B4-Organising Plants And Animals Flashcards
(171 cards)
1
Q
What is the aorta?
A
the artery that leaves the heart from the left ventricle and carries oxygenated blood to the body
2
Q
What are arteries?
A
blood vessels that carry blood away from the heart. They usually carry oxygenated blood and have a pulse
3
Q
What is an atrium?
A
the upper chambers of the heart
4
Q
What are capillaries?
A
the smallest blood vessels. They run between individual cells and have a wall that is only one cell thick
5
Q
What are coronary arteries?
A
the blood vessels that supply oxygenated blood to the heart muscle
6
Q
What is the epidermal?
A
the name given to cells that make up the epidermis or outer layer of an organism
7
Q
What are guard cells?
A
surround the stomata in the leaves of plants and control their opening and closing
8
Q
What is the palisade mesophyll?
A
the upper layer of the mesophyll tissue in plant leaves made up of closely packed cells that contain many chloroplasts for photosynthesis (this layer performs the most photosynthesis
9
Q
What is phloem?
A
the living transport tissue in plants that carries dissolved food (sugars) around the plant
10
Q
What is the pulmonary artery?
A
the large blood vessel that takes deoxygenated blood from the right ventricle of the heart to the lungs
11
Q
What is the pulmonary vein?
A
the large blood vessel that carries oxygenated blood from the lungs back to the left atrium of the heart
12
Q
What is the spongy mesophyll?
A
the lower layer of mesophyll tissue in plant leaves that contains some chloroplasts and many large air spaces to give a big surface area for the exchange of gases
13
Q
What are statins?
A
drugs used to lower blood cholesterol levels and therefore reduce fatty deposits in the blood vessels
14
Q
What is a stent?
A
a metal mesh placed in a blocked or partially blocked artery. They are used to open up the blood vessel by the inflation of a tiny balloon
15
Q
What is translocation?
A
the movement of sugars from the leaves to the rest of the plant through the phloem
16
Q
What is transpiration?
A
the loss of water vapour from the leaves of plants through the stomata when they are opened to allow gas exchange for photosynthesis. It involves evaporation from the surface of the cells and diffusion through the stomata
17
Q
What is urea?
A
the waste product formed by the breakdown of excess amino acids in the liver
18
Q
What are veins?
A
blood vessels that carry blood back to the heart. They usually carry deoxygenated blood and have valves to prevent the backflow of blood
19
Q
What is the vena cava?
A
the large vein that brings deoxygenated blood from the body into the heart
20
Q
What are ventricles?
A
chambers of the heart that contract to force blood out of the heart
21
Q
What is xylem?
A
the non-living transport tissue in plants that transports water and dissolved minerals from the roots to the leaves and shoots.This supports the plant
22
Q
The circulatory is system is a _______ ________ system
A
Closed double
23
Q
What does a closed double system mean?
A
It means that blood always stays within the blood vessels and that blood flows through the heart twice on each complete circuit of the body
24
Q
What is pulmonary circulation?
A
The circulation that brings deoxygenated blood to your lungs from your heart and then oxygenated blood from your lungs to your heart
25
What is systematic circulation?
The circulation that brings oxygenated blood from your heart to the cells all around your body and then deoxygenated back from the body to your heart
26
What is the structure of an artery?
They have a thick wall and then a thick layer of muscle and elastic fibres. They have a small lumen
27
What does an artery do?
Arteries carry blood away from your heart. This blood is bright-red oxygenated blood. Arteries have thick walls containing muscle and elastic fibres. This is because blood in arteries is under high pressure. It can be very dangerous if an artery is cut. Arteries stretch as blood goes through them and go back into shape afterwards
28
What is the structure of a vein?
They have relatively thin walls and have a large lumen. They also have valves to prevent the backflow of blood
29
What does a vein do?
Veins carry blood away from the organs towards your heart. This blood is deoxygenated and is dark red in colour. Veins do not have a pulse. They have thinner walls than arteries and have valves to prevent backflow of blood. Blood is squeezed towards the heart by the action of skeletal muscles
30
What is the structure of a cappilary?
Capillaries have 1 cells thick walls and are a tiny vessel with a narrow lumen
31
What does a cappilary do?
Capillaries form a huge network of tiny vessels linking arteries and veins. Their walls are 1 cell thick. This allows substances such as oxygen and glucose to diffuse quickly into your cells. This also allows waste substances such as CO2 to diffuse into your blood
32
What are coronary veins/arteries?
Coronary arteries supply oxygenated blood to your heart wall muscle and coronary veins take away the deoxygenated blood from the heart wall muscle
33
Which side of the heart has thicker walls and why?
The left side of the heart has thicker walls (especially the left ventricle). This is because it has to pump the blood all around the entire body. This requires strong muscles to make sure that the blood makes it all the way around the body.
34
What are leaky valves?
Over a lifetime, heart valves have to withstand a lot of pressure. This may cause them to leak or become stiff and not fully open. This makes the heart less efficient.
For leaky valves this causes the blood to flow backwards,this requires to heart to work harder to pump the same amount of blood.This means less oxygen reaches the tissues.
35
How are leaky valves treated?
Doctors can operate and replace them with mechanical heart valves. They could be made of substances such as titanium or polymers. They are long lasting, however blood clots can form around them so patients have to take medicine for the rest of their lives. Doctors can also replace leaky valves with biological valves such as valves taken from pigs or cows. These do not form blood clots. However, they only last 12-15 years
36
When are artificial pacemakers needed?
The heart has a natural pacemaker called the SA node (it is found in the right atrium). It generates an electrical stimulus which makes the heart chamber contract/relax. the resting rhythm of a healthy heart is 70bpm. If the SA node stops working properly it can cause serious problems. If the heart beats too slowly it cannot pump blood properly. An artificial pacemaker can be inserted to correct the irregularities in the heart rate. They weigh between 20g and 50g. You will need regular check-ups throughout your life
37
When is an artificial heart needed?
If a heart fails completely an artificial pacemaker cannot save them, in this case they would need a heart transplant. If you have a heart transplant you need to take constant medication to prevent your body rejecting your new heart. If there is not a new heart available they may need a temporary artificial heart. However, artificial hearts can have a risk of blood clot which can lead to death
38
What % of air breathed in is nitrogen?
~80%
38
When are stents used?
This allows blood to pass though and keeps the coronary artery's open,reducing the risk of heart attack in people with coronary heart disease
38
What are atrioventricular valves?
Atrioventricular valves close to stop the backflow of blood in the heart
39
When are statins used?
They reduce blood cholesterol levels and this slows down the rate at which fatty material is deposited in coronary arteries
40
What % of air breathed in is Oxygen?
~20%
41
What % of air breathed out is Oxygen?
~16%
42
What % of air breathed out is nitrogen?
~80%
43
What % of air breathed in is Carbon Dioxide?
0.04%
44
What % of air breathed out is Carbon Dioxide?
~4%
45
What are the adaptations of Alveoli?
There are many alveoli and they have a spherical shape, these provide a very large surface area for the diffusion of Oxygen and carbon dioxide. Alveoli have a very thin wall and this allows for rapid diffusion of Oxygen and carbon dioxide. Alveoli have many capillaries surrounding them, this maintains a steep concentration gradient, making gas exchange rapid and effective
46
Describe how air moves in and out of your lungs
Ventilating the lungs is brought about by the contraction and relaxation of the intercostal muscles between the ribs and the diaphragm, changing the pressure inside the chest cavity so air is forced in or out of the lungs as a result of differences in pressure. When you breath in the oxygen-rich air moves through your mouth/nose then down your trachea (windpipe). It then moves in to your bronchi before splitting into your bronchioles. Finally it moves into your alveoli (air sacs) where it diffuses into the blood
47
What are the plant organs
Flowers, Leaves, Stem, Roots
48
What is the role of a flower?
Flowers allow plants to reproduce
49
What is the role of a Leaf?
Leaves carry out photosynthesis
50
What is the role of a Stem?
Stem supports leaves and flowers, and transports water and nutrients
51
What is the role of a Root?
Roots take up water and minerals from the soil and keep the plant stable in the soil
52
What is the structure of a leaf?
A leaf has an upper epidermis followed by mesophyll tissue which contains palisade mesophyll and spongy mesophyll. The mesophyll tissue is then followed by the lower epidermis. In the lower epidermis there are gaps called stomata. There are xylem and phloem transport systems adjacent to the mesophyll tissue
53
What is the structure of a Stem?
A stem has xylem and phloem arranged in vascular bundles
54
What is the structure of a root?
A root has xylem arranged in an x shape and 4 phloem around the xylem
55
What does the upper epidermis do?
The upper epidermis covers the surfaces and protects them. These cells often often secrete a waxy substance that waterproofs the surface of the leaf
56
What does the palisade mesophyll do?
The palisade mesophyll tissue contains lots of chloroplasts, which carry out photosynthesis
57
What does the spongy mesophyll do?
Spongy mesophyll tissue contains some chloroplasts for photosynthesis but also has big air spaces and a large surface area to make diffusion of gases easier
58
What does the lower epidermis do?
The lower epidermis covers the surfaces and protects them. These cells often often secrete a waxy substance that waterproofs the surface of the leaf. They also contain gaps called stomata
59
What is meristem tissue?
Meristem tissue is at the growing tips of roots and shoots and is made of rapidly dividing plant cells that grow and differentiate into all the other cell types needed
60
Why do flowering plants need a transport system?
They are multicellular and often large, this means that they have a small SA:V ratio. They have to transport glucose made by photosynthesis and water from the soil to all cells in the plant
61
How does water enter the roots?
Osmosis
62
How does temperature effect Transpiration rates?
As temperature increases, the rate of transpiration increases. This is because as temperature increases, the molecules gain more kinetic energy and begin to move faster, and the water evaporates this causes diffusion to occur more rapidly. Also, as temperature increases the rate of photosynthesis increases, so more stomata will open for gas exchange to take place.
63
How does humidity effect Transpiration rates?
As humidity increases, the rate of transpiration decreases. This is because the diffusion of the water vapour out of the leaf is slower. This is due to the leaf already being surrounded by moist air, this makes it harder for the water vapour to diffuse out the leaf
64
How does Wind Speed effect Transpiration rates?
As the air movement increases, the rate of transpiration increases. This is because the moving air removes the water vapour, increasing the rate of diffusion of water vapour from the leaf. A steep concentration gradient is maintained beetween the inside and outside of the cell
65
How do plants control water loss?
Plants have a waxy cuticle that to prevent uncontrolled water loss. The stomata are also on the bottom of the leaf so that they are not facing direct sunlight. If the plant begins to lose water faster than it is replaced by the roots, it can result in some drastic measures:
The whole plant may wilt. Wilting is a protection mechanism against further water loss. The leaves all collapse and hang down. This greatly reduces the surface area available for water loss by evaporation.
Stomata close, this stops photosynthesis and risks overheating . However, this prevents most water loss and any further wilting
66
What does a potometer measure?
the uptake of water
67
Why does a potometer not measure the transpiration rate of a plant?
A potometer measures the uptake of water, not the transpiration rate. This is because although most water taken up by a plant is lost in transpiration, a small amount is used in the plants metabolism
68
Explain how transpiration occurs
Water is absorbed from the soil by the roots. The water passes through the plants to the cells in the leaves. In the leaves, water evaporates from the cells in the leaf into the air spaces between them. This water vapour diffuses out of the plant through the stomata on the leaf surface when the stomata are open
69
What factors effect the rate of transpiration?
Temperature
Humidity
Air flow
light intensity
70
How does light intensity affect the rate of transpiration?
Light intensity increases the rate of transpiration, this is because it increases the rate of photosynthesis, causing the stomata open wider to allow more carbon dioxide into the leaf for photosynthesis. This allows the water vapour the diffuse out the leaf
71
What is cholesterol and why is it harmful?
Cholesterol is an essential lipid that your body produces and needs to function properly. However, too much of a certain cholesterol can cause health problems as it causes fatty deposits in the arteries, which can lead to coronary heart disease
72
What is coronary heart disease?
Coronary heart disease is when the coronary arteries that supply blood to the muscles of the heart get blocked by layers of fatty deposits. This causes the arteries to become narrow, so blood flow is restricted and there is a lack of oxygen to the heart muscle - this can result in pain, a heart attack, and even death
73
What are 2 ways to combat coronary heart disease?
Stent
* Statin
74
What are the disadvantages of statins?
They are a long term drug that must be taken regularly (someone may forget to take them)
They may have negative side effects
The effect is not instant
75
What are the disadvantages of stents?
There may be complications during surgery
* A blood clot may form around the stent
76
Why may someone with a leaky heart valve have difficulty exercising?
A leaking valve in the heart may cause backflow of blood to occur. This means that less blood is pumped around the body. As a result, less oxygen will be supplied to muscles and cells resulting in less aerobic respiration and therefore less energy released. This will cause less efficient muscle contraction. As a result more anaerobic respiration will occur, however the removal of lactic acid and carbon dioxide will be less efficient.
77
What type of heart valve is more long lasting?
Mechanical
78
What type of heart valve can cause blood clots?
Mechanical
79
How is the small intestine adapted for more efficient absorption of nutrients?
Villi provide a large surface area and have a very thin wall to provide a thin diffusion path
Small intestine is very long increasing the time available for absorption
There is a good blood supply to maintain a strong concentration gradient
Cells have many mitochondria for aerobic respiration to release more energy for active transport
80
Why would having only one ventricle make the circulatory system less efficient?
only having 1 ventricle would cause oxygenated and deoxygenated blood to mix, therefore less oxygen reaches the bodily cells
81
Why may amphibians that breath through the use of gills die in water with a low concentration of water?
Concentration gradient is shallower therefore less oxygen diffuses through the gills into the animal. Therefore less aerobic respiration occurs so less energy is released. This will cause the metabolism of the animal to slow and they may die as a result
82
What are enzymes made of?
amino acids (it is a protein)
83
How may pancreatic cancer cause weight loss?
Pancreatic cancer may cause reduced or no enzyme production from the pancreas. Therefore food may not be fully broken down and digested. Therefore less glucose is absorbed into the bloodstream and as a result less glucose is available for respiration so fat is used up as a fuel for respiration. This causes weight loss
84
What is the structure of blood plasma?
Straw yellow liquid
- Made up of water and dissolved substances.
85
What is the function of blood plasma?
Plasma transports many dissolved substances around the body.
Examples include digested foods (e.g. glucose), gases (e.g. carbon dioxide), wastes (e.g. urea) and hormones (e.g. insulin), antibodies, anti-toxins.
Plasma also transports heat around the body.
86
What is the structure of red blood cells?
Very small in size. This provides a large surface area to volume ratio.
They contain Haemoglobin - this is a red pigment that binds oxygen –> oxyhaemoglobin.
They are shaped like discs –(biconcave) but are thicker at the edges.
They have NO nucleus (so there is more space for haemoglobin)
87
What is the function of red blood cells?
To transport oxygen to all the body cells for respiration.
- Haemoglobin binds oxygen molecules forming oxyhaemoglobin.
88
What is the structure of white blood cells?
Much bigger than red blood cells.
Much fewer in number than red blood cells.
They HAVE a nucleus.
They have no definite shape
89
What is the function of white blood cells?
The fight disease in the body.
90
Name the 2 types of white blood cell and explain how they fight disease
Phagocytes – engulf (‘eat’) pathogens.
- Lymphocytes – create antibodies which destroy pathogens.
91
What is the structure of platelets?
These are tiny fragments of cells
They have NO nucleus
They cause blood to clot
92
What is the function of platelets?
Their function is to help form blood clots. This helps seal wounds (and prevent blood loss) when we cut ourselves
93
What type of blood do arteries (usually) carry?
Oxygenated blood
94
What type of blood do veins (usually) carry?
Deoxygenated blood
95
Describe the pathway of blood through the heart.
(RHS) Vena cava –> right atrium –> right ventricle –> pulmonary artery (pumps blood to the lungs) –> (LHS) Pulmonary vein –> left atrium –> left ventricle –> aorta (pumps blood all around the body)
96
Which blood vessel carries deoxygenated blood into RHS of the heart?
Vena cava
97
Which blood vessel carries oxygenated blood into the LHS of the heart?
Pulmonary vein
98
How can blocked coronary arteries lead to heart disease?
In coronary heart disease layers of fatty material build up inside the coronary arteries, narrowing them. This reduces the flow of blood through the coronary arteries, resulting in a lack of oxygen for the heart muscle.
99
Name the 3 main ways of treating heart disease?
Drugs: e.g. statins
Mechanical devices: stents, artificial valves, artificial pacemakers
Heart transplant
100
What is an artificial valve?
Valves in the heart prevent backflow of blood.
If the valve becomes faulty this could prevent the valve from opening fully, or the heart valve might develop a leak.
Faulty heart valves can be replaced using biological or mechanical valves.
101
What is a pacemaker?
The natural resting heart rate is controlled by a group of cells located in the right atrium that act as a pacemaker. Artificial pacemakers are electrical devices used to correct irregularities in the heart rate.
102
What is the structure of stomata?
They are tiny pores on the surfaces of leaves, which can open or close. Guard cells surround the stomata and control the opening and closing of the stomata.
103
What is the function of stomata?
They allow the exchange of gases in and out of the leaf. Water vapour can also leave through the stomata. They control gas exchange and water loss.
104
Explain how stomata control gas exchange and water loss
Guard cells open and close the stomata and in this way control the levels of carbon dioxide that enter the leaf and the oxygen & water vapour that leave the leaf by diffusion. i.e. Stomata control gas exchange and water loss.
105
Why is there less water loss through the stomata during conditions of low light intensity?
In low light the guard cells lose water and become flaccid, causing the stomata to close. They would normally only close in the dark when no carbon dioxide is needed for photosynthesis.
106
Where are most of the stomata found?
On the lower surface on the leaf
107
Describe how guard cells open and close
• Guard cells have an unevenly thickened (cell) wall
• This enables them to, change shape / bend when they gain water by osmosis
108
Which conditions cause stomata to OPEN
• Stomata open during the day and close during the night.
• High water potential outside the stomata
• Light causes stomata to open
109
What is the function of the root hair cells?
To absorb water (by osmosis) and mineral ions e.g. K+ by active transport.
110
How are root hair cells adapted to absorb water and mineral ions?
There are many hairs which gives an increased surface area so the plant can absorb more water by osmosis.thin cell wall, and close contact with soil water.
111
How are xylem cells adapted to transport water?
Composed of dead hollow cells - They have thick lignified walls which gives strength
112
What is the structure of phloem cells?
Living cells (sieve tubes) with companion cells (which provide energy for active transport). Sieve tubes have sieve plates (perforated ends) to allow substances to pass through.
113
The movement of water from roots to leaves is called the __________ __________.
Transpiration stream
114
Name some reasons a plant needs water
1) Cooling the plants
2) For photosynthesis (to make glucose)
3) Support for the plant (cells become turgid)
4) Movement of minerals (which are dissolved in the water)
115
What is the double circulatory system?
The heart is an organ that pumps blood around the body in a double circulatory system. The right ventricle pumps blood to the lungs where gas exchange takes place. The left ventricle pumps blood around the rest of the body.
116
Where are the lungs located
Thorax
117
How does the air in the lungs travel
trachea → bronchi → bronchioles → alveoli
118
What are the alveoli
small air sacs surrounded by capillaries – site of gas exchange
119
What does inhalation do?
Inhalation brings in oxygen → diffuses from alveoli into the blood.
120
What does exhalation so?
Exhalation removes carbon dioxide → diffuses from blood into alveoli.
121
Rate of blood flow
Volume of blood/time
122
Advantages of a heart transplant
Can be a long-term or permanent solution
Can greatly improve quality of life for the patient
123
Disadvantages of a heart transplant
Major surgery – high risk and long recovery
Risk of rejection – patient must take immunosuppressant drugs
Shortage of donors – long waiting lists
124
What is a faulty valve
A faulty valve is one that:
Doesn’t open fully (narrowed/stiffened)
Or leaks and lets blood flow backwards
125
Consequences of leaky valves
Fatigue
Shortness of breath
Swelling (fluid build-up)
Can lead to heart failure
126
Consequences of faulty valves
Chest pain
Fainting
Tiredness
Risk of heart enlargement or failure
127
What can doctors do in the case of heart failure if a replacement is not available.
Artificial hearts are occasionally used to keep patients alive whilst waiting for a heart transplant, or to allow the heart to
rest as an aid to recovery.
128
Advantages of mechanical devices such as stents,artificial pacemakers
Can quickly restore blood flow (e.g. stents open blocked arteries)
Pacemakers help regulate heartbeat
Less waiting than for a transplant
129
Disadvantages of mechanical devices such as stents or artificial valves
Surgery risks (infection, blood clots)
May need maintenance or replacements
Artificial valves may require lifelong medication
130
What is the function of the epidermal tissue?
Protect the plant from physical damage and pathogens (like bacteria and fungi).
Reduce water loss by producing a waxy, waterproof layer called the cuticle.
Allow gas exchange through specialized epidermal cells called stomata (pores) that open and close to regulate the movement of gases like oxygen, carbon dioxide, and water vapor.
Sometimes, epidermal cells have root hairs that increase surface area to absorb water and minerals from the soil (in roots).
131
What is the Structure of epidermal tissue
Made of tightly packed cells covered by a waxy, waterproof cuticle. Has pores called stomata with guard cells.
132
Structure of palisade mesophyll tissue
Contains many chloroplasts; cells are elongated and closely packed near the upper surface of the leaf.
133
Structuee of spongy mesophyll tissue
Loosely packed cells with air spaces between them.
134
Structure of meristem tissue
Made of undifferentiated (unspecialized) cells that can divide rapidly.
135
Function of the meristem tissues
These cells continuously divide to produce new cells.
New cells then differentiate (specialize) into different types of plant tissues like xylem, phloem, or epidermis.
This allows the plant to grow in length (primary growth) and thickness (secondary growth).
136
What is the leaf
A plant organ
137
How to calculate rate of transpiration
Volume of water lost/time
138
What do xylem tissues do?
Xylem tissue transports water and mineral ions from the roots to the stems and leaves.
139
What do phloem tissues do?
Phloem tissue transports dissolved sugars from the leaves to the rest of the plant for immediate use or storage
140
What is the role of the stomata and guard cells
The role of stomata and guard cells are to control gas exchange and water loss.
141
Describe the process of translocation
Sugars made in the leaves are actively loaded into the phloem, lowering the water potential inside the phloem so water enters by osmosis. This creates a high pressure that pushes the sugary sap through the phloem to areas called sinks, where sugars are actively unloaded for use or storage. Water then leaves the phloem, lowering the pressure and allowing continuous flow of nutrients throughout the plant.
142
Calculation to estimate heart rate
Number of beats/time x60
143
explain in detail the importance of a
double circulatory system.
The double circulatory system is essential because it increases blood pressure, ensures efficient oxygen transport, prevents blood mixing, and supports high metabolic rates. Without it, mammals would struggle to maintain their energy needs and survive in demanding conditions.
144
Red blood cell diameter
7-8 micrometers
145
suggest how white blood cells are
adapted to their function.
Phagocytes (like macrophages) can change shape to engulf and digest pathogens.
Lymphocytes produce antibodies that are specific to antigens on pathogens, helping destroy them.
Some lymphocytes also produce antitoxins that neutralise toxins made by pathogens.
White blood cells can move through blood vessel walls and tissues to reach infection sites.
They have a nucleus, which contains genetic material needed to produce antibodies.
146
summarise the process of blood
clotting.
Injury occurs – A blood vessel is damaged, exposing collagen.
Platelet activation – Platelets stick to the damaged site and release chemicals.
Platelet plug forms – More platelets gather, forming a temporary seal.
Clotting factors activate fibrin – Proteins in the blood (including fibrinogen) are activated to form fibrin, a mesh-like structure that strengthens the clot.
Clot stabilisation – The fibrin mesh traps red blood cells, forming a solid clot that seals the wound and prevents further bleeding.
Healing and clot breakdown – Once the vessel heals, the clot dissolves.
This process prevents excessive blood loss and protects against infection
147
Advantages and disadvantages of the model of the blood
Adv:Helps visualize different blood components.
Engaging and easy to understand
Demonstrates relative proportions
Can be modified
Dis:Does not show microscopic scale
Lacks structural details of cells
Cannot show chemical or biological functions
Limited in representing blood flow and circulation
148
explain why an irregular
heartbeat is detrimental to health.
Electrical impulses are sent throughout into the heart to pump blood all around our body and if its irregular this means the impulses will not send blood at the right times either sending too much or too little
149
give some ways in which the heart
can stop functioning efficiently.
blocked artery's,irregular heartbeat,high blood pressure,problem with the valves
150
Advantages and disadvantages of pacemakers and defibrilators
Advantages:helps regulate heartbeat,can prevent sudden cardiac arrest,long term solution
Disadvantages:requires surgery to implant,may need battery replacements,risk of device malfunctions
151
How to calculate the mean number of stomata on a given area of the leaf
Total number of stomata counted/area of the leaf samples
152
What is the lymphatic system?
A network of vessels that collects excess tissue fluid (lymph) from tissues and returns it to the blood via the subclavian veins. It also transports fats from the small intestine and helps in immune responses.
153
How are leaves adapted for efficient gas exchange?
Leaves have a large surface area, thin structure, and many stomata on the lower epidermis to maximize gas exchange. Air spaces in the spongy mesophyll allow rapid diffusion of gases (CO₂ in, O₂ out).
154
How can you interpret potometer data to estimate transpiration rates?
Measure the distance the water bubble moves in the potometer over a set time. Calculate the volume of water taken up (using tube diameter) and divide by time to estimate the transpiration rate (e.g., cm³/min).
155
What are the ethical considerations of using animal-derived heart valves?
Animal-derived valves (e.g., from pigs or cows) avoid blood clots but raise ethical concerns about animal welfare and religious objections to using animal tissue. Patients may prefer mechanical valves to avoid these issues.
156
How does haemoglobin help transport oxygen?
Haemoglobin in red blood cells binds with oxygen to form oxyhaemoglobin in the lungs and releases it in tissues.
157
What is the transpiration stream?
The continuous movement of water from the roots, up the xylem, and out of the leaves as water vapour (transpiration).
158
What happens during inhalation (breathing in)?
Diaphragm contracts and flattens.
Intercostal muscles contract, pulling rib cage up and out.
Volume of chest cavity increases.
Pressure inside lungs decreases, so air rushes in.
159
What happens during exhalation (breathing out)?
Diaphragm relaxes and domes upwards.
Intercostal muscles relax, allowing rib cage to move down and in.
Volume of chest cavity decreases.
Pressure inside lungs increases, so air is forced out.
160
Why is the wall of the left ventricle thicker than the right ventricle?
The left ventricle has to pump blood all around the body (a much longer distance and higher pressure) compared to the right ventricle which only pumps blood to the lungs.
161
Describe the path of oxygenated blood through the heart and body.
Oxygenated blood returns to the left atrium from the lungs via the pulmonary vein.
Passes to the left ventricle.
Pumped to the rest of the body via the aorta.
162
Describe the path of deoxygenated blood through the heart and lungs.
Deoxygenated blood enters the right atrium from the body via the vena cava.
Passes to the right ventricle.
Pumped to the lungs via the pulmonary artery.
In the lungs, it picks up oxygen and loses carbon dioxide.
163
What is haemoglobin
the red pigment that carries oxygen around the body in the red blood cells
164
Whar are red blood cells
biconcave cells that contain the red pigment haemoglobin and carry oxygen around the body in the blood
165
What are white blood cells?
blood cells involved in the immune system of the body. They engulf pathogens and make antibodies and antitoxins
166
What is the atria
the upper chambers of the heart
167
Method of potometer experiment
Set Up the Apparatus:
Cut the plant shoot underwater to prevent air bubbles entering the xylem.
Assemble the potometer, ensuring it is airtight and watertight.
Introduce an Air Bubble:
Allow a small air bubble to enter the capillary tube.
Measure Water Uptake:
Record the movement of the air bubble over a fixed period.
Change Environmental Factors:
Test the effects of light intensity, wind, humidity, or temperature on the bubble’s movement.
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Common Errors and Precautions of potometer experiment
Ensure airtight connections to avoid leaks.
Cut the plant stem underwater to prevent airlock in xylem.
Use the same type of plant shoot for fair testing.
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How to calculate water uptake
Distance moved by bubble/time
