Organisation (part 2) P1

Question 1

small intestine (what happens)

Answer 1

products from digestion absorbed into bloodstream in small intestine

Question 2

small intestine adaptations

Answer 2

• length around 5m = large surface area for the absorption of products of digestion
• interior has villi in

Question 3

villi adaptations

Answer 3

villi - massively increase the surface area for the absorption of molecules

1) microvilli on surface of villi -> increase the surface area even further
2) good blood supply -> bloodstream rapidly removes products of digestion, so increases the concentration gradient
3) thin membrane -> short diffusion pathway

all these features = rapid rate of diffusion
(molecules that cannot be absorbed by diffusion use active transport)

Question 4

fish vs human circulatory system (pros/cons)

Answer 4

fish - single circulatory system (blood less pressure as it passes through the gills before reaching organs, so blood travels to organs slowly so cannot deliver a great deal of oxygen)

humans- double circulatory system (because blood pumps through heart twice it can travel rapidly to cells and deliver oxygen quicker )

Question 5

blood vessels in the heart + what/where they carry

Answer 5

vena cava = brings in deoxygenated blood from body (travels into right atrium)
pulmonary artery = carrys deoxygenated blood from heart to lungs
pulmonary vein = carrys oxygenated blood from lungs to heart
aorta = oxygenated blood from heart to body

Question 6

where in the heart has thicker walls + why

Answer 6

Left hand side of the heart has thicker muscular walls than the RHS because the left ventricle pumps blood around the entire body so needs to provide a greater force

Question 7

coronary artery

Answer 7

branch out of aorta and spread out into heart muscle to provide oxygen to muscle cells of heart

oxygen is used in respiration to provide the energy for contraction

Question 8

pacemaker (where/what/stops working?)

Answer 8

a group of cells which control the natural resting heart rate (found in the right atrium)
- if it stops working implant an artificial pacemaker which is a small electrical device and it corrects irregularities in the heart rate

Question 9

arteries (job/adaptations)

Answer 9

= carry very high pressure blood from heart to organs in the body (carry oxygenated blood except PULMONARY ARTERY)

Adaptations:

1) thick muscular walls -> allows them to withstand the very high blood pressure
2) elastic fibre -> which stretch when a surge of blood passes through, recoils between surges which keeps blood moving

Question 10

capillaries (job/adaptations)

Answer 10

= carry blood through the body to exchange gases and nutrients with body tissues

• allows substances like glucose and oxygen to diffuse from blood to cells
• carbon dioxide diffuses from cells to blood

Adaptations:

1) very thin walls -> short diffusion pathway, so substances can diffuse quicker
2) narrow -> lots can fit in the body tissues giving them a larger surface area to let gas exchange happen more easily

Question 11

veins (job/adaptations)

Answer 11

= carry blood towards the heart ( carry deoxygenated blood EXCEPT PULMOARY VEIN)

Adaptations:

1) contain valves -> prevent the blood from flowing backwards
2) thin walls -> do not carry high blood pressure so do not need thick walls

Question 12

Trachea feature

Answer 12

ring of cartialage -> prevents trachea from collapsing when we inhale

Question 13

alveoli (job/adaptations)

Answer 13

= site of gaseous exchange/ where gases diffuse in and out of the bloodstream

Adaptations:

1) huge surface area
2) thin walls -> quick diffusion pathway
3) good blood supply -> oxygen diffused from alveoli to blood rapidly to ensure that the concentration gradient is as steep as possible

= these adaptations mean oxygen diffused into bloodstream quickly and carbon dioxide diffuse out of blood stream quickly

Question 14

Cross-section (inside) of a leaf (organ)

Answer 14

waxy cuticle: reduces evaporation of water , preventing leaf from drying out

upper/lower epidermis(very thin cells) : protects the surface of the leaf (upper epidermis in particular is transparent which allows light to pass through to photosynthetic cells below)

spongy mesophyll : full of air spaces to allow carbon dioxide to diffuse from stomata through spongey mesophyll to palisade cells, and oxygen diffuse from palisade cells to stomata

stomata : allow co2 to enter and 02 to leave cell through diffusion + controls the amount of water vapour exiting

guard cells : As water leaves the cells, they become flaccid and less bowed, which closes the stomata between them. (open and close the stomata)

Question 15

Meristem tissue

Answer 15

• found at growing tips (shoots and roots)
• contain stem cells which can differentiate into different types of plant tissue

Makes unspecialised cells that have the potential to become specialised (found in tip of roots)

Question 16

Transpiration

Answer 16

Evaporating water from surfaces of leaves (how leaves breathe)

Question 17

Transpiration Stream (process)

Answer 17

1) evaporation of water from surface of leaves
2) water vapour diffused through air spaces in spongey mesophyll and exit leaf via stomata 4
3) now, water from xylem -> leaf to replace water being lost
4) water drawn into root hair cells and up xylem cell vessel to leaf

Question 18

Transpiration Stream importance

Answer 18

1) brings water to leaf for photosynthesis
2) transports dissolved minerals like magnesium used for chlorophyll
3) evaporation of water from leaf cools down leaf

Question 19

Factors effecting Transpiration

Answer 19

1) temp -> greater at higher temps as evaporation is faster when temps are higher
2) dry conditions -> greater when air isn’t humid as evaporation is quicker in dry conditions
3) windy conditions -> greater when windy as wind removes any water vapor allowing more water to evaporate
4) light -> greater at higher light intensity as increases the rate of photosynthesis (stomata open to allow xo2 to enter when they’re open allows water vapor to pass out of leaf)

Question 20

Stomata + guard cells

Answer 20

high light intensity (daytime) -> guard cells swell and change their shape to open stomata = co2 can diffuse into leaf for photosynthesis + water vapor can exit leaf

hot conditions -> plant closes stomata to reduce water loss by transpiration (but plant cannot photosynthesise)

Question 21

Translocation

Answer 21

movement of sugars and other molecules through phloem tissue

Question 22

Food Test RP

Answer 22

carbs (starch) —> place food into spotting tile and cover with iodine (orange to black)

protein —> place food into test tube and drop in biuret solution (blue to purple)

fats (lipids) —> place food into test tube and add in ethanol and water (clear + colourless -> cloudy white)

sugar —> place food into tube add benedicts solution and place into a warm water bath ( blue to green to orange to red) red being a lot of sugar/blue being none

Question 23

Xylem and adaptations

Answer 23

Xylem - transpiration

• movement of water and dissolved minerals from roots to leaves
• found in plant stem
• dissolved minerals = magnesium (chlorophyll)

ADAPTATIONS:

1. very thick walls containing lignin -> provides support HOWEVER sealed with lignin so caused cell to die
2. no end walls -> forms one long hollow tube which allows water to flow easily

Question 24

Phloem and adaptations

Answer 24

Phloem - translocation
-movement of sugars to rest of plant via phloem cells for photosynthesis (alive)
- move up and down
= sugar used for a product of photosynthesis / respiration

ADAPTATIONS:

1) pores -> allow for cell sap (water and sugar) to pass through
- used for
a) used immediately as glucose in respiration
b) stored as starch

Question 25

left and right valve names

Answer 25

right valve : tricuspid valve
left valve: bicuspid valve

(try before you buy)
remember left is right and right is left

Question 26

breathing in

Answer 26

• external intercoastal muscles contract
• ribcage moves up and out
• diaphragm contracts and flattens
• volume of thorax (chess cavity) increases
• pressure of thorax decreases
• air is drawn in

Question 27

breathing out

Answer 27

• external intercoastal muscles relax
• ribcage moves down and in
• diaphragm relaxes and becomes dome-shaped
• volume of thorax decreases
• pressure inside thorax increases
• air is forced out

Question 28

adaptations for gas exchange (lungs)

Answer 28

1) large surface area to allow faster diffusion of gases across the surface
2) thin walls for a short diffusion pathway
3) large capillary network to maintain a high concentration gradient so diffusion occurs faster
4) good ventilation with air so diffusion gradient can be maintained