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Biology AS level section 3 > Chapter 7 - Mass transport > Flashcards

Chapter 7 - Mass transport Flashcards

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1
Q

what skills is the heart dissection testing

A
  1. Safely use instruments for dissection
  2. Produce scientific drawings
  3. Safely and ethically use organisms to measure
    - Plant or animal responeses
    - Physiological functions
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2
Q

what are the aims for the heart dissection

A
  1. To identify the blood vessels of the heart and the coronary arteries
  2. To identify the valves of the heart
  3. To identify the left and right side of the heart
  4. To identify the 4 chambers of the ehart
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3
Q

method of the heart dissection

A
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4
Q

how do you safely pack away after a heart dissection

A
  1. Place all dissection equipment in a beaker of disinfectant
  2. Place all heart, gloves, paper towels in disposable bags
  3. Clean you work surface with disinfectant spray
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5
Q

What is the structure of a haemoglobin molecule

A
  • Primary structure - the sequence of amino acids in the
    four polypeptide chains
  • Secondary structure - the four polypeptide chains are coiled into helixes
  • Tertiary structure - each polypeptide is folded into its precise shape
  • Quaternary structure - all four polypeptide chains are linked to form an almost spherical molecule each containing a prosthetic group (haem group) which is Fe2+ in humans
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6
Q

what is associating in terms of oxygen in haemoglobin (loading)

A

when haemoglobin binds to a molecule of oxygen

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7
Q

what is disassociating in terms of oxygen in haemoglobin (unloading)

A

when a haemoglobin releases its oxygen molecule

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8
Q

What is the role of haemoglobin

A

to associate with oxygen where gas exchange takes place (lungs)

to disassociate from oxygen where it is needed (respiring tissue)

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9
Q

Why does the affinity of oxygen decrease in the presence of carbon dioxide.

A

Carbon dioxide is mildly acidic which alters the tertiary structure of the haemoglobin molecule making it have a lower affinity for oxygen

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10
Q

haemoglobin affinity table

A
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11
Q

What factors affect the oxygen and haemoglobin binding

A

partial pressure of oxygen
partial pressure of carbon dioxide
saturation of haemoglobin with oxygen

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12
Q

why are there different haemoglobins in different organisms

A

each organisms will have haemoglobin molecules with different affinities for oxygen due to different amounts of oxygen and carbon dioxide present in their surroundings.

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13
Q

What is an oxygen disassociation curve

A

the relationship between the partial pressure of oxygen (kpa) and the saturation of haemoglobin.

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14
Q

How does the saturation of haemoglobin affect oxygen and haemoglobin binding.

A

It is hard for the first oxygen molecule to bind. Once it does it changes the shape to make it easier for the second and third molecule to bind. This is positive cooperativity. It is slightly harder for the fourth oxygen molecule to bind as there is a low chance to find a binding site.

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15
Q

How does carbon dioxide affect the oxygen disassociation curve

A

it shifts to the right as the affinity for oxygen has decreased

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16
Q

What is the double circulatory system in a mammal and what is its main feature

A

the double circulatory system is when the blood passes through the heart twice for each circuit that it travels.

It is a closed system which means that blood will remain in the blood vessels.

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17
Q

What are some of the common features of the mammalian circulatory system

A
  1. suitable medium for transport. Water bases to allow substances to dissolve (blood)
  2. means of moving the medium around the body. Heart in animals and transpiration stream in plants
  3. Means of controlling the flow (valves)
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18
Q

Plan diagram of the mammalian circulatory system

A
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19
Q

Diagram of the cross section of a human heart

A
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20
Q

What is the structure of the atria related to its function

A

Thin walled, elastic so they can stretch when filled with blood.

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21
Q

What is the structure of the ventricles related to its function

A

Thick muscular walls to pump blood under high pressure . The left ventricle is thicker than the right because it has to pump blood all the way around the body.

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22
Q

What are the functions of all the 4 main blood vessels that transport

A
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23
Q

What is the cardiac cycle

A

The heart beats around 70 times per minute in most humans. Each time the heart beats it goes through the same stages of contraction and relaxation – this is the cardiac cycle.

24
Q

what is the equation for cardiac output

A

Cardiac output (cm3/min) = Stroke volume (cm3) x heart rate (bpm)

25
Q

What are the three main stages of the cardiac cycle

A

Diastole
Atrial systole
Ventricular systole

26
Q

What happens during diastole

A
  1. Walls of atria and ventricles are relaxed causing a reduction in pressure
  2. Pressure is lower in the ventricles than in the major arteries, so the semi-lunar valves close
  3. Blood returns to the atria of the heart though the major veins
  4. Pressure rises in the atria pushing open the atrioventricular valves
27
Q

What happens during atrial systole

A
  1. Atria contract simultaneously
  2. Pressure is greater in the atria than the ventricles
  3. Blood pushed into the ventricles
28
Q

What happens during ventricular systole

A
  1. Ventricles contract simultaneously
  2. Increases pressure so atrioventricular valves forced shut
  3. Pressure rises further, forcing open the semi-lunar valves
  4. Blood pushed into aorta and pulmonary artery
29
Q

What is the definition of myogenic

A

The heart is myogenic meaning that its contraction is initiated within the muscle itself

30
Q

What are the three types of valves

A

atrioventricular valves
semi-lunar valves
pocket valves

31
Q

what is the function of atrioventricular valves and where are they found

A

they prevent the backflow of blood into the atria during the contractions of the ventricles and are located between the atria and ventricles

32
Q

what is the function of the semi-lunar valves and where are they found

A

they prevent the backflow of blood into the ventricles during diastole

33
Q

what is the function of the pocket valves and where are they found

A

They ensure that blood does not flow back through the veins duing contraction of the veins (from skeletal muscles contracting) and ensures that blood is always flowing towards the heart

34
Q

graph showing pressures of the chambers of the heart during the cardiac cycle

A
35
Q

What are the 3 main types of blood vessel

A

atery
vein
capillary

36
Q

what are arterioles and venuoles

A

they connect ateries and capillaries/veins and capillaries

37
Q

Main features of blood vessels

A

tough fibrous outer layer - reists pressure changes from inside and outside

muscle layer - can contract to control the flow of blood

elastic layer - maintains blood pressure by streching and springing back (recoiling)

thin inner layer (thin endothelium) - smooth to reduce friction

lumen

38
Q

What is the structure of ateries related to their functions

A

Thick muscle layer compaerd to veins - can be constricted or dillated to control volume of vblood passing through them

elastic layer is thick compared to veins - to keep blood pressure high by recoiling to maintain that high pressure and to smooth out the pressure surges created by the heart

great thickness of the wall - stops the vessels bursting under pressure

no valves - blood pressure is too high for blood to be flowing backwards.

39
Q

what is the structure of arterioles related to their function

A

muscle layer is thick than arteries - restrict the flow of blood into the capillaries by contracting

elastic layer is relatively thinner than arteries - blood pressure is lower

40
Q

structure of veins related to their function

A

The muscle layer is relatively thin - carries blood away from tissues so constriction and dilation cannot control the flow of blood

elastic layer is relatively thin - blood pressure is too low for veins to burst

thickness of the wall is too small - pressure is too low so no risk for bursting

there are valves throughout - ensures that there is no backflow of blood as the blood pressure is too low

41
Q

what is the structure of capillaries related to their function

A

thin layer - short diffusion path

narrow diameter - short diffusion pathway

numerous and highly branched - large surface area

narrow lumen - red blood cells are squeezed along the side of the capillary.

there are spaces between the lining of the endothelial cells - allow white blood cells to escape to deal with infection.

42
Q

What is tissue fluid

A

The liquid that surrounds the cells in you body containing water , glucose, amino acids, fatty acids, ions and oxygen.

43
Q

How is tissue fluid formed

A

Capillaries have small gaps in their walls which allow lipids and small molecules to be forced out.

as blood enters the capilaries from the aterioles is creates high hydrostatic pressure so water, glucose, amico acids and oxygen are forced out. This is known as ultrafiltration.

Large molecules will remain in the capilaries creating a water potential gradient. This lowers the hydrostatic pressure in the capillaries and water will re-enter the capillaries via osmosis.

44
Q

what is forced out of the capillaries due to hydrostatic pressure and what is not

A

Forced out:

Water molecules
Dissolved minerals and salts
Glucose
small proteins and amino acids
Fatty acids
Oxygen

Not forced out:

Red blood cells
Platelets
Large proteins

45
Q

Why does not all of the liquid from the tissue fluid get reabsorbed

A

Osmosis will reach an equilibrium and the rest of the tissue fluid will be absorbed into the lymph vessels.

46
Q

diagram of the movement of tissue fluid

A
47
Q

what is the function of the xylem

A

xylem is a tissue made up of dead, hollow, lignified cells that transport water and mineral ions

48
Q

what are the steps in transpiration

A

1) water evaporates from the leaves at the top of the xylem
2) This creates surface tension which pulls more water up into the leaf
3) This is due to the water molecules being cohesive and the entire column of water is pulled up at once
4) Water enters the stem through the roots

49
Q

What are the four main factors that affect the rate of transpiration

A

Light - The lighter it is the faster the transpiration rate
Temperature - the higher the temperature the faster the transpiration rate
Humidity - the lower the humidity the faster the transpiration rate
Wind - the windier it is the faster the transpiration rate

50
Q

what are the steps in setting up a potometer

A

1) Cut a shoot underwater to prevent air from entering the xylem. Cut it at a slant to increase the surface area available for water uptake.

2) Assemble the potometer in water and insert the shoot underwater, so no air can enter.

3) Remove the apparatus from the water but keep the end of the capillary tube submerged in a beaker of water.
4) Check that the apparatus is watertight and airtight.

5) Dry the leaves, allow time for the shoot to acclimatise, and then shut the tap.

6) Remove the end of the capillary tube from the beaker of water until one air bubble has formed, then put the end of the tube back into the water.

7) Record the starting position of the air bubble.

8) Start a stopwatch and record the distance moved by the bubble per unit time, e.g. per hour. The rate of air bubble movement is an estimate of the transpiration rate.

9) Remember, only change one variable (e.g. temperature) at a time. All other conditions (e.g. light, humidity) must be kept constant.

51
Q

What is the evidence for the cohesion tension theory

A

Change in daimeter of the trunk throughout the day
If the xylem vessels break and an air bubble forms water is no longer drawn up the xylem
Water does not flow out when a xylem vessel is broken

52
Q

what are the two components of phloem tissue

A

sieve tube elements -
living cells
no nucleus
few organelles

Companion cells -
provide ATP required for the active transport of substances

53
Q

what is translocation

A

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

54
Q

what is a source and what is a sink

A

source - where the sugars during photosynthesis are produced (leaves)
sink - where the sugars are stored or used (roots)

55
Q

What evidence is there for and agains the mass flow theory

A
56
Q

what is the step by step process of translocation

A
  1. sucrose enters the companion cells from the photosynthetic cells by facilitated diffusion.
  2. Hydrogen ions will be actively transported out of the companion cells into the spaces within the cell walls.
  3. These hydrogen ions will then diffuse down a concentration gradient into the sieve tube element along with sucrose molecules through a co-transporter protein.
  4. At the sink end the solutes are removed from the phloem causing a lower pressure and a more positive water potential
  5. This results in a pressure gradient from the source to sink end pushing solutes to the sink end of the plant

Biology AS level section 3 (2 decks)

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