B3.2 Transport

Question 1

describe the pathway of blood from arteries to veins

Answer 1

blood flows through arteries, which branch into arterioles, then capillaries; capillaries join back together to form venules, then veins

Question 2

structure of capillaries

Answer 2

1 cell thick lumen, outer, and inner layer

Question 3

fenestrations

Answer 3

slits in capillaries allowing larger molecules through faster

Question 4

adaptations of capillaries for chemical exchange

Answer 4

thin walls, small diameter, permeable, large surface area, fenestrations

Question 5

artery structure

Answer 5

small lumen, inner elastic fibre layer, then thick smooth muscle, then collagen

Question 6

vein structure

Answer 6

large lumen, inner elastic fibre layer, then thin smooth muscle, then collagen

Question 7

adaptations of arteries for pumping high-pressure blood

Answer 7

• smooth muscle changes diameter to regulate blood pressure, controlled by automatic nervous system
• elastic walls stretch on blood surge, recoil and increase pressure to propel blood afterwards

Question 8

adaptations of veins for moving low-pressure blood

Answer 8

undirectional, slow flow of blood helped by internal valves preventing backflow and compression from muscles

Question 9

what vessels supply blood to cardiac muscle?

Answer 9

coronary arteries

Question 10

plaque

Answer 10

build-up of cholesterol and other substances in arteries, causing occlusion

Question 11

coronary heart disease

Answer 11

when plaque builds up in coronary arteries, causing heart attack

Question 12

artherosclerosis

Answer 12

hardening and narrowing of arteries due to plaque, caused by macrophages attaching to damage sites, stimulating tissue growth and consuming cholesterol

Question 13

epidemiological

Answer 13

relating to the incidence, distribution, and control of diseases such as coronary heart disease

Question 14

Pearson correlation coefficient

Answer 14

quantifies correlations; if close to 0, no relationship

Question 15

cohesion-tension theory

Answer 15

water transpires, pulling water up xylem by capillary action, creating tension, which pulls water up as one unit as a result of cohesion

Question 16

xylem structure

Answer 16

dead, hollow cells connected to form tube, no cell walls between, pits in sides to let water in/out, fortified with lignin, which resists collapse from tension

Question 17

two categories of flowering plants

Answer 17

monocotyledon, dicotyledon

Question 18

draw and label cross-section of dicotyledonous stem

Answer 18

out to in: thin epidermis, cortex, inner layer with vascular bundles with phloem and xylem in them, lumen; circular

Question 19

draw and label cross-section of dicotyledonous root

Answer 19

out to in: thin epidermis, cortex, vascular bundle with phloem and xylem; squiggly

Question 20

pressure filtration

Answer 20

increased hydrostatic pressure in arteriole end of capillary bed results in walls opening and plasma leaving to become tissue fluid; fluid returns to capillaries again at venule end because of oncotic pressure

Question 21

describe the flow of lymph in lymphatic capillaries

Answer 21

1. some tissue fluid enters lymphatic capillaries rather than capillary bed, becoming lymph
2. internal valves and muscle contractions help lymph to travel from lymphatic capillaries to ducts to trunk then released back to vein
3. lymph nodes along trunk filter bacteria, cancer, etc. in lymph before re-entering blood

Question 22

pulmonary vs systemic circulation

Answer 22

blood flow to and from lungs vs body tissues

Question 23

describe direction of blood flow in single circulation in fish

Answer 23

1. deoxygenated blood pumped from two-chamber heart to capillary beds in gills (pulmonary circulation)
2. blood becomes oxygenated and travels to capillary beds in body tissues (systemic circulation)
3. deoxygenated blood travels back to heart

Question 24

describe direction of blood flow in double circulation in mammals

Answer 24

1. deoxygenated blood enters interior/superior vena cava and into right atrium of four-chamber heart
2. travels through tricupsid/right atrioventricular valve and into right ventricle (pulmonary circulation)
3. travels through right semilunar valve and pulmonary artery to capillaries in lungs
4. oxygenated blood travels through pulmonary veins and into left atrium
5. travels through bicupsid/left atrioventricular valve and into left ventricle (systemic circulation)
6. travels through left semilunar valve and into aorta to be pumped to body tissues

Question 25

adaptations of heart for effective blood flow

Answer 25

thick-walled ventricles with cardiac muscles, sinoatrial node (cells in right atrium that generates heartbeat), thin-walled atria, atrioventricular valves (closes according to pressure differences), semilunar valves, septa, coronary vessels

Question 26

systole vs diastole

Answer 26

when chamber contracts, pressuring blood to leave vs when chamber relaxed

Question 27

myogenic

Answer 27

originating in muscle, involuntary, without stimulus (eg resting heart rate)

Question 28

describe cardiac cycle

Answer 28

1. sinoatrial node (controlled by medulla oblongata) generates action potential, resulting in systole of right atrium
2. impulse reaches atrioventricular node on left wall of right atrium, which sends impulse through Purkinje fibres to ventricles after a 0.1 s delay

Question 29

sketch and label a typical electrocardiogram

Answer 29

• P wave: sinoatrial node generating atrial systole
• Q: atrioventricular node sends impulse
• QRS complex: atrioventricular impulse spends, causing ventricular systole
• T wave: atroventricular node repolarizes

Question 30

how is water pulled up in xylem when no leaves or transpiration is impossible?

Answer 30

1. minerals diffuse into root through epidermis and cortex, then into xylem
2. higher solute solution inside = osmosis inside as well
3. more water inside = increased pressure, pushing water up

Question 31

two pathways that water moves from root hairs to xylem

Answer 31

symplastic (through connected cytoplasms of adjacent cells) or apoplastic (through capillary action in cell walls)

Question 32

phloem structure

Answer 32

composed of living sieve tubes, formed by sieve tube cells joined by porous sieve plates, and companion cells, which are connected to tubes through plasmodesmata, allowing cytoplasm sharing, providing protein and ATP, and keeping alive

Question 33

translocation of sap in phloem

Answer 33

1. movement of sap when sugar from source companion (phloem loading) results in osmosis from xylem
2. pressure increased, causing movement to sink
3. sink uses sugar, causing osmosis back to xylem