserted into arteries to keep them open."

Statins

"Drugs lowering blood cholesterol to reduce plaque formation."

Pacemaker

"Cells in right atrium controlling heart rate."

Artificial pacemaker

"Electrical device correcting irregular heartbeats."

Arteries

"Carry blood away from heart; thick walls; small lumen; high pressure."

Veins

"Carry blood to heart; thin walls; large lumen; contain valves."

Capillaries

"Tiny vessels where exchange occurs; thin one-cell walls."

Blood plasma

"Liquid carrying CO₂

Red blood cells

"Carry oxygen using haemoglobin; biconcave; no nucleus."

White blood cells

"Fight infection using phagocytosis or antibody/antitoxin production."

Platelets

"Fragments that help blood clot."

Lungs

"Organs where gas exchange occurs."

Trachea

"Windpipe leading to bronchi."

Bronchi

"Large airways branching into lungs."

Bronchioles

"Small airways leading to alveoli."

Alveoli

"Air sacs where oxygen diffuses into blood and CO₂ diffuses out."

Alveoli adaptations

"Large surface area; moist walls; thin (one cell); good blood supply; steep diffusion gradient."

Non-communicable disease

"Cannot be spread; caused by lifestyle or genetics (e.g.

Benign tumour

"Non-cancerous; does not spread."

Malignant tumour

"Cancerous; invades tissues; spreads via blood."

Risk factors for disease

"Smoking

Smoking effects

"Damages lung lining; increases heart disease and cancer risk."

Obesity risks

"Type 2 diabetes

Alcohol risks

"Liver disease

Plant organ system

"Root

Epidermis

"Protective outer layer of leaf; often transparent."

Waxy cuticle

"Reduces water loss by evaporation."

Palisade mesophyll

"Packed with chloroplasts for photosynthesis."

Spongy mesophyll

"Air spaces for gas exchange."

Stomata

"Pores allowing gas exchange."

Guard cells

"Control opening and closing of stomata."

Xylem

"Transports water and minerals; one-way; dead cells; strengthened with lignin."

Phloem

"Transports sugars; two-way; living cells with companion cells."

Transpiration

"Evaporation of water from leaves causing water uptake in xylem."

Transpiration pull

"Continuous column of water pulled up due to evaporation."

Factors increasing transpiration

"High temperature

Translocation

"Movement of sugars through phloem."

Food test: starch

"Use iodine → positive = blue-black."

Food test: sugar

"Use Benedict’s solution + heat → green/yellow/brick-red."

Food test: protein

"Use Biuret solution → positive = purple/lilac."

Food test: lipids

"Use Sudan III/emulsion test → red layer forms."

Required practical: enzymes

"Investigate effect of pH on amylase using iodine to test starch breakdown."

Why control variables in enzyme practical

"Ensures a fair test: same temp

Human digestive enzymes practical result

"Higher enzyme activity at optimum pH; slower when denatured."

Heart dissection safety

"Use gloves

Why alveoli give fast gas exchange

"Large surface area

Cancer causes

"Genetics

Statins advantages

"Reduce heart attack risk

Statins disadvantages

"Side effects (muscle pain)

Artificial heart advantage

"Keeps patient alive when no donor is available."

Artificial heart disadvantage

"Risk of blood clots

Pacemaker advantage

"Corrects irregular heartbeat effectively."

Pacemaker disadvantage

"Requires surgery and maintenance checks."

Blood plasma role

"Transports nutrients

Red blood cell adaptations

"Biconcave shape

White blood cell types

"Phagocytes (engulf) and lymphocytes (make antibodies)."

Platelet function

"Trigger clotting at wounds to prevent blood loss."