organisms exchange substances with their environment

Question 1

what surface area: volume do small organisms have?

Answer 1

-large surface area: volume, to allow efficient exchange across the body surface

Question 2

what surface area: volume do large organisms have?

Answer 2

-small surface area: volume, to allow efficient exchange across the body surface

Question 3

how do you calculate the surface area and volume?

Answer 3

surface area=
-area of one side x amount of sides
volume=
-length x width x height

Question 4

what are the features of specialised exchange surfaces? (3)

Answer 4

-large surface area: volume, which increases the rate of exchange
-very thin, providing a short diffusion pathway
-selectively permeable, allows selected materials to cross

Question 5

how does anaerobic respiration increase gas exchange in insects?

Answer 5

1. anaerobic respiration in muscles produce lactate
2. lactate in the muscles decrease water potential
3. water moves from the tracheoles into the muscle by osmosis
4. this decreases the volume of tracheoles
5. this draws air into the tracheoles, therefore increasing gas exchange

Question 6

what are the structures in insects relating to gas exchange? (3)

Answer 6

tracheoles=
-thin, providing a short diffusion pathway
-highly branched, large surface area
exoskeleton=
-prevents water loss
spiracles=
-hairs, preventing water loss
-holes on the surface that can open and close, preventing water loss
-allows oxygen to diffuse into tracheae

Question 7

what are the three ways gases move in and out the tracheal system in insects?

Answer 7

-along a diffusion gradient
-mass transport
-ends of the tracheoles are filled with water

Question 8

what are the structures of the gills in fish relating to gas exchange?

Answer 8

gill filaments=
-contain gill lamellae
gill lamellae=
-many of them, large surface area
-very thin, providing a short diffusion pathway

Question 9

what is counter current flow?

Answer 9

-flow of water over the gill lamellae and the flow of blood travel in opposite directions
-diffusion gradient is maintained throughout the whole gill filament
-if they both flowed in the same direction, far less gas exchange would take place

Question 10

what is the counter current exchange principle?

Answer 10

-blood that is already loaded with oxygen meets water, which has its maximum concentration of oxygen
-therefore diffusion of oxygen from the water to the blood takes place
-blood with little oxygen in it meets water, which has had most of its oxygen removed
-therefore diffusion of oxygen from the water to the blood takes place

Question 11

what are three plant adaptations that allow for rapid diffusion?

Answer 11

1. small pores called stomata, that are not far from the stoma
   -short diffusion pathway
2. numerous interconnecting air spaces in the mesophyll
   -gases can readily come in contact with mesophyll cells
3. large surface area of mesophyll cells
   -rapid diffusion

Question 12

what are three insect adaptations that reduce water loss?

Answer 12

1. small surface area: volume ratio
2. waterproof coverings (exoskeleton)
3. spiracles (openings of the trachea)

Question 13

what are five plant adaptations that reduce water loss?

Answer 13

1. thick cuticle
2. rolling up of leaves
3. hairy leaves
4. stomata in pits or grooves
5. reduced surface area: volume ratio of the leaves

Question 14

what happens when breathing in (inspiration) in humans?

Answer 14

-ribs move outwards
-exterior intercostal muscle contracts, interior intercostal muscle relaxes
-diaphragm flattens by contracting
-thorax volume increases, therefore pressure in the thoracic cavity decreases
-pressure in the thoracic cavity is lower than the atmospheric pressure

Question 15

what happens when breathing out (expiration) in humans?

Answer 15

-ribs move inwards
-interior intercostal muscle contracts, exterior intercostal muscle relaxes
-diaphragm pushes up the lungs by relaxing
-thorax volume decreases, therefore pressure in the thoracic cavity increases
-pressure in the thoracic cavity is higher than the atmosphere pressure

Question 16

what are the structures in the respiratory system?

Answer 16

lungs=
-made up of a series of bronchioles, which end in tiny air sacs called alveoli
trachea=
-flexible airway supported by rings of cartilage
bronchi=
-two divisions of the trachea, each leading to one lung
bronchioles=
-series of branching subdivisions of the bronchi
alveoli
-air sacs at the end of bronchioles

Question 17

what are the alveoli adaptations in gas exchange?

Answer 17

surrounded by collagen and elastic fibres=
-provides structure and elasticity to the lungs
many of them=
-provides a large surface area
one cell thick=
-short diffusion pathway
surrounded by a large capillary network=
-oxygenated blood can be transported away quickly
capillary’s are very narrow=
-short diffusion pathway
red blood cells are flattened=
-slows them down for more diffusion

Question 18

what are the structures in the digestive system?

Answer 18

oesophagus=
-carries food from the mouth to the stomach
stomach=
-stores and digests food, especially proteins
small intestine=
-food is further digested by enzymes
large intestine=
-absorbs water
rectum=
-stores faeces before passed into the anus

Question 19

what are the two types of digestion?

Answer 19

physical=
-teeth
-stomach churns food
-peristalsis in the oesophagus
chemical=
-hydrolyses large, insoluble molecules through enzymes

Question 20

what happens in the carbohydrate digestion of starch?

Answer 20

enzyme=
-amylase
where is amylase produced=
-salivary glands
-pancreas
bond breaking=
-glycosidic bond
product=
-maltose

Question 21

what happens in the carbohydrate digestion of maltose?

Answer 21

enzyme=
-maltase
where is maltase produced=
-lining of the ileum (small intestine)
bond breaking=
-glycosidic bond
product=
-alpha glucose

Question 22

what happens in the carbohydrate digestion of sucrose?

Answer 22

enzyme=
-sucrase
where is sucrase produced=
-small intestine
bond breaking=
-glycosidic bond
product=
-glucose
-fructose

Question 23

what happens in the carbohydrate digestion of lactose?

Answer 23

enzyme=
-lactase
where is lactase produced=
-small intestine
bond breaking=
-glycosidic bond
product=
-glucose
-galactose

Question 24

what happens in the lipid digestion?

Answer 24

enzyme=
-lipase
where is lipase produced=
-pancreas
bond breaking=
-ester bond
product=
-glycerol
-fatty acids

Question 25

what happens in the protein digestion?

Answer 25

enzyme= -peptidases (umbrella term) where are peptidases produced= -pancreas (endo & exo) -small intestine (exo) -stomach (endo) -membrane bound in the ileum (di) bond breaking= -peptide bond product= -amino acids

Question 26

what is exopeptidase?

Answer 26

-hydrolyses terminal amino acids (at the end)

Question 27

what is endopeptidase?

Answer 27

-hydrolyses central peptide bonds

Question 28

what is dipeptidase?

Answer 28

-hydrolyses dipeptides into amino acids

Question 29

what is the structure and function of the villi in digestion? (5)

Answer 29

large surface area in small intestine= -maximises diffusion thin walls= -short diffusion pathway many mitochondria= -ATP for active transport muscles= -moves food good blood supply= -transports molecules

Question 30

what is the absorption of lipids process?

Answer 30

1. bile salts emulsify lipids into micelles 2. micelles come into contact with epithelial cells in the ileum, they are then broken down into monoglycerides and fatty acids 3. these are small and non polar so diffuse across the cell surface membrane 4. triglycerides reform in the endoplasmic recticulum and then move into the golgi, where chylomicrons are formed 5. chylomicrons move out of the epithelial cells by exocytosis and enter lymphatic capillaries called lacteals

Question 31

what is the order of the blood flow around the heart?

Answer 31

-deoxygenated blood, vena, cava, right atrium, right ventricle, pulmonary artery, lungs -becomes oxygenated at the lungs, pulmonary vein, left atrium, bicuspid valve, left ventricle, aorta, body

Question 32

what are the two types of valves in the heart?

Answer 32

semi-lunar valves= -in the aorta and pulmonary artery -prevent backflow of blood into the ventricles when pressure exceeds atrioventricular valves= -between atrium and ventricle on both sides -prevent backflow of blood when contraction of ventricles means ventricular pressure exceeds atrial pressure -left atrioventricular (bicuspid) -right atrioventricular (tricuspid)

Question 33

what is systole and diastole?

Answer 33

systole= -period of contraction diastole= -period of relaxation -normally lasts longer

Question 34

what is the cardiac cycle?

Answer 34

-sequence of events repeated by humans around 70 times each minute when at rest -consists of three stages: atrial and ventricular diastole, ventricular systole and atrial systole

Question 35

what happens in atrial and ventricular diastole?

Answer 35

relaxation of the heart= -low blood pressure in heart, blood moves into atria -AV valves initially closed -as the atria fill, pressure rises and AV valves open allowing blood to pass into the ventricles -semi lunar valves close to stop back flow from the aorta

Question 36

what happens in atrial systole?

Answer 36

contraction of atria= -atria are filled with blood (high pressure) -atria both contract, AV valves open -blood is pushed into the ventricle -semi lunar valves are closed

Question 37

what happens in ventricular systole?

Answer 37

contraction of ventricle= -slight delay to allow ventricles to fill with blood -ventricle walls contract, increasing the blood pressure within them -AV valves close preventing backflow of blood into atria -semi lunar valves open

Question 38

what are the types of blood vessels?

Answer 38

-arteries, veins, capillaries, arterioles, venules

Question 39

what is the blood pressure of the blood vessels?

Answer 39

arteries= high arterioles= -lower than arteries capillaries= -low veins= -low

Question 40

what is the muscle layer size of the blood vessels?

Answer 40

-contract so control flow of blood arteries= -thick arterioles= -thicker than arteries veins= -thick

Question 41

what is the elastic layer size of the blood vessels?

Answer 41

-helps maintain blood pressure by recoiling arteries= -thick arterioles= -thinner than arteries veins= -thick

Question 42

what is the overall wall diameter of the blood vessels?

Answer 42

arteries= -thick arterioles= -thick capillaries= -thin veins= -thin

Question 43

what is the lumen size of the blood vessels?

Answer 43

-central cavity in which the blood flows arteries= -thin arterioles= -thinner than arteries capillaries= -thin veins= -thick

Question 44

what is hydrostatic pressure?

Answer 44

-pressure created by a fluid pushing against the container that it's within

Question 45

what is tissue fluid?

Answer 45

-liquid that surrounds cells -provides: oxygen, amino acids, glucose, ions and fatty acids

Question 46

what is the tissue fluid formation?

Answer 46

arterial end of the capillary= 1. high hydrostatic pressure 2. plasma and small molecules pushed out into the tissue fluid 3. large molecules (cells and protein) remain in the blood, called ultrafiltration 4. returning fluid goes back into the capillary venous end of the capillary= 1. low hydrostatic pressure due to water lost to tissue fluid 2. water is forced back into the capillaries due to hydrostatic gradient 3. low water potential in capillaries so water moves back in via osmosis -some water moves into the lymphatic system, that then drains back into the bloodstream

Question 47

what is the process of transpiration?

Answer 47

-loss of water vapour through the leaves of plants 1. lower water potential in the atmosphere compared to inside the leaf's air spaces -water evaporates out the stomata 2. now a low water potential in air spaces, so water evaporates from the mesophyll cell walls into air spaces 3. water moves from xylem to mesophyll cells (high to low concentration) -this creates cohesion, tension of water molecules (transpiration pull)

Question 48

what is the process of translocation?

Answer 48

-process by which organic molecules and mineral ions are transported from one part of a plant to another at source cells= 1. sucrose is produced in a photosynthetic cell 2. sucrose moves into companion cell by facilitated diffusion 3. sucrose moves into the sieve cell by active transport 4. high sucrose at the top of the phloem, therefore low water potential -water moves into phloem from xylem by osmosis -high hydrostatic pressure at sink cells= 1. decrease of sucrose as it is either stored or used 2. sucrose moves from companion cell into sink cell by diffusion, therefore low water potential -water moves by osmosis out of the phloem -decreased hydrostatic pressure

Question 49

what is the structure and function of sieve and companion cells? (phloem)

Answer 49

sieve cells= -hollow/few organelles, easier flow of substances -thick/strong walls, resist pressure companion cells= -many mitochondria, site of respiration/ATP -many ribosomes, site of protein synthesis

Question 50

what is haemoglobin?

Answer 50

-quaternary protein -made up of 4 polypeptide chains -4 oxygen molecules can bind to 1 haemoglobin molecule -Fe+

Question 51

what is associating and disassociating?

Answer 51

associating= -binding of oxygen to haemoglobin disassociating= -unbinding of oxygen to haemoglobin

Question 52

what is affinity (high or low)?

Answer 52

-chemical attraction

Question 53

what is the role of haemoglobin?

Answer 53

-transport oxygen -at the lungs, haemoglobin has a high affinity for oxygen (high association) -at the tissue, haemoglobin has a low affinity for oxygen (high disassociation)

Question 54

what can oxygen-haemoglobin dissociation curves tell us?

Answer 54

-start at low oxygen saturation at the tissue, where there is a low affinity for oxygen and low partial pressure -difficult for first oxygen to bind -after first oxygen binds, quaternary structure of haemoglobin changes and next oxygen binds much easily -curve starts to increase until it levels off, where 4th oxygen is harder to bind as there is a low probability for it to find the empty slot on the haemoglobin molecule -at 100% oxygen saturation at the lungs, there is a high affinity and high partial pressure