Edexcel A-Level Biology - Topic 1: Lifestyle, Health and Risk

Flashcards to review key concepts from Edexcel A-Level Biology Topic 1: Lifestyle, Health and Risk.

What happens to the surface area to volume ratio as the size of an organism increases?

Decreases

What happens to the diffusion distance as the size of an organism increases?

Increases

What happens to the metabolic rate as the size of an organism increases?

Increases

What are the four features of a mass transport system?

A network to move through, a medium for movement, controlled direction and maintenance of speed.

Why is water a polar molecule?

Uneven distribution of charge within the molecule, with hydrogen atoms having a partial positive charge and the oxygen atom having a partial negative charge.

What does cohesion and adhesion in water enable?

Enables effective transport of water and dissolved substances through xylem vessels.

Why is the impact of hydrogen bonding important in homeostasis?

It has a high heat specific capacity, meaning that a lot of energy is required to change its temperature, therefore minimising temperature fluctuations in living things.

What is the function of arteries and what structural feature helps with this function?

Carry oxygenated blood to the body tissues and have a small lumen to maintain high blood pressure.

What is the function of veins and what structural feature helps with this function?

Carry deoxygenated blood to the lungs (except the pulmonary vein) and have a large lumen to minimize resistance to flow.

What are the features of capillaries?

Are very small, have a narrow lumen, and possess a thin endothelium.

What are the four main blood vessels connected to the heart?

Pulmonary vein, aorta, vena cava, pulmonary artery

What is another name for the atrioventricular valves within the heart?

Mitral/tricuspid/bicuspid

What is the function of the septum in the heart?

Prevents oxygenated and deoxygenated blood from mixing.

What happens during atrial systole?

The atria contract forcing the atrioventricular valves open and blood flows into the ventricles.

What happens during ventricular systole?

Contraction of the ventricles causes the atrioventricular valves to close and semilunar valves to open, allowing blood to leave the left ventricle through the aorta and right ventricle through the pulmonary artery.

What happens during cardiac diastole?

Atria and ventricles relax, pressure inside the heart chambers decreases, causing semilunar valves in the aorta and pulmonary arteries to close, preventing backflow of blood.

What is atherosclerosis?

The hardening of arteries caused by the build-up of fibrous plaque called an atheroma.

What are the risk factors for atherosclerosis?

Genetics, age, diet, gender, high blood pressure, high cholesterol levels, smoking, physical inactivity and obesity

What conditions can atherosclerosis lead to?

Angina, stroke, myocardial infarction, and aneurysms.

What is the purpose of blood clotting (thrombosis)?

Prevents blood loss, prevents entry of disease-causing microorganisms, and provides a framework for repair.

Describe the process of blood clot formation.

Platelets attach to exposed collagen fibres and release thromboplastin triggering theconversion of prothrombin into thrombin, which then catalyses the conversion of fibrinogen into fibrin which forms a network trapping platelets and red blood cells.

How is energy balance related to weight change?

When a greater number of calories is burned through physical activity than is consumed it leads to weight loss. If fewer calories are burned than consumed it leads to weight gain.

What are the ways of determining healthy body weight?

Body mass index (BMI) and waist-to-hip ratio.

What are the three types of saccharides?

Monosaccharides, disaccharides, and polysaccharides.

What happens to water during a condesation reaction (when glycosidic bonds form connecting monosaccharides)?

A molecule of water is removed.

What are the two main isomers of glucose and where are they most commonly found?

Alpha glucose (most common in animals) and beta glucose (most common in plants).

What are examples of disaccharides and their constituent monosaccharides?

Maltose (glucose + glucose), sucrose (glucose + fructose), and lactose (glucose + galactose).

How is glycogen formed?

From molecules of alpha glucose joined together by 1,4 and 1,6 glycosidic bonds.

What are the two polysaccharides that form starch?

Amylose (unbranched chain of glucose molecules joined by 1,4 glycosidic bonds) and amylopectin (branched and made up of glucose molecules joined by 1,4 and 1,6 glycosidic bonds).

What is the structure of saturated lipids such as those found in animal fats ?

Do not contain carbon-carbon double bonds.

What is the structure of unsaturated lipids?

Contain carbon-carbon double bonds and melt at lower temperatures than saturated fats.

What are the properties of lipids?

Waterproof, compact, non-polar and insoluble in water, and conduct heat slowly.

Describe the the structure of Triglycerides.

Made of one molecule of glycerol and three fatty acids joined by ester bonds formed in condensation reactions.

How do phospholipids arrange themselves within membranes?

Form a bilayer in the cell membrane as heads face watery environments whereas the tails move away from them.

What are the two types of lipoproteins?

High density lipoprotein (HDL) and low density lipoprotein (LDL).

What are HDLs and what is their function?

formed from unsaturated fats, protein, and cholesterol; transports cholesterol from body tissues to the liver where it’s broken down.

What are LDLs and what is their function?

Is formed from saturated fats, protein, and cholesterol; transports cholesterol from the liver to the blood.

What are the medical treatments of CVD?

Anticoagulants, statins, platelet inhibitors, antihypertensives

What do statins do to treat CVD?

Reduce blood cholesterol levels by blocking the enzyme which produces cholesterol in the liver.

What are types of antihypertensives?

Beta blockers, diuretics, and ACE inhibitors.