B2: Organisation Flashcards
what is a cell?
- the basic building block of a living organism
what is a tissue?
- a group of cells with a similar structure and function working together.
what is an organ?
- a collection of tissues working together to perform a specific function
what is an organ system?
- a group of organs working together to perform specific functions
what is the main function of the digestive system?
- to digest food and absorb the nutrients obtained from digestion
What is the role of the pancreas and the salivary gland in the digestive system
produce digestive juices containing enzymes
what is the role of the stomach in the digestive system?
- produces hydrochloric acid
- which kills any bacteria present and provides the optimum acidic pH for the protease enzyme to function
what is the role of the stomach in the digestive system?
- produces hydrochloric acid
- which kills any bacteria present and provides the optimum acidic pH for the protease enzyme to function
What is the role of the small intestine in the digestive system?
- site where soluble food molecules are absorbed into the bloodstream
what is the role of the liver in the digestive system?
- produces bile (stored in the gallbladder)
What is the role of the large intestine in the digestive system?
- absorbs water from undigested food, producing faeces
State the function of the gall bladder
- stores bile before released into small intestine
what is the role of enzymes in the digestive system?
-enzymes act as biological catalysts which speed up the rate of biological reactions (breakdown of food) without being used up
How does the shape of an enzyme affect its function
- enzymes have a specific active site which is complementary to their substrate
Define the term ‘ metabolism’
- the sum of all the reactions in a cell or an organism
Give three types of metabolic reactions that enzymes catalyse?
- building larger molecules from smaller molecules eg. glucose to starch
- changing one molecule to another eg glucose to fructose
- breaking down larger molecules into smaller molecules eg carbohydrases to glucose
What are carbohydrates made up of ?
- simple sugars
State the chemical formula of glucose
C^6 H^12 O^6
Name a complex carbohydrate that is made up of glucose
- starch
- cellulose
- glycogen
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Describe the lock and key hypothesis
- The shape of the enzyme active site and the substrate are complementary
- bind together to form an enzyme-substrate complex
How does temperature affect enzyme action up to the optimum initially
- initially, increasing temperature increases enzyme action as molecules have a higher kinetic energy
What is the optimum temperature and ph of an enzyme
temperature = 37
ph= 7 (except protease)
How does temperature affect enzyme action above the optimum
- above the optimum temperature, the shape of the active site is altered
- the enzyme becomes denatured, so it can no longer catalyze the reaction
- the substrate can no longer bind to active site
Why do enzymes not work well at lower temperatures
- inactive - there is not enough kinetic energy to collide and bind to active site
How does pH affect enzyme function?
- optimum pH is 7
- if the pH is too extreme ,the enzyme may denature and the shape of the active site may be altered
Where are carbohydrase , proteases and lipases produced in the body
-carbohydrase
- amylase - salivary gland, pancreas
- maltase - small intestine
proteases:
pepsin - stomach
others- pancreas and small intestine
- lipases: pancreas & small intestine
What is the role of carbohydrase in the digestive system?
carbohydrase: break down carbohydrates into monosaccharides and disaccharides.
Amylase: breaks down starch into maltose
Maltase: breaks down maltose into glucose
What is the role of proteases in the digestive system
proteases break down proteins into amino acids
what is the role of lipases in the digestive system
lipases break down lipids into fatty acids and glycerol
give two ways the products of digestion could be used
- used to build bigger molecules such as carbohydrates and proteins
- glucose is used as a substrate in respiration
Where is bile made and stored in the body ?
Bile is made by the liver
Stored in the gallbladder
Give two roles of bile in the digestive system
- bile is an alkaline substance which neutralises the hydrochloric acid secreted by the stomach
- bile emulsifies lipids to form droplets - this increases the surface area for the lipase enzyme to work on
What is the heart
- an organ that pumps blood around the body
What is the purpose of the circulatory system?
- carries oxygen and other useful substances to bodily tissues
- removes waste substances
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How does the double circulatory system work?
- one pathway carries blood from the heart to the lungs - where the gaseous exchange of oxygen and carbon dioxide takes place
- one pathway carries blood from the heart to the tissues
where does blood pumped by the right ventricles go ?
- the lungs
where does blood pumped by the left ventricle go?
body tissues
why is the double circulatory stem important ?
- it makes the circulatory system more efficient
- oxygenated blood can be pumped around the body at a higher pressure by the left ventricle
How many chambers does the heart have and what are they called
4
- right atrium
- left atrium
- left ventricle
- right ventricle
Why is the wall of the left ventricle thicker?
- the left ventricle has to pump blood at a higher pressure around the whole body .
What are the two main blood vessels associated with the left side of the heart ?
aorta ( left) - carries oxygenated blood from the heart to the body
pulmonary vein ( left ) - carries oxygenated blood from the lungs to the heart
What are the two main blood vessels associated with the right side of the heart
vena cava ( right ) - carries deoxygenated blood from the body to the heart
pulmonary artery ( right ) - carries deoxygenated blood from the heart to the lungs
what is the purpose of valves in the heart ?
prevent the backflow of blood
what is the purpose of coronary arteries ?
- they supply the heart muscle with oxygenated blood
Describe the process of blood flow through the heart (3)
- blood enters the right atrium via the vena cava , and the left atrium via the pulmonary vein
- The atria contract, forcing blood into the ventricles and causing valves to shut
- after the ventricles contact, blood in the right ventricle enters the pulmonary artery ( to the lungs ) and blood in the left ventricle enters the aorta ( to the body )
What is the approximate value of the natural resting heart rate ?
70 beatsper minute
How is the heart rate controlled?
- a group of cells in the right atrium which act as apace maker
- they release waves of electrical activity which cause the heart muscle to contract
How can an abnormal heart rhythm be treated
- using an artificial pacemaker which sends out electrical signals to correct the heart’s rhythm
Name the 3 types of blood vessel in the body
- arteries
- veins
- capillaries
Give the function of an artery and give 2 ways they are adapted to carry out their function
function : carry blood away from the heart
-adaptions :
- thick muscle layer - adds strength to resist high pressure
- thick elastic layer - allows arteries to stretch and recoil in order to withstand high pressure
How are veins adapted for their function ?
function : carry blood towards the heart
wide lumen : aid flow of blood despite low pressure
valves : prevent backflow of blood
How are capillaries adapted for their function?
function : enables transfer of substances between the blood and tissues
- walls are one cell thick - allows for short diffusion path
- permeable walls - substances can diffuse across
- narrow lumen - blood moves slowly allowing for more time for diffusion
How would you calculate the rate of blood flow
volume of blood / number of minutes
Where are the lungs found in the body?
- the lungs are located in the thorax ( within the chest )
- they are protected by the ribcage and separated from the rest of the abdomen by the diaphragm
What 6 tissues make up the gas exchange system ?
- trachea
- intercostal muscles
- bronchi
- bronchioles
- alveoli
- diaphragm
Explain how the lungs are ventilated by the action of intercostal muscles
- intercostal muscles contract
- ribcage moves upwards and outwards
- diaphragm flattens and volume of the chest increases
- increased volume results in decreased pressure
- air is drawn into the lungs down pressure gradient
- the inverse occurs when air moves out of the lungs
Describe how gas exchange occurs at the alveoli
- oxygen diffuses out from the alveoli into the capillary bloodstream down its concentration gradient
- carbon dioxide diffuses out of the capillary bloodstream into the alveoli down the concentration gradient
describe how alveoli are adapted for gas exchange
- small and arranged in clusters- larger surface area
- rich blood supply - maintains concentration gradient
- thin alveolar wall - short diffusion pathway
How would you calculate the breathing rate ?
number of breaths / number of minutes
What substance carries the different components of blood around the body ?
plasma
Which 6 substances are transported by plasma
- red blood cells
- white blood cells
- platelets
- carbon dioxide
- urea
- products of digestion
What is plasma?
- a yellow liquid within blood that transports substances around the body
What is the purpose of red blood cells in blood ?
- to transport oxygen around the body
How are red blood cells adapted for their function (3)
- biconcave shape - increased surface area to volume ratio
- no nucleus - more room for haemoglobin to bind to oxygen
- contain haemoglobin - binds to oxygen
What is the purpose of white blood cells in blood ?
- they form part of the immune system , which protects the body from invading pathogens
How are white blood cells adapted for their function ? (4)
- have a nucleus - contains DNA which codes for proteins
- can produce antibodies
- can produce antitoxins
- can engulf and digest pathogens ( phagocytosis )
What are platelets
- platelets are small cell fragments which aid the clotting of blood at the site of a wound
Describe a platelets function and why it is important
- aid in the process of blood clotting ( conversion of fibrinogen to fibrin )
- as a result, red blood cells are trapped in the fibrin network
- this forms a clot whchc prevents excessive bleeding
- scab formation after the clot has dried) prevents bacteria from entering the wound
What is coronary heart disease ?
- coronary arteries that supply the heart muscle becomes blocked with a buildup of fatty material
- this restricts the supply of oxygen to the heart , leading to a heart attack or death
What is a stent and how does it work ?
- a stent is a metal mesh tube that is inserted into a blocked artery so that it remains open
- the stent is inflated using a balloon which is later removed to allow blood to flow freely
give advantages and disadvantages of the use of stents. (3:2)
adv:
- insertion can be carried out without general anaesthetic
- quick recovery time
- lower the risk of a heart attack
disadvantages :
- risk of postoperative infection
- risk of blood clots at site of stent
What are statins?
- drugs which reduce the level of LDL ( bad) cholesterol
- which contribute to the development of CHD
what are the advantages and disadvantages of statins (2/3)
adv:
- reduce risk of strokes , coronary heart disease and heart attack
- increase level of HDL ( good ) cholesterol
disadv:
- have to be taken continuously
- may have side effects
- effect may not be immediate
what is a heart bypass surgery?
- a surgery where blocked coronary arteries are replaced with sections of veins from other parts of the body
what are the consequences of leaky heart valves
- blood flows in the wrong direction, causing the heart to become less efficient .
- patients may become breathless and die as a result
what types of valves can replace leaky valves?
mechanical: made of metal or polymers
biological: taken from animals ( pigs, sometimes humans)
give advantages and disadvantages of mechanical valves (1/1)
adv:
- lasts for a long time
disadv:
- risk of clotting thus
- need to take medication to prevent blood clotting around valve
what are the advantages and disadvantages of biological valves (1/1)
adv:
- work very well- no medication required
disadv:
- only lasts 12-15 years
what is the purpose of an artifical heart
- intended to support a patients heart while they wait for a suitable donor heart
what are the advantages and disadvantages of artificial hearts? (2/3)
adv:
- less likely to be rejected by immune system
- allows damaged heart to rest to help recovery
disadv:
- risk of infection due to surgery
- risk of blood clots
- have to take blood thinning drugs
what is health?
- the state of physical and mental wellbeing
what is a communicable disease?
- a disease caused by a pathogen which can be transmitted from one person to another
what is a non-communicable disease?
- a disease which can not be transmitted from one person to person
give two ways diet can affect health
- too little food/ lack of nutrition - lead to anaemia & vitamin deficiencies
- too much food/too much unhealthy food- obesity, type 2 diabetes
how can stress affect health?
- prolonged stress is linked to a wide range of health problems
- including heart diseases , cancers and mental health issues
Give 4 examples of how health problems can interact
• Defects in the immune system : more likely to suffer from infectious diseases.
• Viruses living in cells can be the trigger for cancers.
• Immune reactions initially caused by a pathogen can trigger allergies such as skin rashes and asthma.
• Severe physical ill health can lead to depression and other mental illness.
what is a risk factor?
- an aspect of a person’s lifestyle or a substance found in the body or the environment which can increase the risk of a disease
what is a casual mechanism?
- a mechanism which demonstrates how one factor biologically influences another
how do diet, smoking and exercise affect the development of cardiovascular disease?
diet: high levels of LDL cholesterol causes arteries to become blocked, increasing blood pressure and the risk of a heart attack
smoking: raises blood pressure increasing risk of blood clots greater risk of stroke and heart attack
exercise: lowers blood pressure, reducing strain on the heart
how does obesity affect the development of type 2 diabetes?
- obesity is strongly linked with the onset of type 2 diabetes - a disease in which the body stops responding to insulin
how does alcohol affect liver and brain function? (3)
- excessive long-term alcohol use may lead to liver cirrhosis ( scarring of liver)
- increases risk of liver cancer
- damages brain tissues and nerve cells
how does smoking lead the development of lung disease and lung cancer (6)
toxic carbon monoxide is produced:
- this binds to haemoglobin
- so oxygen carrying capacity of blood is decreased
smoking is a risk factor for lung cancer:
- caused by carcinogenic chemicals in smoke (tar)
- cause mutations
- leading to uncontrolled growth of cells
how do smoking and alcohol affect unborn babies?
- carbon monoxide from tobacco smoke reduces the amount of oxygen the foetus receives which can lead to premature birth or stillbirth
- alcohol passes across the placenta and damages the developing foetus. once born the baby may have number of deformities and health problems as part of foetal alcohol syndrome
how do carcinogens affect the development of cancer?
- ionising radiation is a type of carcinogen
- can cause mutations in DNA, potentially leading to cancer
what is cancer?
the development of a tumour as a result of uncontrolled cell division
what is a benign tumour and it’s characteristics
- a tumour ithat is contained in one location usually within a membrane
- they are not cancerous and do not invade other parts of the body
- can grow large very quickly - may cause damage to another organ
what is a malignant tumour?
- a tumour that can spread around the body via the blood and lymphatic system
- can invade other tissues ( metastasis)
- cells divide more rapidly and have a longer lifespan
give 5 examples of factors which can lead to cancer
- genetics - certain genes increase the risk of breast and ovarian cancer
- smoking
- obesity
- ionising radiation - UV light and X-rays
- viral infections - HPV and cervical cancer
how is epidermal tissue adapted for its function?
- epidermal tissue covers the entire plant.
- it has a waxy cuticle which helps reduce water loss from the leaf surface
how is palisade mesophyll tissue adapted for its function?
- contains lots or chloroplasts which allows photosynthesis to progress at a rapid rate
how is spongy mesophyll tissue adapted for its function?
- lots of air spaces which allow gases ( inc. oxygen and carbon dioxide) to diffuse in and out
Give two ways the xylem is adapted for its function
- made up of dead cells which form a continuous hollow tube -with no end walls
- outer walls are thickened with
lignin that strengthen their structure and prevent collapse - making vessel strong and waterproof
how is the phloem adapted for its function? ( 3)
- made up of elongated living cells
- cells have sieve plates that connect them together - allows for the transportation of dissolved sugars up and down the stem
- sieve tube cells have few organelles to allow the efficient transport of substances
- companion cells provide energy needed for active transport of substances along the phloem
How is meristem tissue adapted for its function ?
- made up of stem cells which can differentiate into many different ell types , allowing the plant to grow
give 6 tissues that the leaf organ contain?
- epidermis
- palisade mesophyll
- spongy mesophyll
- xylem
- phloem
- guard cells
what is the function of guard cells?
- control the opening and closing of the stomata , dependent on the water content of the plant
How are stomata adapted for its function
function: allow the control of gaseous exchange and water loss from the leaf
- more stomata on base of leaf minimises water loss as this side is cooler and shaded
- have guard cells which control their opening and closing
What is translocation
- the movement of dissolved sugars from the leaves to other arts of the plant
what is transpiration?
the evaporation of water vapour from the surface of a plant
how does transpiration work?
- water evaporates from the leaf surface via the stomata
- There is strong cohesion between the molecules because of hydrogen bonding.
- so more water is pulled up the xylem in an unbroken column
- more water is taken up from the soil creating a continuous transpiration stream
How does temperature affect the rate of transpiration?
- increases the rate of transpiration
- as there is a higher rate of evaporation and diffusion of water
how does humidity affect the rate of transpiration?
- decreases the rate of transpiration
- it reduces the water vapour concentration gradient. ( higher concentration outside of the leaf)
- the rate of evaporation will decrease , and so will the rate of transpiration
How does wind speed affect the rate of transpiration?
- increases rate of transpiration
- increased air movement lowers water vapour concentration outside of the leaf
- this increases the water vapour concentration gradient , thereby increasing the rate of evaporation and transpiration
How does light intensity affect the rate of transpiration?
- increases the rate of transpiration
- the rate of photosynthesis increases so more stomata open
- this allows the rate of evaporation to increase increasing the rate of transpiration
Q6. Explain how the human lungs are adapted for efficient exchange of gases by diffusion. (6)
- (many) alveoli
- provide a large surface area
- capillary walls are one cell thick
- which provides short diffusion path (for oxygen / carbon dioxide)
- there is a large capillary network ( good blood supply)
- to remove oxygenated blood quickly
- to bring carbon dioxide to the lungs quickly
- to maintain a concentration / diffusion gradient
Sometimes a valve in the heart can start to leak.
Explain why a person with a leaking heart valve has difficulty exercising.
[4 marks]
- some blood flows backwards
- less blood leaves the heart
- reduced blood pressure so
• less oxygen supplied to muscles
• (so) less aerobic respiration
• (so) less energy released
• (so) less (efficient) muscle contraction
Evaluate the use of mechanical replacement heart valves and biological replacement heart valves.
Use information from Table 4 and your own knowledge.
[6 marks]
mechanical valves:
* (+) longer lasting and more durable
* (+) blood clots (on the brain) are more likely (after surgery)
* ( - ) patient has to take anti-clotting medication (for the rest of their
lives)
* biological valves:
+ no additional medication required
- lasts for a shorter time
- more likely to be rejected
both valves:
+ both are readily available
+ little wait time
