B4. Organising animals and plants Flashcards
What is the function of the trachea?
The trachea connects the nose and mouth to to the lungs/bronchi
What are the alveoli?
Alveoli are tiny air sacs surrounded by a network of capillaries, serving as the site of gas exchange between the air and the blood.
Describe the role of the bronchi.
The bronchi branch off the trachea and carry air into the right and left lungs. They contain mucus to trap dust and pathogens
Which process takes place at the alveoli?
The process that takes place in the alveoli is gas exchange
What are the features of alveoli that make them an efficient exchange surface?
They have a large total surface area
They provide a short diffusion distance
They have a good blood supply and good ventilation, maintaining a steep concentration gradient
They are lined with a layer of moisture in which gases can dissolved
How is a steep concentration gradient fir both oxygen and carbon dioxide maintained in the alveoli?
Good ventilation means that a high concentration of oxygen and a low concentration of carbon dioxide is maintained inside the alveoli
A good blood supply ensures that blood is constantly flowing; this means that the blood immediately next to each alveolus is always low in oxygen and high in carbon dioxide
How does a dense capillary network directly surrounding the alveoli help to increase the rate of gas exchange?
A dense network of capillaries directly surrounding the alveoli helps to maximise the rate of gas exchange by providing
a short diffusion distance between the alveoli and the red blood cells
A large surface area over which gas exchange can occur
Why is a faster rate of gas exchange important during exercise?
A faster rate of gas exchange is important during exercise as a greater amount of oxygen is required for a higher rate of respiration in muscle tissues. There is also a higher quantity of carbon dioxide being produced which needs excreting from the body via the lungs
What is the function of the heart?
The heart is an organ that pumps oxygenated blood from the lungs to the rest of the body and deoxygenated blood from the body to the lungs
Describe the pathway of deoxygenated blood through the heart from the body
- Enters the right atrium through the vena cava
- Flows through the atrio-ventricular valve into the right ventricle
- Is pumped through the pulmonary semilunar valve into the pulmonary artery
- To the lungs for oxygenation
Why does the left ventricle have a thicker muscle wall than the right ventricle?
The left ventricle has a thicker muscle wall to pump oxygenated blood at high pressure throughout the body, while the right ventricle pumps deoxygenated blood at lower pressure to the lungs
What role do valves play in the heart?
Valves in the heart to prevent the backflow of blood, ensuring that blood flows in only one direction through the heart chambers and vessels
How does blood return from the lungs to the heart?
Oxygenated blood returns from the lungs to the heart via the pulmonary veins
What supplies the cardiac muscle tissue of the heart with oxygenated blood?
The coronary arteries supply the cardiac muscle tissue of the heart with oxygenated blood, ensuring it receives a constant supply of oxygen and glucose for aerobic respiration to release energy for muscle contraction
How does the heart prevent damage to the capillaries in the lungs?
The heart maintains low pressure in the pulmonary artery, preventing damage to the capillaries in the lungs during blood circulation. The muscle in the right hand side of the heart is thinner and weaker to allow this
Which vein is the only vein in the body to carry oxygenated blood?
The pulmonary vein is the only vein to carry oxygenated blood, returning blood to the heart after gas exchange has taken place
What are the three main types of blood vessel?
Arteries, veins and capillaries
What is the function of arteries?
Arteries carry blood at high pressure away from the heart
How are the walls of arteries adapted to their function?
Arteries have thick muscular walls containing elastic fibres to withstand high blood pressure and maintain it as the blood recoils. They also have a narrow lumen to help maintain high blood pressure?
What is the function of veins?
Veins carry blood at low pressure towards the heart
How are the walls of veins adapted to their function?
Veins have thin walls and a large lumen to reduce resistance to blood flow under low pressure. They also contain valves to prevent the backflow of blood
What is the function of valves?
Valves prevent the back-flow of blood in the veins where blood travels under low-pressure
What are the key features of capillaries?
Capillaries carry blood at low pressure within tissues
Walls that are one cell thick
Allow substance to easily diffuse in and out through their ‘leaky’ walls
1230ml of blood flows through a blood vessel in 120 seconds.
What is the rate of blood flow?
1230 ÷ 2 = 615ml minute -¹
OR
1230 ÷ 120 = 10.25ml sec -¹
Where is epidermal tissue located in the leaves of plants?
Epidermal tissue is present on the upper and lower surfaces of leaves; the upper surface is the upper epidermis and the lower surface is the lower epidermis
What is the role of palisade mesophyll tissue?
To carry out photosynthesis
How is spongy mesophyll tissue adapted for gas exchange?
Spongy mesophyll tissue is adapted for gas exchange by the presence of air spaces between cells. This increases the surface area of the cells that comes into contact with the air, so enabling faster gas exchange
What is the role of guard cells in leaves?
Guard cells control whether the stomata in leaves are open or closed; this allows plants to reduce water loss via the stomata when water availability is limited
Where would meristem tissue be found in plants?
Meristem tissue is found in the growing tips of plant shoots and roots
What is the role of root hair cells?
Root hair cells absorb water and minerals from the soil
How are root hair cells adapted to aid their function?
They have a large surface area
They contain mitochondria which release energy for active transport
Define the term xylem.
Xylem are vessels that transport water and mineral ions from the roots to the upper parts of plants
How are xylem vessels adapted to transport water around plants?
They are hollow and have no end walls to allow continuous water movement
Lignin strengthen xylem cell walls to prevent breakage of vessels
Define the term phloem
The phloem is a tissue that transports dissolved sugars from the leaves to the rest of the plant
How is phloem tissue adapted for its role?
It contains elongated tubes along which dissolved sugars can flow
The end walls of cells contains pores to allow passage of dissolved sugars
Define the term transpiration
Transpiration is the loss of water vapour from the leaves of plants by evaporation
Describe the structure of stomata
The stomata are pores in the leaf surface, surrounded by two guard cells
What is the role of the stomata and guard cells in transpiration?
The stomata and guard cells allow plants to regulate the volume of water lost during transpiration. When water availability is low the guard cells can close, reducing transpiration
Which four factors can affect the rate of transpiration in plants?
Temperature
Humidity
Wind speed/ air movement
Light intensity
What happens to transpiration rate as light intensity increases?
As light intensity increased the transpiration rate increases
What happens to transpiration rate as temperature decrease?
As temperature decreases the transpiration rate decreases
Why does transportation occur faster on a windy day?
Transpiration is faster on a windy day, because wind blows water vapour away from the surface of leaves, maintain a water vapour concentration gradient between the inside and the outside of leaves
How will putting a plant inside a plastic bag affects its rate of transpiration?
Putting a plant inside a plastic bag will decrease its rate of transpiration. This is because the bag will trap water vapour and raise humidity levels, decreasing the wate vapour concentration gradient between the leaf and the surrounding air
Define the term translocation.
Translocation is the movement of dissolved sugar molecules through phloem tissue.
What is coronary heart disease?
Coronary heart disease occurs when the coronary arteries narrow to build-up of fatty deposits; this reduces the flow of blood through the coronary arteries of the heart
Give one advantage and one disadvantages of treating cardiovascular disease using statins
Advantages:
Slows down the rate at which fatty deposits occur
Increasing levels of HDL cholesterol
Disadvantages:
Need to be taken continuously
Can take time to be effective
Can cause side effects
How are stents used in the treatment of cardiovascular disease?
Stents are used to widen the lumen of the coronary arteries; this keeps the arteries open and increases blood flow to the heart muscle
How are stents used in the treatment of cardiovascular disease?
Stents are used to widen the lumen of the coronary arteries; this keeps the arteries open and increases blood flow to the heart muscle
What are the possible consequences of faulty heart valves?
Consequences of faulty heart valves include:
Valves may not fully open
Valves may become leaky
When might an artificial heart be used in the treatment of cardiovascular disease?
A patient is experiencing heart failure
A donor heart is not immediately available
A patient’s heart needs time to rest during recovery
Give one advantage and one disadvantage of artificial hearts in the treatment of cardiovascular disease?
Advantages:
No need to wait for a suitable donor heart
Reduced risk of immune rejection
Disadvantages:
Artificial hearts are less effective than biological hearts an increased risk of blood clotting with artificial hearts
