Biology- Lifestyle, health and risk

Topic 1 of A-Level Biology.

Explain diffusion

Movement of particles with the concentration gradient (high to low)

Requires no energy

Explain osmosis

Movement of water from a low to high concentration

Across a semi-permeable membrane

Requires no energy

Explain active transport

Movement acros the concentration gradient

Requires energy

Transport in small unicellular organisms

Substances can be moved by diffusion

Across short distances

Diffusion is fast enough to meet the organism’s requirements

Transport in complex multicellular organisms

Rely on mass transport systems

Over long distances

MASS FLOW

Explain open circulatory systems

Blood circulates in large open spaces

Heart pumps blood into cavities surrounding the animal’s organs

Substances diffuse between the blood and cells

When the heart muscle relaxes, blood is drawn from the cavity, back into the heart through small, valved openings along it’s length

Explain closed circulatory systems

Blood is enclosed within tubes (blood vessels)

Generates a higher blood pressure a the blood is being forced along narrow channels instead of flowing into cavities

Blood travels faster and more efficiently

Show the dipole nature of a water molecule

Explain hydrogen bonds

Formed due to the dipole nature

Weak attractions

To evaporate water, they have to break which requires lot of energy because there are lots of them.

Why is water a good habitat?

Takes a lot of energy to change the temperature of the water (due to hydrogen bonds and high shc) so the water temp doesn’t fluctuate much

Explain why water is a good transport medium

A liquid= flows

The molecules form bonds with each other (cohesion) so water flows in a masss flow system

Water form bonds with other molecules (adhesion)

What are the functions of each part of the heart?

1. Right Atrium: Receives deoxygenated blood from the body via the superior and inferior vena cava.

2. Right Ventricle: Pumps deoxygenated blood to the lungs through the pulmonary arteries for oxygenation.

3. Left Atrium: Receives oxygenated blood from the lungs via the pulmonary veins.

4. Left Ventricle: Pumps oxygenated blood to the rest of the body through the aorta.

Differences between dicuspid and tricuspid valves

Dicupid: has two cusps, located on the left side

Tricupid: has three cusps, located on right side

What is the order of which blood travels?

Arteries → arterioles → capillaries → venules → veins

Explain the structure of an artery

Thick walls with more collagen, smooth muscle and elastic fibres

No valves (minus the aorta and pulmonary artery)

High pressure of blood

Explain the structure of veins

Thin walls with less collagen and smooth muscle, fewer elastic fibres

Has valves

Low pressure of blood - back to the heart

Explain the structure of capillaries

Walls are one cell thick for diffusion

Low pressure arterioles and venules

Explain what happens during diastole

The heart is relaxed

Elastic recoil causes a low presure in the heart, helping to refill all the chambers with blood

Explain what happens during atrial systole

The atria contrsct, forcing blood into the ventricles

Pressure from the atria force the atrioventricular valves open and blood through.

Explain what happen during ventricular systole

Contraction of the ventricles pushes blood up into the pulmonary artery and aorta

High blood pressure forces the semilunar valves open

Explain the proces of the formation of atherosclerosis

Damage to the endothelium (inner lining of blood vessels)

Cholesterol penetrates the damaged endothelium and accumulates in the arterial wall.

The body responds to the accumulation by sending white blood cells (macrophages) to engulf the LDL, leading to inflammation.

Dead cells, cholesterol, and other substances form a fatty streak, which evolves into a fibrous plaque.

The plaque hardens and narrows the arteries, restricting blood flow.

What are the four things needed for blood clotting?

Platelet, Clotting factors, Fibrin, Other cells

What is the process of how your body forms a clot?

Damaged blood vessel → platelets trapped → thromboplastin → prothrombin → thrombin → fibrogen → fibrin → mesh → platelets trapped → clot is formed

What is the process of the whole formation of atheroclerosis to a blood clot forming?

Artery wall damaged → inflammatory response → large white blood cells enter the wall → cholestrol accumulates → atheroma forms → calcium salts and fibrous tissue accumulate → hard plaque forms → wall elasticity reduced → artery narrows → raising blood pressure → atherosclerosis → platerlets in contact with damaged artery wall → platelets become sticky → platelet plug forms → thromboplasitin released from platelets/damaged tissues → cascade of chemical changes → prothrombin → thrombin → fibrogen → fibrin → mesh → platelets trapped → clot is formed

Define Risk

The probability of occurence of some unwanted effect or outcome.

Define Hazard

Anything that can potentially cause harm

Define Probablility

A precise mathmatical meaning and can be calculated to give a numerical value for the risk.

Whats the difference between causation and correlation

Causation refers to a relationship where one event directly affects another, while correlation is when one variable changes, the other variable tends to change as well, but without a direct cause-and-effect relationship.

Whats the Spearmans rank calculation

Explain a cohort risk study

A cohort risk study is a type of observational study where a group of individuals with shared characteristics is followed over time to assess their health outcomes and the effects of specific risk factors. Takes a very long time and can be expensive.

Explain case-control studies

A case-control study is a type of observational study that compares individuals with a specific condition or outcome (cases) to those without it (controls) to identify potential risk factors or causes.

What makes a good study?

A representative sample, valid results, reliable results, sample size and controlling variables

Standard deviation equation

What does a large or small standard deviation tell us?

A large standard deviation= values are far from the mean, low reliability

A small standard devaition= value are close to the mean, high reliability.

Ethical issues that arise using organisms in experiments

Against= animals cant give verbal or informed consent

For= animals can make their decisions by physically resisting what they’re being tested for

Define blood pressure

the measure of hydrostatic force of the blood against the walls of the blood vessel

High blood pressure can be affected by…

• tissue fluid and oedema

• high salt diet

• loss of elasticity in capillary walls

• high adrenaline levels

• large surface area of blood vessels

Explain how oedema forms/what it is

More excess fluid builds up in tissues which caues swelling. It can be a sign of high blood pressure. Tissue fluid is formed at the arterial end of a capillary where the blood is under pressure. This forces fluid and small molecules into the gaps in the cells of the capillary wall into the inetermolecular pace, forming tissue fluid.

What is a monosaccharide and what does it look like?

A single sugar unit

What is a disaccaride and what does it look like?

Two single sugar units combined

What is a polysaccharide and what does it look like?

A long straight or branched chain of sugar units

What does alpha glucose look like?

What is starch made of?

Amylose and Amylopectin which are both polymer of alpha glucose

Explain Amylose

Its an unbranched chain with 1,4 glycosidic bonds and is a polymer of alpha glucose.

Explain Amylopectin

Its a branched chain with 1,6 and 1,4 bonds. Its a polymer of alpha glucose.

Explain Glycogen

• glucose chain joined by 1,6 and 1,4 glycosidic bonds which allows it to have branches

• its stored in the liver and mucus

Whys are glycogen and starch goofd for storage?

• the glycosidic bonds can be hydrolised to release glucose molecules

• the glucose can be used for respiration to release enegry

• glycogen and starch are branched so there lots of terminal end to releae glucose.

Explain saturated fats

• said to contain the max amount of hydrogen atoms

• the hydrogen chian is long and straight

• there are no carbon-carbon double bonds in the fatty acid chains

• they can pack together closely

• the intermolecular bonds between triglycerides result in fats that are solid at room temperature

Explain unsaturated fats

• they have one double bond between two carbon atoms in each fatty acid chain

• larger number of double bonds that cause a kink in the hydrocarbeon chain, preventing them from packing too close

• can be made solid at room temp by adding hydrogen

Give a brief overview of blood cholesterol

• 25% form food and 75% from the liver

• vital component of cell membranes

• make up some growth hormones and steroid sex hormones

• used to make bile salts

Explain what LDLs (low-density lipoproteins) are

• Transport cholesterol through the bloodstream.

• Known as "bad cholesterol" because high levels can lead to artery-clogging plaques.

• LDLs deliver cholesterol to cells for essential functions like building cell membranes.

• Excess LDL result in high blood cholesterol and may be deposited in artery walls forming atheromas

Explain what HDLs (high-density lipoproteins) are

• They have a higher level of protein and less cholesterol, reulting in higher density

• Made when triglycerides combine with cholesterol and protein

• They transport cholesterol

• When broken down they lower blood cholesterol

How does smoking increase risk of CHD

• Carbon monoxide binds to haemoglobin instead of oxygen resulting in an increased heart rate

• Nicotine stimulate adrenaline and cause arteries to restrict, raiing blood pressure

• Numerous chemical damage the artery walls and trigger atherosclerosis

How does high blood pressure increase risk of CHD

Increases the risk of athersclerosis which increase the risk of CHD

How does inactivity increase risk of CHD

• Raises blood pressure and lowers HDL

• Higher chance of developing type 2 diabetes

• Lower chance of surviving a heart attack or stroke

How does salt increase risk of CHD

• High levels cause the kidney to retain water

• High fluid levels in blood causes elevated blood pressure and cardiovascular disease risks

How does stress increase risk of CHD

• Sometimes linked to poor stress management

• High stress raises adreanaline which causes arteries and arteriole to constict and lead to high blood pressure

How does alcohol increase risk of CHD

• Heavy drinking raises blood pressure, contributes to obesity and can cause irregular heartbeats

• Excess alcohol can result in tissue damage, damage to the liver, brain and heart

How does obesity increase risk of CHD

• Increases risk of coronary heart disease and strokes

• Raises blood pressure, accelerates blood lipids

• More excess fat causes greater risk of CHD