2 h) Transport Flashcards
2.41 understand why simple, unicellular organisms can rely on diffusion for movement of substances in and out of the cell
Unicellular organisms- including fungi and bacteria- have a large surface area to volume ratio and they are small and so the diffusion distance is short, meaning diffusion happens very quickly.
2.42 understand the need for a transport system in multicellular organisms
Multicellular organisms have a small surface area to volume ratio and the distance for diffusion would be very large and so very slow. This wouldn’t support the organism; so they have developed transport systems, like the ventilation system and the circulatory system which speed up the process of getting necessary molecules in and out of the body enough to support themselves.
Flowering plants:
2.43 describe the role of xylem in transporting water and mineral salts from the roots to other parts of the plant
Xylem transport nitrates, phosphates, water and other mineral salts from the roots to other parts of the plants, like the leafs, flowers and buds.
Xylem consists of columns of hollow, dead cells. Substances are carried up the tube dissolved in water.
2.44 explain how water is absorbed by root hair cells
Roots branch to increase the surface area and to increase the chances of finding a water source. Root hairs are epidermal cells on the surface of the root: they also increase the surface area for absorption. They absorb minerals by active transport and water by osmosis. These substances then move to the xylem.
2.45 understand that transpiration is the evaporation of water from the surface of a plant
Transpiration is the name given to the process by which water is evaporated from the surface of a plant.
Heat- from sunlight- is absorbed into the leaf which turns liquid water into gas, the gas then leaves the leaf through the stomata.
2.46 explain how the rate of transpiration is affected by changes in humidity, wind speed, temperature and light intensity
Humidity
Increased humidity decreases transpiration. This is because high water content outside the leaf will mean there is little difference in concentration, so the water will not be able to move- as it naturally does- from an area of high concontrartion to an area of low concentration.
Wind speed
Increased wind speed will increase transpiration. Because if the wind blows away the water vapour being produced their will be a greater difference in water concentration, meaning water will be able to continue leaving the leaf.
Temperature
Increased temperature increases transpiration, as increased heat makes evaporating easyer.
Light intensity
Increased light intensity increases transpiration, as more heat is absorbed by the leaf meaning more water will be evaporated, also there is more photosynthesis meaning more water is being transported through the leaf (so more will need to leave the leaf.)
2.47 describe experiments to investigate the role of environmental factors in determining the rate of transpiration from a leafy shoot
Support a plant in a tray filled with a given amount of water. Place in different conditions and record the time taken for all the water in the way to be taken up by the plant.
https://www.bbc.co.uk/education/guides/zps82hv/revision/6
2.48 describe the composition of the blood: red blood cells, white blood cells, platelets and plasma
The blood has several different components.
55% of the blood is plasma: yellow liquid containing water with different things dissolved in it.
There are many red blood cells (Erythroeytes.)
There are less white cells: Phagosytes; lymphosytes.
Platelets (dead red blood cells) which play an important role in clotting.
2.49 understand the role of plasma in the transport of carbon dioxide, digested food, urea, hormones and heat energy
Water- which is the main component of plasma- is a solvent and a liquid; so plasma carries these different things around the body disolved in water:
Carbon- Hydrogen carbonate
Digested food- soluble sugars and amino acids
Urea
Hormones.
Water also carries heat, which is important in the regulation of body temperature.
2.50 explain how adaptations of red blood cells, including shape, structure and the presence of haemoglobin, make them suitable for the transport of oxygen
Red blood cells carry oxygen around the body. In order to do this they have haemoglobin- which is made from iron- that can bond to oxygen. Red blood cells are enucleate (they have no nucleus) to make room for the haemoglobin. There are no mitochondria as the cells respire anaerobically so the cells don’t use any oxygen.
They are biconcave; they are a flat disk with a dip in the middle. The shape of a flat disk enables them to pass through narrow capillaries They have a dip in the middle to increase the surface area and decrease the distance for diffusion meaning that diffusion of oxygen happens quickly.
2.51 describe how the immune system responds to disease using white blood cells, illustrated by phagocytes ingesting pathogens and lymphocytes releasing antibodies specific to the pathogen
White blood cells are specialised cells which can stop pathogens in your body.
Phagocytes
They can detect the presence of pathogens because of chemicals they give off.
The cell then engulfs the pathogen. It then destroys the cell with digestive enzymes.
Lymphocytes
They release anti-bodies that are specific to the pathogen.
When a lymphocyte meets its specific pathogen it divides: one cells it creates being a memory cell; the other being the cell which will create anti-bodies.
One type of anti-body will attach to the pathogen to attract phagocytes. The other type will disable the cell. A third type will group the pathogens together so that phagocytes can engulf them all.
If the memory cells every meet the pathogen again they will create the anti-bodies very quickly.
2.52 describe the structure of the heart and how it functions
The heart can be thought of in four sections: the right atrium; the right ventricle; the left atrium; the left ventricle. A description of the workings of the heart:
The right atrium fills with blood (from the vena cava) and the valve is closed; This area is squeezed forcing the blood through an atrio-ventricular valve into the right ventricle; This area contracts forcing the blood through the pulmonary artery where it is oxygenated at the lungs; the pulmonary vein fills the left atrium with blood; This contracts forcing the blood into the left ventricle; when the left ventricle contracts the blood is forced out through the aorta.
Things to remember:
Veins lead to the heart; arteries lead away.
Atrium means entrance hall in Latin; hence the atrium is where blood enters the heart.
The left side is bigger than the right as it has to pump blood through the whole body.
You talk about the heart from right to left, as if you were examining someone’s heart and using their own left and right.
2.53 explain how the heart rate changes during exercise and under the influence of adrenaline
During exercise muscles require more energy which is created by respiration, that requires more oxygen to be brought to cells and more carbon dioxide to be taken away, this means the heart needs to increase its speed so that more blood is sent to muscles.
Adrenalin- produced in the adrenal glands in top of the kidneys- stimulates adrenegic receptors in the heart which increase the rate that your heart cells work at.
This is a good source:
http://www.livestrong.com/article/355672-why-adrenaline-speeds-up-heart-rate/
2.54 describe the structure of arteries, veins and capillaries and understand their roles
Arteries
- Take blood away from the heart
- Blood in them is under high pressure
- They are delivering blood to an organ
- Thick, muscle wall; small lumen (to give high blood pressure)
Veins
- Take blood to the heart
- Blood is under low pressure
- Their blood is returning from an organ
- Relatively thin wall; large lumen
- Valves stop blood flowing back in the wrong direction
Capillaries
- Exchange is taken place
- Very thin cell walls (one cell thick) so that substances can diffuse easily
2.55 understand the general structure of the circulation system to include the blood vessels to and from the heart, the lungs, the liver and the kidneys.
Vein- to the heart Artery- away from heart Lung- pulmonary Liver- hepatic Kidney- renal Stomach- gastric Between the gut and liver is the hepatic portal vein.
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