Molecules, transport and health

Describe how atherosclerosis develops in blood vessels.

Damage to endothelium of artery.

Inflammatory response attracts white blood cells.

Cholesterol accumulates to form an atheroma.

Calcium salts and fibers build-up, forming a plaque and narrowing the lumen.

What is a condensation reaction?

A reaction where two molecules join together with the removal of water.

What is a hydrolysis reaction?

A reaction where a water molecule breaks a bond between two subunits.

What is the bond formed between two monosaccharides?

A glycosidic bond.

Which monosaccharides form maltose?

Two glucose molecules.

Which monosaccharides form sucrose?

Glucose and fructose.

Which monosaccharides form lactose?

Glucose and galactose.

What is the role of amylose in plants?

Energy storage; unbranched, compact for storage.

What is the structure of amylopectin?

Branched polymer of glucose; allows faster breakdown.

How is glycogen adapted for energy storage?

Highly branched; allows rapid release of glucose in animals.

What is the difference between saturated and unsaturated fatty acids?

Saturated have no C=C double bonds; unsaturated do.

What bond is formed in a triglyceride?

An ester bond between glycerol and fatty acid.

What is the cardiac cycle?

The sequence of events in one heartbeat, including atrial systole, ventricular systole, and diastole.

Why do animals need a heart and circulatory system?

To allow mass transport and overcome the limitations of diffusion.

How is the structure of an artery adapted to its function?

Thick muscular wall, elastic tissue, narrow lumen – withstand high pressure.

What is the function of capillaries?

Exchange of substances between blood and tissues.

How does the Bohr effect work?

CO₂ lowers haemoglobin's affinity for O₂, causing more oxygen to be released.

Why does fetal haemoglobin have higher affinity for oxygen?

To absorb oxygen from the mother’s blood across the placenta.

What are the stages of atherosclerosis?

Endothelial damage → inflammatory response → plaque formation → narrowed arteries → raised BP.

What triggers the blood clotting process?

Release of thromboplastin.

What does thromboplastin do?

Converts prothrombin into thrombin.

What does thrombin do?

Converts fibrinogen into fibrin.

What is the role of fibrin in clotting?

Forms a mesh to trap blood cells and form a clot.

What are free radicals?

Unstable molecules that can damage cells and contribute to atherosclerosis.

How do antioxidants reduce CVD risk?

They neutralise free radicals and reduce cell damage.

Why do people often misjudge health risks?

Media influence, personal experience, or lack of understanding leads to over/underestimation.

What is the difference between correlation and causation?

Correlation is a relationship between two variables; causation means one directly causes the other.

What is a reliable study?

One that gives consistent results when repeated.

What is a valid study?

One that measures what it’s supposed to measure.

What makes a study design reliable?

Large, random sample; controls; repeatability.

How do HDL and LDL differ?

HDL removes cholesterol from blood; LDL deposits cholesterol in artery walls.

Why is high LDL linked to CVD?

Increases plaque formation in arteries.

What is BMI?

Body Mass Index = weight ÷ height².

What is waist-to-hip ratio?

Waist circumference ÷ hip circumference; used to assess abdominal fat.

How do statins reduce CVD risk?

Lower LDL cholesterol by inhibiting its production in the liver.

What do antihypertensives do?

Lower blood pressure to reduce strain on arteries.

What do anticoagulants do?

Reduce clot formation by affecting clotting proteins.

What do platelet inhibitors do?

Prevent platelets from clumping and forming clot.

Explain how the structure of an artery wall helps it withstand and maintain high pressure.

Thick wall provides strength to withstand pressure.

Elastic fibers allow stretch and recoil to maintain pressure.

Smooth muscle can contract to constrict the lumen and maintian pressure.

What type of bond is between carbon and hydrogen in ribose?

Covalent bond.

Name the bond labelled L in maltose (1–4 glycosidic).

1,4‑glycosidic bond.

What reaction forms maltose from α‑glucose monomers?

Condensation reaction.

Which two monomers make up sucrose?

Glucose and fructose.

How many oxygen molecules can bind to one haemoglobin?

Four molecules.

What indicates haemoglobin’s quaternary structure?

Presence of more than one polypeptide chain.

Which ion is in the haem group (label H)?

Iron ion (Fe²⁺).

Explain why haemoglobin is globular using hydrophilic/hydrophobic terms.

Hydrophilic side chains are on the outside, forming H‑bonds with water.
Hydrophobic side chains are on the interior, avoiding water.
This arrangement makes the protein soluble and globular.

List four modifiable cardiovascular risk factors.

Smoking; high saturated-fat diet; obesity; lack of exercise.

Explain why a water molecule is polar.

Unequal sharing of electrons because oxygen is more electronegative than hydrogen.
This creates δ⁻ on O and δ⁺ on H, making water a dipole.

What is osmosis?

Movement of water from a region of higher water potential to lower water potential across a partially permeable membrane.

Explain how increased temperature might increase disease transmission in humans.

Warmer conditions allow pathogens (e.g., bacteria, viruses) to reproduce and survive more easily.
Vector activity (e.g., mosquitoes) increases at higher temperatures.
Increased human outdoor activity leads to more contact and disease spread.

Describe one way facilitated diffusion differs from simple diffusion.

Uses specific protein channels or carriers in the membrane (rather than lipid bilayer diffusion).

Outline two features of haemoglobin that allow efficient oxygen transport.

Quaternary structure with four polypeptide chains binds four O₂ molecules.
Iron (Fe²⁺) in the haem group binds oxygen reversibly.