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Biology Year 1 > Mass transport > Flashcards

Mass transport Flashcards

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1
Q

What is mass transport

A

the net movement of mass from one location to another

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2
Q

Explain why haemoglobin has a quaternary structure

A

they are made up of 4 polypeptides that can combine with a single oxygen molecule, therefore haemoglobin can carry lots of oxygen to respiring cells

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3
Q

What is association of oxygen and where does take place

A

high affinity for oxygen in the lungs at high oxygen concentration and low carbon dioxide concentration

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4
Q

What is dissociation of oxygen and where does take place

A

low affinity for oxygen thus releasing oxygen at respiring tissues at low oxygen concentration and high carbon dioxide concentration

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5
Q

Why do different species have differently shaped haemoglobins

A

the structure of haemoglobin can change due to its high or low affinity for oxygen e.g. organisms living at high altitudes have high affinity for oxygen at low partial pressures which is a shift to the left

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6
Q

What is the Bohr effect

A

a shift to the right where there is a lower affinity for oxygen so oxygen is released more easily

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7
Q

What is a shift to the left

A

haemoglobin has a higher affinity for oxygen so oxygen is loaded readily but unloads less easily

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8
Q

What effect does carbon dioxide have on haemoglobin

A

it lowers pH thus haemoglobin has lower affinity for oxygen and more readily releases oxygen e.g. Bohr effect

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9
Q

Why do large organisms require a large circulatory sustem

A

increasing size increases surface area to volume ratio to a point where the needs of the organism cannot be reached

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10
Q

Why do mammals have a closed, double circulatory system

A
  • to pump deoxygenated blood through the pulmonary artery to the lungs
  • to pump oxygenated blood through the aorta and around the boddy
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11
Q

How does blood enter the heart

A
  • oxygenated blood enters the left atrium by the pulmonary vein from the lungs
  • deoxygenated blood enters the right atrium by the vena cava after circulating around the body
  • the two sides are separated by the septum
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12
Q

How does the blood reach the kidney’s and lower limbs

A
  • oxygenated blood get to the kidney’s and lower limbs by the renal arteries and release the oxygen
  • the deoxygenated blood flows back towards the vena cava through the renal veins
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13
Q

Which blood vessel supplies the heart muscle

A

coronary artery

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14
Q

What causes myocardial infarction

A

the blockage of the coronary arteries thus the heart muscle is deprived of blood and therefore oxygen and the muscle cells can no longer respire aerobically

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15
Q

Why is the left side of the heart 3x thicker than the right

A

for a stronger contraction to pump blood around the body

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16
Q

What is diastole

A
  • semi luna valves are closed
  • AV valves are open
  • atria and ventricles relax
  • blood passively flows into the atria from arteries
17
Q

What is atrial systole

A
  • atria contract
  • blood forced into ventricles
  • semi luna valves stay shut
18
Q

What is ventricular systole

A
  • ventricles contract
  • pressure closes AV valves, preventing back flow of blood into the atria
  • semi luna valves open and blood forced out into arteries (pulmonary artery and aorta)
19
Q

How do you calculate cardiac output

A

heart rate X stroke volume

20
Q

What is the structure of a artery related to function

A
  • thin inner lining - endothelium to reduce friction and allow diffusion
  • thick muscle layer - can be constricted and dilated to control volume of blood passing through
  • thick elastic layer - stretch and recoil to maintain high pressure and smooth out pressure surges from the heart beating
  • overall thick wall - resists bursting under pressure
  • no valves - blood is under constant pressure
21
Q

What is the structure of a vein related to function

A
  • thin inner lining - endothelium to reduce friction and allow diffusion
  • thin muscle layer - can be constricted and dilated to control volume of blood passing through
  • thin elastic layer - stretch and recoil to maintain high pressure and smooth out pressure surges from the heart beating
  • overall thin wall - under less pressure than arteries
  • valves at intervals - to prevent back flow of blood at low pressures and making sure blood goes in one direction, towards the heart
22
Q

What is the structure of a capillary related to function

A
  • consist of endothelial cells - short diffusion distance for diffusion
  • they are numerous and highly branched - increases the surface area for efficient diffusion
  • narrow lumen - short diffusion distance and red blood cells are slowed down to allow more time for oxygen to be released
  • spaces between the endothelial cells for white blood cells to escape from to deal with infection
23
Q

How is tissue fluid formed

A
  • when the hydrostatic blood pressure at the arterial end of capillary is higher than the osmotic pressure thus tissue fluid moves out the blood plasma
  • at the venous end of the capillary the osmotic pressure is high than the hydrostatic pressure thus tissue fluid moves back into the blood plasma
  • any excess products e.g. water and carbon dioxide moves into the lymphatic capillary
24
Q

How is the structure of the xylem related to its function

A

-very thin - short diffusion distance

-

25
Q

What is transpiration

A

the force that pulls water up the xylem when water evaporates from the mesophyll in the leaves due to:

-cohesion from the hydrogen bonds between the water molecules where water is continuously pulled up[ the xylem

26
Q

How does water move across the leaf and out the stomata

A
  • mesophyll cells lose water by evaporation from the heat of the sun
  • cells now have a lower water potential so water enters mesophyll from neighboring cells by osmosis
  • neighboring cells now have a lower water potential thus a water potential gradient is established and water is pulled up the xylem and out into the atmosphere by the stomata
27
Q

Why does the trunk of a tree vary in diameter with different times of the day

A

during the day the trunks diameter is thinner than in the day because:

  • transpiration is at its greatest
  • thus more tension
  • thus more negative pressure in the xylem
28
Q

What environmental factors can affect transpiration

A
  • low humidity

- more and longer duration of sunlight

29
Q

How can a potometer be used to estimate rate of transpiration

A

the rate of water uptake is almost the same as the water lost to transpiration therefore the rate of transpiration can be calculated under different environmental conditions

30
Q

What is translocation

A

where organic molecules and some mineral ions are transported from one part of the plant to another

31
Q

What is a source

A

the site of the production

32
Q

What is a sink

A

where the product is stored or used for respiration

33
Q

How is sucrose transferred into sieve tube elements

A
  • sucrose is manufactured as a product of photosynthesis with chloroplasts
  • sucrose diffuses down concentration gradient by facilitated diffusion into companion cells
  • hydrogen is actively transported from the companion cells into the cell walls
  • sucrose is co-transported along side hydrogen into the sieve tube elements
34
Q

How does mass flow hypothesis lead to translocation of sucrose

A
  • when the sucrose is co-transported into the sieve tube elements in the phloem by companion cells which lowers the water potential
  • this lowers water potential so water moves from the xylem in to the sieve tube cells by osmosis
  • this results in a high hydrostatic pressure at the source and a low pressure at the sink therefore there is a mass flow of sucrose down to the sink to be used for respiration or stored
35
Q

How does sucrose enter sink cells

A

by active transport

36
Q

What do ringing experiments show and how is it executed

A

to conclude that the phloem is is the tissue responsible for translocation of sugars in plants

  • the protective layer and phloem is removed around a complete circumference of a woody stem
  • the region of the stem above the missing ring will begin to swell
  • the swelling region will be rich in sugars and other organic substances
  • the region bellow the removed ring towards the roots begin to wither and die as the flow of sugars has been interrupted
37
Q

How to radioactive tracers work

A

radioactive isotopes are useful for tracing the movement of substances in plants
-they can be used to bind to sugars produced by photosynthesis and be traced using autoradiography

Biology Year 1 (10 decks)

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