Unit 2 - Organisation Flashcards
1
Q
What is a cell?
A
The basic building block of a living
organism.
2
Q
What is a tissue?
A
A group of cells with a similar structure and
function working together. For example,
muscular tissue contracts to bring about
movement.
3
Q
What is an organ?
A
A collection of tissues working together to
perform a specific function. For example,
the stomach contains glandular, muscular
and epithelial tissues.
4
Q
What is an organ system?
A
A group of organs working together to perform
specific functions. For example, the digestive
system contains organs such as the stomach,
the small intestine and the large intestine.
5
Q
What is the main function of the digestive
system?
A
To digest food and absorb the nutrients
obtained from digestion.
6
Q
What is the role of the pancreas and the salivary
gland in the digestive system?
A
The pancreas and the salivary gland are glands
which produce digestive juices containing
enzymes.
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.
8
Q
What is the role of the small intestine in the
digestive system?
A
The small intestine is the site where soluble
food molecules are absorbed into the
bloodstream.
9
Q
What is the role of the liver in the digestive
system?
A
Produces bile (stored in the gallbladder)
which emulsifies lipids and allows the lipase
enzyme to work more efficiently.
10
Q
What is the role of the large intestine in the
digestive system?
A
Absorbs water from undigested food,
producing faeces.
11
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 (the
breakdown of food) without being used up.
12
Q
How does the shape of an enzyme affect its
function?
A
Enzymes have a specific active site which is
complementary to their substrate.
13
Q
What is metabolism?
A
The sum of all the reactions in a
cell or an organism.
14
Q
What types of metabolic reactions do 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. carbohydrates to glucose.
15
Q
What is the lock and key hypothesis of enzyme
function?
A
The shape of the enzyme active site and the
substrate are complementary, so can bind
together to form an enzyme-substrate
complex.
16
Q
How does temperature affect enzyme action?
A
Up to a certain point, increasing temperature increases
enzyme action, as molecules have a higher kinetic
energy. Above a certain temperature, the shape of the
active site is altered and the enzyme becomes
denatured, so it can no longer catalyse the reaction. The
optimum temperature is around 37°.
17
Q
How does pH affect enzyme function?
A
The optimum pH for most enzymes is 7 (apart
from proteases in the stomach). If the pH is too
extreme, the shape of the active site may be
altered and the enzyme may no longer work.
18
Q
Where are carbohydrases, proteases and lipases
produced in the body?
A
● Carbohydrases: amylase - salivary gland and
pancreas; maltase - small intestine.
● Proteases: pepsin - stomach; others -
pancreas and small intestine.
● Lipases: pancreas and small intestine.
19
Q
What is the role of carbohydrases in the digestive
system?
A
Carbohydrases break down carbohydrates into
monosaccharides and disaccharides. Amylase
breaks down starch into maltose, and maltase
breaks down maltose into glucose.
20
Q
What is the role of proteases in the digestive
system?
A
Proteases break down proteins into amino
acids.
21
Q
What is the role of lipases in the digestive
system?
A
Lipases break down lipids into fatty acids
and glycerol.
22
Q
How are the products of digestion used?
A
They are used to build bigger molecules
such as carbohydrates and proteins.
Glucose is used as a substrate in
respiration.
23
Q
Where is bile made and stored in the body?
A
Bile is made by the liver and stored in the
gallbladder
24
Q
What is the role 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.
25
What is the heart?
An organ that pumps blood around the
body
26
What is the purpose of the circulatory system?
Carries oxygen and other useful
substances to bodily tissues, and
removes waste substances.
27
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.
28
Where does blood pumped by the right
ventricle go?
The lungs
29
Where does blood pumped by the left
ventricle go?
Body tissues
30
Why is the double circulatory system important?
It makes the circulatory system more
efficient - for example, oxygenated blood
can be pumped around the body at a
higher pressure by the left ventricle.
31
How many chambers does the heart have and
what are they called?
4 - right atrium, right ventricle, left atrium,
left ventricle.
32
Why is the wall of the left ventricle thicker?
The left ventricle has to pump blood at a
higher pressure around the whole body.
33
What are the four main blood vessels associated with
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.
● Vena cava (right) - carries deoxygenated blood from the body to
the heart.
● Pulmonary artery (right) - carries deoxygenated blood from the
heart to the lungs.
34
What is the purpose of valves in the heart?
Prevent the backflow of blood
35
What is the purpose of coronary arteries?
Coronary arteries supply the heart
muscle with oxygenated blood.
36
Describe the process of blood flow through the heart
● 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 contract, blood in the right ventricle
enters the pulmonary artery (to the lungs) and blood in
the left ventricle enters the aorta (to the body).
37
What is the approximate value of the natural
resting heart rate?
70 beats per minute
38
How is the heart rate controlled?
Heart rate is controlled by a group of cells in
the right atrium which act as a pacemaker.
They release waves of electrical activity
which cause the heart muscle to contract.
39
How can an abnormal heart rhythm be treated?
Irregular heart rhythms can be treated
using an artificial pacemaker, which
sends out electrical signals to correct the
heart’s rhythm.
39
What are the three types of blood vessel in the
body?
● Arteries
● Veins
● Capillaries
40
How are arteries adapted for their function?
● Function: carry blood away from the heart.
● Thick muscle layer - adds strength to resist high
pressure.
● Thick elastic layer - allows arteries to stretch
and recoil - in order to withstand high pressure.
41
How are veins adapted for their function?
● Function: carry blood towards the heart
● Wide lumen - enables low pressure
● Valves - prevent backflow of blood
42
How are capillaries adapted for their function?
● Function: enable transfer of substances between
the blood and tissues.
● Walls are one cell thick - short diffusion path.
● Permeable walls - substances can diffuse across.
● Narrow lumen - blood moves slowly - more time
for diffusion.
43
How would you calculate the rate of blood flow?
Volume of blood / number of minutes
44
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.
45
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.
46
What tissues make up the gas exchange system?
● Trachea
● Intercostal muscles
● Bronchi
● Bronchioles
● Alveoli
● Diaphragm
47
Explain how the lungs are ventilated by the
action of intercostal muscles
● Oxygen diffuses from the alveoli into the
capillary bloodstream down its concentration
gradient.
● Carbon dioxide diffuses from the capillary into
the alveoli down its concentration gradient.
47
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 lungs down pressure gradient
The inverse occurs when air moves out of the lungs.
48
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.
49
How would you calculate the breathing rate
Number of breaths / number of minutes
50
What substance carries the different components of
blood around the body?
Plasma
51
What substances are transported by plasma?
● Red blood cells
● White blood cells
● Platelets
● Carbon dioxide
● Urea
● Products of digestion
52
What is plasma?
A yellow liquid within blood that
transports substances around the body.
53
What is the purpose of red blood cells in blood?
Transport of oxygen around the body
54
How are red blood cells adapted for their
function?
● Biconcave shape - increased surface area to
volume ratio.
● No nucleus - more room for haemoglobin to
bind to oxygen.
● Contain haemoglobin - binds to oxygen.
55
What is the purpose of white blood cells in
blood?
They form part of the immune system,
which protects the body from invading
pathogens.
56
How are white blood cells adapted for their
function?
● Have a nucleus - contains DNA which codes for
proteins
● Can produce antibodies
● Can produce antitoxins
● Can engulf and digest pathogens (phagocytosis)
57
What is the purpose of platelets in blood?
Platelets are small cell fragments which aid
the clotting of blood at the site of a wound.
58
Why is the function of platelets important?
● Platelets aid in the process of blood clotting
(conversion of fibrinogen to fibrin). As a result, red
blood cells are trapped in the fibrin network,
forming a clot which prevents excessive bleeding.
Scab formation (after the clot has dried) prevents
bacteria from entering the wound.
59
What is coronary heart disease?
Coronary heart disease occurs when the
coronary arteries that supply the heart muscle
become blocked with a buildup of fatty material.
This restricts the supply of oxygen to the heart,
possibly leading to a heart attack or death.
60
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.
61
What are the advantages and disadvantages of
stents?
Advantages
● 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
62
What are statins?
Statins are drugs which reduce the level of
LDL (bad) cholesterol which contributes to
the development of coronary heart disease.
63
What are the advantages and disadvantages of statins?
Advantages
● Reduce risk of strokes, coronary heart disease and heart
attacks
● Increase level of HDL (good) cholesterol
Disadvantages
● Have to be taken continuously
● May have side effects
● Effect may not be immediate
64
What is a heart bypass surgery?
A surgery where blocked coronary
arteries are replaced with sections of
veins taken from other parts of the body.
65
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.
66
What types of valves can replace leaky valves?
● Mechanical - made of metal or polymers
● Biological - taken from animals (pigs,
sometimes humans)
67
What are the advantages and disadvantages of
mechanical valves?
Advantages
● Last for a very long time
Disadvantages
● Need to take medication to prevent blood
clotting around valve
68
What are the advantages and disadvantages of
biological valves?
Advantages
● Work very well - no medication required
Disadvantages
● Only lasts 12-15 years
69
What is the purpose of an artificial heart?
Artificial hearts are intended to support a
patient’s heart while they wait for a suitable
donor heart.
70
What are the advantages and disadvantages of
artificial hearts?
Advantages
● Less likely to be rejected by immune system
● Allows damaged heart to rest to help recovery
Disadvantages
● Risk of infection due to surgery
● Risk of blood clots
● Have to take blood-thinning drugs
71
What is health?
Health is the state of physical and mental
wellbeing
72
What is a communicable disease?
A disease caused by a pathogen which can
be transmitted from one person to another
eg. the flu.
73
What is a non-communicable disease?
A disease which can not be transmitted
from person to person eg. cancer.
74
How can diet affect health?
● Too little food / lack of nutrition - anaemia,
vitamin deficiencies.
● Too much food / too much unhealthy food -
obesity, type 2 diabetes.
75
How can stress affect health?
Prolonged stress is linked to a wide range
of health problems including heart
diseases, cancers and mental health
issues.
76
How can life situations affect health?
Many life factors such as location, gender,
financial status, ethnic group and
healthcare provision can impact a person’s
mental and physical health.
77
Give examples of how health problems can interact
● Infection with certain viruses can lead to cancer eg. hepatitis
infections can lead to liver cancer.
● A compromised immune system (eg. due to cancer) can lead to
a higher risk of infection with communicable diseases.
● Immune reactions caused by a pathogen can trigger allergic
reactions.
● Problems with physical health can lead to mental health issues.
78
What is a risk factor?
A risk factor is 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.
79
What is a causal mechanism?
A mechanism which demonstrates how one
factor biologically influences another.
80
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: nicotine increases heart rate; other chemicals
damage the artery lining and increase blood pressure.
● Exercise: lowers blood pressure, reducing strain on the
heart.
81
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.
82
How does alcohol affect liver and brain function?
● Excessive long-term alcohol use may lead
to liver cirrhosis (scarring of the liver).
● Increases risk of liver cancer.
● Damages brain tissue and nerve cells.
83
How does smoking affect the development of
lung disease and lung cancer?
● Tar in tobacco can damage the alveoli of the
lungs, leading to chronic obstructive
pulmonary disease (COPD).
● Tar also damages the cells which line the
lungs, leading to lung cancer.
84
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 a
number of deformities and health problems as part of
foetal alcohol syndrome.
85
How do carcinogens affect the development of
cancer?
Ionising radiation is a type of carcinogen
which can cause mutations in DNA, potentially
leading to cancer.
86
What is cancer?
Cancer is the development of a tumour
as a result of uncontrolled cell division.
87
What is cancer?
Cancer is the development of a tumour
as a result of uncontrolled cell division.
88
What is a benign tumour?
● A tumour that 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.
89
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.
● Disrupts healthy tissues and may lead to death.
90
Give 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
91
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.
92
How is palisade mesophyll tissue adapted for
its function?
Palisade mesophyll tissue contains lots of
chloroplasts which allows photosynthesis to
progress at a rapid rate.
93
How is spongy mesophyll tissue adapted for its
function?
Spongy mesophyll tissue has lots of air
spaces which allow gases (including
oxygen and carbon dioxide) to diffuse in
and out.
94
How is the xylem adapted for its function?
● Made up of dead cells which form a continuous
hollow tube - allows the movement of water and
mineral ions from the roots to the leaves.
● Strengthened by lignin - makes the vessel strong and
waterproof.
● Has bordered pits - allow minerals to be transported
to specific places.
95
How is the phloem adapted for its function?
● Made up of elongated living cells.
● Cells have sieve plates that connect them
together - cell sap can move through plates
into other cells.
● Sieve tube cells have few organelles to allow
the efficient transport of substances
96
How is meristem tissue adapted for its function?
Made up of stem cells which can
differentiate into many different cell types,
allowing the plant to grow.
97
What tissues does the leaf organ contain?
● Epidermis
● Palisade mesophyll
● Spongy mesophyll
● Xylem
● Phloem
● Guard cells
98
What is the function of guard cells?
Guard cells control the opening and closing
of the stomata, according to the water
content of the plant.
99
How are stomata adapted for their function?
Stomata allow the control of gaseous exchange and
water loss from the leaf.
● More stomata on the base of the leaf - minimises
water loss as this side is cooler and shaded.
● Have guard cells which control their opening and
closing.
100
How are root hair cells adapted for their function?
Root hair cells allow the uptake of water and
mineral ions from the soil.
● Large surface area - maximises rate of
absorption.
● Contain lots of mitochondria -- release energy
for active transport of mineral ions.
101
What is transpiration?
Transpiration is the evaporation of water
vapour from the surface of a plant.
102
What is translocation?
Translocation is the movement of
dissolved sugars from the leaves to other
parts of the plant.
103
How does transpiration work?
● Water evaporates from the leaf surface via the
stomata.
● Water molecules cohere together - more water is
pulled up the xylem in an unbroken column.
● More water is taken up from the soil - creating a
continuous transpiration stream.
104
How does temperature affect the rate of transpiration?
Increasing the temperature increases the rate
of transpiration.
● Higher rate of evaporation and diffusion of
water - therefore rate of transpiration is
increased.
105
How does humidity affect the rate of transpiration?
Increasing relative humidity decreases the rate of
transpiration.
● High relative humidity will reduce the water
vapour concentration gradient. The rate of
evaporation will decrease, and so will the rate of
transpiration.
106
How does wind speed affect the rate of transpiration?
Increasing wind speed/air movement increases the
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.
107
How does light intensity affect the rate of
transpiration?
Increasing the light intensity 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.
