Biology ✿ organisation

order these from biggest to smallest

cells, organs, system, tissue

system, organ, tissue, cells

cell

basic building blocks of all living organisms

tissue

a group of cells with similar structure or function

organs

group of tissues which do specific jobs

systems

groups of organs which work together to form organisms

enzymes

biological catalysts and proteins which increases rate of chemical reaction without being used up

what is the role of the digestive system?

to digest and absorb food

Metabolism

the sum of all the reactions in an organism

Enzymes

biological catalysts made of proteins to speed up chemical reactions without being used up themselves

Explain the “lock and key theory” of enzyme action [3]

• enzymes bind a specific substrate that fits it’s active site

• substrate is broken down

• products are realised

what and where is amylase broken down into?

• simple sugars

• salivary glands, pancreases and small intestine

what and where is protease broken down into?

• amino acids

• pancreas, small intestine and stomach

what and where is lipases broken down into?

• fatty acids and glycerol

• pancreas and small intestine

what is the role of the digestive enzymes?

to breakdown food into small soluble molecules that can be absorbed into the bloodstream

where is bile made?

liver

where is bile stored?

gall bladder

what is the role of bile?

to emulsify fats to make them into small droplets which increases the surface area

give 2 adaptations of Bile

• alkaline to neutralise stomach acid and provides optimum pH for enzymes

• emulsifies fat making them into small droplets to increase surface area

what is the food test and positive result for starch?

• iodine solution

• black-blue colour

what is the food test and positive result for sugars?

• benedict’s solution

• green, yellow or brick-red

what is the food test and positive result for proteins?

• biuret solution

• purple/ lilac

what is the food test and positive result for lipids?

• ethanol

• milky-white

double circulatory system

when the blood passes through the heart twice during one complete circuit of the body

Describe how both the alveoli and villi are adapted to increase absorption [3]

• large surface area to maximise diffusion

• one cell thick walls to reduce diffusion distance

• good blood supply to maintain concentration gradient

give two adaptions of the villi

• contain microvilli to further increase surface area

• contain many mitochondria for active transport

describe the pathway of the blood through the heart [4]

• deoxygenated blood enters the right atrium via the vena cava

• blood flows into the right ventricle which pumps blood to the lungs via the pulmonary artery

• oxygenated blood enters the left atrium via the pulmonary vein

• blood flows into the left ventricle which pumps blood to the rest of the body via aorta

what is the role of the vena cava?

returns deoxygenated blood into the heart from the body

what is the role of the pulmonary artery?

moves deoxygenated blood away from the heart to the lungs

what is the role of the pulmonary vein?

returns oxygenated blood into the heart from the lungs

what is the role of the aorta?

moves oxygenated blood away from the heart to body

pacemaker

a group of cells located in the right atrium which controls the resting heart rate

Artificial pacemakers

an electrical device used to send regular electrical impulses to control resting heart rate

equation for rate of blood flow

volume of blood / time

explain the structure and functions of the artery [3]

• thick walls to withstand high pressure of blood flow

• small lumen to maintain high pressure

• carries blood AWAY from the heart

explain the structure and functions of the vein [3]

• thin walls due to low pressure of blood flow

• large lumen to allow blood to easily flow

• carries blood INTO the heart

explain the structure and functions of the capillary [3]

• one cell thick walls to reduce diffusion distance

• narrow lumen to reduce diffusion distance and slows blood flow for more exchange time

• connects the arteries to veins

what 4 components is the blood made up of?

• plasma

• red blood cells

• white blood cells

• platelets

give the function and 2 adaptations of the red blood cell

• carries oxygen from the lungs to the body’s cells

• no nucleus for more space for haemoglobin

• small and flexible to squeeze through narrow capillaries

give the function and 2 adaptations of the white blood cell

• defends the body against pathogens

• produce antitoxins/ antibodies to fight pathogens

• change shape to engulf pathogens

give the function and 2 adaptations of platelets

• causes blood to clot at wounds to stop bleed and microbes from entering

• no nucleus

• releases chemicals to help blood to clot

give the function and an adaptation of plasma

• to carry the blood components around the body

• liquid to allow easy flow through blood vessels

coronary heart disease

a disease which causes fatty material to build up inside the coronary arteries

explain the effect of a partly blocked coronary artery on the body [4]

• reduced blood flow causing a lack of oxygen and glucose in blood cells

• heart muscles will start anaerobically respiring, producing lesser energy and more lactic acid

• muscle contraction is less so less blood is pumped around the body

• this leads to muscles to become tired quickly, causing them to breath in more oxygen

Explain how the human lungs are adapted for efficient exchange of gases by diffusion. [4]

• many alveoli provide more surface area

• one cell thick walls to shorten diffusion distance

• lungs are ventilated to bring in fresh oxygen

• good blood supply to maintain concentration gradient

Stents

a metal mesh which keeps the coronary arteries open

statins

a drug used to lower blood cholesterol levels by lowering the rate of fatty material deposit

explain the effects on a person if a valve develops a leak [4]

• causes backflow of the blood, causing less blood to leave the heart

• there is less oxygenated blood around the body so cells get less oxygen for respiration

• so they anaerobically respire and less energy is released

• lactic acid is produced, causing the person to become tired easily

explain why veins have valves but arteries do not [2]

• veins carry blood at lower pressure

• so they need valves to prevent backflow of the blood

valves

“gates” which control the direction of blood flow in the veins

leaky valve

when the valve cannot close tightly, causing the backflow of the blood

give 2 advantages + disadvantages of a mechanical valve

• lasts for at least 20-30 years

• doesn’t wear out easily

• must take blood thinning medication everyday

• risk of blood clotting at the valve

give 2 advantages + disadvantages of a biological valve

• no need for blood thinning medication

• lower risk of blood clots

• doesn’t last as long, only 10-15 years

• can wear out easily

health

the state of physical and mental well-being

diseases

major causes of ill health

give 4 ways diseases may interact

• weakens the immune system so they’re more likely to catch diseases

• viruses living in cells can cause cancers

• immune reactions caused by a pathogen can cause allergies

• severe physical health can lead to depression and other mental illness