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Biology > Biology- Unit 4 > Flashcards

Biology- Unit 4 Flashcards

1
Q

Describe diffusion

A

The passive movement of small
Non-polar
Lipid-soluble molecules
Directly through phospholipid bilayer

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2
Q

Describe facilitated diffusion

A

Requires channel proteins
Polar
Charged
Water-soluble molecules

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3
Q

Describe osmosis

A

The movement of water molecules
From low solute conc to High solute conc
Through partially permeable membrane

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4
Q

Describe active transport

A

Can transport all types of molecules
Through carrier proteins
Low conc. to high conc.
Requires ATP

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5
Q

Describe endo and exocytosis

A

Transport large particles

Enclosed in vesicles

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6
Q

What is turgor pressure?

A

Inward pressure caused by protoplasm expanding
Generates hydrostatic pressure
Generates reactive force pushing inwards
Prevents water from moving into a cell

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7
Q

What is the relationship between water potential, osmotic pressure and turgor pressure?

A

Water potential= osmotic pressure + turgor pressure

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8
Q

Describe exhalation

A

Intercostal muscles and diaphragm relax
Volume increases
Pressure decreases
Air diffuses out down pressure gradient

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9
Q

How do insects intake oxygen?

A

Openings called spiracles
Oxygen diffuses down trachea
Trachea lined with rings of chitin so gas exchange doesn’t occur here
Oxygen diffuses into tracheoles

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10
Q

How do fish intake oxygen?

A

Countercurrent exchange system
Water is pumped over gills covered in lamellae
Operculum (gill flap) closes
Floor of fish mouth is raised to increase pressure

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11
Q

Describe the structure of the heart

A 
Four chambers- atria, ventricles
Pulmonary vein
Pulmonary artery
Vena cava
Aorta
Atrioventricular valves- bicuspid, tricuspid
Semilunar valves- pulmonary/ aortic
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12
Q

What is a single circulatory system?

A

System where blood is only pumped once

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13
Q

What is a double circulatory system?

A

System where blood is pumped twice i.e heart to lung, heart to body

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14
Q

What are the advantages of a double system?

A

Concentration gradient is maintained as oxy and deoxy blood don’t mix
Blood pressure in tissues is higher
Blood pressure in lungs is lower

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15
Q

How does the heart contract?

A

Myogenic
1) Deopolarisation of senatorial node (SAN)
2) Depolarisation spreads through atria- causes atrial systole
Stimulates Atrioventricular node (AVN)
3) Slight delay for atrial diastole- AVN depolarises conductive fibres Bundle of His
5) Bundle of His splits into two branches- Purkyne fibres- causes ventricle systole

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16
Q

What is the function of plasma?

A

Transports digested food products, nutrient molecules, hormones, excretory products

17
Q

What is the function of erythrocytes (RBC)?

A

Transport oxygen and some carbon dioxide

Adapted via their biconcave shape and lack of nucleus

18
Q

What is the function of leucocytes (WBC)?

A

Granulocytes-
Neutrophils (phagocytosis)
Basophils (inflammation)
Eosinophils (parasites)

Agranulocytes-
Monocytes
Lymphocytes

19
Q

What is the function of platelets?

A

Blood clotting

20
Q

Describe how blood clots

A

1) When a blood vessel is damages, platelets attach to exposed fibres
2) Platelets release thromboplastin- converts prothrombin into thrombin (Ca+ and vitamin K must be present)
3) Thrombin catalyses the conversion of fibrinogen into fibrin
4) Fibrin forms a network of fibres in which blood cells are trapped to form a clot

21
Q

Describe atherosclerosis

A

1) The endothelium is damages by high cholesterol, smoking, high BP
2) Increases risk of blood clotting in the artery, leads to inflammatory response, WBC move to artery
3) WBC, cholesterol, Ca salts and fibres build up and harden- plaque (atheroma)
4) Leads to narrowing of artery, increasing BP

22
Q

Describe how foetal haemoglobin is different to adult haem

A

Higher affinity for oxygen

23
Q

What is myoglobin?

A

Respiratory pigment with a higher affinity for oxygen than haemoglobin

24
Q

What is hydrostatic pressure?

A

Residual pressure from heartbeat

Higher at arterial end of capillary than venous end

25
Q

What is oncotic pressure?

A

Relatively constant

Higher at venous end than arterial end

26
Q

Describe the structure of the Xylem

A

Dead tissue with open ends
Transport water and minerals
Provide structural support
Contain pits which enable water to move sideways
Lignin enable the plant to remain flexible

27
Q

Describe the structure of the Phloem

A

Living cells
Translocation- movement of nutrients to storage organs
Sieve tubes to transport sugars
Companion cells produce ATP for sieve cells

28
Q

What is the symplast pathway?

A

Moves through cytoplasm via plasmodesmata

29
Q

What is the apoplast pathway?

A

Moves through cells walls and intercellular spaces which are permeable

30
Q

Describe movement of water in the xylem

A

Cohesion-tension model

1) Water moves through root hair cells via osmosis
2) Water moves through xylem through either symplast of apoplast
3) Once the water reaches the Casparian strip (waterproof) it must travel via symplast
4) water reaches xylem, transpiration stream
5) Evaporation causes hydrostatic pressure, tension moves down column due to cohesion
7) Water evaporates from mesophyll cell walls

31
Q

What is cohesion?1

A

Attraction between molecules, water forms hydrogen bonds with other molecules of water

32
Q

What is adhesion?

A

Attraction between unlike molecules, water forms hydrogen bonds with mesophyll cells

33
Q

Describe movement in the phloem

A

Mass flow hypothesis

1) Sucrose is moved from source (high sugar conc.) to the sink (low sugar conc.)
2) Sucrose can be loaded into the phloem via the symplast or apoplast pathway
3) Sucrose is unloaded passively

34
Q

What factors affect the rate of transpiration?

A

Air movement
Humidity
Temperature
Light intensity

35
Q

What are the strengths and weaknesses of the mass flow hypothesis?

A

Strengths-

1) Can use radioactive isotopes to track movement of sucrose through phloem
2) If steam is used to kill a ring of bark then movement stops in phloem
3) Aphids feed off phloem tubes- evidence of high hydrostatic pressure in phloem

Weaknesses-

1) Doesn’t explain bidirectional movement in sieve tubes
2) Doesn’t explain how there is movement of different speeds in sieve tube
3) Doesn’t explain presence of sieve plates
4) Doesn’t explain how sieve and companion cells have to be alive for movement to occur.

Biology (10 decks)

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