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Transport in Animals Flashcards

1
Q

Surface area to volume ratio

A

Surface area/ Volume

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2
Q

What can you say about single-celled organisms SA:V

A

Large SA:V ratio

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3
Q

What can you say about small multi-celled organisms SA:V

A

Smaller SA:V

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4
Q

How does carbon dioxide and oxygen pass through the exoskeleton?

A

Through openings called spiracles on the surface of the exoskeleton.

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5
Q

Why do most multi-cellular organisms don’t do diffusion

A

SA:V too small

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6
Q

Where do spiracles lead into? (insects)

A

They lead into trachea that extend along the insects body

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6
Q

How do multi-cellular organisms get around not being able to do diffusion?

A

Specialised gas exchange eg. lung and gills
Specialised transport system eg. blood

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6
Q

What are insects covered in?

A

Protective exoskeleton made of polysaccharide chitin

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7
Q

How is tracheae reinforced? (insects)

A

They are reinforced by chitin

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8
Q

What are tracheoles?

A

tiny tubes in the respiratory system of insects that enable gas exchange between cells and air

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9
Q

Why is there a short diffusion distance between tracheoles and cells? (insects)

A

They have a narrow diameter and are close to cells
Oxygen used for aerobic respiration can diffuse quicky.

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10
Q

What is tracheal fluid/ describe its role?

A

Found in the ends of the tracheoles
Cells around the tracheole undergo anaerobic respiration (during intense activity) which produces lactic acid.

This lowers the water potential of the cells and it causes tracheal fluid to move into the cell.

Reduces the volume of trachea fluid and it draws air down into the tracheole.

This means more tracheole surface is available for the diffusion of oxygen and carbon dioxide.

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11
Q

Why is gas exchange a passive process for insects?

A

Oxygen diffuses down the concentration gradient from an area of high concentration in the external air to the tracheoles where the concentration is lower.

And carbon dioxide diffuses down its concentration gradient from the high concentration in the tracheoles to the external air.

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12
Q

Why do insects tend to be small?

A

The small size reduces the distance required for diffusion. Much faster diffusion pathway.

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13
Q

Why is water loss a problem for insects?

A

The walls of the tracheoles are moist and the tracheoles contain tracheal fluid. So water vapour can diffuse out of the spiracles.

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14
Q

How do insects reduce water loss from their spiracles?

A

a waterproof exoskeleton that prevents water loss over most of the insect’s body surface.

the ability to close spiracles.

hairs around the spiracles to reduce diffusion of water vapour.

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15
Q

Why do plants need a transport system?

A

To ensure all cells receive sufficient nutrients. Xylem transports water & minerals (passive – transpiration), while phloem transports sugars (active – translocation).

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16
Q

What are the components of vascular bundles in roots?

A

Xylem vessels arranged in an X shape for mechanical support, surrounded by endodermis for water supply, with an inner layer of meristem cells called pericycle.

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17
Q

How are vascular bundles arranged in stems?

A

inside xylem for support & flexibility, phloem outside, cambium (meristem cells) in between producing new xylem and phloem.

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18
Q

How do vascular bundles function in leaves?

A

They form the midrib and veins, supporting and transporting substances. Dicotyledonous leaves have a network of veins.

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19
Q

What are the key features of xylem vessels?

A

Transport water/minerals,

provide structural support,

long dead cell cylinders with open ends forming a continuous column,

contain pits for lateral water movement,

thickened with lignin in spiral patterns for flexibility, water flows only upwards.

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20
Q

How does phloem function?

A

Made of living cells, involved in translocation, contains sieve tube elements for transporting sugars in sap (up or down), companion cells producing ATP for active loading, connected by plasmodesmata.

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21
Q

What is transpiration?

A

Process where water is absorbed by roots, travels up, and evaporates from stomata.

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22
Q

What factors affect transpiration rate?

A

Leaf number, stomata position/size, waxy cuticle, light, temperature, humidity, air movement, and water availability.

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23
How are xerophytes adapted to dry conditions?
Small leaves, thick waxy cuticles, dense mesophyll to reduce evaporation, stomata close in low water, hairs & pits trap moisture, leaves roll to reduce exposure.
24
How are hydrophytes adapted to water environments?
Thin/absent cuticle, open stomata on upper surface, wide flat leaves for light absorption, air sacs for buoyancy, large air spaces for flotation. There us a lack of oxygen and carbon dioxide + lack of soil support
25
How does water enter root hairs?
By osmosis down a water potential gradient.
26
How do minerals enter root hairs?
By active transport against concentration gradient.
27
What are the two pathways for water movement in roots?
Symplast: Water moves through cytoplasm via plasmodesmata. Apoplast: Water moves through cell walls and spaces.
28
What is the role of the Casparian strip?
Forces water from the apoplast pathway into the symplast pathway at the endodermis.
29
How is water moved up the xylem?
1) water and minerals form a continous chain in the xylem vessels due to **adhesion and cohesion** 2) The leaf loses water through transpiration and pulls water & minerals out of the xylem 3) This creates a pressure gradient that water moves along- causes **mass flow** as they move from an area of *high pressure to low pressure*
30
What is translocation?
Energy-requiring process that transports assimilates (e.g., sucrose) from sources (leaves) to sinks (roots/meristems).
31
How does sucrose enter the phloem? (active loading)
1) Atp powers the proton pump which pumps out H+ ions Active transport of H+ from the companion cell to the cell wall 2) H+ passively diffuses into the companion cells through the co-transporter, taking in sucrose at the same time 3) Sucrose diffuses into the sieve tube element via the plasmodesmata
32
What are the types of circulatory systems?
Open (insects): Blood not confined to vessels. Closed (fish & mammals): Blood in vessels. Single (fish): Blood passes heart once per circuit. Double (mammals): Blood passes heart twice per circuit.
33
What are the characteristics of arteries?
Thick walls, elastic tissue (stretch/recoil), smooth muscle (varies flow), smooth endothelium (reduces friction).
34
What is the role of capillaries?
Smallest blood vessels, one-cell thick for rapid exchange.
35
How do veins function?
Wide lumen (max volume), thin walls (low pressure), valves prevent backflow.
36
What is tissue fluid?
Fluid containing oxygen/nutrients that exchanges with cells.
37
How is tissue fluid formed?
Hydrostatic pressure forces fluid out of capillaries, osmotic pressure returns some fluid, remainder enters lymphatic system.
38
How does the lymphatic system function?
1) Prevents swelling oedema 2) Scans for pathogens and initates immune response 3) Absorbs fats from intestine and delivers to the bloodstream.
39
What makes the heart myogenic?
It contracts without nervous stimulation.
40
What initiates heart contraction?
Sinoatrial Node (SAN) acts as pacemaker.
41
What is the role of the atrioventricular node (AVN)?
Delays impulse before ventricles contract.
42
How do electrical signals travel in the heart?
SAN → AVN → Bundle of His → Purkyne Fibres → Ventricles contract.
43
What are the stages of the cardiac cycle?
Atrial Systole: Atria contract, forcing blood into ventricles. Ventricular Systole: Ventricles contract, AV valves close, semilunar valves open, blood ejected. Diastole: Heart relaxes, semilunar valves close, chambers fill.
44
What is haemoglobin?
Water-soluble globular protein with 2 alpha & 2 beta chains, each with an Fe²⁺ haem group binding oxygen.
45
How many oxygen molecules can one haemoglobin carry?
Four.
46
How does partial pressure affect oxygen binding?
High partial pressure increases haemoglobin's oxygen affinity (lungs), low partial pressure decreases affinity (respiring tissues, releasing oxygen).
47
What is the Bohr Effect?
CO₂ lowers haemoglobin’s oxygen affinity, increasing O₂ release in active tissues.
48
How is fetal haemoglobin different from adult haemoglobin?
Higher affinity for O₂ to absorb from mother’s blood, as oxygen saturation is lower in the placenta.
49
What is the difference between a single and double circulatory system?
Single (e.g., fish) blood passes through the heart once per cycle; Double (e.g., mammals) blood passes twice per cycle.
50
What are the four chambers of the heart?
Right atrium, Right ventricle, Left atrium, Left ventricle.
51
Why is the left ventricle thicker than the right?
It pumps blood at a higher pressure to the entire body.
51
What is the function of the right side of the heart?
Pumps deoxygenated blood to the lungs via the pulmonary artery.
52
What is the function of the left side of the heart?
Pumps oxygenated blood to the body via the aorta.
53
What are the names of the heart valves and their functions?
Atrioventricular valves (tricuspid & bicuspid): Prevent backflow into atria. Semilunar valves (pulmonary & aortic): Prevent backflow into ventricles.
54
What is the function of the sinoatrial node (SAN)?
It acts as the heart’s pacemaker, initiating electrical impulses.
55
What is cardiac output and how is it calculated?
The volume of blood pumped per minute. CO = Stroke Volume × Heart Rate
56
What is the function of the atrioventricular node (AVN)?
It delays the impulse before passing it to the ventricles, allowing atrial contraction first.
57
What is the Bundle of His?
Conducts electrical impulses from the AVN to the Purkinje fibers, triggering ventricular contraction.
58
What do the P, QRS, and T waves in an ECG represent?
P wave: Atrial contraction. QRS complex: Ventricular contraction. T wave: Ventricular relaxation.
59
How does exercise affect heart rate?
Increases due to higher oxygen demand and carbon dioxide removal.
60
shapes of lignin
ring spiral reticulate pitted
61
Sources and sinks in term of the translocation of sucrose
source: produces or releases sugars sink: receives translocated sugars winter: Source: roots Sink: leaves summer sources: leaves sink: roots
62
what happens when there is too much/ too little tissue fluid?
too much: oedema (swelling) too little: (not optimum for body cells)
63
water potential =
solute potential + pressure potential
64
what can you say about the pressure in the arteriole and venule ends of the capillaries?
Arteriole ends have a high pressure **(increased water potent.)** so plasma leaks out into the tissue fluid. Venule ends have a lower pressure **(lower water potent.)** so tissue fluid leaks back into the plasma in the capillary. Plasma proteins also make water potential lower.

biology (28 decks)

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