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Biology Unit 2 > 2.3 > Flashcards

2.3 Flashcards

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1
Q

Briefly describe the vascular system of insects

A
  • Open circularoty system
  • Dorsal-tube shaped heart
  • Respiratory gases not carried in blood
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2
Q

What is an open circularoty system?

A
  • Transport medium pumped by the heart is not contained within vessels, but moves freely
  • Transport fluid comes into direct contact with the cells
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3
Q

Briefly describe the vascular system of earthworms

A
  • Vascularisation
  • Closed circularoty system
  • Respiratory gases carried in blood
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4
Q

What is a closed circularoty system?

A
  • Blood pumped by the heart is contained within blood vessels
  • Blood does not come into direct contact with the cells
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5
Q

Describe the advantages of a closed circularoty system

A
  • blood pressure can be maintained
  • blood supply to different organs can vary
  • lower volumes of transport fluid required
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6
Q

what type of circularoty system do fish have?

A

single circularoty system

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7
Q

What is a single circularoty system?

A
  • Circularoty system in which the blood travels through the heart once in one ciruit
  • Blood flows through the heart and is pumped around the body before returning to the heart
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8
Q

What type of circularoty system do mammals have?

A

Double circularoty system

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9
Q

what is a double circularoty system?

A
  • Circularoty system in which the blood flows through the heart twice in 2 circuits
  • Blood is pumped from the heart to the lungs before returning to the heart. It is then pumped around the body,, after which it returns to the heart again.
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10
Q

What are the benefits of a double circularoty system?

A
  • Maintains blood pressure around the whole body
  • Uptake of oxygen is more efficient
  • Delivery of oxygen and nutrients is more efficient
  • Blood pressure can differ in pulmonary aand systematic circuits
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11
Q

Describe the double circulatory system in humans

A

Blood flows through the heart twice in 2 circuits;
* pulmonary circuit
* systemic circuit

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12
Q

Name the 4 chambers of the mammalian heart

A
  • Left atrium
  • Right atrium
  • Left ventricle
  • Right ventricle
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13
Q

identify the strucutresof the heart

A
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14
Q

Describe the pathway of blood around the body, naming the strucutres of the heart.

A

Pulmonary vein - left atrium - left ventricle - Aorta - Body - Vena Cava - Right atrium - Right ventricle - Pulmonary artery - Lungs

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15
Q

show the direction of blood flow through the heart

A
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16
Q

Where are the atrioventricular valves found and what is their function?

A
  • Found between the atria and ventricles
  • Prevent the backflow of blood from the ventricles into the atria
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17
Q

What are the 2 types of atrioventricular valves?

A
  • Bicuspid (left side)
  • Tricuspid ( right side )
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18
Q

Where are the semilunar valves found and what is their function?

A
  • Found between the ventricles and arteries
  • Prevent the backflow of blood from the arteries into the ventricles
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19
Q

Name the 5 types of blood vessel

A
  • Arteries
  • Arterioles
  • Capillaries
  • Venuels
  • Veins
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20
Q

Describe the pathway of blood through the blood vessels

A

heart - arteries - arterioles - capillaries - venules - veins - heart

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21
Q

What is the function of arteries?

A

Carry blood awy from the heart to the tissues, under high pressure.

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22
Q

Relate the structure of arteries to their function.

A

Thick, muscular walls to handle high pressure without tearing. Elastic tissue allows recoil to prevent pressure surges. Narrow lumen to maintain pressure.

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23
Q

What is the function of veins?

A

Carry blood towards the heart under low pressure

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24
Q

Relate the structure of veins to their function

A

Thin walls due to lower pressure. Require valves to ensure blood doesnt flow backwards. Have less muscular and elastic tissue as they dont have to control blood flow.

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25
Q

What is the function of capillaries?

A

Form a large network through the tissues of the body and connect the arterioles to the venules.

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26
Q

Relate the strucutre of capillaries to their function

A
  • Walls only one cell thick, so short diffusion pathway
  • very narrow, so can permate tissues and red blood cells can lie flat against the wall, reducing the diffusion distance.
  • numerous and highly branched, providing a large surface area.
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27
Q

What is the function of the arterioles?

A

Connect the arteries and the capillaries.

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28
Q

What is the function of the venules?

A

Connect the capillaries and the veins

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29
Q

Relate the strucutre of artereioles and venules to their function

A
  • Branch off arteries and veins in order to feed blood into capillaries
  • Smaller than arteries and veins so that the change in pressure is more gradual as blood flows to the capillaries
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30
Q

What is the cardiac cycle?

A
  • The sequence of events involved in one complete contraction and relaxation of the heart
  • Three stages; atrial systole, venricular systole and diastole.
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31
Q

Describe what happens during ventricular diastole.

A

The heart is relaxed. Blood enters the atria, increasing the pressure and pushing open the AV valves. This allows blood to flow into the ventricles. Pressure in the heart is lower than in the arteries, so SL valve remains closed.

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32
Q

Describe what happens during atrial systole

A
  • The atria contract, pushing any remaining blood into the ventricles
  • AV valves pushed fully open.
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33
Q

Describe what happens during ventricular systole

A

The ventricles contract. The pressure in the ventricles increases, closing the AV valves to prevent backflow and opening the SL vavlves. Blood flows into the arteries.

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34
Q

Why is cardiac muscle myogenic?

A

It initiates its own contraction without outside stimulation from nervous impulses.

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35
Q

Explain how the heart contracts

A
  • SAN initiates and spreads impulse across the atria, so they contract.
  • AVN receives, delays, and conveys the impulse down the bundle of His.
  • Impulse travels into the Puryyne fibres which branch across the ventricles, so they contract from the bottom up.
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36
Q

What is a eletrocardiodiogram (ECG)?

A

A graph shpwing the eletrical activity in the heart during the cardiac cycle.

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37
Q

Explain the characteristic patterns displayed on a typical ECG

A
  • P wave - depolarisation of atria during atrial systole
  • QRS wave- depolarisation of ventricles during ventricular systole
  • T wave- repolarisation of ventricles during ventricular diastole.
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38
Q

Describe the strucutre and function of erythrocystes

A
  • Type of blood cell that is anucleated and bioncave
  • Contains haemoglobin which enables the transport of oxyge and carbon dioxide to and from the tissues.
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39
Q

What is plasma?

A

Main component of the blood ( yellow liquid) that carries red blood cells
Contains proteins, nutrients, mineral ions, hormones, dissolved gases and waste.
Also distributes heat.

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40
Q

Describe the role of haemoglobin

A

Present in red bood cells. Oxygen molecules bind to the haem groups and are carried around the body, then released where they are needed in repsiring tissues.

41
Q

How does partial pressure of oxugen affect oxygen-haemoglobin binding?

A

Hameoglobin has a high affinity for oxygen depending onthe partial pressure of oxygen, p ( O2)
* At high p(02), oxygen associated to form oxyhaemoglobin
* At low p(02) oxygen dissociates to form deoxyhaemoglobin.

42
Q

Write an equation for the formation of oxyhaemoglobin

A

Hb + 402 ⇌ Hb:402
( full saturation is rare)

43
Q

What do oxyhameoglobin dissociation curves show?

A

Saturation of haemoglobin with oxygen (%) plotted against partial pressure of oxygen (kPa). Curves further to the left show that haemoglobin has a higher affinity for oxygen.

44
Q

Explain the shape of oxyhameoglobin dissociation curves

A

Sigmoidal curve ( S-shaped)
* when first ozygen molecue binds, it changes the tertiary structure of haemoglobi so that it is easier for the second and third molecules to bind.
* Third molecule changes the tertiary structure of haemoglobin so that it is more difficult for the fourth molecule to bind.

45
Q

How does fetal haemoglobin differ from adult haemoglobin?

A

Has a higher affinity for oxygen than adult haemoglobin due to the presence of two different subunits that allow oxygen to bind more readily.

46
Q

Why is the affinity of fetal haemoglobin important?

A

Enables the fetus to obtain ocygen from the mothers blood.

47
Q

Compare the dissociation curves of the adult and fetal haemoglobin.

A

Fetal haemoglobin dissociation curve to the left. At the same partial pressure, % oxygen saturation is greater due to fetal haemoglobin having a higher affinity.

48
Q

Predict the shape of the dissociation curves of animals adapted to low oxygen level habitats

A
  • Haemoglobin has a greater affinity for oxygen
  • Haemoglobin is saturated at a lower p(02)
  • Therefore dissociation curve is to the left
49
Q

How is carbon dioxide carried from respiring cells to the lungs

A
  • Transported in aqueous solution in the plasma
  • As hydrogen carbonate ions in the plasma
  • Carried as carbaminohaemoglobin in the blood
50
Q

What is the chloride shift?

A
  • Process by which chloride ions move into the erythrocytes in exchange for hydrogen carbonate ions which diffuse out of the erythocytes
  • One-to-one exchange
51
Q

Why is the chloride shift important?

A
  • It maintains the electrochemical equilibrium of the cell
52
Q

What is the function of carbonic anhydrase?

A

Catayses the reversible reaction between water and carbon dioxide to produce carbonic acid

53
Q

Write equations to show the formation of hydrogen carbonate ions in the plasm

A

Carbonic anhydrse enzyme catalyses
C02 + H20 ⇌ H2CO3 (Carbonic acid)
Carbonic acid dissoicates
H2CO3 ⇌ HCO3- (hydrogen carbonate ions) + H+

54
Q

What is the bohr effect?

A

The loss of affinity of haemoglobin for oxygen as the partial pressure of carbon dioxide increase

55
Q

Explain the role of carbonic anhydrase in the Bohr effect

A
  • Carboic anhydrase is present in red blood cells
  • Catalyses the reaction of carbon dioxide and water to form carbonic acid, which dissociates to produce H+ ions
  • H+ ions combine with the haemoglobin to form haemoglobinic cid
  • Encourages oxygen to dissociate from haemoglobin
56
Q

What is rissue fluid?

A
  • Fluid that surrounds the cells of animals
  • Same composition as plasma but does not contain red blood cells or plasma proteins
57
Q

Describe the differnt pressures involved in the formation of tissue fluid

A
  • Hydrostatic pressure + higher at arteriol end of the capillary than venous end
  • Oncotic pressure + changing water potential of the capillaries as water moves out, induced by proteins in the plasma
58
Q

How is tissue fluid formed?

A

As blood is pumped through increasingly smaller vessels, hydrostatic pressure is greater than oncotic pressure, so fluid moves out of the capillaries. It then exchanges substances with the cells.

59
Q

Why does blood pressure fall along the capillary?

A
  • Friciton
  • Lower voulme of blood
60
Q

Whathappens at the venous end of the capilarry?

A
  • Oncotic pressure is greater than hydrostatic pressure
  • Fluid moved down its water potential gradient back into the capillaries
61
Q

Where does some tissue fluid drain?

A

Some tissue fluid drains into the lymphatic system and eventually returns to the blood.

62
Q

Define vasucalr bundle

A
  • Vascular system in herbaceous dicotyledonous plants
  • Consists of two transport vessels, the xylem and the phloem
63
Q

Describe the strucutre and function of the vascular system in the roots of dictotyledons

A

Xylem arrnaged in a X shape to provide resistance against force. Phloem found as patches between the arms. Surrounded by endodermis, aiding water passage

64
Q

Describe the structure and function of the vasucalr system in the stem of dictyledons

A

Vascular bundles organised around a central pith. Xylem on the inside of the bundle to provide support and flexibility, phloem on the outside. Cambium is found between the two

65
Q

Which structure in plants is adapted for the uptake of water and minerals?

A

Root hair cells

66
Q

How is water taken up from the soil?

A
  • root hair cells absorb minerals by active transport, reducing the water potential of the root
  • water potenrial of the root hair cells is lower than that of the soil
  • water moves into the root by osmosis
67
Q

Outline how plant roots are adapted for the absorption of water and minerals.

A

Plant roots are composed of millions of root hair cells which have:
* Long hairs that extend from the cell body, increasing the surface area for absorptipon
* Many mitrochondria which produce energy for the active transport of mineral ions

68
Q

State the three pathways by which water moves through the root

A
  • Apoplast pathway
  • Symplast pathway
  • Vacuolar pathway
69
Q

Describe the apoplast pathway

A

Water moves through intercellular spaces between cellulose molecules in the cell wall. It diffuses down its wter potential gradient by osmosis

70
Q

Describe the symplast pathway

A

Water enters the cytoplasm through the plasma membrane and moves between adjacent cells via plasmodesmata. Water diffuses down its water potential gradient by osmosis

71
Q

Describe the vacuolar pathway

A

Water enters the cytoplasm through the plasma membrane and moves between vacuoles of adjacent cells. Water diffuses down its water potential gradient by osmosis

72
Q

Describe the structure and function of the endodermis

A
  • Innermost layer of the cortex of a dicot root
  • Impregentaed with suberin which forms the casparian strip
  • Endodermal cells actively transport mineral ions into the xylem
73
Q

What is the function of the casparian strip?

A
  • Blocks the apoplast pathwy, forcing water through the symplast route
  • Enables control of the movement of water water and minerals across the root and into the xylem
74
Q

What molecule makes the Casparian strip waterproof?

A

Suberin

75
Q

Relate the structure of the xylem to its function

A
  • Long,continuous columns mae of dead tissue, allowing the transportation of water
  • Contain bordered pits, allowing the sideways movement of water between vessels.
  • Walls impregenated with lignin, providing structural support
76
Q

Define transpiration

A
  • The loss of water vapour from the parts of a plant exposed to the air due to evaporation and diffusion
  • Consequence of gaseous exchange: occurs when the plant opens the stomata to exchange 02 and C02
77
Q

How does water move up the stem?

A
  • Root pressure
  • Cohesion tension theory
  • Capillarity
78
Q

What is the transpirtion stream?

A

The flow of water from the roots to the leaves in plants, where it is lost by evaporation to the enviroment

79
Q

What is root pressure?

A

The force that drives water into and up the xylem by osmosis due to active transport of minerals into the xylemn by endodermal cells.

80
Q

Explain cohesion tension theory

A
  • water molecules form hydrogen bonds with each other, causing them to ‘stick’ together
  • surface tension of the water also creates this sticking effect
  • Therefore as water is lost through transpiration, more is drawn up the stem from the roots.
81
Q

Define capillarity

A

The tendancy of water to move up the xylem, against gravity, due to adhesive forces that prevent the water column dropping back

82
Q

State the factors that affect the rate of transpiration

A
  • Light
  • Temperature
  • Humidity
  • Air movement
83
Q

How does temperature affect the rate of transpiration?

A

A higher temperature increases random motion and rate of evaporation, therefore increasing rate of transpiration

84
Q

How does light affect the rate of transpiration?

A

A higher light intensity increases the rate of photosynthesis, causing more stomata to open for gas excvhange, therefore increasing rate of transpiration,.

85
Q

How does humidity affect the rate of transpiration?

A

High humidity means the water content of the air next to the leaf is high. This reduces the concentration gradient, therefore decreasing rate of transpiration.

86
Q

How does air movement affect the rate of transpiration?

A

Large amounts of air movement blow moist air away from the leaves, creating a steep concentration gradient. Therefore increases rate of transpiration.

87
Q

What is a hydrophye?

A

A plant that is adapted to live and reproduce in very wet habitats e,g water lillies

88
Q

Give adaptations of hydrophytes that allow them to live in wet conditions

A
  • Thin or absent waxy cuticle
  • satomata often opens
  • wide,flat leaves
  • air spaces for buoyancy
89
Q

What is a xerophye?

A

A plant that is adapted to live and reproduce in habitats where water availability is low, e.g cacti and marram grass

90
Q

Give adaptations of xerophyes that allow them to live in dry conditions

A
  • small/rolled leaves
  • densely packed mesophyll
  • thick waxy cuticle
  • stomata often closed
  • hairs to trap moist air
91
Q

What are mesophytes?

A
  • Terrestrial plants adapted to live in enviroments with average conditions and an adequate water supply
  • They have features that enable their survival at unfavourable times of the year
92
Q

Relate the structure of phloem to its function

A
  • sieve tube elements transports sugars around the plant
  • Companion cells designes for active transport of sugars into tubes
  • Plasmodesmata allow communication and the exvhange of substances betwwen sieve tubes and companion cells
93
Q

What are cytoplasmic strands?

A

Small extensions of the cytoplams between adjaccent sieve tube elements and companion cells

94
Q

Describe the function of cytoplasmic strands

A
  • Allow communication and exchange between sieve tube elements and copanion cells
  • Holds the nucleus in place
95
Q

Define transolocation

A

The movement of organic compunds in the phloem, from sources to sinks

96
Q

Summarise the mass-flow hyupothesis of transolocation

A
  • Sugars loaded into sieve tubes via active transport
  • Lowers the water potential, causing water to move in from the xylem
  • Hydrostatic pressure causes sugars to move towards the sink
97
Q

What is autoradiography?

A

A technique used to record the distribution of radioactive material within a specieimen.

98
Q

What is a potometer?

A

An appuratus used to measure water uptake from a cut shoot

Biology Unit 2 (4 decks)

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