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AS Biology > Organisms exchange substances with their environment > Flashcards

Organisms exchange substances with their environment Flashcards

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1
Q

What are the features of specialised exchange systems? (5 things)

A

Large SA:V
short diffusion distance
selectively permeable membrane
movement of environmental median (air) to maintain conc gradient
movement of internal median (blood) to maintain a maintain a conc gradient

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2
Q

State the equation for the relationship between diffusion and the factors that affect it

A

diffusion is proportional to (SA*difference in concertation)/(length of diffusion path)

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3
Q

Name some examples of things that are exchanged between the organism and its environment

A

Respiratory gases (o2 + co2)
Nutrients (AA, glucose, fatty acids etc.)
Waste products (urea +co2)
Heat

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4
Q

What are the features of the gas exchange systems in single celled organisms

A

Small organisms so LSA;V ratio

Body surface only covered by CSM so short diffusion distance

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5
Q

How does respiratory gases move in and out of the tracheal system in insects along a diffusion gradient?

A

During respiration, o2 in cells is used so concertation at end of tracheoles falls
Creates a diffusion gradient which causes o2 to diffuse from atmosphere to the trachea to the tracheoles to cells
As co2 is produced during respiration, a diffusion gradient is created in the opposite direction

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6
Q

How does respiratory gases move in and out of the tracheal system in insects by mass transport?

A

Muscles contract and these can squeeze the trachea enabling mass movements of air in and out . Speeds up the exchange of respiratory gases.

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7
Q

How do respiratory gases move in and out of the tracheal system in insects by the tracheoles in water?

A

During exercise, muscles carry out anaerobic respiration
This produces lactate which is soluble so the water potential of muscle cells decreases
Water moves from tracheoles by osmosis into the muscle cells
Water volume at tracheole ends decrease so air is drawn into the meaning diffusion is in gaseous state.

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8
Q

3 ways movement of gases occurs in insects

A

mass transport
diffusion gradient
tracheoles + water

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9
Q

describe the mechanism of translocation

A

In the source, sucrose is AT into phloem BY THE COMPANION CELLS
This lowers w.p of sieve cell and water moves in sieve from xylem by osmosis
Increase in pressure causes mass movements of sucrose to the sink
Sugars used in respiration

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10
Q

Describe process of inspiration (breathing in)?

A

Internal intercoastal muscles relax, external intercoastal muscles contract
Diaphragm CONTRACTS and FLATTENS
INCREASED VOLUME of the thorax and DECREASES PRESSURE
Pressure outside/ in atmosphere is greater than inside, air forced into lungs DOWN PRESSURE GRADIENT

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11
Q

How does CO2 diffuses into mesophyll cells?

A

CO2 diffuses in through stomata
Stomata is opened using guard cells
CO2 diffuses across air spaces
Down a conc gradient

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12
Q

Describe ‘positive cooperativity’

A

At first, it is difficult for first O2 to bind
As first molecule binds, 4’ structure changes and it becomes less difficult for O2 to bind
As more O2 binds there are less available binding sites

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13
Q

Purpose of pulmonary arteries

A

Carries deoxygenated blood to the lungs

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14
Q

purpose of pulmonary veins

A

carries oxygenated blood back to the heart

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15
Q

purpose of aorta

A

carries oxygenated blood to the body

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16
Q

purpose of vena cava

A

carries deoxygenated blood back to heart from the body

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17
Q

description of circulatory system

A

closed- blood is confined to blood vessels

double- blood goes to back to heart after going to lungs to boost its pressure for faster circulation

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18
Q

Describe process of carbohydrate digestion

A

Starch is broken down by salivary amylase to maltose
Food passes to stomach and stomach acid denatures salivary amylase
Food passes to s. intestine and pancreas releases pancreatic juices and contains amylase which further digest the starch
Membrane bound disaccharide maltase breaks down maltose to maltase

19
Q

How does amylase work

A

hydrolyses alternate glyosidic bonds

20
Q

Describe process of lipid digestion

A

Lipids associate with bile salts to form micelles
Micelles move towards cells and are hydrolysed to monoglycerides and fatty acids
As they are lipid soluble, these cross the phospholipid bilayer

21
Q

Describe process of lipid absorption

A

Monoglycerides and fatty acids in the cells go to endoplasmic reticulum and become triglycerides
Triglycerides go to Golgi apparatus and associate w/ cholesterol and lipoproteins to form chylomicrons
Chylomicrons leave the cell by exocytosis and pass through lacteals into the bloodstream

22
Q

What do exopeptidases do?

A

hydrolyse terminal amino acids of peptide molecules made by endopeptidases

23
Q

what do endopeptidases do?

A

hydrolyses peptide bonds in central region of peptide molecules

24
Q

what do dipeptidases do?

A

hydrolyses peptide bonds between dipeptidases

25
Q

Features of epithelial cells which cause greater absorption

A

Microvilli- provides large surface area
Thin- short diffusion distance
Steep concertation gradient- caused by blood capillaries taking blood with molecules away

26
Q

describe the process of the cardiac cycle

A

Cardiac cycle is myogenic
SAN sends wave of electrical activity causing atrial contraction
Non conducting tissue prevents immediate contraction of ventricles
AVN delays impulses allowing atrial to fully empty before ventricles contract
AVN sends impulses to Bundle of His
Causes ventricles to contract from apex upwards

27
Q

what is ventilation?

A

brings air with high o2 concertation

removes air with low o2 concentration

28
Q

why does the pressure inside the capillary decrease from arteriole end to veniole end?

A

Due to loss of fluid

Also narrow lumen results in friction of blood cells against capillary wall

29
Q

pulmonary ventilation equation:

A

Tidal vol (dm-3) x ventilation rate (min-1)

30
Q

Reasons why gas exchange is rapid across aveoli (4)

A

RBC are flattened against capillary, slows diffusion and shorter diffusion distance
Both alveoli and capillary have large surface area
Walls of alveoli and capillaries are very thin- short diffusion distance
Breathing movements ventilate the lungs

31
Q

Structure of bronchioles

A

Subdivisions of bronchi

Surrounded by muscle and lined with epithelial cells

32
Q

Why do bronchioles have muscles

A

To control air flow in and out of the alveoli

33
Q

Structure of alveoli

A

Small air sacs with collagen and elastic fibres- stretch when alveoli is full with air

34
Q

Structure of the lungs

A

Lobed structures made of bronchioles

35
Q

Structure of bronchi

A

Subdivisions of the trachea

Produce mucus to trap dirt and bring it back to the throat

36
Q

Structure of the trachea

A

Walls are made of muscle which is lined with ciliated epithelial and goblet cells
Supported by cartilage to prevent trachea collapsing with pressure changes

37
Q

purpose of elastic fibres in blood vessels

A

stretches when blood pressure is high and recoil when pressure decreases and this helps to maintain pressure

38
Q

features of epithelial cells

A

Microvilli: large surface
LOTS of mitochondria: to produce ATP for active transport
Carrier proteins: for active transport
Channel and carrier proteins: for facilitated diffusion
Membrane-bound enzymes: digest disaccharides / produce glucose

39
Q

Ways fish are adapted to have a fast rate of diffusion?

A

Countercurrent flow- maintains a diffusion gradient
Thin epithelium- short diffusion distances
Gill lamellae is perpendicular to gill filaments- large surface area

40
Q

purpose of coronary arteries

A

supply oxygen to the heart muscle/tissues

41
Q

what damage could be done to the lungs that prevents breathing in or out

A

damages the elastic tissue of the lungs
creates scar tissue
the elastic tissue cannot recoil as much

42
Q

Role of heart in formation of tissue fluid

A

Ventricular contraction causes a high hydrostatic pressure in the capillary
Fluid diffuses down a pressure gradient out of the capillary

43
Q

How is chromosome number halved during meiosis?

A

Independent segregation of homologous chromosomes produces two daughter cells

44
Q

Describe crossing over

A

Homologous chromosomes associate
Chaismata forms
Alleles are exchanged producing new combination of alleles

AS Biology (5 decks)

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