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[ GCSE ] biology > B2: Organisation > Flashcards

B2: Organisation Flashcards

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1
Q

what is a cell?

A
  • the basic building block of a living organism
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2
Q

what is a tissue?

A
  • a group of cells with a similar structure and function working together.
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3
Q

what is an organ?

A
  • a collection of tissues working together to perform a specific function
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4
Q

what is an organ system?

A
  • a group of organs working together to perform specific functions
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5
Q

what is the main function of the digestive system?

A
  • to digest food and absorb the nutrients obtained from digestion
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6
Q

What is the role of the pancreas and the salivary gland in the digestive system

A

produce digestive juices containing enzymes

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7
Q

what is the role of the stomach in the digestive system?

A
  • produces hydrochloric acid
  • which kills any bacteria present and provides the optimum acidic pH for the protease enzyme to function
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8
Q

what is the role of the stomach in the digestive system?

A
  • produces hydrochloric acid
  • which kills any bacteria present and provides the optimum acidic pH for the protease enzyme to function
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9
Q

What is the role of the small intestine in the digestive system?

A
  • site where soluble food molecules are absorbed into the bloodstream
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10
Q

what is the role of the liver in the digestive system?

A
  • produces bile (stored in the gallbladder)
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11
Q

What is the role of the large intestine in the digestive system?

A
  • absorbs water from undigested food, producing faeces
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12
Q

State the function of the gall bladder

A
  • stores bile before released into small intestine
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13
Q

what is the role of enzymes in the digestive system?

A

-enzymes act as biological catalysts which speed up the rate of biological reactions (breakdown of food) without being used up

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14
Q

How does the shape of an enzyme affect its function

A
  • enzymes have a specific active site which is complementary to their substrate
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15
Q

Define the term ‘ metabolism’

A
  • the sum of all the reactions in a cell or an organism
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16
Q

Give three types of metabolic reactions that enzymes catalyse?

A
  • 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
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17
Q

What are carbohydrates made up of ?

A
  • simple sugars
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18
Q

State the chemical formula of glucose

A

C^6 H^12 O^6

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19
Q

Name a complex carbohydrate that is made up of glucose

A
  • starch
  • cellulose
  • glycogen
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20
Q

i have one request

A

delete me pls

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21
Q

Describe the lock and key hypothesis

A
  • The shape of the enzyme active site and the substrate are complementary
  • bind together to form an enzyme-substrate complex
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22
Q

How does temperature affect enzyme action up to the optimum initially

A
  • initially, increasing temperature increases enzyme action as molecules have a higher kinetic energy
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23
Q

What is the optimum temperature and ph of an enzyme

A

temperature = 37
ph= 7 (except protease)

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24
Q

How does temperature affect enzyme action above the optimum

A
  • 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
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25
Q

Why do enzymes not work well at lower temperatures

A
  • inactive - there is not enough kinetic energy to collide and bind to active site
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26
Q

How does pH affect enzyme function?

A
  • optimum pH is 7
  • if the pH is too extreme ,the enzyme may denature and the shape of the active site may be altered
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27
Q

Where are carbohydrase , proteases and lipases produced in the body

A

-carbohydrase
- amylase - salivary gland, pancreas
- maltase - small intestine
proteases:
pepsin - stomach
others- pancreas and small intestine
- lipases: pancreas & small intestine

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28
Q

What is the role of carbohydrase in the digestive system?

A

carbohydrase: break down carbohydrates into monosaccharides and disaccharides.
Amylase: breaks down starch into maltose
Maltase: breaks down maltose into glucose

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29
Q

What is the role of proteases in the digestive system

A

proteases break down proteins into amino acids

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30
Q

what is the role of lipases in the digestive system

A

lipases break down lipids into fatty acids and glycerol

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31
Q

give two ways the products of digestion could be used

A
  • used to build bigger molecules such as carbohydrates and proteins
  • glucose is used as a substrate in respiration
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32
Q

Where is bile made and stored in the body ?

A

Bile is made by the liver
Stored in the gallbladder

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33
Q

Give two roles of bile in the digestive system

A
  • 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
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34
Q

What is the heart

A
  • an organ that pumps blood around the body
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35
Q

What is the purpose of the circulatory system?

A
  • carries oxygen and other useful substances to bodily tissues
  • removes waste substances
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36
Q

delete

A

card

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37
Q

How does the double circulatory system work?

A
  • 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
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38
Q

where does blood pumped by the right ventricles go ?

A
  • the lungs
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39
Q

where does blood pumped by the left ventricle go?

A

body tissues

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40
Q

why is the double circulatory stem important ?

A
  • it makes the circulatory system more efficient
  • oxygenated blood can be pumped around the body at a higher pressure by the left ventricle
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41
Q

How many chambers does the heart have and what are they called

A

4
- right atrium
- left atrium
- left ventricle
- right ventricle

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42
Q

Why is the wall of the left ventricle thicker?

A
  • the left ventricle has to pump blood at a higher pressure around the whole body .
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43
Q

What are the two main blood vessels associated with the left side of the heart ?

A

aorta ( left) - carries oxygenated blood from the heart to the body
pulmonary vein ( left ) - carries oxygenated blood from the lungs to the heart

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44
Q

What are the two main blood vessels associated with the right side of the heart

A

vena cava ( right ) - carries deoxygenated blood from the body to the heart
pulmonary artery ( right ) - carries deoxygenated blood from the heart to the lungs

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45
Q

what is the purpose of valves in the heart ?

A

prevent the backflow of blood

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46
Q

what is the purpose of coronary arteries ?

A
  • they supply the heart muscle with oxygenated blood
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47
Q

Describe the process of blood flow through the heart (3)

A
  • 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 )
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48
Q

What is the approximate value of the natural resting heart rate ?

A

70 beatsper minute

49
Q

How is the heart rate controlled?

A
  • 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
50
Q

How can an abnormal heart rhythm be treated

A
  • using an artificial pacemaker which sends out electrical signals to correct the heart’s rhythm
51
Q

Name the 3 types of blood vessel in the body

A
  • arteries
  • veins
  • capillaries
52
Q

Give the function of an artery and give 2 ways they are adapted to carry out their function

A

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

53
Q

How are veins adapted for their function ?

A

function : carry blood towards the heart
wide lumen : aid flow of blood despite low pressure
valves : prevent backflow of blood

54
Q

How are capillaries adapted for their function?

A

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

55
Q

How would you calculate the rate of blood flow

A

volume of blood / number of minutes

56
Q

Where are the lungs found in the body?

A
  • 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
57
Q

What 6 tissues make up the gas exchange system ?

A
  • trachea
  • intercostal muscles
  • bronchi
  • bronchioles
  • alveoli
  • diaphragm
58
Q

Explain how the lungs are ventilated by the action of intercostal muscles

A
  • 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
59
Q

Describe how gas exchange occurs at the alveoli

A
  • 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
60
Q

describe how alveoli are adapted for gas exchange

A
  • small and arranged in clusters- larger surface area
  • rich blood supply - maintains concentration gradient
  • thin alveolar wall - short diffusion pathway
61
Q

How would you calculate the breathing rate ?

A

number of breaths / number of minutes

62
Q

What substance carries the different components of blood around the body ?

A

plasma

63
Q

Which 6 substances are transported by plasma

A
  • red blood cells
  • white blood cells
  • platelets
  • carbon dioxide
  • urea
  • products of digestion
64
Q

What is plasma?

A
  • a yellow liquid within blood that transports substances around the body
65
Q

What is the purpose of red blood cells in blood ?

A
  • to transport oxygen around the body
66
Q

How are red blood cells adapted for their function (3)

A
  • biconcave shape - increased surface area to volume ratio
  • no nucleus - more room for haemoglobin to bind to oxygen
  • contain haemoglobin - binds to oxygen
67
Q

What is the purpose of white blood cells in blood ?

A
  • they form part of the immune system , which protects the body from invading pathogens
68
Q

How are white blood cells adapted for their function ? (4)

A
  • have a nucleus - contains DNA which codes for proteins
  • can produce antibodies
  • can produce antitoxins
  • can engulf and digest pathogens ( phagocytosis )
69
Q

What are platelets

A
  • platelets are small cell fragments which aid the clotting of blood at the site of a wound
70
Q

Describe a platelets function and why it is important

A
  • 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
71
Q

What is coronary heart disease ?

A
  • 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
72
Q

What is a stent and how does it work ?

A
  • 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
73
Q

give advantages and disadvantages of the use of stents. (3:2)

A

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

74
Q

What are statins?

A
  • drugs which reduce the level of LDL ( bad) cholesterol
  • which contribute to the development of CHD
75
Q

what are the advantages and disadvantages of statins (2/3)

A

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

76
Q

what is a heart bypass surgery?

A
  • a surgery where blocked coronary arteries are replaced with sections of veins from other parts of the body
77
Q

what are the consequences of leaky heart valves

A
  • blood flows in the wrong direction, causing the heart to become less efficient .
  • patients may become breathless and die as a result
78
Q

what types of valves can replace leaky valves?

A

mechanical: made of metal or polymers
biological: taken from animals ( pigs, sometimes humans)

79
Q

give advantages and disadvantages of mechanical valves (1/1)

A

adv:
- lasts for a long time
disadv:
- risk of clotting thus
- need to take medication to prevent blood clotting around valve

80
Q

what are the advantages and disadvantages of biological valves (1/1)

A

adv:
- work very well- no medication required
disadv:
- only lasts 12-15 years

81
Q

what is the purpose of an artifical heart

A
  • intended to support a patients heart while they wait for a suitable donor heart
82
Q

what are the advantages and disadvantages of artificial hearts? (2/3)

A

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

83
Q

what is health?

A
  • the state of physical and mental wellbeing
84
Q

what is a communicable disease?

A
  • a disease caused by a pathogen which can be transmitted from one person to another
85
Q

what is a non-communicable disease?

A
  • a disease which can not be transmitted from one person to person
86
Q

give two ways diet can affect health

A
  • too little food/ lack of nutrition - lead to anaemia & vitamin deficiencies
  • too much food/too much unhealthy food- obesity, type 2 diabetes
87
Q

how can stress affect health?

A
  • prolonged stress is linked to a wide range of health problems
  • including heart diseases , cancers and mental health issues
88
Q

Give 4 examples of how health problems can interact

A

• 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.

89
Q

what is a risk factor?

A
  • 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
90
Q

what is a casual mechanism?

A
  • a mechanism which demonstrates how one factor biologically influences another
91
Q

how do diet, smoking and exercise affect the development of cardiovascular disease?

A

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

92
Q

how does obesity affect the development of type 2 diabetes?

A
  • obesity is strongly linked with the onset of type 2 diabetes - a disease in which the body stops responding to insulin
93
Q

how does alcohol affect liver and brain function? (3)

A
  • excessive long-term alcohol use may lead to liver cirrhosis ( scarring of liver)
  • increases risk of liver cancer
  • damages brain tissues and nerve cells
94
Q

how does smoking lead the development of lung disease and lung cancer (6)

A

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

94
Q

how do smoking and alcohol affect unborn babies?

A
  • 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
95
Q

how do carcinogens affect the development of cancer?

A
  • ionising radiation is a type of carcinogen
  • can cause mutations in DNA, potentially leading to cancer
96
Q

what is cancer?

A

the development of a tumour as a result of uncontrolled cell division

97
Q

what is a benign tumour and it’s characteristics

A
  • 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
98
Q

what is a malignant tumour?

A
  • 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
99
Q

give 5 examples of factors which can lead to cancer

A
  • 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
100
Q

how is epidermal tissue adapted for its function?

A
  • epidermal tissue covers the entire plant.
  • it has a waxy cuticle which helps reduce water loss from the leaf surface
101
Q

how is palisade mesophyll tissue adapted for its function?

A
  • contains lots or chloroplasts which allows photosynthesis to progress at a rapid rate
102
Q

how is spongy mesophyll tissue adapted for its function?

A
  • lots of air spaces which allow gases ( inc. oxygen and carbon dioxide) to diffuse in and out
103
Q

Give two ways the xylem is adapted for its function

A
  • 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
104
Q

how is the phloem adapted for its function? ( 3)

A
  • 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
105
Q

How is meristem tissue adapted for its function ?

A
  • made up of stem cells which can differentiate into many different ell types , allowing the plant to grow
106
Q

give 6 tissues that the leaf organ contain?

A
  • epidermis
  • palisade mesophyll
  • spongy mesophyll
  • xylem
  • phloem
  • guard cells
107
Q

what is the function of guard cells?

A
  • control the opening and closing of the stomata , dependent on the water content of the plant
108
Q

How are stomata adapted for its function

A

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

109
Q

What is translocation

A
  • the movement of dissolved sugars from the leaves to other arts of the plant
110
Q

what is transpiration?

A

the evaporation of water vapour from the surface of a plant

111
Q

how does transpiration work?

A
  • 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
112
Q

How does temperature affect the rate of transpiration?

A
  • increases the rate of transpiration
  • as there is a higher rate of evaporation and diffusion of water
113
Q

how does humidity affect the rate of transpiration?

A
  • 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
114
Q

How does wind speed affect the rate of transpiration?

A
  • 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
115
Q

How does light intensity affect the rate of transpiration?

A
  • 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
116
Q

Q6. Explain how the human lungs are adapted for efficient exchange of gases by diffusion. (6)

A
  • (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
117
Q

Sometimes a valve in the heart can start to leak.
Explain why a person with a leaking heart valve has difficulty exercising.

[4 marks]

A
  • 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
118
Q

Evaluate the use of mechanical replacement heart valves and biological replacement heart valves.
Use information from Table 4 and your own knowledge.
[6 marks]

A

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

[ GCSE ] biology (10 decks)

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