Paper 1 - Transport Flashcards
What is the xylem made of?
- Dead cells
- Lignin to waterproof the xylem
- cellulose to strengthen the xylem and allow for flexibility
Describe the role of the phloem in transporting sucrose and amino acids between the leaves and other parts of the plants
- transports the sucrose into directions because of end walls, allowing two-way transport
- transport substances from photosynthesising leaves to non-photosynthesising regions in the root and stem
- sieve plates have no nuclei, and cannot respire, they only contain cytoplasm
- sieve plates have companion cells to produce energy for them
- sucrose can be transported as a liquid called plants up, which can travel through the pores in the sieve cells
Describe the role of the xylem and transporting water and minerals from the roots to other parts of the plant
- soil has a higher water potential than inside of the cell
- As a result, water enters the root hair cell via osmosis
- The movement of water dilutes the cells contents, increasing its water potential
- Water moves out of the root hair cell
- Water moves into the cortex (outer tissue of the root)
- Water continues to move in this way, because it is constantly being taken up by the xylem in the middle of the root
Where are amino acids transported to via plasma?
To the body cells
Where are antibodies transported to via plasma?
The site of infection
How does the blood circulation system work?
- De-oxygenated blood comes into right atrium from the vena cava
- De-oxygenated blood is pumped (on the right side) out through the pulmonary artery to become oxygenated
- Oxygenated blood flows through pulmonary bein into left atrium and then into left ventricle when left atrioventricular valve opens
- Oxygenated blood is then forcefully pumped (on the left side) up through the aorta to the head and arms, down to the hepatic artery to the liver, the digestive system, the renal artery to the kidneys, to the sex organ and to the legs
- De-oxygenated blood in the digestive system travels up the hepatic portal vein and joins the hepatic vein of the liver
- All blood flows through veins and e-enters heart via vena cava
How does the structure of veins relate to their function?
- Veins are under lower blood-pressure
- Veins have thin walls made of little elastic tissue of fibre
- They do not need to stretch or recoil
- They have a wider lumen
What is the composition of blood?
- Red blood cells
- White blood cells
- Platelets
- Plasma
Explain how coronary heart can cause death
- Begins with the blockage in the coronary artery
- Oxygen cannot get to the heart muscle cells
- Heart muscle cells cannot respire
- Heart muscle dies
- This is called a heart attack and is a result of coronary heart disease (CHD)
How does the immune system respond to pathogens using white blood cells?
- Lymphocytes produce antibodies that latch onto cells and detect their antigens
- If antigens are ‘non self antigens’ the phagocytes will produce pseudopodia to surround, enclose and engulf the pathogen
- Digestive enzymes are secreted into the vacuole to break down the microrganism
- Once the pathogen has burst, the lymphocyte produces antitoxins to neutralise the toxins released by the pathogen
How are capillaries adapted for their function?
- Very thin walls for diffusion of hormones, oxygen, nutrients and urea
- Capillaries themselves are very thin so they can fit between cells to supply blood to the organs
Describe the structure of the heart
Vena cava
→
Right atrium
→
Right atrioventricular valves
→
Right ventricle
→
Pulmonary artery
→
Pulmonary vein
→
Left atrium
→
Left atrioventricular valves
→
Left ventricle
→
Aorta
+++
Septum
+
Ventricular walls (left is thicker)
How does the structure of the arteries relate to their function?
- Blood is under higher pressure
- Therefore arteries have thick walls made of fibres and elastic tissue to be able to stretch and recoil
- They also have a thinner lumen
How does heart rate change under the influence of adrenaline?
- Fight-flight response is triggered
- More oxygen needed to make ATP energy is preparations for intensive use of muscle cells
Why can unicellular organisms rely of diffusion for movement of substances in and out of the cell?
- Very small size/volume
- Very high SA : Vol ratio
- Allows for very fast diffusion
