Chapter 3.3 Exchanging Substances Flashcards

Question

Process of carb digestion in humans

Answer 1

1) **saliva** contains amylase that hydrolyses starch > maltose 2) food swallowed and enters **stomach** which acidic conditions denature amylase preventing further hydrolysis 3) in **small intestines** mixed with **pancreatic juices** that contain amylase and maintain optimum conditions 4) muscles in intestine push food along ileum. **epithelial lining** produces maltase on cell surface hydrolysing maltose > glucose *(lactose and sucrose also hydrolysed in this way by membrane bound enzymes)* 5) Glucose absorbed by epithelial cell (see transport topic)

Answer 2

1) lipids broken up in tiny droplets (**micelles**) by **bile salts** from liver. This process called **emulsification** and ^ SA to speed up action of lipase. 2) micelles travel to ileum on contact to lipase on surface they are hydrolysed-> **monoglyceride and fatty acids.** 3) monoglyceride and fatty acids **diffuse** into epithelial cell 4) then transported to **ER** where recombine -> triglycerides 5) move to **Golgi** -triglycerides associated with cholesterol & lipoproteins to form **chylomicrons** (special partial adapted for lipid transport) 6) chylomicron moves out of epithelial cell by **exocytosis** 7) then enter **lymphatic capillary** found in each villus 8) lymph then passes them to blood stream

Answer 3

*Digestion of proteins takes place in stomach and duodenum of small intestine.* ▸ *the stomach contains enzyme of protease which begins to break down peptide bonds in polypeptide chains into smaller chains In small intestine on the membrane ▸ Endopeptidases break the peptide bond in the middle of the peptide chain. ▸ Exopeptidases acts at the end of the peptide chain and helps in releasing the last amino acid.

Answer 4

Transport of products of digestion across epithelial cells into the bloodstream

Answer 5

To become part of an organism (When Soluble food molecules are used to build new parts of cells)

Answer 6

Move food to stomach **Peristalsis**- contraction of muscles

Answer 7

To produce bile that neutralises stomach acid and emulsifies lipids

Answer 8

1) long, folded to increase surface area 2) villi (finger like projections on inner layer) ^ SA and is lined with single layer of epithelial cells =short diffusion pathway 3) microvilli (smaller projections on villi) ^ SA and is site of some enzymes like maltase are found

Answer 9

- primary structure specific sequence of amino acids - amino acids are joined together by peptide bonds - secondary structure of alpha coil helix - H bonds between Amine and carboxyl group - tertiary/quaternary structure create 3D shape - bonds between R groups e.g ionic, hydrophilic, disulfate, H - hydrophobic amino acids embedded in section that interact with fatty acid in bilayer - hydrophilic amino acids in the inner and outer phosphate groups of bilayer

Answer 10

The process of breaking down large insoluble molecules by enzymes during hydrolysis with the addition of a water molecule into smaller soluble molecules that can be absorbed and assimilated.

Answer 11

Hydrolyse peptide bonds in the middle region of proteins + smaller polypeptide chains

Answer 12

Hydrolyse peptide bonds on terminal amino acids + single amino acid + dipeptides

Answer 13

Hydrolyse dipeptides into single amino acids

Answer 14

See diagram - trachea (*windpipe held open by rings of cartilage*) - bronchus (*smaller pipes that lead to right/left lung*) - bronchioles (*smaller tubes in the lungs*) - alveoli (*air sacs*)

Answer 15

**tranchea** - supported by C-shape cartilage rings to prevent collapsing during breathing **bronchus** - lined with ciliates epithelial cells and goblet cells. *goblet cells= secrete mucus to trap dust/microorganism, cilia then waft mucus out* **alveolus** - adaptions folllow fick’s law

Answer 16

**INSPIRATION** 1) **external intercostal** and diaphragm muscles contract - ribcage moves 🔼 ,out and diaphragm flatterns 2) 🔼 volume in **thoracic cavity** causes 🔽 pressure in thorax cavity so that it is below atmopsheric pressure 3) air flows down pressure gradient so air moves into lung (this process is an active process requiring energy) **EXPIRATION** 1) external intercostal and diaphram muscles relax, ribs move 🔽 and in, diaphram curves upwards again. 2) 🔽 volume in thorax cavity means pressure 🔼 above atmospheric 3) air moves down pressure gradient out of the lungs (normal expiration is a passive process however duing forced expiration or heavy exercise internal intercostal muscles contract antagonisticly to external pulling ribcage further Down and in.

Answer 17

- thin wall of alveoli (single layer of thin, flat alveolar epithelium) *Short diffusion pathway* - lots of alveoli *Increase surface area* - alveoli have good capillary network and blood supply *Maintains concentration gradient* - ventilation process *maintains concentration gradient - moist surfaces of alveoli walls *dissolve gases increasing diffusion*

Answer 18

A device that measures volume and speed of inhalation/exhalation See notes for example

Answer 19

- large SA of leaf = increasing rate of diffusion - leaves are thin = shortening diffusion pathway - permeable through stomata Internally spongy mesophyll - creates Larger SA -air spaces allow lateral diffusion of gases - allows most cells to have direct contact with air - moist allowing gas to move between gas + lipid phase

Answer 20

Xerophyte- plant that is adapted for life in area of little to no liquid water Adaption to prevent water loss in marram gras: - sunken stomata trap moist air (reducing conc gradient of water preventing evaporation) - layer of ‘hairs’ on epidermis trap water vapour around stomata - curled leaves protect stomata from wind and trap moist air - reduced number of stomata - thick waxy waterproof cuticle

Answer 21

1) the volume of air in each breath - usually 0.4 - 0.5 dm3 2) the number of breaths per minute - usually 15 breaths 3) the maximum volume of air that can be breathed out in 1 sec 4) maximum volume of air it is possible to breath forcefully out of the lungs after a really deep breath in

Answer 22

Lung disease caused by bacteria, immune system build a wall around the bacteria in the lungs. This forms small hard lumps (tubercules). Infected tissue with tubercles dies damaging exchange surface so tidal volume is 🔽. TB also causes fibrosis. Tidal volume 🔽 so less air inhaled in so patients must breath faster Common symptoms of turberculosis= cough (with blood), mucus, chest pain, shortness of breath

Answer 23

Fibrosis= formation of scar tissue in lungs (Can be result of infection, or substances exposure e.g asbestos) Scar tissue= thicker &less elastic so lungs cannot expand as much so hold less air- tital volume 🔽 and FVC 🔽. diffusion is slower due to thickened tissue - loonger pathway symptoms = shortness of breath, dry cough, chest pain, fatigue, weakness

Answer 24

Asthma = airway becomes inflamed and irritated During asthma attack- smooth muscle lining bronchioles contract and mucus is produced this constricts airway, making it difficult to breath. Air flow severely reduced Symptoms include= wheezing, tight chest. Shortness of breath.

Answer 25

Emphysema= caused by smoking or long exposure to air pollution Trapped substances cause inflammation, attracting phagocytes to area. Phagocytes produce an enzyme that breaks down protein elastin in alveoli walls. This prevents alveoli recoiling expelling air well. Also damage to alveoli wall reduces surface area. Symptoms= shortness of breath, wheezing

Answer 26

1. Micelles constrain bile salts and fatty acids/monoglyceride 2. Make fatty acids/monoglyceride more soluble in water Or - release fatty acids/monoglyceride at lining of ileum 3. Fatty acids/ monoglycerides absorbed by diffusion 4. Triglycerides reformed in cells 5. Vesicles move to cell membrane and release via exocytosis

Answer 27

At the **ateriole end** of capillary, the **outward** hydrostatic pressure is **greater** than the inward osmotic pull. Water, ions and small molecules are filtered out of the blood into the spaces between the cells- this is tissue fluid. The loss of fluid from the hood leads to a fall in hydrostatic pressure as the blood approaches the venule end of capillary. At the **venule** end of capillary, the **inward** osmotic pull now exceeds the outward hydrostatic pressure and some of the water re-enters the capillary by osmosis. Tissue fluid is drained away from the cells by the lymphatic system and returned to the circulation near the heart.

Answer 28

Use premade diagrams /see notes

Answer 29

Arteries Arterioles Capillaries Venules Veins

Answer 30

Lumen Tunica intima (Inner layer) Tunica media (elastic layer & smooth muscle) Tunica adventitia (tough outer wall made of connective tissue)

Answer 31

* single layer - flattened epithelial cells Smooth surface to🔽 friction allow quick blood flow (In arteries this is folded to allow it to expand under 🔼 pressure)

Answer 32

-smooth muscle & elastic fibres - smooth muscles contract > narrowing lumen 🔼BP & 🔽flow to capillary bed - elatic fibres stretch &recoil > maintain blood pressure (BP) diastolic

Answer 33

-elastic fibres & collagen layer *collagen = tough, fibrous protein > strengthen walls (In large arteries/veins this layer also has small blood vessels

Answer 34

-walls made from flattered endothelial cells >ensures 🔽 diffusiob distance so substances can be exchanged

Answer 35

**withstand high pressure** *thick walls* - tunica media very thick *lots of collagen fibres* - give strength (All of these prevent damage to walls as a *folded endothelium* - allows expansion result of high pressure) *elastic fibres* - allow expansion **maintain pressure** *elastic fibres recoil/stretch* - puts pressure on blood inside artery *contraction of smooth muscle* - narrows lumen 🔼 pressure **control volume of blood flowing to capillary bed** *contraction of smooth muscle* - narrow lumen (vasoconstriction) 🔽 blood flow *relaxtion of smooth muscle* - widening lumen (vasodilation) 🔼 blood flow

Answer 36

*thin muscle layer* (compared to arteries) - constriction/ dilation cannot control flow of blood to tissue *thin elastic layer* - at low pressure so cannot create recoil action or expand as much *small thickness of walls* - pressure within veins is too 🔽 to risk bursting, this also flattens easily to aid blood flow within *valves at intervals throughout* - ensures blood doesn’t flow backwards (pressure too 🔽) When skeletal muscles contract, veins = compressed Pressuring blood within. Valves ensure that this pressure directs blood in only 1 direction > ❤️

Answer 37

-diastole (no contraction of cardiac muscles) - atrial systole (atria contracts) - ventricular systole (ventricle contracts) - diastole again ..

Answer 38

- atria contracts due to pacemaker cells - pressure in Arita is higher than ventricles So … cuspid valves open and blood move from Arita -> ventricles

Answer 39

-atria relaxes -ventricles contract - pressure in ventricles 🔼 above atrial pressure = cuspid valves close - pressure 🔼 above arterial pressure = semi lunar valves open blood forces into arteries (via aorta)

Answer 40

AT END OF CYCLE -ventricles relax - pressure drops below artery pressure, semi-lunar valves close Then AT BEGINNING OF CYCLE - atrial filling - blood moves from veins into atria down pressure gradient

Answer 41

The contraction of heart muscles can be controlled by itself (not nervous system)

Answer 42

-all stimulus for contraction of heart originate from within cardiac muscles - sino-atrial node emits electrical impulses that spread rapidly across both atria which stimulates wave of contraction (atrial systole) - border between atria & ventricular made of non conducting fibrous tissue to prevent impulses leading to ventricles contracting - impulses can only pass through AV node - slows spread of electrical transmitting (Atria can complete contractions + empty before ventricle contraction) - as AV node depolarises impulses quickly spread down bundle of his + purkinji fibres to ventricules (ventrical systole occurs from apex up ventricules.

Answer 43

Cardiac output = heart rate X stroke volume

Answer 44

- autonomic innervation - hormones (e.g. adrenaline) - fitness level - age

Answer 45

- heart size - fitness level - gender - duration of contraction

Answer 46

**Medulla Oblongata** 2 parts to it - cardioacceleratory centre - cardioinhibitory centre

Answer 47

- blood pressure. (Detected by baroreceptors) - carbon dioxide concentration ( detected by Chemorecpetors) - oxygen concentration -pH of blood

Answer 48

- blood pressure is detected by baroreceptors in aorta + cardio artery - If Bp too low nerve impulses sent along sensory nerves -Bp too low = cardioaccelerator centre in Medulla (brain) sends impulse down sympathetic acceleratory neurone - at synapse between sympathetic neurone & SAN noradrenaline (neurotransmitter) is released increasing heart rate

Answer 49

- Bp is detected by chemoreceptors in aorta + cardio artery - If Bp too high nerve impulses sent along sensory nerves -BP too high = cardioinhibitory centre in Medulla (brain) sends impulse down parasympathetic neurone (vagus nerve) - at synapse between parasympathetic neurone & SAN acetylcholine (neurotransmitter) is released reduce heart rate

Answer 50

- sympathetic Fight or flight like response -parasympathetic Feed and breed (normal reaction)

Answer 51

The movement of assimilates (organic molecules made by plants) around the plant

Answer 52

Xylem - water & dissolved minerals Phloem - sucrose, amino acids, other assimilates

Answer 53

From source (leaf cell) which has high hydrostatic pressure to sink (root cell) which has low hydrostatic pressure

Answer 54

1) in leaf (source) active transport pumps H+ ions out of cell. Facilitated diffusion va co-transport proteins carries sucrose against gradient out of cell into companion 2) sucrose concentration in companion cell ^ 3) sucrose diffuses (simply) through plasmodesmate (gaps in sieve tube elements- STE and companion cell) 4) conc. of sucrose in STE ^ which decreases water potential in STE 5) water moves into STE from xylem by osmosis 6) water moving into phloem increases hydrostatic pressure at the source.

Answer 55

Opposite process to before (loading) 1) sucrose actively unloaded from the phloem at the sink 2) sucrose then diffuses out of STE (sieve tube element) into companion cells down conc. gradient though plasmodesmate 3) water potential in phloem ^ as it looses solute 4) water moves from phloem to xylem via osmosis 5) hydrostatic pressure in phloem decreases

Answer 56

-Thin peripheral cytoplasm - specialised with few organelles + companion cells carry out all metabolic functions needed for the sieve tube elements

Answer 57

The movement of assimilates (made in the plant) around the plant E.G amino acids, sucrose, etc

Answer 58

Tissues that synthesis organic molecules (assimilates) such as glucose -these can be leaves or roots depending on the season

Answer 59

Tissue that utilises organic molecules such as leaves, fruits, flowers, roots

Answer 60

Loss of water vapour from the leaf

Answer 61

1> Magnesium - for the formation of chloroplast 2> Nitrates - for formation of amino acids 3> phosphates - cell membranes and DNA

Answer 62

Root hair cell absorbs water and mineral ions from soil . Moves through cortex cells Then into xylem tube via osmosis Moves into spongy mesophyll via osmosis The diffuses into air as vapour through stomata

Answer 63

* narrow hollow vessel with walls strengthened with lignin and tracheids (* xylem parenchyma cells act as packing and provide support )

Answer 64

Lignin - waterproofs to reduce water loss from xylem - acts to keep fibres together - vey strong to provide mechanical strength agains tension - allows adhesion of water to side helping water rise by capillary action Narrowness of vessel increases capillary action

Answer 65

1) hydrostatic pressure decreases by water leaving vessels 2) water moves up from roots where higher hydrostatic pressure due to active loading of ions 3) osmosis of water though cells from xylem 4) water vapour diffuses through leaf air spaces 5) if water vapour conc in leaf is higher than outside, wate vapour diffuses out of leaf via stomata

Answer 66

**Due to pressure gradients water column is under tension** - water molecules have dipoles causes an attraction between them (cohesion) - water is ‘pulled’ up the xylem by transpiration when this happens the pull is transmitted all the way down the water column, pulling all water molecules up vessel (applying tension) -for this to work the xylem vessel must be a continuous column of water (no air bubbles)

Answer 67

1) **light intensity** - ⬆️light ⬆️ rate stomata open to allow gas exchange for photosynthesis. large number of stomata open means increased diffusion of water vapour 2) **Temperature** - ⬆️ temp ⬆️rate increased evaportation rate & increases diffusion as moleucles have more kinetic energy. 3) **Humidity** - ⬆️ hunidity ⬆️rate increased humidity decreases water potential gradient between air space in leaf& air 4) **Wind** - ⬆️ wind ⬆️rate air removes water vapour from stomata opening, increases water potential gradient steepness.

Answer 68

1) cut shoot underwater to prevent air from entering the xylem. 2) make slanted cut to increase the surface area for water uptake and minimise chance of air bubbles 3) assembly the potometer under the water with shoot under water too. This prevents air entering and maintains continuous column with water in potometer 4) dry the leaves 5) apparatus must be watertight and airtight (with Vaseline)

Answer 69

Haemoglobin is a polypeptide with a quaternary structure that has been evolved to make it efficient at loading oxygen in one set of condition and then unload in other set of conditions.

Answer 70

Primary structure - sequence of amino acid in 4 polypeptide chain Secondary structure - each of the polypeptide chains is coiled into a helix Tertiary structure - each polypeptide chains is folded into a precise shape to carry O2 molecule Quaternary structure - all 4 polypeptide chains are linked together to form an almost spherical molecule.

Answer 71

Harem group which contains Fe2+ ion. Each Fe2+ ion can combine with a single o2 molecule

Answer 72

In the lungs haemoglobin binds with oxygen (This is called Loading or associating)

Answer 73

In respiring tissue haemoglobin releases its oxygen which is called unloading or dissociating

Answer 74

Haemoglobin with high affinity for O2 Oxygen is taken up more easily But oxygen is releases less easily

Answer 75

Haemoglobin with low affinity for O2 Oxygen is taken up less easily But oxygen is releases more easily

Answer 76

- readily associate with oxygen at the surface where gas exchange takes place - readily dissociate from oxygen at those tissues requiring it

Answer 77

Each species produces a Hb with different amino acid sequences. The Hb of each species therefore has slightly different tertiary and quaternary structure and hence different oxygen binding properties. Depending on the structure of Hb ranged from those that have high affinity for O2 to those that have lower affinity for O2

Answer 78

The graph of the relationship between the saturation of Hb with oxygen and the partial pressure of oxygen

Answer 79

See notes but it is an S- shaped curve - Hb molecules make difficult for the first O2 molecule to bind to one of the sites *at low conc O2, little O2 bind to Hb. Gradient is shallow initially* - binding of the first O2 molecule changes the quaternary structure causing it to change shape and make it easier for other molecules to bind - there small increase in the partial pressure of O2 to bind the 2nd O2. *positive cooperatively because biding of 1st makes it easier and so on- the gradient steepens* - after binding the 3rd molecule it is difficult to bind the 4th and final O2. This is due to most biding sites being occupied and therefore less likely that a single o2 molecule will find an empty site to bind to *gradient of the curve reduces and the graph flattens off*

Answer 80

The further to the left the curve - the greater the affinity of Haemoglobin for O2 *so it loads O2 readily but unloads it less easily*

Answer 81

The further to the right the curve - the lower is the affinity for Hb *so it loads O2 less readily but unloads it more easily*

Answer 82

In greater concentrations of CO2, the curve shifts to the right (the Bohr effect) - for example in rapidly respiring tissues conc of CO2 is high. The affinity of Hb for oxygen is reduced with coupled with low conc of O2 in muscles means oxygen unloads readily causing oxygen dissociation curve to shift to the right

Answer 83

As partial presssure of Carbon Dioxide increases, the conditions become acidic causing Hb to change shape. The affinity of Hb for O2 therefore decreases, so O2 is released from Haemoglobin. This is known as the Bohr Effect

Answer 84

As partial pressure of O2 increases, the affinity of Hb for O2 also increases, so oxygen binds tightly to Hb. When partial pressure is low, oxygen is released from haemoglobin

Answer 85

It is hard for the first oxygen molecule to bind. Once it does, it changes the shape to make it easier for the second and third molecules to bind, known as positive cooperativity. It is then slightly harder for the fourth oxygen molecule to bind because there is a low change of finding a binding site.

Answer 86

- partial pressure of oxygen is high - low concentration of carbon dioxide increases the lungs, so affinity is high - positive cooperativity (after the first oxygen molecule binds, binding of subsequent molecules is easier)

Answer 87

- partial pressure of oxygen is low - high concentration of Carbon dioxide in respiring tissues, so affinity decreases

Answer 88

Low Conc of CO2 causes - affinity of Hb for oxygen to increase - oxygen is readily loaded by Hb -oxygen dissociation curve is shifted to the left

Answer 89

The pH of blood is slightly lowered due as more carbon dioxide dissolved into it This lower pH changes the shape of Hb into one that enables oxygen to unload readily (Lower affinity for oxygen) Hb releases oxygen into the respiring tissues **the opposite effect is seen in areas of low carbon dioxide concentration**

Answer 90

No different species have different types of Hb, each with their own oxygen dissociation curve. (Each one is evolved to adapt to different environments and conditions)