Biology EMPA

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  • Created by: Rebecca
  • Created on: 26-03-13 10:35
Define diffusion
Diffusion is the passage of molecules from an area of high concentration to an area of low concentraion
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Is the process of diffusion active or passive?
Passive- requires no energy
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How do you calculate the rate of diffusion?
Amount diffused across a surface/ time taken to diffuse
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4 factors that affect the rate of diffusion
Temperature, SA, concentration gradient and thin exchange surface
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Hicks Law
Diffusion= SA*concentration gradient/length of the diffusion pathway
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What do organisms exchange by gas exchange?
respiratory gases, excretory gases, nutrients an heat
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Surface area: Volume ratio
The larger an organism the smaller the SA:V ratio
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Features of gas exchange
large SA:V ratio, thin diffusion pathway, partially permeable, maintain a diffusion gradient
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what is the aim of a leaf?
To carry out photosynthesis
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Why do leaves have a spongy mesophyll
to increase Surface Area
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Define xerophyte
Plants that are specially adapted to live in dry conditions
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Give 2 examples of xerophytes
Cacti and Marram Grass
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Thick Cuticle
to reduce water loss
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Small or needle shaped leaves
stop water being lost through evaporation
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Few stomata
to stop evaporation
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Stomata sunk into epidermis
increase boundary layer to reduce concentration gradient also reduce wind movement
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Hairs around stomata
trap heat to reduce wind movement and boundary layer
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What special feature did Marram grass have?
Leaves can roll up to reduce wind vapour being blown away
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Features of gas exchange in lungs
large SA:V ratio, very thin, partially permeable, movement of blood
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Emphysema
Disease that develops over 20 years impossible to diagnose until lungs are irreversibly damaged
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What do normal lungs do?
Contain protein called elastin which makes up large quantities of elastic tissue. tissue stretches and recoils
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What do lungs with emphysema do?
Tissues are permanently stretched and not able to force air out per breath
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What happens to alveoli?
damages this reduces surface area and some burst
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Symptoms of emphysema?
Shallow difficulty breathing, chronic cough, bluish skin coloration
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Explain shallow difficult breathing
difficulty exhaling due to loss of elasticity, lungs cannot be emptied so fresh air cannot be drawn in
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Explain chronic cough
effort to remove damaged tissue and mucus that cannot as cilia has been destroyed
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Explain bluish skin coloration
due to low levels of oxygen in blood as poor gas exchange
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Risk factors for lung disease
smoking, occupations, air pollution, genetic make-up or infection
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Explain tidal volume
amount of breath breathed in and out
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Explain breathing rate
how many breaths per minute
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Explain vital capacity
total amount breathed in and out per breath
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Cigarette smoking and conorary heart disease
carbon monoxide, nicotine, red blood cells sticky and reduction of oxygen carrying capacity
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explain carbon monoxide
combines with haemoglobin to form carboxyhaemoglobin to reduce oxygen carrying capacity of the blood, making it work harder and raises blood pressure, risk of stroke
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explain nicotine
produces adrenaline, raises HR and blood pressure and risk of stroke
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explain red blood cells sticky
increases risk of thrombosis and hence myocardial infraction or stoke
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explain reduced oxygen carrying capacity
means insufficient for exercise so if exercise increased risk of myocardial infraction as heart cannot get oxygen
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Other cards in this set

Card 2

Front

Passive- requires no energy

Back

Is the process of diffusion active or passive?

Card 3

Front

Amount diffused across a surface/ time taken to diffuse

Back

Preview of the back of card 3

Card 4

Front

Temperature, SA, concentration gradient and thin exchange surface

Back

Preview of the back of card 4

Card 5

Front

Diffusion= SA*concentration gradient/length of the diffusion pathway

Back

Preview of the back of card 5
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Comments

Neelima

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hi  have you done the empa? are these things you need to know?

katie

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what was the title of your empa?

Petra

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are these the actual qs? 

Hajra

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Ficks*

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