3.4.12- A-A* (AO3/4)- Mass transport Flashcards
When the top of a plant is cut off, leaving only the stem and the roots, a phenomenon known as ‘bleeding’ is often seen. ‘Bleeding’ is when small amounts of the xylem sap exude from the top of the cut stem .
How is this evidence for the cohesion-tension theory of transpiration?
1- Absorption of water in the roots Mineral ions enter the roots via active active transport transport. This means that energy is used to transport minerals into the root hair cells against their concentration gradient. This lowers lowers the water potential within the cell and results in water moving in into the root via osmosi osmosis.
2- Hydrostatic pressure
As water moves into the roots, the hydrostatic pressure increases. As one water molecule enters, it forces the next water molecule to move further into the root because of the strong
hydrogen
hydrogen bonds between the water molecules. This creates a ‘domino’ effect, and water molecules are forced into the
xylem
xylem, the water transporting vessel.
3- Bleeding
When the top of the stem is chopped off, ions continue to be transported into the roots and water continues to push other water molecules up the xylem tube. This results in xylem sap being forced out the top of the stem.
Rowing is a form of high-intensity activity and often relies on anaerobic respiration. Anaerobic respiration produces lactic acid from pyruvate.
Use this information to suggest how the Bohr effect might lead to more oxygen being supplied to muscle tissues which are highly active.
1- Lactic acid Lactic acid releases hplus H+ ions into solution therefore lowering the ph
2- H+ ions allosterically regulate haemoglobin. The binding of H+ to haemoglobin lower reduces the affinity of haemoglobin for oxygen oxygen.
3-Bohr effect
This decreased affinity for oxygen means that the
dissasociation
dissociation curve of haemoglobin shifts to the
right
right. Effectively, this means that at the same external partial
pressure
pressure of oxygen, there will be
less oxygen bound to haemoglobin.
4- Implication for muscle
In anaerobically respiring muscle, the release of lactic acid therefore causes haemoglobin to release more oxygen. This means that the anaerobically respiring tissue can begin to respire aerobically. This form of respiration is more favourable because it produces more {ATP|energy] per glucose molecule used.
One vein that carries blood towards a major organ
The hepatic portal vein carries blood towards the liver from the intestines.
The liver is a major site of metabolism. Excess glucose is stored as glycogen in the liver and several other important metabolic processes happen there. It is important that the products of digestion are transported directly to the liver so that levels can be regulated.
This is also important in drug design. Drugs that are taken orally will pass through the liver before they reach other tissues. This is called the ‘First Pass Effect’. Drugs must, therefore, be designed to not be broken down by metabolism in the liver.
Explore the importance of the transfer of substances within an organism.
Gas exchange similarities and differences
When organisms evolve from single cells to
muticellular
multicellular organisms, their surface area to volume ratio
decrease
decreases. This means that they cannot rely on
diffusion
diffusion for the exchange of substances, for example, gases. Compare the similarities and differences of the insect
tracheal
tracheal system, the human double
circulatory
circulatory system and the fish
singlu
single circulatory system.
Explore the importance of the transfer of substances within an organism.
Talk about the different transport mechanisms of digestion
Food is transferred through the digestion system by the contraction of longitudinal and circular muscles in a process known as peristalsis
Explore the importance of the transfer of substances within an organism.
How transport is achieved without muscle tissue in plants
Discuss the bi-directional transport of sucrose in the phloem and why the cohesion of water water molecules is important in the transpiration transpiration stream.
Explore the importance of the transfer of substances within an organism.
Discuss transport on a small scale as well
How is transport achieved across a membrane? Explore specific processes that rely on a concentration
gradient
gradient, such as
facilitated
facillitated diffusion of Na+ and K+ ions in nerves, or
active
active processes that require energy, such as the secondary active transport of glucose into the intestine.
Other examples of transfer
In an essay, it could be argued that the transfer of
genetic
genetic material both physically, in the movement of the sperm cell, and also theoretically, in terms of passing on
dna
chromosomes to offspring, is a form of transfer of substances.
Explore the importance of the transfer of substances within an organism.
TIPS for essay
Remember to provide a broad range of ideas and some specific examples of each of these ideas. It is important to express your comprehensive understanding of the course.
