chapter 7- mass transport

Question 1

how many oxygen molecules can bind to haemoglobin

Answer 1

four

Question 2

what is deoxyhaemoglobin?

Answer 2

the form of haemoglobin without oxygen

Question 3

what is oxyhaemoglobin

Answer 3

the form of haemoglobin without oxygen

Question 4

what is the partial pressure of oxygen

Answer 4

the concentration of oxygen in the body

Question 5

where does haemoglobin have a higher affinity for oxygen

Answer 5

wherever the pO2 is high

Question 6

what does CO2 do to haemoglobin

Answer 6

it binds to haemoglobin and changes the shape of the molecule so that it has a lower affinity for oxygen

Question 7

what is the Bohr effect

Answer 7

it is the right shift of oxygen disassociation curve, leading to lower affinity of haemoglobin and increased unloading to oxygen to respiring cells

Question 8

when does the left shift of the bond disassociation curve occur

Answer 8

for organisms living art high altitudes, underground or foetuses
- all low 02 environments

Question 9

when does the right shift of the bond disassociation curve occur

Answer 9

• Bohr effect
  -organisms with high metabolic rates
  -small and inactive so need more 02

Question 10

what does the left pump of the hear do and its adaptation

Answer 10

• it receives oxygenated blood from the lungs and pumps it to the body
• thicker walls to produce more pressure to pump blood longer distances

Question 11

what does the right pump of the heart do and its adaptation

Answer 11

• right receives deoxygenated blood from the body and pumps it to the lungs
• thinner walls as less pressure required to pump blood to the lungs

Question 12

what is an adaptation of the ventricles and why

Answer 12

the ventricles have a much thicker muscular wall than the atria as they have to generate more pressure to pump the blood longer distances

Question 13

what do valves do and how do they work

Answer 13

• ensure blood flows in the correct direction
• higher pressure on one side causes the valves to open
• higher pressure on the other side causes the valves to close

Question 14

what are they three types of valves and where are they found

Answer 14

• atrioventricular valves - between the left atrium and the left ventricle, and the right atrium nd right ventricle
• semi-lunar valves- between the left ventricle and the aorta, and the right ventricle and the pulmonary artery
• pocket valves- in the veins that occur throughout the venous system

Question 15

what is the cardiac cycle

Answer 15

Diastole - atria and ventricles both relax blood enters atria and ventricles
Atrial systole -atria contracts blood enters ventricles
Ventricular systole- ventricles contract blood enters arteries

Question 16

how do you calculate cardiac output

Answer 16

stroke volume (cm3) x heart rate (bpm)

Question 17

what is the name of the pacemaker cells and where are they found

Answer 17

• sinoatrial node (SAN)
• within the wall of the right atrium

Question 18

what are types of cardiovascular disease

Answer 18

coronary heart disease
thrombosis
myocardial infraction

Question 19

what is mass flow

Answer 19

the way substances move over long distances requiring a source of energy

Question 20

why do some organisms use mass flow

Answer 20

• surface area to volume ratio too small
• distance for diffusion too long
• mass flow takes gases and nutrients close to all cells

Question 21

what is the route which blood flows

Answer 21

ventricle— artery — arteriole — capillary — venule — vein — atrium

Question 22

what is tissue fluid

Answer 22

the fluid that surrounds all cells in the body

Question 23

what evidence supports the cohesion-tension theory

Answer 23

• change in the diameter of tree trunks accourding to the rate of transpiration
• if a xylem vessel is broken and air enters it, the tree can no longer draw up water
  -when a xylem vessel is broken, water does not leak out, as would be the case if it were under pressure

Question 24

what is translocation

Answer 24

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

Question 25

what are the components of the phloem

Answer 25

made up off: -sieve tube elements -sieve plates - companion cells

Question 26

what organic molecules and inorganic ions can be transported in the phloem

Answer 26

- sucrose -amino acids -potassium -chloride - phosphate -magnesium ions

Question 27

what is the mechanism of translocation

Answer 27

mass flow theory

Question 28

what are the steps of mass flow in translocation

Answer 28

- in the source sugars are actively transported into the phloem -by companion cells -this lowers the water potential of the sieve cell and water enters by osmosis -this causes an increase in pressure which causes mass movement towards the sink -sugars are used/ converted in the root for respiration or storage

Question 29

is translocation active of passive?

Answer 29

active

Question 30

what evidence supports the mass flow hypothesis

Answer 30

- there is a pressure within sieve tubes, as shown by sap being released when they are cut - the concentration of sucrose is higher in leaves (source) than in roots (sink) - downwards flow of the phloem occurs in daylight, but ceases when leaves are shaded or at night - metabolic poisons/ and or lack of oxygen inhibit translocation of sucrose in the phloem - companion cells possess many.mitochondia and readily produce a\ATP

Question 31

what are the two experiments used to investigate transport in plants

Answer 31

Ringing experiments tracer experiments

Question 33

what are steps in the ringing experiment

Answer 33

- a section of the outer layers (protective layer and phloem) is removed around the complete circumference of a woody stem while is is still attached to the rest of the plant - the region of the stem immediately above the missing ring of tissue is seen to swell - Samples of the liquid that has accumulated in this swollen region are tested and found to be rich in sugars and other dissolved organic substances. - Some non-photosynthetic tissues in the region below the ring (towards the roots) are found to wither and die, while those above the ring continue to grow.

Question 34

what are the steps in tracer experiments

Answer 34

- radioactive isotopes (e.g Carbon 14) is used to make radioactively labelled carbon dioxide - a plant is then grown in an atmosphere containing carbon 14 resulting in the carbon 14 being incorporated into the sugars produced in photosynthesis - these sugars are then traced as they move along the plant using autoradiography

Question 35

what evidence proves that translocation of organic molecules occurs in the phloem?

Answer 35

- when the phloem is cut, a solution of organic molecules flows out - Plants provided with radioactive carbon dioxide can be shown to have radioactively labelled carbon in phloem after a short time -Aphids are a type of insect that feed on plants. They have needlelike mouthparts which penetrate the phloem. They can therefore be used to extract the contents of the sieve tubes. These contents show daily variations in the sucrose content of leaves that are mirrored a Little later by identical changes in the sucrose content of the phloem